earth pressures against an experimental retaining wall backfilled with silty clay

the measurement is described of the lateral soil pressures produced by the compaction of a silty clay backfill against a 2 metre high retaining wall. in addition to monitoring the soil pressures and the total vertical and horizontal thrusts acting on the wall, measurements of pore water pressure were made to establish the effective stress state of the soil fill. following completion of the filling operations, the conditions were maintained for several months to observe changes in pressure acting on the wall as a result of excess pore pressure dissipation. thereafter, active and passive failures of the soil were induced by rotating the wall about its toe. the investigation indicated that significantly higher lateral pressures were developed on the 2 metre high wall than could be created by the self weight of the soil fill. these high pressures were attributed to the influence of the compaction plant. the study also demonstrated that only a very small rotation of the experimental wall (approx 1/20 degree) was required to achieve the active state. the passive condition, which was investigated using 1 metre height of fill, required in excess of 7.5 degrees to mobilise the full passive resistance of the soil.(a)