地铁车站超深基坑开挖施工监测与数值模拟

Construction Monitoring and Numerical Simulation of Super Deep Foundation Excavation for Subway Station

依托天津地铁1号线东延工程上的李楼站大长宽比平面超深基坑工程,基坑标准段和盾构井段长宽比分别为23.6和18.8,对车站基坑开挖施工过程中的现场监测数据进行分析,并利用FLAC3D软件对基坑开挖支护的全过程进行数值模拟,将典型地表沉降观测点及地下连续墙最大变化点位的深层水平位移实测数据与模拟结果进行对比分析。结果表明:数值模拟结果与实际监测数据规律符合较好;随着开挖步数的增加,基坑支护外侧土体的位移量逐渐增加,最大沉降量发生在基坑开挖全部完成时,地表沉降观测点DBC-04-0j的最大地表沉降实测值与模拟值分别为39mm和30mm,分别相当于最大开挖深度的0.212%和0.164%,均满足<50mm的要求;基于数值模拟结果,围护墙体ZQT-04的实际最大水平位移和模拟位移分别为39.8mm和35mm,均满足<50mm的要求。

In the east extended engineering of Lilou station for Line 1 of Tianjin Metro,large length-width ratio plane super-deep foundation excavation was excavated. The ratio of the standard section is 23. 6 and the shield section is 18. 8. Based on it,the site monitoring data were analyzed during excavation in the paper. Meanwhile,FLAC3 D was applied to simulate and analyze the whole procedure of its excavation and support. The numerical simulation results were compared with the monitoring data including typical surface settlement observation points and the maximum deep horizontal displacement change point of underground continuous wall. The results show that the numerical simulation results are eligible. With the increase of steps, soil mass displacement value outside of the bracing arrangement increases gradually. The maximum value of surface settlement occurs when the excavation is completed. The simulation value and the monitoring value of the maximum surface settlement observation point DBC-04-0 j are 39 mm and 30 mm, equivalent to 0. 212% and 0. 164% of the maximum excavation depth,respectively. All the data are less than 50 mm,meeting the demand. Based on the simulation results,the maximum simulation value and monitoring value of the retaining wall ZQT-04 horizontal displacement are 39. 8 mm and 35 mm,and all the data are less than 50 mm,meeting the demand.