深基坑开挖对临近高速公路影响及支护系统受力与变形研究

Research on influence of deep foundation pit excavation on adjacent expressway and stress and deformation of support system

由于城市基础建设的快速发展,出现了很多近邻高速公路的基坑,对基坑及近邻高速公路的变形控制提出了新的要求.为控制临近高速公路基坑施工变形与保证高速公路安全,根据某深基坑临近高速公路施工的工程概况、施工方法与加固措施,采用有限元方法考虑车辆荷载后建立三维数值模拟模型,系统性地分析了基坑开挖过程中及开挖后高速公路路面的位移、支护结构的位移及内力变化规律.结果表明:基坑开挖后高速公路路面呈现中间沉降、两侧隆起的现象,路面与支护结构均会发现偏向基坑方向的水平位移,支护结构会整体“上浮”,支护结构呈现出中间横梁受压、两侧横梁受拉且压力远大于拉力的现象,增加支护密度可以有效减小路面与支护结构位移.

The rapid development of urban infrastructure has led to the numerous foundation pits close to highways,posing new challenges for deformation control of both the foundation pits and the adjacent expressways.To ensure the safety of expressways adjacent to deep foundation pits,this study uses the finite element method to establish a three-dimensional numerical simulation model considering the vehicle load based on the project overview,construction methods,and reinforcement measures of a deep foundation near an expressway.Then the displacement of the highway pavement,the displacement and the internal force of the supporting structure during and after the excavation were systematically analyzed.The results reveal that there is a phenomenon of uplift on both sides of the middle settlement.The horizontal displacement of the pavement and supporting structure towards the direction of the foundation pit is found,and the supporting structure present a“float up”as a whole.The middle beams of the supporting structures are under compression,while the side beams are under tension,with the compressive forces significantly exceeding the tensile forces.Increasing the supporting density can effectively reduce the displacement of both the pavement and the supporting structure.