NORTH AMERICAN TUNNELING 2004

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Author: Levent. Ozdemir

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PROCEEDINGS OF THE NORTH AMERICAN TUNNELING CONFERENCE 2004, 17–22 APRIL 2004, ATLANTA, GEORGIA, USA

North American Tunneling 2004 Edited by

Levent Ozdemir Colorado School of Mines, Golden, Colorado, USA

A.A. BALKEMA PUBLISHERS LEIDEN / LONDON / NEW YORK / PHILADELPHIA / SINGAPORE

Copyright © 2004 Taylor & Francis Group plc, London, UK

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Copyright © 2004 Taylor & Francis Group plc, London, UK All rights reserved. No part of this publication or the information contained herein may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, by photocopying, recording or otherwise, without written prior permission from the publisher. Although all care is taken to ensure the integrity and quality of this publication and the information herein, no responsibility is assumed by the publishers nor the author for any damage to property or persons as a result of operation or use of this publication and/or the information contained herein. Published by: A.A. Balkema Publishers, a member of Taylor & Francis Group plc www.balkema.nl and www.tandf.co.uk For the complete set (book CD ROM), ISBN 90 5809 669 6 CD ROM: ISBN 90 5809 670 X Printed in The Netherlands


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North American Tunneling 2004, Ozdemir (ed) © 2004 Taylor & Francis Group, London, ISBN 90 5809 669 6

Table of Contents

Foreword Levent Ozdemir

XI

Organization

XIII

Session 1 – Differing site conditions as applied to design/build contracts Track 1 – Project management Design review boards – current state of practice A. Elioff & W.W. Edgerton

5

Drawing from past experience to improve the management of future underground projects C. Laughton

15

The ECIS story J.W. Critchfield & B. Miya

21

Track 2 – Security of critical infrastructure and key national assets: use of underground space Internal blasting and impacts to tunnels Wern-ping (Nick) Chen

29

Track 3 – Mechanized tunneling Improvements of the capabilities of cutting tools and cutting systems R. Bauer

37

MTBM and small TBM experience with boulders S.W. Hunt & F.M. Mazhar

47

Joint orientations for TBM performance analysis using borehole geophysics to orient rock cores T. Tharpe, B. Crenshaw & J. Raymer

65

Slurry type shielded TBM for the alluvial strata excavation in downtown area W.R. Jee

73

Estimating ground loss from EPB tunneling in alluvial soils for ECIS project, Los Angeles T.R. Seeley

79

Some aspects of grouting technology for Manhattan tunnels M. Ryzhevskiy & P. Barraclough

87

Track 4 – Specialized urban construction Design and construction of an LRT tunnel in San Jose, CA P.J. Doig

V Copyright © 2004 Taylor & Francis Group plc, London, UK

95

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Underpinning design and construction – Atlantic Avenue Station complex rehabilitation, New York, USA A. Grigoryan & L.G. Silano

101

Slurry walls accelerate shaft construction in rock in Los Angeles M.P. McKenna, K.K. So, M.A. Krulc & E. Itzig-Heine

109

Performance of Russia Wharf Buildings during tunneling H.S. Lacy, M.D. Boscardin & L.A. Becker

121

Blasting adjacent to high voltage duct banks K.R. Ott, D.A. Anderson & S.E. Haq

129

Subway rehabilitation – secant wall cofferdams and penetration of tunnel liner V. Tirolo & N. Hirsch

135

Overcoming the complex geotechnical challenges of urban construction T.J. Tuozzolo

143

Session 2 – Subsurface investigations and geotechnical report preparation for design/build projects Track 1 – Risk allocation Risk management in tunneling – occupational safety health plans for drill and blast and tunnel boring machines A. Moergeli

153

Managing underground construction risks in New York N. Munfah, S. Zlatanic & P. Baraclough

163

Risk allocation in tunnel construction contracts W.R. Wildman

171

Getting back on-track: Exchange Place Station Improvements M.F. McNeilly, S.A. Leifer & G.F. Slattery

177

Influence of geologic conditions on excavation methodology E.C. Wang, L.M. Hsia, C.C. Chang & A.N. Shah

185

Track 2 – Owners opinion forum Discussion and panel talk sessions – no written papers

Track 3 – Non-mechanized construction Santiago’s Metro expands C.H. Mercado, G.S. Chamorro & K. Egger

195

Benchmark for the future: the largest SEM soft ground tunnels in the United States for the Beacon Hill Station in Seattle J. Laubbichler, T. Schwind & G. Urschitz

201

Application of the Press-In Method in East Side Access tunnel project J. Liu & V. Nasri

209

Shotcrete for tunnel final linings – design and construction considerations V. Gall, K. Zeidler, N. Munfah & D. Cerulli

215

Robotic shotcrete applications for mining and tunneling M. Rispin, C. Gause & T. Kurth

223

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Development of the LaserShell method of tunneling C.M. Eddie & C. Neumann

231

Ground support design and analysis: Exchange Place Station Improvements M.R. Funkhouser & M.F. McNeilly

241

Track 4 – Ground modification for underground construction Cantilever frozen ground structure to support 18 m deep excavation D.K. Chang, P.W. Deming, H.S. Lacy & P.A. van Dijk

251

New chemical grouting materials and delivery equipment technologies G.N. Greenfield & A.C. Plaisted

259

Jet grout bottom seal for cut and cover tunnel T.M. Hurley

265

North airfield drainage improvement at Chicago O’Hare International Airport: soil stabilization using jet grouting D.A. Lewis & M.G. Taube

271

Ground freezing and spray concrete lining in the reconstruction of a collapsed tunnel S.J. Munks, P. Chamley & C. Eddie

277

Ground freezing for urban applications P.C. Schmall, D. Maishman, J.M. McCann & D.K. Mueller

285

Session 3 – Design/build contracting practices Track 1 – Predicting and controlling cost and schedule An economic approach to risk management for tunnels B. Altabba, H. Einstein & H. Caspe Top down construction of Ramp L, Value-Engineering Change Proposal for the Massachusetts Turnpike Authority, Contract CO9A4 W.D. Driscoll & G.A. Almeraris Contemporary methods of budget preparation B. Martin & S. Sadek

295

303 313

Geotechnical mapping methods utilized in the Chattahoochee Tunnel Project, Cobb County, Georgia, USA J. Reineke, J. Raymer, M. Feeney & K. Kilby

319

Value engineered design facilitates Grand and Bates Relief Sewer Tunnel Construction, St. Louis, MO J.R. Wheeler & N.E. Thomson

327

Track 2 – Show me the money Discussion and panel talk sessions – no written papers

Track 3 – Investigation, inspection and rehabilitation Monitoring excavations using 3D Laser Scanning and Digital Close-Range Photogrammetry T. Trupp, L. Liu & Y. Hashash

VII Copyright © 2004 Taylor & Francis Group plc, London, UK

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Durability and corrosion protection of support systems in soil and rock tunnels M.R. Jafari, V. Nasri & M. Wone Investigation of complex geologic conditions for the Second Avenue Subway tunnel alignment in New York City, New York C.P. Snee, M.A. Ponti & A.N. Shah

345

357

An automated structural monitoring system for the Federal Reserve Bank of Boston T.L. Weinmann & L. Edgers

363

A deep horizontal boring – technical and contractual issues J. Glastonbury, K. Ott, J. Freitas, B. Russell, M. Wooden, W. Meakin & J. Canale

373

Rehabilitation of the Big Walker Mountain Tunnel in Bristol, Virginia D. Kukreja & P. Moran

381

Corrosion evaluation of the Manhattan rocks and corrosion protection of the rock reinforcement system for subway tunnels M. Ryzhevskiy & M. Berman

389

Rehabilitation of the Amtrak Long Island City ventilation structures S.G. Price

395

Using seismic tomography and holography ground imaging to improve site investigations E.J. Kase & T.A. Ross

401

Track 4 – Machine mining – soft ground to hard rock to everything in between Conditions encountered in the construction of the Braintree-Weymouth Tunnel Project, Boston, Massachusetts D.W. Deere, J. Kantola & T. Davidson

411

The Manapouri Tailrace Tunnel No. 2 construction – a very large TBM tunnel in very strong rock D.W. Deere, S. Keis & C. Watts

421

South Austin Regional Waste Water Treatment Plant Interconnect Tunnel Project S. Cheema, K. Koeller, R. Pohren, G. Sherry & R. Webb

433

Tunneling through an operational oilfield and active faults on the ECIS Project, Los Angeles, CA, USA E. Keller & M. Crow

441

Rock tunneling at the Mill Creek project M. Schafer, B. Lukajic, R. Pintabona, M. Kritzer, T. Shively & R. Switalski

449

Construction of the Dougherty Valley Tunnel, San Ramon, California, USA G.S. Nagle & H. Thom

453

City of Los Angeles Northeast Interceptor Sewer Tunnel Z. Varley, R. Patel & J. McDonald

461

Session 4 – Design/build risk Track 1 – SEM/NATM practices/prescriptive specifications NATM and its practice in the US Wern-ping (Nick) Chen & H. Caspe

473

SEM/NATM design and contracting strategies J. Gildner & G.J. Urschitz

477

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Engineers, contractors, and soft-ground tunneling equipment W.H. Hansmire & J.E. Monsees

485

Track 2 – Transit oriented development – making the case for going underground Atlanta West Area Combined Sewer Overflow Storage Tunnel and Pumping Station R.C. Divito, W. Klecan & G.D. Barnes

497

Track 3 – Analysis and design Consideration on machine data and load in TBM excavation for tunnel support selection N. Isago, H. Mashimo, W. Akagi & H. Shiroma

507

A durability design for precast concrete segments for tunnel linings G. Bracher & D. Wrixon

515

Design and construction of the Lindbergh Terminal Station, Twin Cities, Minnesota E.E. Leagjeld, B.K. Nelson, C.R. Nelson, D.L. Petersen, R.L. Peterson & B.D. Wagener

521

Design and impact of the Beacon Hill Station exploratory shaft program C. Tattersall, T. Gregor & M.J. Lehnen

529

Comparison of the predicted behavior of the Manhattan TBM launch shaft with the observed data, East Side Access Project, New York V. Nasri, W.S. Lee & J. Rice

537

Drop shafts – selection principals J.F. Zurawski & E. Petrossian

545

Stability evaluation and numerical modeling Exchange Place Station Improvements J.F. Lupo & M.F. McNeilly

553

Track 4 – Conventional underground construction Tunnel and shaft construction for the Pingston Hydro Project B. Downing, Z. Vorvis, G. Rawlings & P. Kemp

561

Shoal creek raw water intake and pump station construction on Lake Lanier D. Ackerman, R. Wiek & R. Gutridge

571

Design and construction of shafts at the San Roque Project M. Funkhouser, R. Humphries, W. Warburton, J. Daly & E. O’Connor

575

Ten years’ experience using roadheaders to bore tunnels for the Bilbao Metro J. Madinaveitia

581

Rio Piedras Project, San Juan, Puerto Rico B. Fulcher, N. Kofoed, P. Madsen & M. Bartlett

589

Devil’s Slide Tunnels Y. Nien Wang, B. Hughes, H. Caspe & M. Amini

605

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Foreword

The theme of this North American Tunneling Conference (NAT 2004) is “Underground Construction – The Sensible Solution to Urban Problems”. This title reflects the increasing importance of locating facilities underground for enhanced security and function of urban areas and to build critical infrastructure for sustainable development. This conference includes papers covering a wide range of subjects dealing with nearly all aspects of underground construction, tunneling and effective utilization of underground space. The papers are grouped under four major tracks. Track 1 addresses the management of underground projects and includes presentations on project management, risk allocation and predicting and controlling cost and schedule. Track 2 includes presentations and panel discussions on issues related to security of critical infrastructure and key national assets, owner’s opinion forum, financing of underground projects and transit oriented development making the case for going underground. Track 3 addresses new advances in technology, including sessions on mechanical tunneling, non-mechanized construction, investigation, inspection and rehabilitation and analysis and design of underground structures. Track 4 covers trials, tribulations and triumphs in tunneling industry by presenting significant case histories. The sessions address specialized urban construction, conventional underground construction and machine mining in soft ground, hard rock and mixed-face conditions. I would like to express my appreciation to NAT 2004 organizing committee, track and technical program chairs, panel members and the authors for their contribution to the success of the conference. The continuing support of cooperating organizations, AMITOS, TAC, NUCA, NASTT and UTRC is also acknowledged. Levent Ozdemir Proceedings Editor

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Organization

NAT 2004 EXECUTIVE COMMITTEE Raymond W. Henn, Conference Chair Lyman Henn, Inc., Denver, CO Refik Elibay, Vice Chair Jordan Jones & Goulding, Atlanta, GA Susan Nelson, Executive Director AUA, Minneapolis, MN William W. Edgerton, Chair, Track I Managing Underground Projects Jacobs Associates, San Francisco, CA Brenda M. Bohlke, Chair, Track II Public Policy and Underground Projects PB Consult, Herndon, VA Robert J.F. Goodfellow, Chair, Track III Advances in Technology URS Corp, Gaithersburg, MD Gary Almeraris, Chair, Track IV Case Studies: Trials, Tribulations and Triumphs of Tunneling Slattery/Skanska, Whitestone, NY George Yoggy, Exhibition Chair GCS LLC, Allentown, PA Thomas Clemens, Technical Tour Chair American Commercial, Louisville, KY Carin Mindel, Exhibition Manager AUA, Minneapolis, MN

SESSION CHAIRS Dan Dobbels, Haley & Aldrich Brian Fulcher, Kiewit Construction Company Michael Goode, Telford Consulting Michael Greenberg, NYC Department of Environmental Protection John Kaplin, Gilbane Building Company Gary Irwin, City of Portland Bureau of Engineering Laurene Mahan, PBConsult, Inc. Bill Mariucci, Kiewit Construction Joseph M. McCann, Freeze Wall Chris Mueller, URS Corporation Galen Nagle, URS Corp.

