城市敏感环境下超深基坑工程变形控制关键技术研究与实践

Research and Practice on Key Technologies for Deformation Control in Ultra-Deep Foundation Pit Engineering within Urban Sensitive Environments

摘要: 在城市敏感环境下实施超深基坑工程面临地质软弱性、水文复杂性与环境高敏感性的三重挑战。本研究依托上海虹桥商务区核心区某轨道交通车站工程，针对最大开挖深度23.8米的基坑，聚焦软土流变地层与承压水系统耦合作用引发的变形控制难题。工程需同时应对申昆路主干道动载扰动、最小净距10.46米的高压燃气管线以及33米近距敏感建筑的严苛约束。通过量化软弱土层蠕变、承压水波动及动载扰动的耦合致变机制，构建四维协同技术体系：围护结构采用1000毫米厚“两墙合一”地下连续墙并在转角幅位置辅以高压旋喷桩止水帷幕；开挖过程遵循分层分块先撑后挖原则划分12个施工段，结合钢支撑轴力伺服系统实时补偿荷载；通过18口减压井智能启停将承压水位波动控制在设计值±300毫米范围；基于814个监测点构建三级阈值响应机制，依托BIM平台实现监测预警伺服闭环联动。工程实效表明：围护结构最大水平位移136.65毫米，邻近建筑差异沉降3.58毫米，燃气管线累计沉降值等均低于安全阈值。研究成果显著提升复杂环境地下工程安全可控性，形成可复用的超深基坑技术范式。

Abstract: Implementing ultra-deep foundation pit projects in urban sensitive environments faces the triple challenges of weak geology, complex hydrology, and high environmental sensitivity. This study, based on a certain rail transit station project in the core area of Shanghai Hongqiao Business District, focuses on a foundation pit with a maximum excavation depth of 23.8 meters, concentrating on the deformation control problems caused by the coupling effect of soft soil rheology and confined water systems. The project needs to simultaneously deal with the dynamic load disturbance of the main road of Shenkun Road, a high-pressure gas pipeline with a minimum clear distance of 10.46 meters, and a 33-meter nearby sensitive building under strict constraints. By quantifying the coupling deformation mechanism of soft soil creep, confined water fluctuation, and dynamic load disturbance, a four-dimensional collaborative technology system was constructed: the retaining structure adopts a 1000-millimeter-thick “two-wall-in-one” underground continuous wall and is supplemented with high-pressure jet grouting piles for water cutoff at the corner sections; the excavation process follows the principle of layer-by-layer and block-by-block excavation after support installation dividing the project into 12 construction sections, and combining the steel support axial force servo system to compensate for the load in real time; the fluctuation of the confined water level is controlled within ±300 millimeters of the design value through the intelligent start-stop of 18 relief wells; a three-level threshold response mechanism is established based on 814 monitoring points, and the monitoring and early warning servo closed-loop linkage is realized through the BIM platform. The project results show that the maximum horizontal displacement of the retaining structure is 136.65 millimeters, the differential settlement of adjacent buildings is 3.58 millimeters, and the cumulative settlement value of the gas pipeline is all below the safety threshold. The research results significantly enhance the safety and controllability of underground projects in complex environments and form a reusable technical paradigm for ultra-deep foundation pits.