Influence of grouting on rehabilitation of an over-deformed shield tunnel lining in spatially variable soil

Abstract

This study investigates the effect of grouting on an over-deformed operating shield tunnel considering soil spatial variability using the random finite difference method (RFDM). The compression modulus of soil is highlighted and simulated with a horizontally stratified anisotropic random field discretized by the Karhunen-Loeve expansion. The random finite difference model is firstly verified using an actual grouting case. Then, Monte Carlo simulations are executed to quantitatively evaluate the influence of soil spatial variability on the rehabilitation of the shield tunnel. On this basis, deformation rehabilitation of the tunnel by grouting under random pressure is explored initially. Results demonstrate that the spatial variability of the soil is the dominant factor affecting the rehabilitation of the shield tunnel under presumed constant grouting pressure. Meanwhile, the variability of the grouted area is mainly derived from the spatial variability of the soil. The correlation between the convergence reduction and maximum bending moment variation is more sensitive, affected by the variability of the soil and the grouted area. When the grouting pressure is further regarded to be randomly distributed, the effect of the variability of the grouted area will be significant on the amplification of the uncertainty of the tunnel performance.