Stress and Strain Monitoring of Reinforced Soil Test Wall

Abstract

Stresses and strains were measured in a full-scale reinforced test wall constructed to evaluate the design procedure and performance of geosynthetic-reinforced walls constructed with silty-clay backfill over a soft foundation. The measurements consisted of monitoring wall deformation, setlement, strains along the reinforcement, vertical and horizontal stresses, and pore water pressure under the wall. The instrumentations and measurements of wall deformation, soil stresses, and reinforcement strains during and after construction are presented. The wall consisted of three sections reinforced with various geogrid types and spacing. The first section was built with closely spaced, low-strength geogrid. The second section was constructed by using higher strength geogrid at a maximum vertical spacing. The reinforcement and spacing of the third section were based on standard design procedures. Deformations along the reinforcement were monitored with strain gauges. The magnitudes and distributions of the strains varied in the three wall sections. The strains were used to predict the reinforcement loads and stresses in the reinforced soil system. The concept of normalizing reinforcement stress was useful in defining the relative "rigidity" of the wall and in determining the horizontal stress coefficient of the wall. The locus of maximum stresses in the reinforcement did not correspond to the (45 + ϕ/2) line and varied according to the reinforcement rigidity. A comparison was made between the measured and predicted maximum tensile loads in the reinforcements. The results indicated that the loads predicted by the Ko-stiffness method were closer to the measured loads than those predicted by the AASHTO simplified method.