盾构近接立交桥基础安全影响三维数值分析

摘要

To improve the safety of shield tunneling construction crossing the group piles foundation of adjacent overpass, a three-dimensional numerical model was established by using the finite element method to simulate the crossing process of shield tunneling dynamically.The variation in the horizontal displacement of group piles foundation and the deformation of ground surface influenced by shield tunneling were analyzed.The results showed that the shield tunneling has the greatest influence on the horizontal displacement of pile foundation.The growth process of horizontal displacement can be divided into three stages, including before shield tunneling reaching, during crossing and grouting, and the ratio of horizontal displacement in the three stages is 6:3:1.The influence range of shield tunneling on the horizontal displacement of pile foundation in the vertical direction is 1D (shield diameter), which is 3D in the horizontal direction.Additionally, due to the dual influence of soil layer and pile foundation settlement, the bridge structure between the left and the right side of shield tunneling behaves a larger displacement.The monitoring of bridge structure in this region should be strengthened in the actual construction.%为了提高盾构近距离穿越立交桥群桩基础施工中的安全性,采用有限元方法建立三维数值模型对盾构穿越群桩基础过程进行动态模拟,分析了群桩基础水平位移的变化规律以及地表受盾构影响的变形规律.结果表明:盾构掘进对桩基础水平位移影响最大,且水平位移增长过程分为盾构到达前、穿越时以及注浆阶段3个阶段,3个阶段水平位移值比例为6∶3∶1;盾构在竖直方向对桩基础水平位移的影响范围为1D(盾构直径),水平方向为3D;此外,处于盾构左右双线之间的桥梁结构由于受到土层和桩基础沉降的双重影响,会产生较大的位移,实际施工中建议加强该区域桥梁结构的监测.