Numerical study on crack problems in segments of shield tunnel using finite element method

Crack problems of segments of shield tunnel are analyzed under the conditions of construction stage and service stage. 3D finite element method was adapted to establish elaborate numerical models of segments. For crack problems in construction stage, two models were used to analyze the following contents: (1) crack states of segments under jacking forces; (2) crack states of segments when two segments relatively twist. For crack problems in service stage, first, different external forces acting on segments are abstracted to seven computational models, then crack distribution of these models were analyzed. The analysis results indicate, in construction stage and service stage, cracks mainly appear in circumferential seam, bolt holes and hand holes of segments. Under normal load level, no cracks appear in inner arc and outer arc of segment surfaces. Improving the anti-crack performance of concrete near hand holes and bolt holes, the probability of crack and breakage can be effectively reduced, which can save maintenance expense in service period.