Assessing the Long-Term Performance of Mechanically Stabilized Earth Walls (2012) / Chapter Skim
Currently Skimming:
Pages 51-203
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 52... ...
Materials from FHWA's Wall Inventory Program
|
From page 55... ...
Materials from Nebraska Department of Roads
|
From page 125... ...
Materials from Ohio Department of Transpportation
|
From page 137... ...
Materials from Utah Department of Transportation
|
From page 138... ...
Example MSE Wall Evaluation Form (Plan/Drainage View and Cross-Section sheets not shown)
|
From page 143... ...
Abbreviations used without definitions in TRB publications: AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998)
|
From page 144... ...
TRANSPORTATION RESEARCH BOARD 2012 EXECUTIVE COMMITTEE* OFFICERS Chair: Sandra Rosenbloom, Professor of Planning, University of Arizona, Tucson Vice Chair: Deborah H
|
From page 145... ...
NAT IONAL COOPERAT IVE H IGHWAY RESEARCH PROGRAM NCHRP SYNTHESIS 437 TRANSPORTATION RESEARCH BOARD WASHINGTON, D.C. 2012 www.TRB.org Research Sponsored by the American Association of State Highway and Transportation Officials in Cooperation with the Federal Highway Administration SUBSCRIBER CATEGORIES Bridges and Other Structures • Highways • Maintenance and Preservation • Railroads Assessing the Long-Term Performance of Mechanically Stabilized Earth Walls A Synthesis of Highway Practice CONSULTANT Travis M
|
From page 146... ...
NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Systematic, well-designed research provides the most effective approach to the solution of many problems facing highway administrators and engineers. Often, highway problems are of local interest and can best be studied by highway departments individually or in cooperation with their state universities and others.
|
From page 147... ...
The National Academy of Sciences is a private, nonprofit, self-perpetuating society of distinguished scholars engaged in scientific and engineering research, dedicated to the furtherance of science and technology and to their use for the general welfare. On the authority of the charter granted to it by the Congress in 1863, the Academy has a mandate that requires it to advise the federal government on scientific and technical matters.
|
From page 148... ...
NCHRP COMMITTEE FOR PROJECT 20-05 CHAIR CATHERINE NELSON, Oregon DOT MEMBERS KATHLEEN S AMES, Michael Baker, Jr., Inc.
|
From page 149... ...
FOREWORD PREFACE By Jon M Williams Senior Program Officer Transportation Research Board Mechanically stabilized earth (MSE)
|
From page 150... ...
CONTENTS 1 SUMMARY 3 CHAPTER ONE INTRODUCTION Background and Objective, 3 Methods of Study, 3 Organization of Report, 4 5 CHAPTER TWO STATE OF MECHANICALLY STABILIZED EARTH WALL INVENTORY PRACTICE Introduction, 5 Parties with Responsible Charge for Mechanically Stabilized Earth Walls, 5 Agencies Having Inventories, 6 Nature and Scope of Inventories, 6 Constraints on Inventory Development and Asset Management Activities, 8 10 CHAPTER THREE COLLECTION OF MECHANICALLY STABILIZED EARTH WALL DATA Types of Data Contained in Wall Inventories/Databases, 10 Frequency of Field Inspections and Monitoring Activities, 16 Collection of Corrosion and Degradation Data, 16 20 CHAPTER FOUR ASSESSMENT AND USE OF MECHANICALLY STABILIZED EARTH WALL DATA Assessment and Interpretation of Data, 20 Use of Performance Assessments in Decision Making, 22 24 CHAPTER FIVE OUTCOMES AND LESSONS LEARNED Policies and Practices Developed to Improve Performance of Mechanically Stabilized Earth Walls, 24 Most Important "Lesson Learned", 25 27 CHAPTER SIX CONCLUSIONS Current State of Practice, 27 Direction of State of Practice, 27 Effective Practices, 28 Areas Needing Improvement and/or Research, 28 29 REFERENCES 31 APPENDIX A SURVEY QUESTIONNAIRE 43 APPENDIX B LIST OF SURVEY RESPONDENTS
|
From page 151... ...
45 APPENDIX C "MOST SIGNFICANT LESSON(S) LEARNED" AS REPORTED BY AGENCIES 47 APPENDIX D RESEARCH PROBLEM STATEMENT 49 APPENDIX E EXAMPLES OF EXISTING METHODOLOGY AND TOOLS DEVELOPED AND PROVIDED BY AGENCIES APPENDIX E IS WEB-ONLY AND CAN BE FOUND AT WWW.TRB.ORG, SEARCH ON "NCHRP SYNTHESIS 437." Note: Many of the photographs, figures, and tables in this report have been converted from color to grayscale for printing.
|
From page 152... ...