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Levent Ozdemir, Colorado School of Mines Stephen C. Redmond, Frontier Kemper Constructors Tibor Rozgani, Colorado School of Mines Heiner Sander, ILF Vince Tirolo, Slattery/Skanska

AUA BOARD OF DIRECTORS Officers Raymond W. Henn, President Thomas F. Peyton, President-Elect George D. Yoggy, Past President Hugh S. Caspe, Treasurer Susan R. Nelson, Executive Director Directors Gary Almeraris Charles H. Atherton Brenda M. Bohlke Jack Brockway Thomas Clemens Joseph P. Gildner Michael Greenberg Hugh Lacy Robert A. Pond Gregory L. Raines Kirk Samuelson Don Zeni Designated Representatives Charles W. Daugherty Randall J. Essex D. Tom Iseley Levent Ozdemir

XIV Copyright © 2004 Taylor & Francis Group plc, London, UK

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Session 1 Differing site conditions as applied to design/build contracts


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Session 1, Track 1 Project management


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Design review boards – current state of practice Amanda Elioff Parsons Brinckerhoff, Los Angeles, California, USA

William W. Edgerton Jacobs Associates, San Francisco, California, USA

ABSTRACT: This paper summarizes the current state of practice on the use of design review boards, or consulting boards, as used primarily used during design of underground construction projects. It discusses the various types of boards in use and reviews the history, and then, using the results of an industry survey of both owners and consultants, it discusses the purpose and typical uses, provides examples of specific outcomes, and reviews the methods of selection and modes of operation. It summarizes the advantages and disadvantages, evaluates the use of the construction manager to provide design review, and provides recommendations for future users based upon the lessons learned to date.

1 INTRODUCTION

•

Owner agencies have used a number of different methods for evaluating or “verifying” the design of underground facilities before advertising for bids. These methods include: Independent Peer Review, Value Engineering, Boards of Consultants, and Technical Review Committees. For the purposes of this paper, we have developed the following definitions:

•

•

•

This paper focuses on the current state of practice of Boards of Consultants, and Technical Review Committees, and is not intended to evaluate the use of either IPPR or VE panels.

Independent Project Peer Review: An independent panel tasked with design review for some outside party such as financing agency, congressional committee, etc. This process typically includes an in-depth review of criteria, analysis, and calculations. Value Engineering: Formal evaluation of design documents that evaluates design and to some extent anticipated construction methods and is focused primarily on cost objectives. This process typically consists of a one-week workshop with participants specially-trained in value-engineering skills, and results in recommendations for design changes to reduce cost while maintaining objectives. Board of Consultants: A separate board or panel under contract to the owner agency to evaluate the design prepared by the design consultant. This review can be done at specific time periods as the design proceeds, and is intended to determine bigpicture design issues and does not typically review detailed analysis or calculations. Can also be referred to as a Technical Advisory Panel (TAP).

2 HISTORY OF DESIGN CONSULTING BOARDS Owners have relied upon individual consultants to supplement the prime designer for some time. (See Terzaghi (1958) which contains an excellent review of his personal experience serving as an individual consultant on design and construction projects.) Review boards have been employed on major complex public works projects dating at least to the early 19th century during the bridge building era. (Petroski, 1996). Similarly, boards have been assembled for large dam projects under construction by public agencies such as the Tennessee Valley Authority, the US Army Corps of Engineers (COE) and the Bureau of Reclamation. In recent years, major large subway projects, for example the Bay Area Rapid Transit (BART)

5 Copyright © 2004 Taylor & Francis Group plc, London, UK

Technical Review Committee: A Board that is formed as a part of the design team, to evaluate the design progress and solutions on a periodic basis. The type of review and evaluation is similar to that performed by a Board of Consultants, with the primary difference being that the Board’s client is the design firm, rather than the owner agency.

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have stated that “The purpose of the Board should be to provide an objective, balanced and impartial view of the overall design and construction progress on a project. The Board should not be used as a substitute for normal consulting services …” Hoek & Imrie (1995). This usually requires an “independent” board that reviews the work of others (e.g., designers) at pre-determined intervals. To achieve this purpose, the owner must keep the review as a separate function and not let the consulting board become a part of the design team, thus insuring its “independence” and the ability for the board to testify (if necessary) as to the design adequacy. (2) More recently, boards have been used to improve both the efficiency and accuracy of the work product, acting as a part of the design team. The work product is typically plans, specifications, other contract documents, and (sometimes) cost estimates. To fulfill this purpose the consulting board (or technical review committee) need not be “independent” but can contribute to the design process at any time, even continuously at certain key period. Since the board or panel is an integral member of the team, the members cannot be presumed to provide an “independent” review of the work products.

System, designed in the 1960s, WMATA (1970s) and Los Angeles Metro (1980s-present) have maintained boards in some form to advise on project design. Within the past 30 years there has been an increase in the use of consulting boards. This may be in part due to the increasing complexity and multi-disciplinary nature of large projects. It may also be due to increasing oversight of the use of public funds and the arguably increased level of litigation resulting from the construction of such large projects. To the extent that this litigation is founded upon the theory of inadequate or defective design documents, both owners and designers are motivated to minimize these problems. 3 SURVEY From April to October 2003, an industry survey was conducted which asked questions concerning (1) the history of the use of such boards, primarily in the underground industry, (2) the purpose and typical uses of these boards as they are currently constituted, (3) typical criteria for selection of board members, (4) various modes of operation, and (5) approximate cost. The survey also solicited feedback from the respondents as to the use of the construction manager providing such design review, the perceived advantages and disadvantages of boards, and recommendations for improvement in the future. The results of this survey are incorporated into this paper. The survey instrument itself is available from the authors upon request. Although respondents were promised confidentiality, the raw data itself, absent attribution, is also available for subsequent researchers upon request. The survey was sent to 95 people identified by the authors as either consultants or owners who have experience either employing or participating on boards. We received 48 replies, a 51 percent response rate. The respondents’ experience represents over 500 boards as users of the process (i.e., receiving advice, either as an owner, designer, or construction manager), and over 300 boards as board members (i.e., providing advice). A list of the projects from upon which the respondents have based many of their comments is included as an Appendix. Projects represented by the experience of the survey respondents include tunnels both in soft ground and rock, transit stations, underground powerhouses, wastewater treatment plants, large dams, highway projects, pipelines, microtunnels, and large diameter shafts.

Occasionally a funding agency will require a design review board, and when that is the case, the owner’s purpose is to fulfill the specific agency requirements. Examples of such agencies are the Federal Energy Regulatory Commission (FERC), and the Federal Highway Administration (FHWA). Other agencies provide internal review teams when there are significant specialty design issues or high-risk elements. In the case of the Federal Transit Administration (FTA), project management oversight consultants (PMOC’s or PMO’s) are be established to “help ensure that grantees [of federal funds] constructing major transit projects have the technical capability to carry out the projects’ design and construction according to accepted engineering principles,” GAO (2000). The PMO function was incorporated into FTA “new starts” projects after some quality, cost and construction management issues occurred in the 1970s and early 80s. The oversight function includes review and evaluation of various project processes to ensure: compliance with statutory, administrative, and regulatory requirements. The PMOC and the other members of the design team typically work together in the design phase, but although the typical operation of PMOC is similar to that of consulting boards, because the purpose is to assure compliance with specific funding agency requirements, it does not serve the same function as a design review board, and the owner may not rely upon it to fulfill the same purpose

4 PURPOSE AND TYPICAL USES Two primary reasons are given for creating a design review board: (1) To reassure upper level decision makers that the design solution is adequate. Previous commentators


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Changes in concept: Examples included changes from an exploratory shaft to an exploratory tunnel, and changes in tunnel ventilation systems to implement European design methods in the United States. More effective methods: In one example, use of explosives was deemed too dangerous by the design team and owner, as neither believed it would be safe or would be acceptable to the public. The consulting board was able to convince the design team that blasting could be done safely, if designed and implemented properly, and this resulted in savings of significant time and money. Contract packaging/Contracting methods: Examples cited were recommendations for pre-qualification of bidders, changes in contract pricing methods (e.g., plugged prices), and owner purchased TBM’s to save schedule. In addition to these examples of specific outcomes, consulting boards have been instrumental in the development of and/or “blessing” the use of new or “never been done before” design and contracting approaches: Acceptance of unique or first time designs can be difficult for some owners, and conservative designers to accept. The boards’ recommendations for additional testing to verify design assumptions was cited in a few cases, such as for special seismic designs, high loading assumptions, and gas barriers.

Table 1. Technical issues addressed by board. Technical issue

Percent of respondents

Geotechnical Engineering Design Methods Estimating/Scheduling Constructability Contracting Methods Equipment Selection/Approval Risk Evaluation/Assessment Special Construction Techniques

93 67 54 89 48 39 67 65

for which a design review board is established. In addition, the selection of PMOC consultants is usually much different, and the criteria and skill of the participants varies significantly from that used on consulting boards. Consulting boards and panels are usually formed to provide advice and make recommendations on certain technical issues. The industry survey indicated the percentage of respondents who have used such boards for these technical issues as given in Table 1. In some cases design consulting boards continue to provide consultation during construction, and in such cases they evaluate construction issues such as verification of design intent, basis of design, and contractor performance. There is little evidence that such design boards are used to resolve disputes between the contracting parties, although in some cases they have advised the owner on pre-dispute technical issues. Consulting boards discussed in this paper are not Dispute Resolution Boards. (For further information on DRB’s, see Matyas et al. (1996)).

6 SELECTION OF BOARD MEMBERS Members are selected for most consulting and/or review boards on the basis of recommendations by the design team or others. In fact, 95% of the survey respondents indicated that this is the most common method. In some cases an RFP or letter of interest is sent to the industry, and the board members selected using this method. 20% of the respondents had used this method, but only 5% used this method exclusively; i.e., did not rely upon recommendations of the design team. The background of board members appears to be quite varied. Members of academia (university professors) are used frequently, as are contractors, construction managers, and other designers. The industry survey indicated the percentage of respondents who have selected members with the backgrounds as given in Table 2. The use of individual consultants with one specific technical specialty is the most popular; and the technical specialties are determined based upon the key issues on the individual project. For most underground projects, board member backgrounds include geology, geotechnical engineering, tunnel boring machine (TBM) design, ground support design, and other specialties as required. Also noted was the use of operations and maintenance staff, the program manager,

5 SPECIFIC OUTCOMES Survey respondents gave numerous examples of outcomes resulting from consulting board meetings. These can be categorized as changes in design approach, construction methods, concepts, and contracting packaging and/or methods: Changes in design approach: Numerous respondents reported alignment changes (higher or lower tunnel profile) to improve excavation conditions, reduce settlement, avoid hazardous material, and subsequently save cost. Other recommendations were additional explorations, to collect more geologic or groundwater data. Changes in excavation method: These included changes from excavation by Tunnel Boring Machine (TBM) to use of the Sequential Excavation Method (SEM), use of closed face and/or pressurized face TBMs in lieu of open face shields to control settlement or mitigate hazardous conditions, and recommendations for changes in excavation sequence.


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Most consulting boards are asked to reduce their observations to a written report at the end of the meeting. The only exception to this policy appears to be when the owner’s primary consideration is to limit the cost of the board, and in such cases results are reported verbally to the design team. In 70% of the reported cases, both verbal and written comments are provided. Also, in addition to comments to the design team, 80% of the survey respondents indicated that the board has provided comments to owner-agency upper level staff at a meeting. This comports with one of the underlying purposes that is to provide independent review.

Table 2. Backgrounds of respondents. Background

Percent of respondents

Academia Construction Contractors Construction Managers Designers

77 64 60 81

retired government employees, and upper management representatives from other public agencies. Owners that continue board operation through construction sometimes change the makeup, deleting academia and designers, and adding ex-contractors and construction managers to better evaluate the construction issues. In at least one case, a board has had access to a separate group of specialists, “… individuals that are not involved in the design of the project but available to serve in an ad hoc capacity to the Board on an asneeded basis on specialty issues” (Shamma et al. (2003)).

