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

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.