The Model Test about Over-Consolidated Soils’ Stress and Deformation as Water Pressure Increasing

Abstract

The main compression layer of Xi’an is over-consolidated. Based on the property, the physical model is designed as a steel cylinder which is 2.5m diameter,3m high. The soil layers are inter-bedded with silty clay and medium-fine sand. The consolidation pressure and overburden pressure is 295KPa. The process of soil deformation was simulated as the water recovering by increasing the water pressure in the medium-fine sand layer. Data monitoring test reveal that the deformation of the medium-fine sand layer and the silty clay layer is piecewise consequent，the consolidation will stop when the water pressure surpass a certain threshold value; During this test, the deformation of sand have the consistency with the variation of stresses in the medium-fine sand, but the deformation of the silty clay layer lagged to the variation of stress. The increase of water pressure in medium-fine sand cause compression pressure of others soil layers to increase. Based on the study of this test, we could predict that the land subsidence of Xi’an will not stop unless the confined water pressure surpasses the threshold value. What is more, we can reduce the subsidence through spasmodic pumping without cutback of pumping.