COMPUTATION METHOD FOR LONGITUDINAL DEFORMATION OF SHEILD TUNNEL LINING STRUCTURE BASED ON FLEXIBILITY BEAM MODEL

Thelongitudinal bending stiffness of a shield tunnel is not uniform along the tunnel because of the influence of a longitudinal force and the yielding of longitudinal bolts. Aiming to solve this issue, a typical inner force distribution mode under the uneven settlement of a shield tunnel was first introduced to build inner force shape functions. Then, a flexibility beam model was established with the aid of the numerical integration method in longitudinal and circumferential level. Based on this model, the distribution of circumferential joint deformation along the tunnel axis under flexible and rigid boundary conditions was derived. The influence of the integration strategy on the calculation accuracy was also investigated. The results show that: 1) the longitudinal axial force and yielding of bolts are two important factors in the calculation of structural longitudinal deformation, which should not be neglected, 2) the deformation pattern of the structure is very complicated as local concentrated deformation is considered. The proposed flexibility model could avoid the limitation of dealing with the complex deformation pattern in traditional stiffness models, and provide an accurate method to calculate the longitudinal deformation of a shield tunnel lining structure with little computational cost.