Effects of jack force and construction steps on the change of lining stresses in a TBM tunnel

This study investigated the effects of construction sequence and thrust force from hydraulic jacks on the stress distribution of the tunnel lining by analyzing field data measured at a real Tunnel Boring Machine (TBM) tunnel construction site. A three-dimensional Finite Element (FE) model that incorporated the major design components of a TBM tunnel lining, such as face pressure, shield, grout, and hydraulic jack, as well as the simulation of a step-by-step construction procedure was also proposed. Specifically, the ring joints between linings were modeled using anisotropic solid elements to predict the effects of the jack force on the axial stresses in the lining. The proposed FE model was verified by comparing the numerical results with field data and various analytical and empirical formulas. Through this FE method, extra analyses were conducted with various ground conditions, dimensions of tunnel, and jack forces to investigate the effects of construction stage loads on the behaviors of a TBM tunnel. From analyzing these parametric results and field data, it was concluded that soil elastic modulus has strong influence on axial stresses in lining due to jack forces, and the axial stress of linings converged to roughly 30% of the peak stress.