Information for lesson "A Data Base and Analysis of 171 Failed MSE Walls Using Geosynthetic Reinforcement - Dr. Robert Koerner - 1.5 PDH"
Description: Mechanically stabilized earth walls, berms and slopes with geosynthetic reinforcement have been developed since the 1970’s; first with geotextiles and then geogrids. Our estimate is that approximately 50,000 exist and the technology is utilized worldwide. Unfortunately, there have been many failures; some with excessive distortion while others have actually collapsed in whole or part. The main statistical findings of the 171 case histories that we have on file are as follows:
1. 96% were privately owned walls 2. 78% were in North America 3. 71% were masonry block faced (i.e., SRWs) 4. 65% were 4 to 12 m high 5. 91% were geogrid reinforced (the others were geotextiles) 6. 86% failed in less than four years 7. 61% used silt and clay backfill soils 8. 72% had poor to moderate compaction 9. 98% were caused by improper design or construction; none (0%) were geosynthetic manufacturing failures 10. 60% caused by internal or external water (i.e., the remaining 40% were caused by soil related issues)
Details of this data set will be described and from it four salient features will be discussed in detail; (i) fine grained soil backfills, (ii) compaction of these same soils, (iii) routing of internal drainage systems, and (iv) surface and adjacent water control. Concluding comments will include specific recommendations to designers and contractors alike.
(i) Understand the idiosyncrasies of MSE structures (ii) Learn about the major circumstances of failures (iii) Learn the significance of soil issues vis-à-vis water issues (iv) Learn of the various weaknesses of soil issues and water issues insofar as failures are concerned (v) Learn about four specific issues which are involved in most of the failures (vi) Understand the negative implications that this large group of failures has on the credibility of the technology and on everyone involved in it
Owners of MSE walls, berms and slopes in both the public and private sectors; federal, state and regional geotechnical, transportation, and environmental engineers; engineers from municipal districts and townships; private and municipal land developers, architectural and landscape designers; general civil consulting engineers; testing laboratories servicing these organizations; manufacturers and representatives of geosynthetic materials; contractors and installers of MSE walls, berms and steep soil slopes; academic and research groups; and others desiring technically related information on this important aspect of our constructed infrastructure.
Specific Topics Covered
1. Introduction and Background 2. GSI’s Involvement in Gathering Data 3. The Two Failure Classifications 4. Main Statistical Findings 5. Design and Construction Issues 6. Summary Comments
Objectives: Participants will become familiar with details of geosynthetic reinforced MSE structures. Different modes of failure (deformation versus collapse) will be illustrated. These 171 failures will be categorized insofar as soil related versus water related along with the primary accompanying details. This webinar will hopefully lead to mitigating the large number of current failures in the future.