考虑渗流影响的深基坑开挖模拟与监测分析

Simulation and monitoring analysis of deep foundation pit excavation under seepage condition

某专业化煤炭码头翻车机房圆形深基坑地下水位较高且临近办公楼,基坑开挖安全需着重考虑地质条件、地下水位及周边环境的影响;结合此基坑开挖监测实例,应用有限元软件模拟基坑分步开挖时渗流及近接建筑物对基坑稳定的影响,并利用仿真结果指导监测点位的布置及监测方案优化;仿真结果显示,考虑渗流作用时,土体内的有效应力值增加,基坑开挖时邻近建筑物地连墙顶部将产生22 mm侧向位移,距离地连墙10 m处产生59 mm沉降,土体孔隙水压力随施工进展逐渐消散;监测结果与计算结果差异较小,考虑渗流作用的有限元模拟能很好地对高水位基坑开挖进行仿真分析,建议在进行高水位深基坑变形计算时考虑渗流引起的有效应力的变化。

The groundwater level of the round deep foundation pit of a specialized coal wharf car-dumping machine room is high and adjacent to the office building. The safety of excavation needs to take into account the geological conditions, the influence of groundwater level and the surrounding environment; combined with the excavation monitoring example, the finite element software is used to simulate the influence of seepage and the stability of the adjacent building, and the simulation results are used to guide the layout of the monitoring points and the optimization of the monitoring scheme; the simulation results show that the effective stress value increases when considering the seepage effect, a 22 mm lateral displacement will occur at the top of the underground diaphragm wall adjacent to the building, and a 59 mm settlement will occur at a distance of10 m from the underground diaphragm wall. The pore water pressure of the soil will gradually dissipate as the construction progresses. The difference between monitoring results and calculation results is small. The finite element simulation considering the seepage effect can well simulate the excavation with high groundwater level. It is suggested that the effective stress caused by the seepage flow should be consider when the excavation with high groundwater level.