基于邻近运营地铁隧道的苏州财富广场深基坑工程,从基坑支护结构设计、深层承压水处理等方面采取了一系列针对性措施来保护地铁隧道。首次在苏州地区采用超深TRD工法等厚度水泥土搅拌墙,有效地隔断了深层承压含水层,避免了承压水降水对地铁隧道的影响,相比采用地下连续墙隔断方案,大大节省了工程投资。建立三维有限元模型对基坑开挖过程进行了模拟分析,结果表明:基坑围护体和地铁隧道位移计算值和实测值较吻合,地铁隧道位移的分布和发展与基坑围护体的位移及开挖进程密切相关,地铁隧道水平和竖向位移主要产生在邻近基坑开挖的范围内,隧道底部埋深与基坑挖深较接近时隧道产生隆起。该基坑工程成功实施,基坑开挖和降水满足保护地铁隧道的要求。
The deep foundation pit project of Suzhou Fortune Plaza is adjacent to subway tunnels in operation. A series of technical measures were taken to protect the subway tunnels such as the structural design of the supporting system and the treatment method of the deep confined water. The super deep TRD construction method of cement-soil wall with uniform thickness was firstly used in Suzhou area to cut off the deep confined water layer effectively. As a result, the influence of pumping the confined water on the subway tunnels was effectively avoided. Comparing to using the underground diaphram wall to cut off the deep confined water, the project investment was significantly reduced by using super deep TRD construction method of cement-soil wall with uniform thickness. Three-dimensional finite element model was established to simulate the foundation pit excavation process. The results show that the calculated displacement values of the retaining wall and the subway tunnels are in good agreement with the measured values. The distribution and development of the displacement of the subway tunnels are closely related to the displacement of the retaining wall and the excavation process of the foundation pit. The horizontal and vertical displacement of the subway tunnels mainly occur in the range of the neighboring excavation. The tunnels are uplifted when the bottom of the tunnels was close to the bottom of the foundation pit. The foundation pit is successfully excavated. The effects of foundation pit excavation and dewatering on the subway tunnels satisfy the requirements of protecting the subway tunnels.