Analysis of the influence of tunnel lining cracks on bearing capacity

Abstract:

In order to clarify the influence of crack characteristics on the bearing capacity of lining structures under loose load, the stress and deformation characteristics, failure modes and ultimate bearing capacity of structures with cracks were studied by 1∶10 model test and numerical analysis. The results show that: For specimens with prefabricated crack length less than L/3 (longitudinal length of specimen) and depth less than 0.7H (thickness of the specimen), the fracture development process is characterized by stages. The failure of specimens is caused by the failure of the vault and belongs to ductile failure. For the specimens with prefabricated crack length no less than 2L/3 or depth no less than 0.9H, there is no stage characteristics in the crack development process, and the failure of the specimens is caused by the failure of the vault, which belongs to the brittle failure. With the increase of crack length and depth, the structural ultimate bearing capacity decreases. When the length of prefabricated crack is L/3 and the depth is 0.3H, 0.7H, 0.9H, and when the length is 2L/3 and the depth is 0.3H, 0.7H, the ultimate bearing capacity of the specimen is 86.96%, 78.26%, 73.91%, 69.57%, 60.87% of the complete specimen. Compared with the crack depth, the length has more obvious effect on the mechanical properties of the structure, and can be taken as an important index of fracture evaluation. A formula for calculating the bearing capacity of the lining based on the characteristics of cracks is proposed, which can be used to determine the ultimate bearing capacity of the lining with cracks, and provide a basis for the evaluation of structural performance, the selection of reinforcement timing and reinforcement parameters.