During a significant two-day rain event a large portion of a Mechanically Stabilized Earth (MSE) wall supporting a shopping center in Nashville, Tennessee, completely failed. The MSE wall varied in height up to 30 feet and supported an asphalt drive that was within several feet of the existing structure. The failure collapsed most of the asphalt drive and jeopardized the shopping center structure’s foundation. The failure was a result of poor MSE wall backfill and inadequate surface drainage above the wall. The MSE wall was constructed using a lean to fat clay with sand (phosphate) and silt. Additionally the wall was founded on 10 to 20 feet of poor quality clay underlain by a zone of extensively weathered limestone with intermittent and random small to large voids.
A competitively bid Design-Build RFP was advertised to a handful of geotechnical contractors who submitted cost-proposals utilizing various technologies for completing this repair. Due to their low cost, rapid mobilization, and the high factor of safety inherent in their design, all phases of stabilization effort were ultimately awarded to GeoStabilization International®’s Design-Build team. This work included all engineering as well as constructing stabilization systems for the existing slope, commercial structure, portions of MSE wall that were still standing, GCS™ services for building the wall, and providing SuperMicropile™ foundation improvements for the stability of the newly constructed wall.
A rockfall event occurred along a section of Interstate 70 in CO. A large boulder fell onto the westbound lane, destroying the guardrail, before landing on the eastbound lane below.