超深等厚度水泥土搅拌墙在邻近隧道深大基坑深厚承压水处理中的应用

Application of Ultra-Deep and Equal Thickness Cement-Soil Mixing Wall in Deep Confined Water Treatment of Deep Foundation Pit Adjacent to Tunnel

上海世博园某项目基坑为邻近隧道的大面积深基坑工程,且拟建场地大部分区域的地下⑦、⑨层承压水连通,止水帷幕难以完全隔断深厚的承压含水层,给邻近隧道的保护及基坑开挖带来双重风险。为此,基坑围护体采用了厚 1 000 mm “两墙合一”地下连续墙结合55 ~ 59 m超深等厚度水泥土搅拌墙(TRD )隔水悬挂帷幕的设计,并通过垂直度控制、浆液配制及工艺参数选择等技术措施,确保了 TRD成墙质量。基坑开挖期间,悬挂帷幕的设置有效地减小了降水对周边环境的影响,同时,基坑围护变形以及对邻近隧道的影响均在可控范围之内,实现了项目的预期目标。

The foundation pit of a project in Shanghai World Expo Site is a large-scale deep foundation pit project adjacent to the tunnel, and the underground ⑦ and ⑨ layers of the proposed site are connected by confined water. The water-stop curtain is difficult to completely cut off the deep confined aquifer, which brings double risks to the protection of adjacent tunnels and the excavation of foundation pits. For this reason, the foundation pit retaining body adopts the design of 1 000 mm "dual-purpose diaphragm wall" combined with 55-59 m ultra-deep trench cutting re-mixing deep wall (TRD) water-proof suspension curtain and ensures the quality of TRD wall-forming through technical measures such as verticality control, slurry preparation, and process parameter selection. During the excavation of the foundation pit, the setting of the suspended curtain effectively reduces the influence of dewatering on the surrounding environment. At the same time, the deformation of foundation pit support and its influence on adjacent tunnels are within the controllable range, which achieves the expected goal of the project.