Mechanically stabilized earth (MSE) walls are an important class of infrastructure assets whose long-term performance depends on various factors.
|
From page 153... ...
2 responses is broad, certain topics appear more frequently than others, with the four most frequent being (in order of decreasing frequency) drainage, construction, backfill, and modular block issues.
|
From page 154... ...
3CHAPTER ONE INTRODUCTION BACKGROUND AND OBJECTIVE Mechanically stabilized earth (MSE) walls were introduced in the United States about 40 years ago (see Elias et al.
|
From page 155... ...
4 extensible and inextensible internal wall reinforcements are also considered. Although the current body of literature contains many descriptions and references to the monitoring and assessment of MSE walls, much of that literature relates to conditions existing during and immediately after construction.
|
From page 156... ...
5INTRODUCTION As with bridges and pavements, retaining walls are an essential component of our transportation infrastructure. However, unlike pavement and bridges, retaining walls (of which MSE walls are a growing subclass)
|
From page 157... ...
6 panel walls, two-stage panel walls, and block walls, respectively. The majority of panel walls possess metallic reinforcement.
|
From page 158... ...
7one could assign one, three, or six wall numbers to the MSE wall segments present at a bridge site. (There could be even more than six if additional walls segments were used to support the exterior sides of ramps.)
|
From page 159... ...
8 mation regarding maintenance does not appear to be systematically maintained by any party. CONSTRAINTS ON INVENTORY DEVELOPMENT AND ASSET MANAGEMENT ACTIVITIES During oral interviews with select survey participants, the participants frequently identified the lack of a government/ legislative directive along with the lack of allocated funding as significant impediments either to initially developing their MSE wall inventory or subsequently populating it with performance data from inspection activities.
|
From page 160... ...
9evaluation and inventory of its MSE walls out of corrosion concerns (Wheeler 2002)
|
From page 161... ...
10 At perhaps its most basic level, effective asset management consists of three components: (1) data collection; (2)
|
From page 162... ...
11 FIGURE 1 Element condition narrative guidance (DeMarco et al.
|
From page 163... ...
12 developing. The inspecting engineer describes the overall wall performance as ‘low,' providing appropriate narrative describing the state of global distress, and rates the wall performance at a ‘4' per the rating definitions.
|
From page 164... ...
13 • Joint spacing • Condition of "v-ditch" (i.e., drainage way at top of wall) • Coping deterioration • Drainage runoff • Drainage at the front of the wall.
|
From page 165... ...
14 Wall panels shall be checked for cracking, spalling, other forms of deterioration, and collision damage. • Drainage systems through or along MSE walls should be inspected to verify water is free flowing into and out of the appropriate facility.
|
From page 166... ...
15 Other examples of using new technologies to monitor the performance of MSE walls include the incorporation of fiber-optics into geosynthetic reinforcement (Lostumbo and Artieres 2011)
|
From page 167... ...
16 conducted "in the absence of any special condition or circumstance that makes it prudent to inspect more often")
|
From page 168... ...
17 thickness loss, as well as decreases in tensile strength. With electrochemical methods, potential and polarization resistance measurements are made and correlated with dimensions of the reinforcement.
|
From page 169... ...
18 State Description California Has been installing inspection elements with new construction since 1987, and has been perform ing tensile strength tests on extracted elements. Some electrochemical testing of in-service reinforcements and coupons has also been performed.
|
From page 170... ...
19 year intervals for a minimum of four retrievals, or one-third the expected life of the facility. The state of practice for assessing degradation and corrosion in MSE walls, as indicated by 14 survey participants who provided specific responses, is shown in Table 13.
|
From page 171... ...
20 After wall condition and performance data have been collected, assessments can be performed to determine how well MSE walls are meeting their performance objective(s)
|
From page 172... ...
21 Rating Description Excellent No significant indication of distress or deterioration. Good Some indications of distress or deterioration, but wall is performing as designed.
|
From page 173... ...
22 In addition to the relative importance of certain wall features and conditions, survey participants were also asked to rate how significant they thought certain potential failure/distress modes were relative to the long-term performance of MSE walls. The failure/distress modes were those typically considered in wall design procedures.
|
From page 174... ...
23 • Disruption of highway operations, including full or partial closure of the roadway, or appurtenant facilities; • Disruption of adjacent utility lines, such as water mains or electrical conduits; • Environmental consequences, such as damage to a significant wildlife habitat or blockage of a watercourse; and • Damage to cultural assets or sensitive land uses. Again, as outlined by Brutus and Tauber, the consequences of adverse wall performance or failure can be affected by: • The volume of earth retained by and otherwise contained in the wall, which in turn is most frequently reflected by the height of the wall; • The proximity of the wall ERS to the roadway or other potentially affected facilities or structures; • The intensity of usage of potentially affected facilities, such as traffic volume on a roadway or occupancy of a building; • The structural robustness of adjacent buildings and facilities; and • The vulnerability of occupants and/or users.
|
From page 175... ...
