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.

The genesis of Xi’ an ground fissures and the recent activity characteristics and tendency have been introduced firstly. The architectural damage caused by ground fissures and current hazard prevention methods have been described secondly. The applications of a new material used in controlling underground engineering and coal mine disaster have been introduced. The mechanical properties of the new material have been stated also. As a result, a new foundation treatment method has been envisaged to make it possible to construct architectures on ground fissures.

An in-situ water injection test across Xi’ an ground fissures has been done, in order to simulate the activity of the fissures after water seeps, from October to December, 2005. According to the settlement observed of the bottom of testing pit, it is proven that the surface water seepage speeds the movement of ground fissures. Usually, the soil on the hanging wall of the fissures is more fragmentized than that on the footwall, which is propitious to water seepage. The seepage promotes the interaction between water and soil particles and brings about the differential settlement of two sides of fissures. Therefore, surface water seepage accelerates the activity of the ground fissures.