沉井预封底水力冲洗下沉工艺在砂质地层中的应用

Application of bottom sealing of caisson hydraulic flushing sinking process in sandy stratum

西气东输二线东段上海支干线途经区域(苏浙沪地区)地质主要为砂质地层,土壤含水率及地下水位较高,为解决顶管隧道沉井涌水涌砂、封底周期长等难题,针对永利河顶管隧道沉井施工现状,采用沉井预封底水力冲洗下沉工艺进行施工。结合工程实例,阐述了地质勘查、工艺制定、设备选择、沉井纠偏、风险预测及防范措施等控制要点。沉井预封底水力冲洗下沉工艺在该工程中的成功应用,有效缩短施工周期约39%,降低施工成本约37.28%,减少了对井外地层的扰动,保证了周围建(构)筑物的安全,降低了公共关系协调难度。

The main geology around Shanghai branch gas pipeline （area of Jiangsu, Zhejiang, Shanghai） of the east segment of the Second West-to-East Gas Pipeline Project, is sandy soil, with high moisture content of soil and underground water level. In order to solve the problems like water and sand gushing, long bottom sealing cycle and so on, in light of the current construction way of pipe-jacking tunnels and caisson at Yongli River, prefabed bottom sealing is adopted. Combined with engineering cases, the paper presents the control points such as geological prospecting, process design, equipment selection, deviation-rectifying of sink, risk prediction, preventive measures and so on. The successful application of bottom sealing of caisson hydraulic flushing sinking process shortens the construction period about 39 %, saves about 37.28 % of construction costs, reduces the disturbance to the formation outside the caisson, ensures the safety of structures around the environment, lowers the difficulty in coordinating public relations. （3 Figures, 4 References）