盾构下穿既有群桩基础受力特性数值分析

发布时间：2019-03-16 11:17

【摘要】：基于天津地铁7号线盾构近距离穿越立交桥群桩基础工程,建立三维有限元模型对盾构施工穿越群桩基础过程进行动态模拟,对群桩基础的轴力、剪力、弯矩和桩侧摩阻力随盾构开挖的变化规律进行了分析。结果表明,盾构穿越桩基础过程会导致邻近桩基础在盾构深度区域产生较大的轴力、剪力与弯矩。其中,轴力的增大集中在盾构到达前、穿越时与注浆3个阶段,产生的轴力比值为1∶4∶1;剪力与弯矩的变化发生1 D(盾构直径)深度范围内,且在垂直于盾构方向造成的影响远大于盾构掘进方向;盾构开挖后,盾构中心线深度以上的桩基础承受随桩深度减小的桩侧负摩阻力,导致群桩基础的承载力减小,桩基础处于较不利的受力状态。
[Abstract]:Based on Tianjin Metro Line 7 Shield Group pile Foundation Project, a three-dimensional finite element model is established to simulate the dynamic process of shield construction through pile group foundation, and the axial force and shear force of pile group foundation are analyzed. The variation law of moment and pile side friction with shield excavation is analyzed. The results show that the process of shield crossing pile foundation will cause the adjacent pile foundation to produce larger axial force, shear force and bending moment in the shield depth region. Among them, the increase of axial force is concentrated before the arrival of shield, crossing time and grouting three stages, the ratio of axial force to axial force is 1 ~ 4 ~ 1; The variation of shear force and bending moment occurs in the depth range of 1 D (diameter of shield), and the influence on the direction perpendicular to the shield is much greater than that in the direction of shield tunneling. After shield excavation, the pile foundation above the center line depth of shield machine bears negative friction resistance on the pile side with the decrease of pile depth, which leads to the reduction of bearing capacity of pile group foundation, and the pile foundation is in a disadvantageous state of force.
【作者单位】：长安大学公路学院;中铁第一勘察设计院集团有限公司;
【基金】：陕西省科技厅社会发展科技攻关项目,项目编号2016SF-412 陕西省科技统筹创新工程计划项目,项目编号2015KTZDGY01-05-02
【分类号】：U455.43

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