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利用有限元分析方法对盾构开挖对3×3群桩的沉降、变形及桩侧摩阻力的影响进行研究.当桩与隧道中心距离相同时,由于桩间土中附加应力叠加(群桩效应)的影响,隧道开挖引起的群桩中基桩的桩顶沉降大于单桩桩顶沉降;隧道开挖会引起群桩的竖向荷载在各基桩中重新分配,一般来说,中间桩的桩顶竖向荷载增加,边桩的桩顶竖向荷载减小;隧道开挖引起的群桩中各基桩的桩顶沉降主要取决于三个因素:基桩与隧道中心的距离、群桩效应的影响及基桩桩顶荷载的重分配;群桩基桩的水平位移主要取决于该基桩与隧道中心的距离,同时,由于承台的连接作用群桩中其它桩会增加或减小该基桩侧移;隧道开挖过程中桩侧摩阻力主要受到下面因素的影响:桩间土中附加应力叠加(群桩效应)、前排桩对中间桩及后排桩的桩侧摩阻力的保护(屏蔽效应)、桩顶荷载的重分配及桩身变形.
The influence of shield excavation on the settlement, deformation and pile-side friction resistance of 3 × 3 pile groups is studied by finite element analysis method. When the distance between pile and tunnel center is the same, Effect), the settlement of the top of the pile in the pile group caused by tunnel excavation is larger than that of the single pile. The tunnel excavation will cause the vertical load of pile group to be redistributed in each pile. Generally speaking, the middle The vertical load on the top of the pile increases and the vertical load on the top of the side pile decreases. The settlement of the top of each pile in the pile group caused by tunnel excavation mainly depends on three factors: the distance between the foundation pile and the tunnel center, The effect of pile group effect and the redistribution of pile top load; the horizontal displacement of group pile foundation pile mainly depends on the distance between the foundation pile and the center of the tunnel; at the same time, The lateral displacement of the foundation pile is reduced; the frictional resistance of the pile side during tunnel excavation is mainly affected by the following factors: additional stress superimposed on the soil between the piles (pile group effect), the front pile on the pile side of the middle pile and the rear pile Protection of friction (shielding effect), redistribution of pile top loads and pile body Shape.