内撑式地连墙变形特征及其参数优化研究

随着国内深基坑工程的不断发展,越来越多的基坑支护形式被提出并得到了广泛的实践,为了保证基坑工程的安全,限制基坑变形与保护周边环境,选用适当的支护形式与支护参数显得尤为重要。本文依托广州新白云国际机场第二高速公路北段暗埋隧道深基坑工程,采用有限差分软件FLAC^3D建立数值模型,取地连墙厚度、地连墙入土深度、横向支撑布置形式3个变量,探讨了不同支护参数取值对内撑式地连墙支护结构中地连墙侧向位移和支撑轴力分布的影响,提出合理的支护参数取值建议与优化效果。结果表明,基坑存在明显的坑角约束作用,限制坑角地连墙侧移与支撑轴力;地连墙整体侧移在地连墙厚度0.6~0.8 m时明显较大,且由于刚度不足出现反弯点;地连墙底部嵌固作用可有效限制侧移量,地连墙侧移随开挖深度变化曲线呈现“中间大,两头小”的抛物线形状;将支撑整体下移2 m,可有效减小墙体最大侧移,改善支护效果。

Research on Deformation Characteristics and Parameter Optimization of Diaphragm Wall with Interior Bracing Structure

With the continuous development of deep foundation pit engineering in China, more and more foundation pit supporting forms have been proposed and widely practiced. In order to ensure the safety of foundation pit engineering, limit the deformation of foundation pit and protect the surrounding environment, it is particularly important to select appropriate supporting forms and supporting parameters. In this paper, based on the northern section of Guangzhou New Baiyun International Airport Highway No.2 dark buried tunnel deep foundation pit engineering, the finite difference software FLAC^3D numerical model was set up, taking wall thickness, buried depth, and horizontal support as three variables, to discuss the variation of the lateral displacement of the wall and supporting axial force distribution. The reasonable value of support parameters and optimization results were proposed. The results show that the foundation pit has obvious angle constraint, which limits the lateral movement of the ground connecting wall and the axial force of the support. When the thickness of the ground connecting wall is 0.6m~0.8m, the overall lateral movement of the ground connecting wall is obviously larger, and the reverse bending point occurs due to insufficient stiffness. The bottom of the wall can be fixed to limit the lateral movement. The curve of lateral movement of the wall with the depth of excavation presents a parabolic shape of “big in the middle, small at both ends”. Moving the overall support down 2 m can effectively reduce the maximum lateral movement of the wall and improve the supporting effect.