Tail void grouting material: A parametric study on the role of hydro-mechanical characteristics in mechanized tunneling

Abstract

This paper investigates the influence of the hydro-mechanical properties of the tail void grouting material on short and long-term behavior of the tunnel. These characteristics are of high importance affecting the deformations and pore pressure regime around the tunnel as well as forces and deformations in the linings. Various properties of the tail void grouting material including thickness of grouting layer, permeability, stiffness, hardening ratio, shrinkage, and creep behavior are investigated using 3D Finite Element Method. The effect of each parameter variation on the representative surface settlements as well as deformations and excess pore pressures around the tunnel along with the axial forces and radial displacement of the linings has been thoroughly investigated. According to the results, a high hardening ratio corresponding to a fast-hardening grout could lead to 75% lower surface settlement. Utilization of a low permeable grout results in excess pore pressure remaining in the system which is 4.5 times higher than using a high permeable grout. The magnitude axial forces of the lining will depend on the direction of dissipation, when the permeability of the grout is concerned.