Analytical study on the backfill grouting in mitigation of vibrations from a tunnel embedded in a half-space

Abstract

Ground vibrations from operating railway in tunnels is a significant obstacle to sustainable development of subway. The backfill grouting layer, formed during shield tunneling, serves as a critical medium in propagation of tunnel vibrations, highlighting its potential in vibration mitigation. A semi-analytical model for the tunnel-grouting layer-soil system is proposed in this study, in order to clarify the influence of backfill grouting layer on the dynamic responses in a half-space, subjected to tunnel vibrations. In establishment of the closed-form solution, the tunnel and grouting layer are considered as two nested hollow cylinders embedded in a half-space, with applying the Fourier transform and wave transformation. As a validation, the numerical results from the proposed semi-analytical model are compared with those reported in literature. Parametric studies, with respect to the geometric configuration (i.e., the thickness) and material parameters (i.e., the Young's modulus, material damping, and density) of the backfill grouting layer in the mitigation of tunnel vibrations, are carried out. It is found that incorporation of the backfill grouting layer significantly changes the dynamic responses of the soil and, by appropriately designing its material parameters, especially the Young's modulus, effective mitigation of tunnel vibrations can be achieved.