The role of hydro-mechanical properties of the tail void grouting material in mechanized tunnelling

Application of tail void grouting material during mechanized tunnelling has an influential effect on hydraulic and stress-deformation regime around the tunnel. In this study, the variation of the hydro-mechanical (HM) properties of the grout has been investigated through 3D Finite Element Method to better understand the interactions around the tunnel under various geological conditions. The model has been validated using available data of the hardening soil small strain (HSS) model. An advanced constitutive model accounting for time-dependent hardening has been assigned to the grouting material. The effect of the parameter variation in the grouting layer on the deformations and excess pore pressures is evaluated using a parametric analysis. According to the results, the hardening rate of the grouting material, compared to other input properties, has the most significant impact on the HM characteristics of the surrounding ground as well as axial forces in the lining.