Experimental and numerical investigation on cracking mechanism of tunnel lining under bias pressure

Lining cracking is a common issue in tunnels, which severely affects the integrity and service life of the tunnel. Bias pressure is one of the most important factors leading to lining cracking. In the present study, scale tests were carried out with different acting ranges of the bias pressure, and the bearing capacity, deformation behavior and crack morphology of the lining were measured. Then, the applicability of the extended finite element method (XFEM) in simulating lining cracking was validated using the scale test results. Furthermore, the crack evolution process and cracking mechanism of the lining caused by the bias pressure were investigated in detail by XFEM. The results showed that there was one intrados crack at the center of the bias pressure acting region, whereas two extrados cracks were symmetrically distributed on both sides of the bias pressure acting region. The intrados crack was a tensile crack with ‘ Λ ’ shape, which initiated first followed by the two extrados cracks. The eccentricity of the lining cross section was the key factor controlling the crack evolution. As the acting range of the bias pressure increased, the eccentricity of the cross section of the intrados crack gradually decreased, which led to a decrease in the crack propagation depth and width. This work can provide some helpful guidance for addressing the tunnel lining issues.