8 COST Most boards are composed of senior-level people who operate on a consulting basis and are compensated by the hour. (For information concerning contract provisions for senior-level consultants, see Dunnicliff & Parker, 2002). The hourly rates are relatively high compared to those of the design team, but owners who have used consulting boards report that the limited use of the board’s time, in part because of the ability of most experienced consultants to quickly identify the root issues, results in total cost to the project that is quite low, comparatively speaking, for the value added. Reported cost ranges from 0.5% to 1.5% of the total design fee; less than 0.1% of the construction cost. The total cost of the design review board ranges from $30,000 to $300,000, although the total cost is quite variable depending upon the frequency of meetings, length of the design period, and number of project contracts.

7 MODES OF OPERATION Virtually all of the survey respondents have used consulting boards during the planning and design phases of the project. A surprising 70% have continued the use of these boards into the construction phase, although only 15% have used them in the post-construction phase, presumably to defend contract disputes with the contractors. During the planning phase, most consulting boards meet only one or two times, although some respondents indicated 10 to 12 meetings, and some have experienced quarterly meetings. (These responses were received from individuals who were part of large construction programs that included more than one construction contract.) During design, some boards meet once, and some up to 6–8 times; although most respondents indicated from 2–3 meetings. These meetings are typically held at pre-determined milestone times, such as 30%, 60% and 90% design completion. The type of work reviewed at early periods is typically quite different from that reviewed at later stages of completion. More importantly, the ability and willingness of the design team to accept recommendations at the later stages of design is limited. Typical meetings are from one to five days in length. Summary or relevant documents are usually provided to the board for review in advance, and at the beginning of the meeting the designer makes a short presentation setting forth the key issues and the status of work currently under development. In some cases a tour of the work site is provided, especially if local conditions are critical to the design solution.

9 ADVANTAGES AND DISADVANTAGES 9.1


Advantages

There are advantages to using consulting boards, some of which have been previously mentioned. Advice from a senior advisory board provides an independent check on the design criteria, which is helpful because “Those involved in the design and construction of a project can often become so involved in the details of the work that they find it difficult to stand back and take an impartial view of alternate approaches” (Hoek & Imrie (1995)). This advice can also provide the owner with the support to make decisions and design changes when warranted. If completed early enough in the process, it can provide a level of credibility and a “stamp of approval” to the design solution, and also provides the owner with confidence in its designer. Survey respondents confirmed this summary and also provided a range of other advantages summarized in categories as follows:

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a format to brief the Agency directors, PMO and other invited guests to all or summary portions of the meeting. These representatives may otherwise have little direct contact with the designer for questions and answers about the design or for relating political issues to the design team. When used during construction, the board can provide the owner with “third party” advice on contract disputes or differing site conditions, which is helpful if there is disagreement between the designer and CM. Risk Management: The board’s assessment of project risk is not likely to be as “sugarcoated” or conservative as that provided by the design team, thus providing more value to the owner agency. Conversely, the board may point out over conservatism in design.

Overall review of project: Coming to the project with experienced, “fresh” sets of eyes, the board’s review and concurrence with the design approach and criteria developed bring additional confidence to owners and engineers. In the process of review, they may point out overlooked issues, and recommend new areas to look into or additional study, such as more geotechnical exploration. For programs with multiple design contracts and no program manager, the board can provide a level of consistency with the design criteria and other factors. Bring additional experience, perspective, and trust: Given the collective years of experience, and worldwide exposure, the board members are able to compare the project at hand to past experiences, i.e., lessons learned from many underground projects. These board members may have access to information about other projects well before it is published. In some cases, negative experiences are never published, thus making it difficult to apply these lessons learned to future projects without the input of people who possess the appropriate first hand knowledge and can relate it confidentially in a venue such as a consulting board meeting. The board can also provide input to specialties that are not present in the personnel on the design team. This generally results in better quality contract documents that are more consistent, constructible, and results in better bid prices. Advice from disinterested “outsiders” may be more acceptable to politicians and the public. One survey respondent attributed the following quote to Walter Douglas: “ you hire a consultant (1) because you face a difficult problem you have never faced so you hire someone who has or (2) you need an expert to say something you could say but it is more believable because of his or her reputation. Point number two is particularly applicable as politicians, agency boards of directors, and others in upper management may be more willing to accept “bad news” if the source is a group of renown experts rather than staff or the design consultant. Focus on Key issues: In the process of preparing for the board meetings, designers and owners, must assemble relevant information for preview and presentation to the board. To have an effective meeting, they must develop the key issues they would like the board to address. These periodic meetings assist the design team by providing a “time-out” from the day-to-day crash program of completing the design documents. This allows for a review of “where are we going” that is of benefit to all participants. Often, it is not until faced with an upcoming meeting that the questions/issues are well defined. Increase Communication: The format of a “roundtable” type discussion, over a day to several days promotes better interaction between the personalities involved and facilitates better understanding of all positions and issues. The board meetings also provide

9.2


Disadvantages

While disadvantages of consulting boards were cited less often, survey respondents did report several related to time and cost, disagreement between members, overreliance on board opinions, potential for late changes, and problems associated with the composition of the board: Time and Cost: Time and cost to prepare for and conduct, and present conclusions from the meeting may be as much as a week or two. Not only the board members, but also the project’s top management and designers may be tied up for days at these meetings, impacting the design schedule. The logistics of gathering all board members together can also be somewhat time consuming, since such senior people typically have full calendars. The design schedule can be impacted not only by the time for preparation and meetings, but also by the time required to review and revise the design documents should the board recommend changes. This can be a financial burden for smaller projects. Reliance on the Board: The presence of a consulting board can affect the design team’s view of responsibility for design decisions. Some designers (and owners) may be tempted to use such boards as “cover”, thus allowing them to avoid accountability for their design solution. Potential for Late Changes: The nature of the periodic review can make designers feel they must defend their design because they don’t have time to change it and still meet schedule. This works against the principle of collaboration, and can lead to the designer and/or owner disregarding the board’s advice to stay on schedule. Group Dynamics/Board Composition: Several instances were reported where board members disagreed, were uncooperative, or conversely, were too willing to compromise, resulting in “design by committee syndrome.” Boards and panels, in evaluating all of the issues, may not be able to find any middle ground. As a result, reaching consensus can be difficult,

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and such consensus is important for owners whose primary purpose is to convince upper level management that the design is adequate. On the other hand, there is also the disadvantage of “Design by Committee” which is different than “achieving consensus.” Without an effort to identify the reasons for all recommendations, when presented with a choice between alternate approaches or actions, there is a tendency to do both, thus resulting in an over-conservative design solution. Not all board members are helpful, nor do they all understand their role: Some want to be the designer, some may want to manage the entire process, some merely want to obstruct the designer’s progress for competitive reasons, and some simply are not qualified to be on the board. Opinionated panel members can also be counter-productive leading to conflict and/or delay.

•

• •

10 USE OF THE CONSTRUCTION MANAGER FOR DESIGN REVIEW There have been some suggestions that the owner could use its construction manager (CM) to perform the design review functions that are sometimes done with a consulting board or technical review board. The arguments in favor of this approach include: 10.1

• • • • •

•

Arguments in favor of using the CM

The CM’s construction experience will benefit the design solution. A document review from the point of view of a construction specialist will identify inconsistencies in the documents. Better bids will result if the contractors know that the CM has been involved at an early stage. The CM may be better equipped to consider market conditions and the advantages/disadvantages of different contract size and packaging strategies. It’s a good way to get the CM up to speed on the design intent, and have them buy into the design, thus reducing future disagreements with the designer. Review can be continuous rather than at specific times, allowing more timely and therefore less expensive design modifications than would be possible by waiting for the next scheduled consulting board meeting.

10.2

10.3

Can both be used?

Many users feel that both methods should be used, with the consulting board used early in the process, and the CM used later to provide constructability input and a consistency check of the documents prior to advertising. Many respondents said that the most important element in both methods is the use of knowledgeable personnel. 11 RECOMMENDATIONS After evaluating the comments from industry representatives, we offer the following recommendations for improving the results and the success of consulting boards. These recommendations are summarized by category: Purpose/Use, Member Selection, and Operation.

Arguments against using the CM 11.1

On the other hand, there are several disadvantages of using the CM instead of a separate design consulting board to perform these functions:

•

The future construction phase services contract may bias the CM’s recommendations to what the owner wants to hear. A separate consulting board would provide more independence from the process, i.e., the board has no self-interest in the outcome. Bringing on the CM earlier will increase the owner’s costs, and could encourage a postponement of the CM procurement, thus delaying critical input into the design. In addition, once mobilized, it is difficult to cut back CM’s costs if the project schedule slips due to public resistance or financing difficulties. Separate review boards are usually lower cost, as a result of a board’s “spot” reviews of specific issues, as opposed to the CM’s continuous review as a part of the design process. The CM may be perceived as less technically qualified (i.e., credible) on key issues. Because the design is undefined, it is difficult to identify the key issues and thus select the appropriate CM staff early enough in the design process to make beneficial use of their input. Also, procuring the CM at such an early stage may result in reliance upon staff that is subsequently unavailable when the construction starts. Using the construction manager adds an extra layer of review that cause delay and confusion of responsibility, especially if the CM firm is also a designer.

•

The CM staff tends to be generalist in nature, and the industry expert who can provide the technical expertise to the specific design problem is typically an individual consultant, not part of a CM firm.


Purpose/Use

Review panels are most effective when retained and used aggressively during the concept design phase. It is more difficult to change direction when panels are convened after the project design is well advanced. Consider having a two part process, consisting of an early board to address the overall

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approach, and a subsequent technical board with some construction experience to address technical and constructability issues. Define the purpose and scope of the board for each specific project. Decide whether it is to be “independent” or an “integral part” of the design team. Confirm the meeting frequency and use these meetings as milestones in the design schedule. Determine what output is required, and write the scope of work for the board to define all of the above. Make the individual consulting contracts compatible with the purpose. For “independent” boards, ensure that the board members have a separate contract with the owner agency, not through the design engineer. For boards that are expected to function as an “integral part” of the design team, contracting through the designer is acceptable and perhaps preferable from a risk and liability perspective. On major projects, use a standing Board of Consultants to achieve consistency across separate projects that are all part of a large program.

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Member selection

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Select consultants whose technical expertise match the specifics of the project. In order to achieve a balance of expertise, select members with a diversity of experience (i.e., contractors, other owner reps, peers, and academic folks). Include representatives from the end-user; e.g., maintenance and operations personnel. Include experienced constructability experts. Recently retired construction executives can be effective panel members. Formally interview prospective board members before appointment in order to determine availability, understanding of public projects, predetermined positions and whether the board would have an “open” mind to innovations. Identify potential conflicts of interest, which could include competing design firms, a prospective member with contractor clients who may be potential bidders, or previous representation of third parties who may be opposed to the project. The board should have no stake in the outcome of the project. If so it can lead to some questionable “advice” and conclusions. Appoint consultants who are supportive of each other, and in particular, ask “... if they are willing to work with specific other potential members” (Hoek & Imrie (1995)). If the designer is solely responsible for selection of the board members, there is anecdotal evidence that the same members appear repetitively on many different boards. Whether this practice is beneficial is subject to debate, however given an ongoing consultant-designer relationship, the owners’ interests may not be considered using this approach.

• • • • •

Operation

Plan for meetings sufficiently in advance so that they are well organized and to ensure that the board members have a good understanding of the project. If information is limited, the board may not be able to raise critical issues, and its effectiveness will be limited. “Failing to keep the Board advised of critical decisions or events” and “Meeting only when the project is in trouble and expecting the Board to somehow rectify the problem or protect the parties” are ways to misuse the Board (Shamma et al. (2003)). The owner and/or designer should make a brief presentation at the beginning of the meeting to establish ground rules and bring the board up to date on recently completed studies, investigations, etc. Ask the board to reply to specific needs on the project. Be specific about the type of review or recommendations requested. Allow time before the meeting for the board to review documents, and after the meeting to think about and document their recommendations. Develop the client/consultant relationship so that it is not only technical and professional, but also business-like. Develop a rapport between the owner, designer, and the board members. Do not permit the board to “direct” the design. This can happen with a very aggressive and assertive consultant on the board. Give consultants feedback on what worked and what did not. This allows for continuous improvement in the process. To avoid diminishing the Board’s effectiveness, the Owner should be careful not to tell the Board what the Owner wants to hear (Shamma et al. (2003))

12 CONCLUSION As one respondent aptly wrote, “Each large underground project has common elements and elements that are unique to the individual project. How one uses boards is a function of the project, funding sources, public and political involvement, and how to get the best thinking and advance it with real


Consider member personality. “Personality is also critical, since an effective Board consists of individuals unafraid of stating their opinions but who, on the other hand, do not attempt to dominate with dogmatic or irrational behavior” (Hoek & Imrie (1995)). Avoid those whose history indicates a trend toward becoming the “savior of the project.” Pay particular attention to selection of a chairman, to organize and direct the board’s operations so that the board collaborates with the other members of the design team.

