Plate load tests on unsaturated clayey sand subjected to drying-wetting processes

The results of plate load tests on unsaturated clayey sand are given. The samples are subjected to different drying-wetting processes. It is shown that the bearing capacity under an unsaturated condition is much larger than that under a fully saturated condition. Different drying-wetting processes result in different ultimate bearing capacities even when the water tables are on the same level. Suction and degree of saturation at different depths are measured, and the influences of drying-wetting processes on the bearing capacity are analyzed by the locations of hydraulic states on the soil-water characteristic curve. An equation for the bearing capacity of ununiformed distributed suction profiles is proposed. The bearing capacity calculated using this equation agrees well with the test results. This study shows that the influences of suction and drying-wetting processes should be considered in the foundation design and interpretation of the results of plate load tests on unsaturated clayey sand.