Study on instability mechanism of reinforced concrete pipe jacking in soft soil stratum

In order to explore the stability failure mechanism of reinforced concrete pipes during jacking in soft soil stratum and the influencing laws of various factors, a method for determining the pipe instability considering the pipe-soil contact state, pipe deflection, jacking force, buoyancy and slurry pressure was proposed through theoretical analysis. The applicability of this method was verified based on the field test data of the Tangxun Lake pipe jacking project in Wuhan. In addition, the effects of geological parameters, jacking force, pipe deflection angle and slurry pressure on the pipe instability were investigated through numerical simulation. The results show that: 1) The pipe-soil contact state and pipe deflection have a significant effect on the ultimate stress and additional stress of the soil around the pipes. 2) The stability failure of pipe can be effectively determined by calculating the initial stress, additional stress and ultimate stress of the soil around the pipe. 3) The most obvious phenomenon of the pipe instability is the increase of the pipe displacement, and the pipe at the maximum axial deviation can be selected for stability failure analysis in actual construction. 4) In soft soil stratum, slurry pressure, buoyancy, pipe deflection, and jacking force are the main factors causing the stability failure of pipe, and the above parameters should be monitored and controlled during construction.