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News. (December 2002 and subsequent discussion: March 2003, June 2003, and September 2003.) Hoek, E., & Imrie, A.S., 1995. Guidelines to establish project consulting boards. International Water Power and Dam Construction. August 1995. Matyas, R.M., Mathews, A.A., Smith, R.J., & Sperry, P.E. 1996. Construction Dispute Review Board Manual, McGraw-Hill. Petroski, Henry 1996. Engineers of Dreams: Great Bridge Builders and the Spanning of America. Vintage Books. Shamma, J.E., Tempelis, D., & Nakamura, D. 2003. Board of Consultants – A Requirement for Hard Rock Tunneling Projects. Proceedings of the Rapid Excavation Tunneling Conference; Society for Mining, Metallurgy, and Exploration. Terzaghi, K. 1958. Consultants, Clients and Contractors. Journal of the Boston Society of Civil Engineers. January 1958. United States General Accounting Office, 2000. Mass Transit, Project Management Oversite Benefits and Future Funding Requirements, Report to Congressional Requesters.

world aspects.” By incorporating the advice and recommendations of expert consultants through the process of a formally established design review board, the design and construction of underground and heavycivil projects can be completed more effectively and with less project risk. However, establishing an efficient design review board, selecting the right members, and operating it successfully requires the active consideration of the purpose for which the boards’ recommendations are solicited. Owner agencies contemplating the use of a design review board should consider lessons learned from previous projects, and take an active part in the establishment, member selection, and operation of the consulting board. The efficient use of both consulting boards and construction managers can contribute positively to project success.

ACKNOWLEDGEMENTS APPENDIX – REPRESENTATIVE PROJECTS

The authors wish to acknowledge the following participants who have provided a significant amount of information or assistance in the development of this paper: Alistair Biggart Hugh Caspe Pete Douglass Herb Einstein Refik Elibay Joe Guertin Bill Hansmire Ray Henn Roger Ilsley Jon Kaneshiro Gregg Korbin Jim Lammie Jack Lemley Dan Meyer Lew Oriard Harvey Parker Ralph Peck Pete Petrofsky Tom Peyton Ed Plotkin Bill Quick Wolfgang Roth Tim Smirnoff Joe Sperry Fred Estep Kim Chan

Examples of projects, which have used Consulting Boards or Panels – some of these projects are in various stages of completion at this writing. The authors acknowledge that project names may not be accurate and are reported as provided in survey:

Ron Drake Paul Gilbert Joe Gildner Paul Gribbon Richard Harasick Geoff Hughes George Morschauser Priscilla Nelson Joe Pratt Martin Rubin John Shamma Lily Shraibati Ralph Tripani Al Wattson Lee Wimmer Howard Lum Tom Kuessel Judy Cochran Ed McSpedon Richard Proctor Gordon Revey Rube Samuels Gordon Smith Francis Fong John Ramage Birger Schmidt

Subways Tunnels Sound Transit Central Link LRT, Seattle, WA Bay Area Rapid Transit Project, (BART), CA Washington Metropolitan Area Transit Authority Los Angeles Metro Rail, CA Baltimore Metro, MD Eastside Access, New York, NY Buffalo LRT, Buffalo, NY Shepard Line, Toronto, Ontario, Canada San Diego LRT Extension, San Diego, CA Tri-Met Tunnels, Portland, OR Water and Sewer Tunnels City of L.A., Central Outfall Sewer Rehabilitation Chattahoochee Interceptor, Cobb County, GA Mercer Street Tunnel, Seattle, WA Narragansett Bay Comm., CSO, Providence, RI MWRA Inter-Island Tunnel, Boston, MA MetroWest Water Supply, Boston, MA Claremont Tunnel seismic upgrade, Oakland, CA North Dorchester CSO, Boston, MA East Central Interceptor Sewer (ECIS), L.A., CA North East Interceptor Sewer (NEIS), L.A., CA MWD, Inland Feeder System, Los Angeles, CA South Bay Ocean Outfall, San Diego, CA Milwaukee Water Pollution Abatement, WI Upper Diamond Fork Project, Provo, UT

REFERENCES Dunnicliff, J., & Parker, H.W., 2002. The Care and Feeding of Individual Consultants and Their Clients, Geotechnical


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Glenwood Canyon Tunnel, CO Central Artery Tunnel, Boston, MA Doyle Drive, San Francisco, CA Whittier Access Tunnel, AK Malmo City Tunnel, Sweden Wolf Creek Pass, CO Cumberland Gap tunnels, TN and KY Pinglin Highway Tunnels, Taiwan

Stanley Canyon, CO Wasatch County Water Efficiency Project Nancy Creek Tunnel, Atlanta, GA Colombia Slough CSO, Portland BES, OR Brightwater Conveyance Tunnels, Seattle, WA Baumgartner Interceptor Tunnel, St. Louis, MO Detroit River Tunnel, MI SWOOP, San Francisco, CA

Other Underground Uses

Highway Tunnels

Superconducting Super Collider, Dallas, TX Positron Electron Project (PEP), Palo Alto, CA

Interstate H-3, HI Devils Slide Tunnel, CA


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Drawing from past experience to improve the management of future underground projects Chris Laughton Fermi National Accelerator Laboratory, Illinois, USA

ABSTRACT: The high-energy physics community is currently developing plans to build underground facilities as part of its continuing investigation into the fundamental nature of matter. The tunnels and caverns are being designed to house a new generation of particle accelerators and detectors. For these projects, the cost of constructing the underground facility will constitute a major portion of the total capital cost and project viability can be greatly enhanced by paying careful attention to design and construction practices. A review of recently completed underground physics facilities and related literature has been undertaken to identify some management principles that have proven successful in underground practice. Projects reviewed were constructed in the United States of America and Europe using both Design-Build and more traditional Engineer-Procure-Construct contract formats. Although the physics projects reviewed tend to place relatively strict tolerances on alignment, stability and dryness, their overall requirements are similar to those of other tunnels and it is hoped that some of the principles promoted in this paper will be of value to the owner of any underground project.

vertical shaft and numerous chambers and caverns up to 25 m in span. Sadly, the Superconducting Super Collider (SSC) project, the largest such project so far attempted, was terminated before tunnel construction was complete. This project, perhaps above all others referenced, stands as an excellent example of what can be achieved when good contracting practices tailored to underground construction are adopted. The physics community is now developing a new set of accelerator projects, including the Tera ElectronVolt Superconducting Linear Accelerator, the Next Linear Collider and the Very Large Hadron Collider. The scope of underground construction for these facilities will be larger than any so far undertaken. Rock tunnel housings as currently envisaged will range in length from approximately 50 to 250 km. In addition, a number of new proposals for detector-based underground experimental programs are being developed, notably relative to the study of beta and neutrino particles, at sites in Brazil, France, Japan, Russia and the USA. Effective management of underground design and construction is a critical focus of the planning process as these projects move forward. The goals of this planning are to deliver satisfactory facilities quickly at an affordable price (“better, faster, cheaper”).

1 INTRODUCTION Over the past twenty years the particle physics community has built a number of underground projects worldwide. Underground sites are preferred for many experiments because the groundmass overlying the facility acts to block the passage of particles and/ or radiation that could otherwise have a deleterious impact on the experiments and/or the surrounding environment. Underground accelerator-based projects constructed in this timeframe include the Super Proton Synchrotron, the Large Electron Positron and the Large Hadron Collider located at the European Particle Physics Laboratory, in Switzerland and France; various projects at the Deutches Elektronen-Synchrotron in Germany and the Stanford Linear AcceleratorCollider, Superconducting Super Collider Laboratory and Neutrinos at Main Injector (NuMI) projects in the USA. A number of underground detector sites have also been constructed in this same timeframe, notably including excavations made within existing mine boundaries at the Creighton, Homestake, Kamiokande, and Soudan mines or located adjacent to road tunnels within the Fréjus, Mont Blanc and Gran Sasso alpine massifs. The combined underground scope of these projects totals close to 100 km of tunnel, 10 km of


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2 UNDERGROUND PLANNING

3 TUNNELING IS DIFFERENT

The main design and construction phases of a rock tunnel project are shown in the flowchart in Figure 1. The flowchart is based on that proposed by the International Tunneling Association and discussed by Lowe (1993). This chart outlines the basic steps in tunnel design and construction from alignment through construction. The flowchart omits reference to some key tasks, notably those associated with estimating and scheduling the work. However, the flowchart does provides a framework for the discussion that follows in which ten general principles are proposed to support an effective tunnel design and construction process.

Decisions made at the start of the project will have a great influence on project outcome. As far as a tunnel project is concerned, probably the most critical decisions that need to be addressed at the outset are related to preparing the owner for changes to his normal construction practices. The owner may need some convincing that “normal” business practices may not work so well underground. “First-time” tunnel owners, in particular, may see no particular benefit or need to change established ways of doing business and will need convincing that the changes are worth the effort, notably because

•

Site Investigation & Alignment

• •

Rock Mass Characterization

Of course, the underground project may go smoothly or encounter problems irrespective of whether an owner decides to take such precautions. However, such precautions are warranted in order to be responsive to the particular vagaries of the underground project. It will take more effort in the short-term, but will provide for more effective protection of the project over time. If the owner can be convinced of the value of these changes up front, the rest should be easy!

Excavation Methods & Means & Structural Elements

Detailed Design & Modeling Experience Estimation Bypass

Design & Safety Criteria Review

4 FAMILIARITY WITH LOCAL CONDITIONS An early understanding of the host rock mass conditions is a critical element in the design process. To evaluate a site’s suitability, regional and locationspecific geologic information will need to be gathered. Information should be collected on rock units, structural folds and faults, groundwater and in situ stress regimes. This geological information will need to be assimilated and interpreted at an early stage in design in order to characterize the rock mass along the alignment(s) and provide input for concept constructability and engineering analyses. Early acquisition and interpretation of this data is key in support of the design process. This data will help quickly eliminate showstopper situations and avoid much of the “wheel-spinning” (multiple layouts, designs and drafting work) that can occur during design and can consume a sizeable amount of a highly limited resource. At the earliest stage of design, shown in Figure 1, adequate site investigation data can generally be drawn

Accept/Reject

Risk Assessment & Contract Structure

Tunnel Construction

Field Observation

Stability

Figure 1. Tunnel design process flowchart.


normal design and construction partner(s) may not be able to provide the types and breadth of support necessary for underground construction significant resources will need to be expended on site investigation and this work will need to start early the bid documents may need to be changed to address the added elements of risk that tunnel construction brings to contracting.

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from field visits and desk studies. In all but the remotest of areas, published matter can be found to support desk studies (e.g. topographic and geologic, land use mapping and related studies). The design team should also seek to supplement the public domain data sets with specific information on construction projects of a similar nature undertaken in the region. As underlined by Trautman and Kulhawy (1983) such information can most readily be tracked down with the help of a local “geo-practitioner” (geologist, engineering geologist, geological engineer). Such individuals will know where the data is and, more importantly, know how to access it. Their familiarity with local formations and involvement on other projects will prove invaluable to the team throughout design and construction. Every design team needs access to such a professional, particularly at the outset of the project when data acquisition and rock mass characterization skills are at a premium.

Rock Conditions Excavation Size Structural Behavior Excavation Shape

Excavation Support Initial Stresses

Figure 2. Factors influencing the structural behavior of a tunnel, after Sutcliffe et al. (1990).

with due regard to the constraints of the construction process results in a more practical design and ultimately provides for a more affordable and lower risk construction product. A more integrated design strategy that involves the contractor can also provide for a more innovative approach to tunneling (Songer and Molenaar, 1996) and help to lower risks associated with unreasonable end-user demands.

