Temporal variation laws of longitudinal stress on cross section of shield tunnels

The longitudinal stress acting on the cross section of shield tunnels will affect the waterproof properties of the segments and the stiffness of the circumferential joints, which will thus affect the development trend of the longitudinal nonuniform settlements. At present, the longitudinal stress is estimated based on the experience in actual engineering. By solving the differential equation, the temporal variation laws of the longitudinal stress are proposed. The theoretical solution is also compared with meatured data from field experiments, and they matches well. The results show that the longitudinal stress decreases in fluctuations with time. The magnitude of the remaining stress is related to the creep coefficient of concrete and the compression modulus of formation. There is 20.4%~44% of the initial longitudinal stress left.