复杂环境下基坑开挖监测和数值模拟研究

Research on Monitoring and Numerical Simulation of Foundation Pit Excavation in Complex Environment

文章以呼和浩特市地铁2号线4号标段的车站基坑开挖作为依托,通过对基坑开挖全过程的监控数据进行分析,着重分析地表沉降和轴力等变形随着时间的变化规律。通过FLAC 3D软件进行基坑开挖过程的流固耦合分析,并将得出的数值模拟结果与实际工程的监测进行对比分析。结果表明:沉降最大出现在距离基坑周边大概6 m处,基坑开挖长时间停工暴露会造成沉降和变形,由于降水的停止,地下水流入使沉降在一定程度上减少;数值模拟的结果与实际监测相差不大,验证了用高压旋喷桩、深层搅拌桩的围护加固技术对整个基坑的安全是有效的,提高了基坑的稳定和安全性。

Taking the excavation of station foundation pit of Hohhot metro line 2 lot 4 as the background,the monitoring data of the whole excavation process of foundation pit are analyzed,especially focusing on the change rules of surface settlement and axial force varying with time.And the fluid-solid coupling analysis of the foundation pit excavation process is conducted through Flac 3D software,the obtained numerical simulation results are compared with the actual engineering monitoring data.The results show that the maximum settlement occurs at the place about 6 m away from the periphery of the foundation pit.The long-term exposure of the foundation pit induced by excavation suspension will cause settlement and deformation.Due to the stop of dewatering,groundwater inflow makes the settlement decrease to a certain extent.The numerical simulation results are not much different from the actual monitoring results,which verifies that the reinforcement technology of high-pressure jet grouting piles and deep mixing piles is effective for the safety of entire foundation pit and it can improve the stability and safety of the foundation pit.