Measured and predicted loads in steel strip reinforced c−ϕ soil walls in Japan

More than 30,000 steel strip reinforced soil walls have been built in Japan since their introduction in the early 1970s. The current Japanese method of computing tensile loads in the reinforcement strips is based on the Coherent Gravity Method first developed in France more than three decades ago. At that time, the method was calibrated against measured loads from seven instrumented structures based on soil friction angles in the range of 35–46°. In Japan, however, there are many reinforced soil walls that have been built successfully using cohesive-frictional soils with fines contents as high as 35% and lower friction angles. The present paper uses the results of load measurements from 18 instrumented wall sections, reported previously in the literature, and nine instrumented Japanese walls to examine the prediction accuracy of the Coherent Gravity Method described in the Public Works Research Center (2003) guidelines. The current design chart for the coefficients of earth pressure, used to compute tensile reinforcement loads, is empirically adjusted for soil backfills falling into three different friction angle ranges. The new design chart is calibrated to satisfy an average load exceedance level that matches the value adopted when the Coherent Gravity Method was first calibrated.