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Mechanically stabilized earth (MSE) walls have been increasingly utilized in the United States since 1972 and in Texas since 1979. MSE walls provide earth retention for commercial, industrial and transportation projects throughout Texas. Within the transportation industry, the traditional design life of MSE walls is 75 years, with new projects requiring 100 year design life. The millions of square feet of existing MSE walls are generally less than half of the anticipated design life, making identifying and assessing the existing wall inventory a significant asset management component for optimizing maintenance expenditures. This thesis proposes and applies a system that assesses and rates MSE walls based on as-built design assessment, physical condition, safety impacts, and owner defined elements. The program developed in this thesis has been generally tailored to application in transportation infrastructure with MSE walls having greater than two years of service, founded in and retaining both cohesive and cohesionless soils.
"Mechanically stabilized earth (MSE) walls are an important class of infrastructure assets whose long-term performance depends on various factors. As with most all other classes of assets, MSE walls need periodic inspection and assessment of performance. To date, some agencies have established MSE wall monitoring programs, whereas others are looking for guidance, tools, and funding to establish their own monitoring programs. The objective of this synthesis project is to determine how transportation agencies monitor, assess, and predict the long-term performance of MSE walls. The information used to develop this synthesis came from a literature review together with a survey and interviews. Of the 52 U.S. and 12 Canadian targeted survey recipients, 39 and five, respectively, responded. This synthesis reveals that unlike bridges and pavements, MSE walls and retaining walls in general are often overlooked as assets. Fewer than one-quarter of state-level transportation agencies in the United States have developed some type of MSE wall inventory beyond that which may be captured as part of their bridge inventories. Fewer still have the methods and means to populate their inventories with data from ongoing inspections from which assessments of wall performance can be made. In the United States, there is no widely used, consistently applied system for managing MSE walls. Wall inventory and monitoring practices vary between agencies. This synthesis examines existing practices concerning the nature, scope, and extent of existing MSE wall inventories. It also examines the collection of MSE wall data, including the types of performance data collected, how they are maintained in wall inventories and databases, the frequency of inventory activities, and assessment practices relevant to reinforcement corrosion and degradation. Later parts of this synthesis discuss how MSE wall performance data are assessed, interpreted, and used in asset management decisions. This synthesis finds that the most well-implemented wall inventory and assessment system in the United States is the Wall Inventory Program developed by FHWA for the National Park Service. However, this system, like some others, uses 'condition narratives' in a process that can be somewhat cumbersome and subjective. Other systems use more direct numeric scales to describe wall conditions, and an advantage of such systems is that they are often compatible with those used in assessments of bridges. As experience with MSE walls accumulates, agencies will likely continue to develop, refine, and better calibrate procedures affecting design, construction, condition assessment, and asset management decisions. One portion of this synthesis is dedicated to summarizing the actions taken thus far by survey respondents to improve the long-term performance of their MSE walls. Many agencies prescribe the use of a pre-approved wall design and/or wall supplier. Other actions or policies frequently focus on drainage-related issues."--Summary.
The first book to provide a detailed overview of Geosynthetic Reinforced Soil Walls Geosynthetic Reinforced Soil (GRS) Walls deploy horizontal layers of closely spaced tensile inclusion in the fill material to achieve stability of a soil mass. GRS walls are more adaptable to different environmental conditions, more economical, and offer high performance in a wide range of transportation infrastructure applications. This book addresses both GRS and GMSE, with a much stronger emphasis on the former. For completeness, it begins with a review of shear strength of soils and classical earth pressure theories. It then goes on to examine the use of geosynthetics as reinforcement, and followed by the load-deformation behavior of GRS mass as a soil-geosynthetic composite, reinforcing mechanisms of GRS, and GRS walls with different types of facing. Finally, the book finishes by covering design concepts with design examples for different loading and geometric conditions, and the construction of GRS walls, including typical construction procedures and general construction guidelines. The number of GRS walls and abutments built to date is relatively low due to lack of understanding of GRS. While failure rate of GMSE has been estimated to be around 5%, failure of GRS has been found to be practically nil, with studies suggesting many advantages, including a smaller susceptibility to long-term creep and stronger resistance to seismic loads when well-compacted granular fill is employed. Geosynthetic Reinforced Soil (GRS) Walls will serve as an excellent guide or reference for wall projects such as transportation infrastructure—including roadways, bridges, retaining walls, and earth slopes—that are in dire need of repair and replacement in the U.S. and abroad. Covers both GRS and GMSE (MSE with geosynthetics as reinforcement); with much greater emphasis on GRS walls Showcases reinforcing mechanisms, engineering behavior, and design concepts of GRS and includes many step-by-step design examples Features information on typical construction procedures and general construction guidelines Includes hundreds of line drawings and photos Geosynthetic Reinforced Soil (GRS) Walls is an important book for practicing geotechnical engineers and structural engineers, as well as for advanced students of civil, structural, and geotechnical engineering.
This book gathers selected proceedings of the annual conference of the Indian Geotechnical Society, and covers various aspects of soil dynamics and earthquake geotechnical engineering. The book includes a wide range of studies on seismic response of dams, foundation-soil systems, natural and man-made slopes, reinforced-earth walls, base isolation systems and so on, especially focusing on the soil dynamics and case studies from the Indian subcontinent. The book also includes chapters addressing related issues such as landslide risk assessments, liquefaction mitigation, dynamic analysis of mechanized tunneling, and advanced seismic soil-structure-interaction analysis. Given its breadth of coverage, the book offers a useful guide for researchers and practicing civil engineers alike.
Creating a more efficient reinforcement for Mechanically Stabilized Earth (MSE) Walls is important because it will reduce the amount of material needed to construct MSE walls, and will reduce overall construction costs for companies and contractors. This thesis explores four main geometries of metallic crimped and metallic crossbar type reinforcement constructed with both, smooth steel and #4 rebar steel. Metal round bar was chosen because, compared to metallic rectangular strip reinforcements, there is less surface area in contact with the soil which will then reduce the amount of corrosion loses. Throughout testing, it was found that crimped metal round bar was able to produce the required pullout resistance but created too much extensibility (the amount of length the crimps straightened). The reinforcement made with crossbars and metal round bar were found to produce the required amount of pullout resistance with little to no extensibility.