基坑抽水引起周围地面沉降机理及防治措施

抽水引起周围地面沉降和构筑物地基沉降已成为工程建设中的一个环境灾害问题。根据抽水引起周围地面沉降的机理分析，提出了由抽水引起地下水水头压力变化、含水层颗粒迁移、含水层压缩和水体的膨胀的更具普遍意义的地下水运动方程，该方程可以简化成Biot和Helm的地下水运动方程。在此基础上，通过实例分析和方案对比，提出了抽水引起周围地面沉降的防治措施，并分析了各种措施的适用范围及优缺点。

Mechanism analysis of land subsidence due to groundwater withdrawal and control measures

The land subsidence and the construction’s foundation subsidence caused by groundwater withdrawal from deep foundations are the environmental disaster problems in city construction. When groundwater is pumped from a confined aquifer, groundwater level decline will lead to increase effect stress and motion of solid grain in soil layer. Accordingly, it takes place land subsidence. According to this mechanism analysis of land subsidence, a groundwater movement equation considering water expansion, aquifer compressibility and solid grain movement due to groundwater pressure decline is established. It also can be found that Biot’s and Helm’s formula are the special case or the simple mode of the groundwater movement equation. The proposed equation is applied to analyze and calculate land subsidence in foundation engineering. The result indicates the presented groundwater movement equation can efficiently explain the mechanism of land subsidence. Through analysis of alternatives, several control measures are proposed such as waterproof wall, local pumping well, unsymmetrical well group, and small pumping rate.