5 CONTRACTORS’ DESIGN INPUT By the time a basic rock characterization has been attained for a site, key underground end-user requirements will also need to have been established. These requirements will typically include a definition of the space and environmental needs of the operating systems as installed. In this regard, the physics end-user is likely to focus on issues such as foundation stability, dryness and alignment given that the success of their operations (accelerator and/or detector) will be highly dependent upon these aspects of the opening’s performance. However, before decisions are made and drawings developed defining alignment and crosssectional requirements, the end user should be made aware that some compromises might be needed if the facility is to be built economically. Absolutes in precision, stability and watertightness cannot be met easily in a natural, variable rock material and the needs of the experiment will need to be balanced against the practical constraints that the ground mass imposes. To reach the economic compromises discussed above, the requirements setter(s), the designer(s) and builders should ideally have an opportunity to discuss the factors that will impact tunnel behavior, as shown in Figure 2. Ironically, contractors, who undoubtedly have the best appreciation of the constraints of tunnel construction and are the ones who will ultimately price and build the facility, are often completely excluded from all stages of the design process. A way needs to be found, regardless of the contract format, to solicit the input of the tunnel builder in order to establish an understanding of the process and build-up confidence in the practicality of the design (Atkinson et al., 1997). A tunnel design developed

6 CASE HISTORY BENCHMARKING One basic question that needs to be addressed during design is that of precedent. Have similar tunnels been built before? And if they have, what was the outcome? Such questions usually emanate from the owner or their representative who are interested in understanding exactly what kind of situation they have gotten into! These are reasonable questions for which the owner should expect comprehensive answers. Underground projects with similar rock mass and construction methods and means should be researched and made available for the design team to review. Some papers and reports that have compiled tunnel project data bases include the United States National Committee on Tunneling Technology (USNCTT) (1984), Sinha (1986), Parkes (1988), the Association Française des Travaux en Souterrain (AFTES) (1994), and, Nelson et al. (1994). These databases are recommended as a resource for anyone seeking an objective evaluation of case histories, they describe mining performance and problems encountered over the length of the tunnel. In addition to the compiled data base material listed above, tunnel construction issues are often reported in a number of industry journals and in conference proceedings such as those of the Australian Tunneling Conference, International Tunneling Association, North American Tunneling Conference, Rapid Excavation and Tunneling Conference and Tunneling Symposium.


Excavation Method

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Whatever the level of risk anticipated on the job it is important to find a mechanism that allows this risk to be objectively expressed and communicated to others. To manage such risks effectively the impacts of risk on cost and schedule are perhaps best expressed under a series of “what if ” scenarios. These scenarios are needed to complement the deterministic cost and schedule performance reporting systems and will serve to remind management that although underground problems are not shown as activities on the schedule the possibility of encountering them is real! Even the most thorough site investigation of the most uniform geologic conditions will not be able to completely define the scope of an underground construction contract. Some surprises from the natural material should always be anticipated along the way and an effort should be made to provide management with a clear expression of risk as an integral part of the normal reporting process.

The owner’s confidence in the viability of the “tunnel plan” will be improved if comparable case history data can be compiled and assimilated. The owner will be even more convinced if visits to similar sites can be organized. Examination of case studies also serves as a reality check on plans. A similar case whose outcomes are inconsistent with current projections may raise useful questions or may point to key parameters that differ between the projects. 7 INTEGRATED ENGINEERING In the title of their 1979 paper, Curtis and Rock frame the problem of working on structural linings underground as follows: “Tunnel Linings – Design?” This title is a simple acknowledgement that ground loading on a tunnel lining is difficult to predict even in the most homogeneous of groundmasses. This uncertainty can result in conservatism and/or complexity in design; for example, the use of thick cast-in-place linings to support an otherwise strong rock mass. The over-design of the final lining is difficult to avoid when loading conditions cannot be predicted with great certainty. Key to minimizing such overdesigns is a consideration of the ground’s ability to contribute to the long-term stability of the opening. To this end there is a need to better integrate the geotechnical engineer’s knowledge in to the structural engineer’s model. Such integration may allow greater opportunity for a discussion of the strengths of the rock mass and ultimately result in the streamlining or even elimination of a “permanent structure.”

9 CONTRACTING STRATEGIES Nowadays, design and build is commonly held to have distinct advantages over more traditional Engineering-Procurement-Construct contracting, but design and build will not always provide the best solution. Under the right circumstances, a design and build approach may save the owner time and money and offer the individual contractor the best opportunity to integrate the design needs of construction with their preferred methods and means. As Cording (1985) notes, “The separation of design and specifications from the contractor’s planning create unnecessary impediments and adds unnecessary costs to the project.” However, there are circumstances where the owner may wish to maintain greater active control of the underground project through its execution, notably where public interest is high and/or architectural features are an important part of the project. As pointedout by Boye and Eskensen (2003) the argument for design and build is weakened as public involvement in the permanent works design (geometry, layout, aesthetics) and complexity of the contract interfaces increases. As the needs for prescriptive language in design and construction is reduced, the case becomes stronger for leaving the contractor greater flexibility in his/her choice of methods and means within the framework of the design and build contract option.

8 RISK MANAGEMENT Risks associated with underground construction are notoriously difficult to describe and quantify and setting realistic expectations for scope, cost and schedule is always a major challenge. Risks underground are strongly influenced by a number of factors, including the diversity/complexity of the geology, the density of the site investigation coverage, the amount and relevance of compiled case history information, the flexibility of the selected mining methods and means and the skill-set of the construction team. Risk analyses should be performed at critical junctures during design and construction to ensure that risks are properly characterized. Risk analysis should be performed to identify the types of risk to which the project is exposed and provide for an estimate of their frequency of occurrence, and the severity of their impact, ultimately in terms of cost and schedule. Management should use such information to decide upon the type and extent of mitigation required for each type of risk event.

10 ORGANIZING FOR SUCCESS All of the issues discussed above, while important, are secondary when compared to the need for assembling and maintaining a good project team to manage the work. Care should be exercised in the selection of


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the framework of discussion. Issues should be framed in such a way that participants are not asked to answer leading questions and attention should be made to ensure that individuals are not placed in positions where conflicts of interest might arise. The review process should encourage frank and open discussion between participants aimed at comprehensively addressing agenda topics and answering specific questions. Review outcomes should include a single attendee-reviewed document that faithfully records the topics discussed, findings and recommendations. Any review recommendations that require follow-up should be addressed and appropriate actions taken.

Department of Energy

M&O Contractor

Texas Commission

AE/CM Contractor(s)

Design Consultants

Technical Systems

Construction Contractors

Figure 3. Management organization for the SSCL, after USNCTT (1989).

12 LESSONS LEARNED Many of the decisions made during the course of a tunnel project are experience-driven. Despite improvements in rock mass modeling and the prediction of mining performance the industry is likely to remain heavily dependent on this “experience factor” for the foreseeable future. Within the industry there is an ongoing need to share and learn from our collective experiences, both good and bad. The industry, cannot afford to let every owner learn from his/her own mistakes. If past successes and failures go unreported opportunities for improved practices will be lost and the same common errors will continue to be repeated. A more concerted effort is needed to methodically analyze and openly discuss the underlying reasons for success and failure of tunnel jobs. Sharing these experiences would allow the tunneling protagonists the opportunity to get smarter more quickly and allow potential owners better insight in to the workings of the underground construction industry.

all team members whether searched and selected from in-house staff or out-sourced. At a minimum, candidate members should be expected to demonstrate a requisite level of individual and corporate competence, and work products should be provided that exemplify the candidate’s ability to fulfill projectspecific roles. Focus should be placed on judging the relevance of past experience (similar requirements, geology, methods and means, etc.). When there is inadequate expertise within the owner’s existing organization, responsibility for the management of the design and/or construction may be delegated, as shown in Figure 3. Here the SSCL Architect/Engineer and Construction Manager (AE/ CM) team was carefully selected following guidelines setout by the US National Committee on Tunneling Technology, Geotechnical Board (USNCTT, 1989). The selected AE/CM (Parsons Brinckerhoff and Morrison Knudsen) provided a dedicated team of experienced professionals to the SSCL project. The project was managed to cost and schedule up until its termination in the early 1990s.

13 CONCLUSIONS Digging a hole underground is not as simple as it sounds. Cost and risk are potentially much higher than they are for equivalent surface-based or cut and cover structures. Tunneling really does present the owner with a different set of construction challenges than he/she may be accustomed to dealing with. At the outset of the tunnel project, focus should be placed on educating the owner to the particular vagaries of the underground contract. As work commences attention should be paid to developing an early appreciation of the site in general and the rock mass in particular. During the design, focus should be placed on properly integrating the end-user and engineering needs of the facility with the construction preferences of the contractor.

11 THE VALUE OF REVIEWS Technical reviews are a common part of most large tunnel projects. They can be regarded as a distraction from the core project objectives, but if properly run they can provide valuable opportunities for improved communication and learning between project members and ultimately result in a better project. Reviews are most likely to be effective if the agenda is established ahead of time and if participants are invited based on their ability to address agenda items. In some instances, an individual may be nominated to play the role of “devils advocate” to encourage and broaden


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Underground Transport, Future Developments in Technology, Economics, and Policy, Boston, MA, US., April, pp. 121–141. Lowe, P.T. (1993), “The Planning and Design of the Prospect to Pipehead Tunnel.” Proceedings, 8th Australian Tunneling Conference, Sydney, Australia, 24–26 August, pp. 21–27. National Research Council (1989), “Contracting Practices for the Underground Construction of the Superconducting Super Collider”, Washington DC, p. 99. Nelson, P.P., Al-Jalil, Y.A. and Laughton, C. (1994), “Tunnel Boring Machine Project Data Bases and Construction Simulation,” Geotechnical Engineering Center Report GR. 94-4 to the National Science Foundation, December. Parkes, D.B. (1988), “The Performance of Tunnel-Boring Machines in Rock,” Construction Industry Research and Information Association, Special Publication No. 62, p. 56. Songer, A.D. and Molenaar, K.R. (1996), “Selecting DesignBuild: Public and Private Sector Owner Attitudes.” Journal of Management in Engineering, November– December, pp. 47–53. Sutcliffe, M.L., Rogers, S.F., Whittaker, R.N. and Roberts, B.H. “Integrated Approach to Geotechnical Assessment of Rock Tunnel Stability and Performance.” Proceedings of Tunnel Construction ’90, London, UK, April 1990, pp. 145–153. Trautman, C.H. and Kulhawy, F.H. “Data sources for Engineering Geologic Studies.” Bulletin of Association of Engineering Geologists, Vol. XX, No. 4, pp. 439–454. US National Committee on Tunneling Technology (1984), “Geotechnical Site Investigations for Underground Projects.” National Research Council, Washington DC, National Academic Press.

For tunneling particular attention should be placed on establishing and updating expectations for costs and schedule performance. Regardless of the contracting strategies and the instruments chosen to mitigate and/or allocate risks, the owner will need to be regularly briefed on issues of project risk as tunnel projects are vulnerable to critical path delays. Reviews can be valuable tools for providing fresh technical and contractual insights to the management team. During construction, the contract will require active management in order to ensure that contract provisions are met and, that ground conditions are evaluated and timely decisions made as necessary. At the end of each tunnel job the process and outcome should be objectively reported so that any lessons learned can serve as a reference and guide for other owners and industry professionals alike. REFERENCES AFTES, Working Group No. 4 on Mechanization of the Excavation Process (1994), “Fiche Signalétiques de Chantiers Mécanisés, Recueil 94.” Atkinson, A., Cavilla, J. and Wells, J. “Securing the Contractor’s Contribution to Buildability in Design.” Project Report 27, CIRIA. London 1997. Boye, C. and Eskesen, S.D. (2003), “Specifying underground Works – the Challenge of Developing the Optimal Requirements.” Proceedings Underground Construction Conference, London September, 2003 pp. 509–520. Cording, E.J. (1985), “Constraints on Tunneling Technology,” Proceedings of the Conference on Tunneling and


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The ECIS story J.W. Critchfield Parsons Brinckerhoff, Los Angeles, CA, USA

B. Miya Bureau of Engineering, City of Los Angeles, CA, USA

ABSTRACT: At $240 M, the East-Central Interceptor Sewer (ECIS) is the largest construction contract ever awarded by the Los Angeles Department of Public Works. Four Earth Pressure Balance (EPB) Tunnel Boring Machines, in an urban setting excavated the 18.4 km tunnel. Construction management issues that affected the completion cost and schedule involved construction access, design changes, permeation grouting, existing utilities, community issues, tunneling mishaps, and unforeseen conditions. These challenges were met and overcome by the combined efforts of the City and the Construction Contractor, to complete a vital infrastructure improvement, as mandated by the State of California.

