地下公共车行通道基坑支护的设计与施工

Design and Construction of Foundation Pit Support for Underground Public Car Channel

摘要:

基于实例横琴新区国际居住区的地下公共车行通道，分析了通道基坑施工面临的难题，采用岩土理正及MIDAS/GTS软件，按照基坑实际的支护情况进行了三维建模，根据实际的开挖工况进行了相应的模拟计算。对数值模拟结果进行分析，与实际的监测数据进行对比验证，为钻孔灌注桩和内支撑支护体系的可靠性提供了验算和证明。当土体开挖后，土体变形主要是朝开挖后的临空面方向运动。当开挖深度较小时，土体变形量较小。基坑的不断开挖导致土体朝着临空面方向的变形也不断增大，且逐渐呈现出中间变形大，其中变形量最大的部位，靠近基坑底部，这与内支撑结构土体的变形特征是一致的。土体的最大水平位移约为14.98 mm，远远小于最大允许值39.52 mm，说明支护后的基坑处于一个安全稳定的状态。通过对基坑方案中SMW工法支护和沉井支护进行设计，对基坑支护设计及关键施工工艺进行分析，对基坑施工中的监测工艺进行研究，可对类似工程项目提供一定的借鉴意义。

Abstract:

With the advancement of subway construction and urban development, the factors affecting the safety of subway structure are increasing. The complication of the influencing factors makes the subway management departments control all aspects more strictly. The appropriate measures should be taken to reduce or eliminate the impact of road construction on the safety of subway structure in the construction of the roads above subway. As a kind of light material layer, the foamed concrete is widely used in filling subgrade above the rail traffic structure. However, the foamed concrete can no longer be used as the filling material above the rail traffic structure under the complicated conditions due to its high water absorption after construction. To solve related problems, EPS as light weight material is used to replace the equivalent load subgrade of the new road above the subway in this project. By summarizing the design experience, it is hoped to provide reference for the scheme selection and design of other related projects.