24 As MSE wall performance is monitored, assessments can be made regarding the adequacy of the wall's design, construction, and maintenance. These assessments can in turn be used to change practices and policies with the intent of improving wall performance, particularly for future walls.
|
From page 176... ...
25 now requiring production testing of MSE backfill stockpiles on-site rather than just at the material source. With respect to post-construction inspection, no new developments were reported beyond a few agencies that now make a complete inspection of the wall at the end of construction routine.
|
From page 177... ...
26 Lessons involving either MSE wall backfill or modular blocks accounted for about 14% and 10% of responses, respectively. With respect to backfill, one respondent replied, "Use of fine grained select fill has resulted in the migration of material out from behind walls.
|
From page 178... ...
27 Combining a literature review with a survey and interviews, this synthesis project has attempted to determine: • The current state of practice in assessing the performance of mechanically stabilized earth (MSE) walls, particularly in the long term; • The direction of the state of practice; • What the current and effective practices are; and • What areas need improvement and/or research.
|
From page 179... ...
28 In summary, current effective practices for inventorying and assessing the performance of MSE walls include: • Use of inventory and assessment systems with features that are as simple to use and as objective as reasonably possible • Use of rating criteria that are specific to particular wall elements and/or conditions • Use of numeric rating scales that correspond to other scales already in use for other asset classes such as bridges • Incorporation of MSE wall inventory and assessment systems together with systems for other asset classes. Current effective practices for improving the performance of MSE walls include: • Use of pre-approval process for wall design and/or wall supplier • Provision of adequate internal and external drainage.
|
From page 180... ...
29 REFERENCES AASHTO, Asset Management Data Collection Guide, AASHTO-AGC-ARTBA Task Force 45, AASHTO, Washington, D.C., 2006, 100 pp. Allen, T.M.
|
From page 181... ...
30 Walls, Berms and Slopes," GRI White Paper #19, Geosynthetic Institute, Folsom, Pa., 2011, 18 pp. Lostumbo, J.M.
|
From page 182... ...
31 APPENDIX A Survey Questionnaire
|
From page 194... ...
43 SURVEY RESPONDENTS (BY INDIVIDUAL) Ahmad, Ken; Foundation Engineer; Ontario, Ministry of Transportation (Ontario, Canada)
|
From page 195... ...
44 Tennessee Texas Utah Vermont Virginia West Virginia Wisconsin Wyoming Alberta, Canada New Brunswick, Canada Nova Scotia, Canada Ontario, Canada Saskatchewan, Canada Missouri Montana Nebraska Nevada New Hampshire New Mexico New York North Carolina North Dakota Oregon Puerto Rico South Carolina South Dakota
|
From page 196... ...
45 • "Use the right technology for the right application. For example, consider need and possibility to achieve various settlement/rigidity constraints and match service level to appropriate cost for application." • "Providing a sound and firm foundation for support of the wall; and providing proper drainage within the wall system and adjacent to the wall geometry." • "Performance depends on quality of construction and quality of retained backfill materials." • "Make sure the contractor is using the specified reinforced fill material and is constructing according to plans." • "By having a formal wall approval process we have limited the use of modular block wall systems and the deterioration of these facing elements due to deicing chemicals." • "The systems can last forever but must be designed and built correctly." • "Electrochemical property requirements for backfill material were not specified for one wall built in the late 70s.
|
From page 197... ...
46 • "None of our installations have reached an age where failure would be anticipated. To date, no significant performance issues have been identified." • "[ .
|
From page 198... ...
47 PROBLEM TITLE Prediction of Remaining Service Life for Mechanically Stabilized Earth (MSE) Walls RESEARCH PROBLEM STATEMENT There are an estimated 16.3 million square meters of various types of walls along the nation's highways (DiMaggio 2008)
|
From page 199... ...
48 Task 3: Apply the method in order to both calibrate and verify it against case histories and/or known performance data for particular groups of MSE walls. It is recognized that a rigorous assessment of the method's predictive ability by comparison with existing wall inventories will be limited by the availability of performance data as well as the ages of walls in our existing MSE wall inventories.
|
From page 203... ...
Abbreviations used without definitions in TRB publications: AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005) TCRP Transit Cooperative Research Program TEA-21 Transportation Equity Act for the 21st Century (1998)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.