1.2

1 INTRODUCTION 1.1

Ground conditions along the tunnel alignment include a thin surficial layer of fill overlying alluvial and marine sediments. There are three generally recognizable deposits, from the ground surface downward: Recent alluvium – inter-fingered layers of streamdeposited loose to dense silty and sandy soils with gravel, cobbles and boulders, including some local deposits of soft organic soils. Encountered in about 5 to 10% of the tunnel. Lakewood formation – alluvial and shallow marine deposits including layers, lenses and pockets of generally dense silty sands and sandy silts, with gravel, cobbles and boulders. Encountered in about 80% of the tunnel. San Pedro formation – deep marine deposits composed of hard silts and clays with zones of dense sand and gravel. Encountered in about 10 to 15% of the tunnel. Hydrogen sulfide and methane were encountered in these deposits. The tunnel alignment is within or near several oil fields. Contaminated soil and groundwater were encountered at some work sites. Several active and inactive faults are present along the tunnel alignment. The most significant is the Inglewood Fault, located in the vicinity of the Baldwin Hills, near the downstream end of the project. The regional groundwater table is generally 25 to 50 m below tunnel invert. However, water is above the

Project description

The North Outfall Sewer – East Central Interceptor Sewer Project (NOS-ECIS) is designed to divert wastewater from the middle portion of the existing 80 yearold NOS. This will provide increased capacity to handle wastewater flows and allow the NOS to be rehabilitated. The project is the first phase of an urgently needed program required to prevent sewer overflows during storm events. A Cease and Desist Order (CDO) mandated construction, under threat of heavy financial penalties, from the California Regional Water Quality Control Board. An 18.4 km-long tunnel was constructed from East Los Angeles, westward to Culver City, along the alignment shown in Figure 1. The depth to tunnel invert ranges from approximately from 10 to 30 m, with a maximum depth of about 110 m under the Blair Hills. The excavated diameter was 4.7 m. The finished inside diameter is 3.35 m. The alignment was divided into five tunnel drives. Other project elements include 7 shafts, 31 maintenance holes, 11 junction structures for future connections, 2 diversion structures, a 90 m-long siphon and a 250 m-long micro tunnel, and a connection to NORS and other sewer lines. Conduits for fiber optic cables are incorporated into the final tunnel lining.


Ground conditions

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Figure 1. Project location.

tunnel crown at the east end of the project, beneath the Los Angeles River. Water is also perched within the various soil layers and trapped within fault zones. 1.3

Construction environment

The alignment is largely within public right-of-way, but does cross beneath several private properties and structures. The neighborhoods near the construction sites include residential and commercial areas with numerous schools, churches and other sensitive facilities. Accordingly, site access and work hours are restricted and limitations are imposed on construction noise and vibration. Hundreds of existing structures are present within the zone of influence above the tunnel excavation. The tunnel is directly under several buildings and major utilities, the Interstate 10 and 110 Freeways, the Los Angeles River Channel, the Metropolitan Transportation Authority (MTA) Blue Line, Union Pacific and Amtrak Railroads, and the new Alameda Corridor facilities. 1.4

Figure 2. Completed sewer pipe in tunnel.

tunnel lining consists of segmental pre-cast concrete rings, installed and grouted at the tail of machine. Sections of Precast Concrete Cylinder Pipe (PCCP), lined with polyvinyl chloride (PVC) as corrosion protection, were installed inside the tunnel to complete the sewer, as shown in Figure 2. Cellular concrete was used to fill the annulus between the carrier pipe and

Construction methods

EPB tunnel boring equipment was specified as the primary means to control ground loss during excavation, limit surface settlements, and prevent damaging existing structures. Four Lovat EPB tunnel boring machines (TBM) excavated five sections of tunnel. The initial


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An Owner-Controlled Insurance Program (OCIP) and a Project Labor Agreement (PLA) were included in the construction contract. A local hiring goal was incorporated into the PLA.

the tunnel segments. Fiber optic conduits are embedded in the annular grout. Permeation grouting, with cement or chemicals, was specified to improve ground strength prior to excavation beneath critical structures. No compaction grouting or structural underpinning was expected to be necessary. A geotechnical instrumentation program was used to monitor ground movements around the tunnel and measure effects on existing structures. A preconstruction survey was also conducted to document the condition of existing structures. Conventional mining methods was also used. Staged excavation and support installation was needed to excavate beneath the siphon and to construct starter tunnels and breakouts for junction structures. The connection to the active NORS was specified to be accomplished almost entirely underground, due to work site restrictions at the downstream end of the project. Micro-tunneling technology was used to construct portions of the siphon and for a primary connecting sewer. Large shafts and junction structures were constructed within soldier pile and slurry wall shoring systems. Small diameter shafts and maintenance holes were be installed by drilling. 1.5

2 MANAGEMENT CHALLENGES Issues and events that affected the cost of construction and the schedule for completion are outlined below. 2.1

Property acquisition and construction access issues soon became apparent, once ECIS was underway. The City struggled to obtain dozens of underground easements, often from intransigent property owners. Shaft construction for the Siphon Inlet cut off driveways to four homes. Planned back alley access turned out to be impracticable and City real estate agents scrambled to arrange for construction of a temporary driveway across the private properties. Work areas and traffic control plans on city streets needed to be revised to accommodate larger than anticipated equipment. Arrangements for a construction site at the North Outfall Relief Sewer (NORS) connection in Culver City took over a year longer than expected, due to numerous third-party complications.

Construction contract

Bids were opened in November 2000. A low bid of $240 M was submitted by the Joint Venture of Kenny, Shea, Traylor & Frontier-Kemper. The Engineer had estimated construction costs at $255 M. The Board of Public Works established a construction budget of approximately $280 M, including the bid amount, plus $10 M for insurance and $30 M as a construction contingency. Funding is provided entirely by local sources. The Contract, awarded in January 2001, is the largest construction contract ever for the LA Board of Public Works. Notice-to-proceed was given in February 2001. The original contract duration was 1000 calendar days, giving a contract completion date in midNovember 2003, to meet a completion deadline imposed by the State of California. 1.6

2.2

Design changes

A major design change was necessary on the ECIS project. The original design called for cast-in-place concrete structures at the bottom of each maintenance hole, some of which have junction structures for future sewer connections. The Contractor used 3-D Computer modeling to demonstrate that cast-in-place construction was impracticable and proposed an alternative scheme using pre-fabricated concrete and steel pipe. Eight unneeded maintenance holes were deleted to offset extra costs. The configuration of a slurry wall shaft at the upstream end of the project had to modified to make it constructable on a small work area, immediately adjacent to operating railroads. Additional modifications were made to facilitate connection of the Northeast Interceptor Sewer (NEIS), by another contractor. The NORS connection work site needed extensive site development work. Additional temporary shoring was constructed that allowed recovery of a tunnel boring machine and the installation of carrier pipe, as part of a schedule recovery strategy. Odor control facilities were added to the contract after award. Additional chemical injection and air scrubbers were needed to control odor during construction of sewer connections. Interim carbon filters

Project management

Design work was performed by the City of Los Angeles Bureau of Engineering, with assistance from Parsons Brinckerhoff Quade & Douglas. Construction management duties were carried out by a combined team of Bureau of Engineering and Bureau of Contract Administration personnel, together with consultant staff led by a Joint Venture of Parsons Brinckerhoff Construction Services and Brown & Root Services.


Construction access

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Figure 4. Maintenance hole/tunnel intersection.

to advertising the contract for construction. A oneblock long section of the large concrete box culvert had to be demolished and reconstructed at higher elevation. This entire effort was performed on a time and materials basis, at a total cost of $4.6 M, exceeding the contract allowance by $1.2 M. Relocation of underground utilities and overhead lines was a ubiquitous problem at maintenance hole sites. At one location, the presence of critical overhead electric and underground services combined with high-speed traffic control issues made it impracticable to use a large drill. The 3 m diameter maintenance hole had to be hand-excavated to a depth of 24 m.

Figure 3. Maintenance hole installation.

were added at three sites to serve until permanent Air Treatment Facilities can be constructed for the completed sewer system.

2.5

Community issues

The largest single extra cost was for permeation grouting work. Several unit price bid items were included in the contract, assuming that both cement and chemical grout would be injected from the surface and from within the tunnel. The contract also assigned responsibility for design of the grout program to a specialty subcontractor. The contractor design was completely different, including only chemical grout and working only from the surface. This resulted in some unused bid items, for cement and underground work, and massive quantity overruns on chemicals and surface work items. The total volume of grout used was 11,000,000 liters, roughly the same as the design. The total cost was $12.6 M, exceeding the bid price by $5.5 M. The engineer estimate had included $14 M for permeation grouting.

Respect for the community is of paramount importance to the Board of Public Works. Restrictions were placed on work hours, noise, vibration levels and traffic, to reduce the burden of construction activity on neighborhoods. Costs for mitigating construction noise, vibrations and disruption exceeded the contract allowance, mainly for the construction of additional noise barriers, and for additional traffic controls to maintain access to properties. Prevailing wages requirements of the Project Labor Agreement were misunderstood by the trucking subcontractor, in preparation of their bid. The City issued a $2.8 M change order to remedy the situation. The narrowly defined PLA local hiring goal of 40% proved impracticable. Using the PLA definition, local hiring peaked at 26%, but averaged 14% overall. The percentage of Los Angeles residents on the project was 30%.

2.4

2.6

2.3

Permeation grouting

Existing utilities

EPB tunneling was mandated to control the excavation, limit ground loss, and minimize surface settlement.

City surveyors discovered that a major LA County storm drain conflicted with the ECIS tunnel, just prior


Tunneling mishaps

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Extra work was required at the NORS connection because the geometry of the existing structure was different than expected and the flow level within the operating sewer was higher due to operational changes since the design was completed. 3 PROJECT COMPLETION 3.1

The critical path of the schedule was directly effected early in the project. Archaeological work and the delay associated with real estate dealings for the temporary driveway at the siphon inlet added 99 calendar days to the contract duration. During the course of the work, additional delays began to accumulate. Major identifiable delays were associated with obtaining and developing the NORS work site and with repairing the tunnel mishaps. More insidious delays resulted from the cumulative and inter-related effects of design changes, and other extra work activities. In June 2003, the City and Contractor negotiated a “global schedule agreement”. Under terms of the agreement all schedule issues to-date were resolved by development of a revised schedule which will place ECIS in service by June 2004 and complete all contract work by August 2004. The agreement also provided for payment of $2.0 M and for release of a portion of funds retained from progress payments. Subsequently the City approached the State Board to request an extension of the CDO completion date. The State accepted the City’s explanation and justification for the delay based upon unforeseen conditions, and granted an extension consistent with the global agreement.

Figure 5. Chimney caused by ground loss during a tool change.

There was no more important technical objective on the project, even though the application for ECIS tunneling in dry sandy ground was somewhat unusual and controversial. The EPB tunneling machines were generally effective in achieving the goal of controlling ground loss and limiting surface settlements. However, lapses in application of the EPB techniques did result in over-excavation. The process of stopping the TBM to maintain the cutterhead sometimes resulted in unintended ground loss. Chimneys, as shown in Figure 5, formed above the TBM during a tool change stops along the Alameda Corridor, which had just opened to commercial service. An extensive program of Compaction Grouting was performed to repair the ground along a 300-meter section of the alignment. A short section of tunnel lining was deformed and some heaving of the railroad tracks resulted from the compaction grouting operations. 2.7

3.2

Construction cost

The approximate cost to complete the project, as estimated in November 2003, is summarized in Table 1, along with a breakdown of extra costs. At $259.2 M, the expected final completion cost exceeds the Engineer Estimate by 2% and is 8% more than the original bid price. The total cost is considered acceptable, at 96% of the originally assigned budget.

Unforeseen conditions

A “mono” (grinding stone) artifact was recovered during soldier pile drilling at the siphon inlet shaft. The State Historical Preservation Officer required the shaft excavation to proceed in lifts, under supervision of the Project Archeologist. An abandoned oil well casing was found within the work shaft at the upstream end of the project. A specialty contractor was needed to investigate and remove a portion of the old casing. The hand-excavated maintenance hole encountered two additional differing site conditions. An unmarked sewer line conflicted with the excavation and had to be relocated. Unexpected flowing ground conditions required dewatering and grouting work to complete the excavation.

3.3

Lessons learned

ECIS has been one of the most challenging projects ever undertaken by the Department of Public Works. The quality of the completed work is excellent. The City considers the project successful with respect to schedule and budget. Key lessons learned are summarized as follows: Construction access. Acquire easements and work sites prior to beginning construction. Allow


Schedule

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Table 1. Cost to complete summary. Engineer estimate Original contract Bid Contingency funds (12%) Insurance Assigned budget

$255.0 M $240.3 M $29.7 M $10.0 M $280.0 M

Extra costs Design changes Construction access Permeation grouting Existing utilities Unforeseen conditions Community issues Tunnel mishaps Total extra cost Cost to complete

$2.0 M $1.8 M $5.5 M $1.6 M $2.9 M $3.2 M $1.9 M $18.9 M $259.2 M

Committee is helpful to elevate utility issues for resolution. Community issues. Provide adequate funding allowances to meet commitments to the community. Tunneling. EPB has been shown to be the tunneling method of choice and it will be specified on future projects in Los Angeles. Unforeseen conditions. Cooperation and perseverance between the Owner and Contractor, with help from the various stakeholders can overcome unforeseen conditions.

ACKNOWLEDGEMENTS The authors would like to acknowledge the contributions and support of the following individuals:

•

realistic space for construction equipment and operations. Design changes. Review designs thoroughly for constructability. Permeation grouting. Consider implications of bidding schemes to reduce the potential for unintended consequences. Existing utilities. Accurate as-built information about existing utilities is difficult to find. An Executive

• • •


Commissioners Valerie Shaw and Ellen Stein, Los Angeles Board of Public Works. City Engineer Vitaly Troyan and Deputy City Engineer Tim Haug. Inspector of Public Works Stan Sysak and Bureau of Contract Administration Inspectors John Reamer, Chris Smith and George Stofila. Project Director Ted Budd, and Patrick Kenney, of the Kenny Shea Traylor Fontier-Kemper Joint Venture.

