Influences of tunnel slope on shield tunnelling-induced heave and subsidence of ground surface

Based on the Mindlin solution, the vertical movements of ground surface induced by the vertical component of the additional thrust at the excavation face and the friction force imposed on the surrounding soils by the shield skin are calculated through numerical integration. The results are verified by field observations. The analysis indicates that the longitudinal ground surface is expected to be globally heaved due to the vertical component of the additional thrust and the friction force, and the point where the maximum heave observed moves to the cutter-head with the increase of pitch angle of shield tunnelling. Under a fixed pitch angle, the maximum heave of ground surface declines exponentially with the increase of tunnel depth.