ASCE GSP 178-2008 GEOCONGRESS 2008 GEOSUSTAINABILITY AND GEOHAZARD MITIGATION.pdf

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1、 GEOTECHNICAL SPECIAL PUBLICATION NO. 178 GEOCONGRESS 2008GEOSUSTAINABILITY AND GEOHAZARD MITIGATION PROCEEDINGS OF SESSIONS OF GEOCONGRESS 2008 March 912, 2008 New Orleans, Louisiana SPONSORED BY The Geo-Institute of the American Society of Civil Engineers EDITED BY Krishna R. Reddy Milind V. Khire

2、 Akram N. Alshawabkeh Published by the American Society of Civil Engineers Library of Congress Cataloging-in-Publication Data Geocongress-2008 (2008 : New Orleans, Louisiana) Geosustainability and geohazard mitigation : proceedings of sessions of Geocongress 2008, sponsored by the Geo-Institute of t

3、he American Society of Civil Engineers March 9-12, 2008, New Orleans, Louisiana / edited by Krishna R. Reddy, Milind V. Khire, Akram N. Alshawabkeh. p. cm. - (Geotechnical special publication ; No. 178) Includes bibliographical references and index. ISBN 978-0-7844-0971-8 1. Environmental geotechnol

4、ogy-Congresses. I. Reddy, Krishna R. II. Khire, Milind V. III. Alshawabkeh, Akram N. IV. Title. TD171.9.G44 2008 628.4-dc22 2008001082 American Society of Civil Engineers 1801 Alexander Bell Drive Reston, Virginia, 20191-4400 www.pubs.asce.org Any statements expressed in these materials are those of

5、 the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publication to any specific method, product, process, or service constitutes or implies an endorsement, recommendation, or warranty there

6、of by ASCE. The materials are for general information only and do not represent a standard of ASCE, nor are they intended as a reference in purchase specifications, contracts, regulations, statutes, or any other legal document. ASCE makes no representation or warranty of any kind, whether express or

7、 implied, concerning the accuracy, completeness, suitability, or utility of any information, apparatus, product, or process discussed in this publication, and assumes no liability therefore. This information should not be used without first securing competent advice with respect to its suitability f

8、or any general or specific application. Anyone utilizing this information assumes all liability arising from such use, including but not limited to infringement of any patent or patents. ASCE and American Society of Civil EngineersRegistered in U.S. Patent and Trademark Office. Photocopies and repri

9、nts. You can obtain instant permission to photocopy ASCE publications by using ASCEs online permission service (http:/pubs.asce.org/permissions/requests/). Requests for 100 copies or more should be submitted to the Reprints Department, Publications Division, ASCE, (address above); email: permissions

10、asce.org. A reprint order form can be found at http:/pubs.asce.org/support/reprints/. Copyright 2008 by the American Society of Civil Engineers. All Rights Reserved. ISBN 978-0-7844-0971-8 Manufactured in the United States of America. Geotechnical Special Publications 1 Terzaghi Lectures 2 Geotechni

11、cal Aspects of Stiff and Hard Clays 3 Landslide Dams: Processes, Risk, and Mitigation 7 Timber Bulkheads 9 Foundations geoenvironmental engineering has continued to evolve as a discipline that bridges between engineering and basic sciences to address geo-specific environmental problems. It was imper

12、ative to organize GeoCongress 2008, March 9-12, 2008, in New Orleans, Louisiana to highlight recent advances, new directions and opportunities for sustainable engineering to protect the environment and infrastructure. The Congress attracted a significant number of papers and more than 400 were accep

13、ted. The papers were divided into three Geotechnical Special Publications (GSPs) that capture the multidisciplinary aspects and the challenges of the sustainability of the geoenvironment. The first GSP, Geotechnics of Waste Management and Remediation, tackles the challenges of sustainability in reme

14、diation and waste management, and covers topics on new and conventional remediation technologies, design and operational aspects of bioreactor landfills, innovations in design and assessment of covers and liners, management of mining wastes, and recycle and reuse of waste materials. The second GSP,

15、Geosustainability and Geohazard Mitigation, tackles the challenges of sustainability in geotechnics, and covers topics on education, sustainable materials and infrastructure, risk-based analysis and design, and impacts and mitigation of geohazards. viiThe third GSP, Characterization, Monitoring and

16、Modeling of GeoSystems, covers mechanical and chemical soil behavior, testing, and modeling. The GSP presents innovations on subsurface characterization and monitoring, characterization of rocks, problematic Soils and waste materials; and sensor technologies. Recent developments in numerical and com

