Thermal-mechanical coupling of shield tunnel lining structure under non-uniform temperature field

In order to understand mechanics variation of the shield tunnel lining segment in fire, the initial stress field of tunnel was firstly set up with the fluid-solid coupling model according to the mode of occurrence of rock and the hydrogeology condition. The ventilation and heat convection conditions in the tunnel were simulated. The non-uniform increment temperature load was applied to the subway tunnel and the concrete segment lining structure was analyzed using the thermal-mechanical coupling. The rules of segment deformation and its stress variation distribution were also obtained to confirm the deformation behavior and the broken positions of the segment in fire, respectively. The results showed that, under the fire temperature, the maximum horizontal and vertical pressures of the subway tunnel shield lining segments are 10.5 and 8.9 times of initial values, respectively. The action is at the 90°±22.5° position of the segment. The total displacement increases significantly after 400°C.