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Session 1, Track 2 Security of critical infrastructure and key national assets: use of underground space


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Internal blasting and impacts to tunnels Wern-ping (Nick) Chen HNTB Corporation, Boston, MA, USA

ABSTRACT: During an external explosion event, the ground would shelter a nearby tunnel and the explosion impact to the tunnel may be minimum; however, if the explosion occurs in the tunnel, the implication from the explosion event may be enormous. Publications and researches for internal blast loading and its impact to tunnels are limited. The intents of this paper are to review general blast loading phenomenon and structure response to this type of loadings; to recommend load factors and dynamic material strength during a blast event for limit state design; to qualitatively estimate the impacts of internal blast loadings to tunnels; and to propose feasible hardening countermeasures and other security alternatives. Literature review was performed to explore current policies and design criteria for blast loadings on tunnels.

tunnels is seldom, it can happen. What are the sources that cause internal blast in a tunnel? It may be from trucks with chemical explosives, may be from the transportation of military vehicles, and may be from terrorist attacks. Next questions are: What is the special condition for a blast in a tunnel that is different from that of surface structures? What is the size of this blasting source? How is the blasting pressure determined? What is the response of tunnel structures from blast attack? What is the material behavior of structures in a blast event? What are exiting policies and criteria for design and prevention of blasting in tunnels? The purpose of this paper is to address these issues.

1 INTRODUCTION Traditionally, tunnels, as others underground structure, are very resilient to dynamic loadings, which include seismic events. The reason of this phenomenon is that once the ground is stabilized by tunnel supports during excavation, the redistribution of stresses in the ground occurs and eventually the ground reaches a new state of equilibrium and is self-supported. After this new state of equilibrium is reached, man-made ground supports are no longer needed in theory, since the inherent strength of the ground is mobilized. During an internal blasting event, with the composite effect from tunnel supports and the ground, the blasting impact to tunnel itself may be small. Local concrete spalling of tunnel lining is likely to occur, but the overall integrity of the tunnel remains. On the other hand, its damages to life and functional systems of the tunnel may be tremendous. This is especially critical for transportation tunnels. Consequences and damages to transportation tunnels from an internal blasting event can include:

• • • •

2 BLAST PHENOMENON A unique feature of blast loading in tunnels is its confinement. Overpressure builds up in tunnels, from a blast event, at different phases. First, the incident pressure reaches tunnel walls and generates reflected overpressure. Because of confinement, this reflected overpressure generates re-reflected overpressure. This process produces a series of blast waves of decaying amplitude. While this is happening, the second loading phase develops as the gaseous products of detonation independently causing a build-up of pressure, the gas pressure. The phenomenon is different from a free-air burst that is remote from any reflecting surface. The free-air blast is categorized as spherical airburst. In applying the spherical airburst to the hemispherical surface

Life safety issues from blasting overpressure, falling debris, fires, smokes, and flooding, Damages to transportation vehicles, Damages to ventilation systems, and Damages to tunnel structures, causing lining spalling and cracks, which may subsequently cause inundation to the tunnel if the tunnel is subaqueous and the inflow is excessive and can’t be stopped.

Tolerance for these consequences is null, but how do we detect and prevent it. Though blasting incident in


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The most widely used blast wave scaling approach is developed independently by Hopkinson (1915) and Cranz (1926), which is commonly referred as the cubic root scaling.

burst, such as an explosive sitting directly on the ground or in a tunnel, an enhancement factor of 1.8 is generally recommended. The hemispherical blast pressure may also be obtained from blast chart based on tests. Figure 1 displays the pressure and time relationship after a blast, where negative pressure occurs after time t0. Figure 2 shows the Shock-reflection phenomenon in a region where , incident angle, is greater than 45° (Norris et al., 1959). 2.1

(d1/d2) (W1/W2)1/3

(1)

(R1/R2) (W1/W2)1/3

(2)

W1 and W2 are charge masses of charge diameters d1 and d2, respectively. Ranges at which a given overpressure is produced can thus be calculated from Equation (2), where R1 is the range at which a given overpressure is produced by W1 and R2 is the range at which the same overpressure is generated by W2. It is inferred that the charge weight is inversely proportional to the cubic of the standoff distance, R; therefore, the best way of mitigating a blast event is to increase the standoff distance. Spherical blast pressure, airburst, can be obtained from classic derivation or from blast curves generated by experimental testing such as those generated by the Departments of the Army, the Navy, and the Air Force (1990). Analytic results by Brode (1955) are listed below.

Blast loading

The industry standard to determine the magnitude of an explosive is in terms of its equivalent weight to TNT. Most explosive device used by terrorist attack in the US is a mixture of Ammonium Nitrate and Fuel Oil (ANFO), which is about 80% equivalency to TNT. Conversion factors for other explosives to TNT equivalent weights can be found in many other literatures, such as Conrath’s (1999).

Ps 6.7/(Z3) 1 bar for Ps 10 bar

(3)

Ps 0.975/(Z) 1.455/(Z2) 5.85/(Z3) 0.019 (4) bar for 0.1 Ps 10 bar Z is the scaled distance, given by Z R/W1/3

Ps is the peak static overpressure. R is the distance from the center of a spherical charge in meters and W is the charge mass expressed in kilograms of TNT. Hemispherical blast pressure can be obtained by multiplying the results from the spherical results by the factor 1.8 or from blast curve generated by the Department of the Army, the Navy, and the Air Force (1990), as shown in Figure 3, where, Pr (psi) is the reflected overpressure, ta (ms) shock arrival time, td positive phase duration, Lw (ft) positive phase wave length U shock front velocity (ft/ms), and is and ir side-on and normally reflected impulse (psi-ms), respectively. Analytical hemispherical blast pressure can be derived based on works by Rankine and Hugoniot (1870) and Liepmann and Roshko (1957) as:

Figure 1. Pressure–time relationship after a blast.

Pr 2Ps [(7po 4Ps)/(7po 4Ps)]

(6)

where, po is the ambient air pressure. Published testing result for blasting pressure in confined space, such as tunnel, is not available. This blast pressure must consider shock wave re-reflection

Figure 2. Shock-reflection in a region where is greater than 45° (Norris et al.).


(5)

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•

phenomenon. Baker et al. (1983) has estimated this pressure as: PrT 1.75Pr1

(7)

PrT is the total peak pressure and Pr1 is the first reflected pressure as identified in Figure 3 or Equation (6).

2.2

2.3

•

Dynamic structure strength

The strain rate of a material will increase in a fast rate of loading condition. In such a condition, the mechanical properties of the material behave differently. Concrete and steel strengths are usually higher in a fast rate loading condition than at in a static loading condition. The factor by which the static stress is enhanced to calculate the dynamic stress is called the dynamic increase factor (DIF). Typical values are shown in Tables 1 to 3. Tables 1 to 3. Dynamic Increase Factor (DIF) for Design (Mays and Smith, 1995).

Structural response to blast loading

The positive duration, td, of a blast wave and the natural period of a structure determine the response characteristic of the structure. The structure shall be design in accordance with its response behavior as described below, where is the natural frequency of the structure.

•

Dynamic response (0.4 td 40) – True dynamic loading only occurs when the plosive phase duration of a blast wave is equivalent to the natural period of a structure, and is seldom occurred in underground structures.

Quasi-static response (40 td ) – When the natural period of the structure is much less than the positive phase duration of a blast wave, the structure will be fully displaced before the decay of the blast load. Such loading is quasi-static or pressure loading condition, such as the gas pressure in a tunnel after blast. Impulse response (0.4 td ) – When the positive phase duration of a blast wave is much less than the natural period of a structure, the blast wave decays significantly before the structure has had time to respond. Most blast events in tunnels have this type of response, since tunnel structures, in combination with the ground, are massive.

Table 1. Concrete Type of stress

fdcu/fcu

Bending Shear Compression

1.25 1.00 1.15

Table 2. Reinforcing bars Type of stress

fdy/fy

fdu/fu


1.20 1.10 1.10

1.05 1.00 –

Table 3. Structural steel Type of stress

fdy/fy*

fdu/fu


1.20 1.20 1.10

1.05 1.05 –

* Minimum specified fy for grade 50 steel or less may be enhanced by the average strength increase factor of 1.10.

Figure 3.

where, fy – static yield stress, fdy – dynamic yield stress, fu – static tensile strength, fdu – dynamic tensile strength, fcu – static concrete compressive strength, and

Hemispherical blast curve (TM 5-1300, 1990).


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Table 4. Threat parameters for tunnel design. Very High 2,000 lb

High 500 lb

Medium 100 lb

Low 50 lb

From 12,000 lb Truck

From 5,000 lb Truck

From 4,000 lb Car

From 4,000 lb Car

gas pressure build-up in blasting events; however, it does not protect personnel in the tunnel from injuries, since the injuries are directly associated with the initial overpressure and debris (or fragmentation if a bomb is cased). It is, therefore, concluded that detecting and preventing adverse explosives from entering tunnels is the primary countermeasure for blasting events in tunnels.

fdcu – dynamic concrete compressive strength. The modulus of elasticity for steel and concrete are insensitive to loading rates. Also, since blast loading is an ultimate event, its design load factor shall be set to unity. 2.4

4 POLICIES AND DESIGN CRITERIA An attempt was made to review existing policies and design criteria for tunnels under internal blasting events. Most of these documents are from military facility programs and policies triggered from tragic events between 1990s and earlier 2000s caused by terrorist attacks.

Threat parameters

Blast threat to tunnels is most likely from explosives or bombs in vehicles. Therefore, the maximum possible load from a blast will be a function to the size of the vehicles that carry the explosives. Table 4 is a recommendation for threat parameters for private-sector facilities (Conrath et al., 1999), which is suitable for tunnel design purpose as well. It also includes the likelihood of each threat occurrence and its associated vehicle size.

4.1

The section summarizes results from literature reviews of the latest available policies under blasting or terrorist attack events. These documents include:

•

3 COUNTERMEASURES Besides detecting and preventing blast threats from the outside of tunnels, physical countermeasures for tunnels under blasting events include:

• • • • • •

Structure hardening to improve structure resistance to blasting load, Provide shielding around tunnel, such as tube in tunnel and separating tunnels from direct exposure to blasting, Provide shielding around critical structural elements, including ventilation and fire fighting systems, Provide mechanisms in a tunnel to automatically detect and isolate blasting events and prevent their spreading (a blast proof automatic venting system would be required), Ground strengthen around tunnels by contact grouting and consolidation grouting, Provide external groundwater cut off mechanisms around, above, or in the tunnel by ground improvement, slurry walls, and internal automatic bulkheads.

•

•

Structural hardening is not cost-effective for blasting events in tunnels, since it is difficult and costly to design each element of a tunnel system to be blastproof. Even so, the life and safety issues for users in the tunnels can’t be guaranteed. For example, blast-proof automatic venting system is a countermeasure against


Policies

Use of Underground Facilities to Protect Critical Infrastructures, Summary of a Workshop (Little et al., 1998) – It is a summary for workshop conducted to discuss the use of underground facilities for protection of critical infrastructures. This workshop discussed findings of the President’s Commission on Critical Infrastructure Protection (PCCIP) and key issues in going underground, but no policy issue was addressed. A Guide to Updating Highway Emergency Response Plans for Terrorist Incidents (AASHTO, 2002a) – This document addresses the existing state and DOT emergency management plans and practices, the standard view of the terrorist threat since 9/11, and a process guidance as to how state Departments of Transportation (DOTs) can update their emergency response plans. No specific policy is addressed in this document. A Guide to Highway Vulnerability Assessment for Critical Asset Identification and Protection (AASHTO, 2002b) – This guide was developed as a toll for state DOTs to (1) assess the vulnerabilities of their bridges, tunnels, roadways, and inspection and operation facilities, (2) develop countermeasures to deter, detect, and delay the consequences of threats, (3) estimate the capital and operating costs of such countermeasures, and (4) improve security operational planning for better protection against future acts of terrorism. This document addresses mostly surface structures. It does not mention specifics to tunnels or underground structures.

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Though not design criteria, several design manuals developed by federal agencies (mostly for military use) are helpful for general blast deigns. These manuals would be used to assist the development of specific criteria for blasting designs for civilian facilities and tunnels in the future. These manuals include (their distribution may be limited):

National Need Assessment for Ensuring Transportation Infrastructure Security (AASHTO, 2002c) – This document examines three key security planning program areas: (1) protecting critical mobility assets, (2) enhancing traffic management capabilities, and (3) improving state DOT emergency response capabilities. It estimates the total costs for the proposed initiatives, including capital investment and operations and maintenance expenses during the TEA-21 six-year reauthorization period. Annual cost for tunnel related security program and 54 critical tunnels are identified; however, emphasis of this document is still on bridges and surface facilities.

