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承压水降压引起的地面沉降由含水层、弱透水层和潜水层的变形组成。当承压层降压时间短、弱透水层固结变形较小时,可以假设弱透水层为严格的隔水层。采用层状弹性体系理论,基于位移协调条件分别建立了单井抽水以及第三类基坑工程降水(隔水帷幕插入降水含水层)引起的土层变形分析模型,与数值模拟和现场抽水试验结果的对比,验证了文中方法的正确性。研究结果表明,上覆土层弹性参数变化对地表变形的影响可以忽略;抽水井附近的土层变形呈现“上小下大”特点,一定距离以外含水层与地面沉降大致相等,根据承压含水层降深要求,可估算出基坑外的水位降深。
Ground subsidence caused by pressure water pressure relief consists of the deformation of aquifers, aquitards and submersion layers. When the pressure bearing layer buckling time is short, the deformation of the weak aquitard deformation is small, we can assume that the impermeable layer is a rigid impermeable layer. Based on the theory of layered elastic system, the model of soil deformation caused by single-well pumping and the third type of foundation pit dewatering (water curtain insertion into precipitation aquifer) was established based on the displacement coordination conditions. The numerical simulation and field pumping test results The comparison verifies the correctness of the method in this paper. The results show that the influence of the change of soil elastic parameters on the deformation of the ground surface can be neglected. The deformation of the soil near the pumping wells shows the characteristics of “small upper and lower big”, and the aquifer is approximately equal to the ground subsidence at a certain distance. Depletion of aquifers requires a reduction of water level outside the foundation pit.