MECHANICALLY STABILIZED EMBANKMENT CONSTRUCTED WITH LOW QUALITY BACKFILL. FINAL REPORT

This report presents the results of a three year evaluation of Mechanically Stabilized Embankment (MSE) constructed using low quality backfill (greater than 32% passing the #200 sieve). Four MSE walls were constructed in mid-1982 along Interstate 80 near Baxter, California, utilizing the clayey silt and clayey sand embankment available within the project limits. Two walls were instrumented to monitor stresses in the reinforcement, both horizontal and vertical movement, and lateral pressure on the wall face. The bid price for the MSE alternative was 12% lower than the reinforced earth walls and 15% lower than concrete crib walls. The lower cost is attributed to reduced excavation and on-site availability of backfill. Dummy bar-mats were buried in the backfill at various depths and pulled out a year later to deternmine pullout resistance values for various configurations. Laboratory pullout tests were conducted in a direct shear device using bar-mats with the same configurations. Pullout test results are compared. No definitive relationship exists between field, laboratory, or theoretical results; number of transverse bars and resistance; or resistance and overburden. The walls have performed well. Stresses measured in the reinforcement were distributed in a manner similar to expected distribution.