An extended data base and recommendations regarding 320 failed geosynthetic reinforced mechanically stabilized earth (MSE) walls

In 2013, the authors wrote a paper which was published in the Journal of Geotextiles and Geomembranes on the failure of 171-mechanically stabilized earth (MSE) walls reinforced with geotextiles or geogrids, Koerner and Koerner (2013). The paper generated many reprint requests via both the publisher and the authors, and it won the best paper of the year award. Furthermore, it generated considerable awareness of the situation and generated additional case histories while providing details of such failures. Presently, we have 320 failures which are reported in this paper. The database includes 99 cases of excessive deformation and 221 cases of collapse of at least part of the respective walls. The main statistical findings (including the original 171 failures) are as follows: 1. 313 (98%) were private (as opposed to public) financed walls. 2. 253 (79%) were located in North America; the vast majority being in the U.S. 3. 240 (75%) were masonry block faced. 4. 226 (71%) were 4-12 m high. 5. 301 (94%) were geogrid reinforced; the other 6% were geotextile reinforced. 6. 246 (77%) failed in less than four years after their construction (12 of which actually failed during construction). 7. 232 (73%) used silt and/or clay backfill soils in the reinforced zone. 8. 245 (76%) had poor-to-moderate compaction. 9. 317 (99%) were caused by improper design or construction (incidentally, none were caused by geosynthetic manufacturing material failures). 10. 201 (63%) were caused by internal or external water (the remaining 37% were caused by soil related issues). While the number of reported walls in this paper is almost double the number reported in 2013, the change in percentages of the above items is relatively small with the notable exceptions of walls failing in longer time intervals (by 9%) and even greater use of fine grained backfill soils (by 12%). As with the original paper, updated opinions and recommendations in several of the above listed areas are presented. Also, several new types of failures are reported, such as guard fence instability and soil erosion at the toe of the wall. However, the overall critical issues continue to occur and no lessening of failures is apparent with this new set of data. The critical issues are the following; fine grained silt and clay soils continue to be used for the reinforced zone backfill. poor placement and compaction of these same fine grained backfill soils is regularly reported. drainage systems and utilities continue to be located within the reinforced soil zone. there is little attempt at water control either behind, beneath or above the reinforced soil zone, and. design details appear to be inadequate or not followed by the installation contractor. While the issues reported in 2013 did indeed prompt the initiation of an inspector's certification program (Geosynthetic Certification Institute - Inspector Certification Program) it has not been very successful and has attracted only 24-participants to date. Hopefully this updated paper will energize the parties involved and the MSE reinforced wall community at large to take appropriate action in correcting the situation described herein.