Experimental retaining wall facility - lateral stress measurements with sand backfill

as part of the trrl research programme to investigate soil-structure interaction, a pilot scale earth retaining wall has been built at the laboratory sufficiently large to avoid any scale effects influencing the results and to enable normal construction methods to be used. this report describes the experimental retaining wall and its facilities and gives details of the initial experiments to measure the lateral soil pressures produced by compaction of a washed sand, and the active and passive pressures produced when the wall was moved away from and into the soil respectively. the experimental evidence shows that the residual earth pressures produced by the compaction of sand behind a rigid retaining wall was significantly higher than would be expected from the self-weight of the soil alone. however, only very small movements (< 4mm) of the test wall away from the soil were sufficient to reduce the earth pressures to the active condition for a fill height equivalent to 3.4 metres. a study of the passive case showed that a peak lateral thrust occurred on a metre high test wall after a movement of about 25mm of the wall into the soil. (a)