17、putational geotechnics, emerging technologies, fate and transport modeling, uncertainty modeling, and micro- and environmental geo-mechanics are also covered in this GSP. The paper review process was managed by the editors and Paper Review Board. The review board had a very active and essential role

18、 in reviewing papers, organizing the conference sessions, and making the GSPs possible. The editors sincerely appreciate the help and patience of the Review Board. The editors also appreciate the help of Ms. Sheana Singletary of ASCE for her help in managing paper submissions and dealing with the gl

19、itches of the database. We hope that these GSPs will serve as valuable references to all working in geoengineering. Editors Krishna R. Reddy Milind V. Khire Akram N. Alshawabkeh viiiReview Board Tarek Abichou, Florida State University Murad Abu-Farsakh, Louisiana State University Gopal Achari, Unive

20、rsity of Calgary Jose Andrade, Northwestern University Ahmet Aydilek, University of Maryland Maria Claudia Barbosa, Universidade Federal do Rio de Janeiro Ronald Bell, hydroGEOPHYSICS, Inc. Craig Benson, University of Wisconsin-Madison Giovanna Biscontin, Texas A the enormous scale and complexity of

21、systems for hazard mitigation, both in space and in time, makes it difficultto achieve a high level of reliability.5. Dealing with uncertainty is a real challenge; physical factors and the role ofuncertainty in decision making are important considerations in how best toaccount for and represent unce

22、rtainty in hazard mitigation.6. Effective communication is essential in mitigating natural hazards; it isimportant that we reach out to and work with specialists who are experts incommunication.I use hurricane protection in New Orleans as a case history to illustrate anddemonstrate this framework.IN

23、TRODUCTIONAmerican Society of Civil Engineers Code of Ethics, Fundamental Canon #1:“Engineers shall hold paramount the safety, health and welfare of the public”Natural hazards, such as hurricanes, earthquakes and floods, can be catastrophic.More than 200,000 people died due to the 2004 tsunami in th

24、e Indian Ocean.Hurricane Katrina in 2005 caused thousands of fatalities, hundreds of billions ofdollars of property damage and the irreparable devastation of a major city. While1natural hazards cannot be prevented, the impact that these hazards have on the safety,health and welfare of the public can

25、 be mitigated.As civil engineers, we have a central role in mitigating the impact of naturalhazards. We are responsible for identifying the means available to mitigate theirimpact. These means can range from preventing impacts with natural and man-madebarriers to avoiding impacts with land-use and e

26、vacuation policies. We are responsiblefor assessing how much the possible means for mitigation will cost and how well theywill work. Finally, we are responsible for working with the owners, operators andusers to decide which mitigation means to use, how to implement them and how tomaintain and susta

27、in them. These decisions are the key to hazard mitigation.Our role is extremely challenging. It requires that we collaborate with numerousand varied disciplines beyond engineering: scientists to understand a hazard and hownatural and man-made systems will respond in the face of a hazard, sociologist

28、s tounderstand how people will respond to a hazard and to various means for mitigation,economists to understand costs and impacts, policy makers to understand how toimplement mitigation means, and communication specialists to understand how toengage the public in making and implementing decisions fo

29、r hazard mitigation. Itrequires that we interact with the owners and operators, which will generally be publicagencies and governmental bodies, and that we interact with the users, the public weare trying to protect. It requires that we participate in difficult decisions that directlyaffect the safe

30、ty, health and welfare of the public and that are constrained by limitedresources.OwnersOperatorsScientistsSociologistsPolicyMakersUsers(Public)EconomistsCommunicationSpecialistsEngineersFIG. 1. Central Role of Engineers as Leaders in Mitigating Impacts fromNatural Hazards (adapted from the Center f

31、or Creative Leadership)Our role in hazard mitigation requires that we be leaders, as representedconceptually in Figure 1. We need to be leaders in our own profession (the inner circlein Fig. 1). We need to be leaders among the disciplines that provide input andGEOCONGRESS 2008: GEOSUSTAINABILITY AND

32、 GEOHAZARD MITIGATION 2guidance to the decision makers and implementers (the middle circle in Fig. 1). And,we need to be leaders within the groups who will make, implement and be affected byhazard mitigation decisions (the outer circle in Fig. 1). Being a leader means that wetranscend boundaries and

