Finite Element Method Simulation for the Influence of Hardening Characteristic of Grouting Materials at the Shield Tail on Mechanical Response of the Lining and Ground

The filling of the grout in the shield tail clearance of the shield is a significant measure to ensure the construction quality of shield tunnel. The process of the pressure dissipates and material hardening of grouting have a great impact on the deformation and force of the soft soil layers and shield tunnel. However, the related researches focusing on this issue are rarely reported in the literature. By considering the interaction between shield machine and soil, the interaction between lining grouting layer and soil, as well as the hardening process of grouting materials and the dissipation process of grouting pressure, a finite element method(FEM) numerical simulation model of shield tunneling was conducted in this study. Based on a case of shield tunnel in Qingdao, this FEM model was verified by measured ground settlement and convergence deformation. To obtain the development principle of the deformation and force of the soil layers and shield tunnel due to the pressure dissipates and material hardening of grouting, the FEM numerical models without considering the hardening process of grouting materials and the initial solidified time of grouting materials being 2 hours, 6 hours and 12 hours were calculated, respectively. The FEM results show that the settlement and horizontal displacement of the soil layers within 8 hours of grouting, and the surrounding earth pressure and internal force of the shield tunnel increase significantly, while increase slowly after the grouting time exceeds 8 h.