| Land subsidence is geological environmental phenomenon due to the compression of upper soil. Land subsidence cause ground elevation slowly decrease, when serious it may become geological disasters. Xi'an has experienced land subsidence in 1950s.since then the ground fissures and land subsidence mutual influence and coincides due to superstitions of tectonic stress field and overdrawing ground water. By the beginning of this century, land subsidence and ground fissures has resulted economic losses of 40 billion Yuan and great harm to people's lives. Statistics show that most water head in aquifer become stable due to the diversion project implementation of Heihe River and tougher groundwater management. Water head in some areas have risen significantly. But there are no rebounds in some area even continuing compress and show large subsidence in these conditions. On one hand this phenomenon can be explain as the influence of construction and engineering activity, on the other hand, of the creep of sand aquifer.Based on the extensive collection data of land subsidence, this paper analysis pumping groundwater, tectonic movement, construction and other factors sequentially. and summarizing the major factors of land subsidence in Xi'an for testing design. The creep behavior of saturated sand of Xi'an aquifer is studied by high-pressure infiltration and consolidation system. The test results show that the sand deformation not only on the stress exerted on it but also the time elapses. Under certain effective stress, the deformation increase as time elapse. The paper analysis the creep curve of medium fine sand, and the results show that the creep behavior can be described by 5 components general Kelvin model. The 5 parameters of Kelvin model changed with stress and show some regularity. In this paper, the deformation of Xi'an medium fine sand is linked to the mechanism of Xi'an land subsidence. The plasity and creep characteristic is important factors of Xi'an land subsidence.
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