Elastoplastic Numerical Simulation and Elastic Performance Evaluation of Shield Tail Brush Compression

The shield tail brush forms a ring-shaped 2-4 grease cavity sealing system between the shield tail shield shell and the assembled segment ring, preventing groundwater, soil sand, mud and synchronous grouting slurry entering the tunnel, to ensure the safety of tunnel environment clean and tidy and shield tunneling, so accurate grasp of the shield tail brush mechanical properties is to ensure that the shield tail seal and shield tunneling security. Based on Midas GTS, the elastoplastic force calculation model of tail brush was established to simulate the change of binding force during the loading and unloading process of tail brush. The rationality of the calculation model was verified by comparing with the test results. Meanwhile, the binding force, stiffness coefficient, residual height and residual Angle of the clamping plate were obtained. The results show that: 1) The variation of bonding force obtained by numerical simulation is basically consistent with the experimental data, which verifies the rationality of the established numerical model and material parameter selection; 2) In the process of shield brush compression, the shield tail clearance decreases gradually, the bonding force increases almost linearly, and the residual height and residual angle of the compression plate decrease almost linearly, but the plastic deformation proportion increases gradually while the elastic deformation proportion decreases gradually, and finally tends to account for about 50% each. 3) The elastic performance of the tail brush is the key to the sealing performance evaluation of the tail brush. Its elastic performance can be evaluated according to the binding force, stiffness coefficient, residual height and residual angle of the compression plate; 4) According to the failure situation of the tail brush on site, three failure modes are concluded to be related to the failure of the escape of the tail grease to maintain the stability of the grease pressure in the grease chamber, and the escape of the grease is determined by the elastic properties of the tail brush. The elastic performance evaluation index of tail brush established in this paper can be used as reference for performance evaluation of tail brush.