近距离平行盾构施工数值模拟及影响因素分析

Numerical Simulation and Influence Factors Analysis of Close Distance Parallel Shield Construction

以某地铁项目为例,通过数值模拟,研究新建隧道近距离平行施工对既有隧道产生的影响,考虑了"先左孔后右孔"和"先右孔后左孔"两种施工工序,重点分析盾构施工中地层损失率、盾构顶推力和注浆情况的影响规律。结果表明,"先左孔后右孔"施工工序对地层位移和已建隧道管片的应力、应变影响较小,地层损失率越小,地表沉降量越小,产生的地表最大沉降量越小,地表沉降坡度越缓;盾构顶推力越大,地表沉降量越大,当掘进深度达到一定值后,地表沉降量逐渐减小,直至趋于稳定;注浆材料弹性模量越大,地表沉降量越小。

Taking a subway project as an example,through the numerical simulation,the influence of the close distance parallel construction of the new tunnel on the existing tunnel is studied,considering the two construction processes of first left hole,then right hole and first right hole,then left hole,and the analysis of the influence law of the ground loss rate,shield jacking force and grouting situation in the shield construction is focused on.The results show that the construction processes of first left hole,then right hole has little influence on the stratum displacement and the stress and strain of the tunnel segment,and the smaller the ground loss rate is,the smaller the surface subsidence.The smaller the maximum surface subsidence and the slower the slope of surface subsidence.When the tunneling depth reaches a certain value,the surface settlement gradually decreases until it tends to be stable.The larger the elastic modulus of grouting material is,the smaller the surface settlement is.