Grouting Theory and Strategy of Simultaneous Control of the Horizontal and Vertical Deformations of Tunnels

Abstract

Disturbance induced by excavation is a major threat to the structural and operational safety of the tunnel in the vicinity of the excavation. Grouting is considered to be an efficient method for controlling tunnel deformation. However, it is difficult to achieve simultaneous control of the horizontal and vertical deformations of the tunnel in practice, which may encounter substantial construction risks and potential safety hazards to the tunnel near the excavation. To address this issue, a finite-element simulation was conducted to analyze the effect of grouting on the horizontal and vertical deformations of the tunnel based on a case history. The results indicated that the horizontal displacements of the tunnel can be effectively recovered when vertical grouting is adopted separately, whereas the vertical displacements are barely affected. Further, the vertical grouting and oblique grouting below the tunnel are combined, which is capable of simultaneously recovering the horizontal and vertical displacements of the tunnel. In addition, to restore the heave of the tunnel, a combination of vertical grouting and unloading holes is utilized when the tunnel is in the heave region induced by excavation. This novel grouting method enables the simultaneous recovery of the horizontal and vertical deformations of the tunnel and expands the application of the active grouting control method.