• •

From above reviews, it is clear that most of these documents provide guidelines and guidance in handling infrastructure security and threat identification and prevention, but not policies. Furthermore, most of these documents address on surface facilities, such as buildings, highways, and bridges. Document that directly addresses tunnel policies does not exist.

•

• 4.2

Design criteria

Civilian blasting design criteria for infrastructures does not exist either. Most design criteria for facilities are developed by US federal agencies for federal properties and most design manuals are derived by the US Department of Defense, Department of State, and General Services Administration for antiterrorism requirements for military, embassy, and federal facilities. The following sections review these criteria and design manuals. They could be used as guides in developing specific tunnel documents in the future. Most criteria that were reviewed are for federal surface facilities. Their applications to civilian infrastructures and tunnels are not direct and must be revised. These criteria include:

• •

• •

• •

GSA Security Criteria (GSA, 1997) – This document has been used for new facility designs and has been the basis of performance standards in retrofit analyses of existing buildings. ISC Security Design Criteria for New Federal Office Buildings and Major Modernization Projects, (ISC, 2001) – This document is fundamentally built from GSA Security Criteria. Its purpose is to adopt GSA criteria to suit all federal agencies. This document was review by NRC in 2003. Major comments by NRC are that though the intent of this document is performance based, its performance-based design process is unclear and explicit statement that mandates the use of the ISC criteria for all projects is missing. The intent of this document is clear, but its execution may be an issue since it is not mandated.

•

5 CONCLUSION Conclusions drawn from this paper are:

•


Structures to Resist the Effects of Accidental Explosions (U.S. Departments of the Army, Navy, and Air Force, 1990). It is the mostly used publication by both military and civilian organizations. A Manual for the Prediction of Blast and Fragment Loadings on Structures, DOE/TIC-11268 (U.S. Department of Energy, 1992). This manual provides guidance for facilities subject to accidental explosions and aids in the assessment of the explosion-resistant capabilities of existing buildings. Protective Construction Design Manual, ESL-TR87-57 (Air Force Engineering and Services Center, 1989). This manual provides procedures for the analysis and design of protective structures exposed to the effects of conventional (non-nuclear) weapons. Fundamentals of Protective Design for Conventional Weapons, TM 5-855-1 (U.S. Department of the Army, 1986). This manual provides procedures for the design and analysis of protective structures subjected to the effects of conventional weapons. Design of Structures to Resist Nuclear Weapons Effects, Manual 42 (ASCE, 1985). This manual was prepared for civilian use, and has been widely distributed throughout the world. The Design and Analysis of Hardened Structures to Conventional Weapons Effects (DAHS CWE) (DNA, 1995). This new Joint Services manual, written by a team of more than 200 experts in conventional weapons and protective structures engineering. Security Engineering, TM 5-853 (U.S. Department of the Army, 1993). Terrorist Vehicle Bomb Survivability Manual (Naval Civil Engineering Laboratory, 1988). This manual contains information on vehicle barriers and blast survivability for buildings. Structural Design for Physical Security – State of the Practice Report (ASCE, 1995). This report is intended to be a comprehensive guide for civilian designers and planners who wish to incorporate physical security considerations into their designs or building retrofit efforts.

Blast wave propagation in tunnels is complicated. Blast pressure for design must take into

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consideration the shock wave re-reflection phenomenon. No blast testing result for tunnels is available. This paper presents a simplified procedure for blasting pressure in tunnels and provides recommended blast loads for tunnel designs. This paper provides countermeasures for tunnels under blast events; however, the best defense for blast events is early detecting and preventing adverse explosives into tunnels. Mandate security policy for civilian infrastructures does not exist in the US. Unified security policy for tunnels does not exist. It varies from state to state and from tunnel to tunnel. Mandate civilian blast design criteria for infrastructures do not exist. Blast design criteria and manual for tunnels does not exist. Blasting events in tunnels can happen. The need to address issues, polices, and design criteria for blasting in tunnels are immediate.

Baker, W.E., Cox, P.A., Westine, P.S., Kulesz, J.J. and Strehlow, R.A. (1983) “Explosion Hazards and Evaluation,” Elsevier. Brode, H.L. (1955) “Numerical Solution of Spherical Blast Waves,” J. App. Phys., Mo. 6, June. Cranz, C. (1926) “Lehrbuch Der Ballistik,” Springer, Berlin. Conrath, E.J., Krauthammer, T., Marchand, K.A. and Mlakar, P.F. (1999) “Structural Design for Physical Security – State of the Practice,” American Society of Civil Engineers. Department of the Army, the Navy, and the Air Force (1999) “Structures to Resist the Effects of Accidental Explosions,” Revision 1 (Department of the Army Technical Manual TM 5-1300, Department of the Navy Publication NAVFAC P-397, Department of the Air Force manual AFM 88-22), November. General Service Administration (1997) “GSA Security Criteria,” October. Hopkinson, B. (1915) British Ordance Board Minutes 13565. Interagency Security Committee (2001) “ISC Security Design Criteria for New Federal Office Buildings and Major Modernization Projects,” May. Little, R.G., Pattak, P.B. and Schroeder, W.A. (1998) “Use of Underground Facilities to Protect Critical Infrastructures, Summary of a Workshop,” National Academy Press. Mays, G.C. and Smith, P.D. (1995) “Blast Effects on Buildings,” Thomas Telford. Norris, C.H., Hansen, R.J., Holley, M.J., Biggs, J.M., Namyet, S. and Minami, J.K. (1959) “Structural Design for Dynamic loads,” McGraw-Hill Company, Inc. National Research Council (2003) “ISC Security Design Criteria for New Federal Office Buildings and Major Modernization Projects – A Review and Commentary,” The National Academies Press. Rankine, W.J.H. Phil. (1870) Trans, Roy, Soc., 160, pp 277–288.

REFERENCES American Association of State Highway and Transportation Office, in cooperation with the Federal Highway Administration (2002a) “A Guide to Updating Highway Emergency Response Plans for Terrorist Incidents,” May. American Association of State Highway and Transportation Office, in cooperation with the Federal Highway Administration (2002b) “A Guide to Highway Vulnerability Assessment for Critical Asset Identification and Protection,” May. American Association of State Highway and Transportation Office (2002c) “National Need Assessment for Ensuring Transportation Infrastructure Security,” October.


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Session 1, Track 3 Mechanized tunneling


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Improvements of the capabilities of cutting tools and cutting systems R. Bauer VOEST-Alpine Mining Tunneling & Construction

ABSTRACT: Newest improvements of the capabilities of cutting tools and cutting systems for hard rock conditions within the Icutroc research project. Underground excavations for infrastructural development and extraction of minerals in urban areas is increasingly becoming a necessity. Wherever conditions and circumstances permit mechanical rock excavation methods such as roadheaders, drum miners or tunnel boring machines are used. However in the past, certain situations (e.g highly abrasive material and/or high strength of the material to be cut) precluded the usage of certain mechanical excavation methods such as roadheaders. In such cases drill and blast was the only economical and practical alternative. With the development of Icutroc, an exiting new opportunity for cutting rock that provides numerous practical, logistical, environmental, and safety benefits, was introduced and is on the edge of making a big impact on the construction and mining world in the US. The continuous, mechanical cutting process provides an excellent opportunity for automatization with a high potential for various cost reductions. Furthermore it is very often the only viable solution in urban, congested areas where drill and blast is restricted or prohibited.

industrial initiator. Further partners were two customers (Thyssen Schachtbau and Somincor) as well as three research institutes (Seibersdorf Research Institute, Vienna, Armines CGES, Paris and the mining engineering department of the Montanuniversity Leoben, Austria)

1 PROJECT OBJECTIVE What does Icutroc mean and what implications will it have for the future of the North American tunnel and construction world? Icutroc is a corporate research and development project that was partly funded by the European community. Its original main target was to develop the necessary cutting tools to be able to apply higher cutting forces to economically cut higher rock strengths. When VOEST Alpine Bergtechnik, situated in Zeltweg, Austria took the initiative in 1995 to start a research and development program under the acronym “Icutroc” the goal was to extend the range of economic applications for the existing roadheader lines by moving into territories of harder and more abrasive rock types. The project objective was to achieve the required target with a type of roadheader that does not exceed 130 metric tons of operating weight and to stay within a range of 300 kW installed power on the cutterhead. The reason for these premises were that the maneuverability of the machine shouldn’t be sacrificed neither should the investment cost for this roadheader type exceed an acceptable, economic range. 1.1

1.2

Research partnership

The research program incorporated VOEST Alpine Bergtechnik and Sandvik Rock Tools as the main


The Icutroc research approach

The Icutroc research approach was characterized by a combined development work addressing the necessary improvements of the cutting system and the machine system. Additionally Icutroc aimed to significantly improve the mechanical and wear properties of the cutting tools. In detail the whole project included: Development and refining of cutting systems and processes followed by simulations of their real world behavior by using computer-aided modeling and FEM-calculations. Better understanding of the interaction between rock/rock mass behavior and its influence on the cutting process. New concepts and material designs of cutting tools and new production technologies to manufacture these tools. Laboratory testing of these units. Testing and optimization of the newly developed system by civil engineering and mining end users under practical conditions.

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Figure 1. Icutroc’s project target for the development of a hard rock roadheader.

techniques in order to harmonize the factors of the cutting process with the characteristics of the cutting machine. Thereby taking into consideration the rock properties, geometric parameters of the cutting unit and the operating characteristics of the cutting system (cutting speed, sump in depth and machine stiffness). A finite element model of the complete machine has been set up for the simulation of the elastic behavior of the system. Concepts to reduce the elasticity of the cutting system were investigated to meet the required stiffness parameters for hard rock cutting. A substantial improvement of the overall system stiffness for the cutting action could be achieved by the boom stabilization system acting on the hydraulic boom cylinders. The boom stabilization system allows for a better adherence to the preset cutting depth as well as an improved compliance with a uniform swivel process. Together with the added benefit of reduced vibrations (the boom stabilization system also reduces the “bouncing” of the boom significantly) the shorter overall path length of picks further improves pick life. Development of a new rock mass rating specifically adapted for the new generation of roadheader technology, which increased the quality and reliability of performance prediction tremendously. In order to gain a revised RMR, two approaches were used first the theoretical net cutting rate based on cuttability of intact rock thereby reflecting the machine characteristics. Second the effective net cutting rate directly measured on site reflecting the actual operating conditions. Outcomes of this investigation were an exceptional correlation between NCReff/NCRtheor and the

Depending on the toughness and abrasivity, economically cutting of rock hardness up to 200 Mpa. Provide all conceptual prerequisites to implement updated control and data logging facilities, as they are required due to project conditions. The economic and environmental significance of this project is emphasized by the fact that the research work was funded by the European union within the Brite-Euram III program for Industrial and Material Technologies, managed by the European CommissionDG XII. 1.3

Development of a new cutting process

Using the newly developed VOEST Alpine cutterhead design software accounting for parameters such as optimized forces, cutting depth, cutting distances, slew and feed speed of the cutter boom, cutter head diameter, geological parameter, etc. the research project was able to design lacing layouts that resulted in the highest possible cutting efficiency. These cutting systems employing low speed cutting and providing greater power at the cutterhead in connection with the development of a new generation of cutting tools, were able to cope with the higher forces to be expected when cutting rock above 130 Mpa.

2 DEVELOPMENT OF AN ADAPTED MACHINE SYSTEM The research project included intensive modeling of the complete system using computer simulation


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Figure 2. Specifically for Icutroc developed cutter heads designed with VOEST Alpine’s proprietary software. Rating of uniaxial compressive strength

Rating of block size Block size [m3]

Rating 20

UCS [MPa]

Rating

>0,6

1–5

15

0,3–0,6

16

5–25

12

0,1–0,3

10

25–50

7

0,06–0,1

8

50–100

4

0,03–0,06

5

100–200 >200

2 1

0,01–0,03

NORTH AMERICAN TUNNELING 2004

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Scientific american (September 2004)

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North American P-51 Mustang

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NORTH AMERICAN TUNNELING 2004

North American Indian

North American FJ Fury

Scientific american (June 2004)

Scientific american (October 2004)

North American pinot noir

Scientific american (May 2004)

Scientific american (December 2004)

North American F-86A

North American Indian Motifs

North American Wildlife

Hadrosaurus (North American Dinosaurs)

North American Indian

North American T-28

North American Bc-1

The North American Indian

Troodon (North American Dinosaurs)

Scientific american (September 2004)

Scientific american (November 2004)

Scientific American January 2004

Scientific american (March 2004)

Quantum Theory of Tunneling

Quantum Theory of Tunneling

North American P-51 Mustang

North American B-25 Mitchell

North American F-86 Sabre

North American B-25 Mitchell

North American AJ-1 Savage

North American FJ-1 Fury

North American B-25 Mitchell

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