复合成层地层盾构隧道施工引起土体变形计算研究

Calculation of soil deformation caused by construction of shield tunnels in composite layered strata

为解决盾构上部多层水平覆土且开挖面内上下水平分层的复合地层条件下盾构施工引起的土体变形问题,在统一土体解析解法的基础上对其中土质条件影响参数进行修正,使其可以进行复合地层条件下的土体变形计算,并对土体移动焦点范围进行了重新的划分。将修正后的统一土体解析解法与类随机介质理论相结合,得到可以解决盾构开挖面上存在多种土层情况的计算方法,并且可适用于任意开挖面形状的盾构施工。研究结果表明:经过多组工程案例验算,验证了方法的可行性;开挖面上某一土层厚度等量增加会使土体变形发生非线性变化;由于土体损失比变形传递路径对土体变形的影响更大,相同洞径比下的土体变形可能存在差异。

In order to solve the problem of soil deformation caused by shield construction under the condition of multi-layer horizontal soil covering on the upper part of the shield and the upper and lower horizontal layers in the excavation face,on the basis of the unified analytical method for soils,the influence parameters of soil conditions are modified so that the soil deformation can be calculated under composite strata,and the focus range of soil movement is re-divided.By combining the modified unified soil analytical method with the analogous stochastic medium theory method(ASMTM),a method can be obtained to solve the problem of multiple soil strata on the shield excavation surface,and can be applied to the shield construction with any shapes of excavation surface.The results show that the feasibility of the proposed method is verified through several engineering cases.The nonlinear change of soil deformation occurs when the thickness of a certain soil layer increases by the same amount.Since the soil loss has more influences on the soil deformation than the deformation transfer path,the soil deformation may be different under the same cavity diameter ratio.