A new facility for measurement of earth pressure at-rest

To investigate the effect of stress-history on the earth pressure at-rest, an instrumented model retaining wall facility was developed at National Chiao Tung University. To achieve an at-rest condition, a stiff 1.6 m-high model wall and soil bin were made, so that the lateral wall deformation could be minimized. Soil-pressure transducers were attached to the center zone of the model wall to investigate the distribution of earth pressure. Air-dry Ottawa sand was used as backfill for the model wall experiments. The distribution of earth pressure at-rest induced by the 1.5 m thick loose backfill were approximately linear and in good agreement with Jaky's theoretical solution. For the pluviated fill, the measured coefficient of earth pressure at-rest, K_o would be independent of the thickness of backfill. Calculations based on the experimental data indicated that the resultant forces were located at 0.34H to 0.35H above the base of the wall. It is hoped that the NCTU non-yielding retaining wall facility would provide a powerful tool to examine and justify the results obtained from theoretical and numerical studies based of many different assumptions.