33、 put ourselves at the center of these groups. Stepping up tothis role is our ethical responsibility and provides the true value of our profession tosociety.I present here a framework to guide engineers in fulfilling our central role andresponsibility in hazard mitigation. I will use the New Orleans

34、Hurricane ProtectionSystem as a case history to illustrate and demonstrate the main ideas. Backgroundinformation for this case history can be found at ASCE (2005), ASCE (2007), ILIT(2006) and IPET (2007). I feel that this case history is relevant because it underscoresthe significant challenges in e

35、ffectively mitigating natural hazards and because itcoincides with the venue for this conference. However, the framework is general andthe ideas are applicable to a variety of different natural hazards, locales, and means ofmitigation.DECISION MAKING IS KEYThe decisions about which mitigation means

36、to use, how to implement them andhow to maintain and sustain them are the key to hazard mitigation. Therefore, our rolein hazard mitigation should consistently be cast in the light of how decisions are goingto be made and implemented.Decision trees are useful tools for organizing, deliberating about

37、 and makingdecisions (Benjamin and Cornell 1970; Ang and Tang 1984). Decision trees structurethe basic components of a decision: alternatives, outcomes and consequences, asillustrated in Figure 2. The sequence of the limbs from left right indicates the order ofevents in the decision-making process.

38、Decision trees incorporate uncertainty in thatthe outcomes are not known with certainty. In the example in Figure 2, the decisionabout mitigation will be made before knowing whether or not a major hurricane willimpact the area in the next 50 years.Decision trees provide a common platform from which

39、all of the stakeholders (Fig.1) can collaborate. They prompt questions such as the following:What are all of the possible alternatives to mitigate natural hazards? How dothe possible alternatives interact with one another? For example, does thepresence of engineered barriers inadvertently lead to co

40、mplacency so thatevacuation is less effective? Do engineered barriers damage natural barrierssuch as wetlands?What is known about the occurrence and magnitude of the hazard? What isknown about how well an alternative will work? Will the performance of analternative change with time?What are the cons

41、equences associated with implementing an alternative andwith its performance? Which consequences are relevant to the variousstakeholders? Over what time horizon should consequences be considered 1 year, 50 years, 100 years?Decision trees can be expressed in any accessible language and they are commo

42、nlyused in a variety of different scientific, economic and public policy applications.GEOCONGRESS 2008: GEOSUSTAINABILITY AND GEOHAZARD MITIGATION 3Therefore, decision trees facilitate communication and collaboration with and amongthe decision makers, implementers and users.FIG. 2. Example Decision

43、Tree for New Orleans Hurricane Protection SystemDecision trees provide a framework for making decisions. For comparativepurposes, the value of a decision alternative is expressed in terms of the expectedconsequences associated with that alternative. The expected consequences represent aweighted aver

44、age of all the possible consequences listed on the right-hand side of thedecision tree (Fig. 2), where each possible consequence is weighted by its probabilityof occurrence:all i outcomesExpected Consequence ProbabilityConsequence for Outcome i for Outcome i= (1)To illustrate, Table 1 shows an examp

45、le set of calculations for the decision tree in Fig.2 using monetary cost as a measure of value. While illustrative, the quantitative valuesin Table 1 for consequences and probabilities are reasonable for the New OrleansHurricane Protection System. Improving the engineered barriers reduces theprobab

46、ility of major flooding, but does not protect life and property in the event that amajor flood occurs (Table 1). Conversely, improving evacuation reduces theconsequence of a flood if it occurs, but does not reduce the probability of a majorflood occurring. A comparison of expected consequences provi

47、des a practical andconvenient means for comparing the decision alternatives in the face of uncertaintyabout whether or not another major hurricane flooding event will occur in the next 50years. It also provides a theoretically sound and defensible means of comparison (e.g.,Benjamin and Cornell 1970,

48、 Kenney and Raiffa 1976, and Ang and Tang 1984).Improve EvacuationRaise and Armor Leveesand WallsAt Least One Major FloodingEvent in Next 50 Years due toHurricanesNo Major Flooding in Next 50Years due to HurricanesDecision NodeOutcome NodeConstruction and O we do it personally as individuals with li

49、feinsurance policies. For example, The Economist (2004) estimates the monetary valueplaced on a human life by society in the United States at about $7 million. While civilengineers tend to be uncomfortable with the idea of putting a quantitative value onhuman life, it is imperative that we deal with it explicitly, whether in monetary termsor some other measure such as utility (e.g., Kenney and Raiffa 1976). It is ourresponsibility to participate in and provide guidance to the difficult