Liner forces response to very close-proximity tunnelling in soft ground

Abstract

Since there are limited literature focused upon the tunnel liner forces response to the very close-proximity tunnelling, a consensus has not yet reached. This study characterised the response of tunnel liner forces to the excavation of soft soil twin tunnels in the very close proximity, with reference to the field measurements and 2D numerical simulations. The “belta” method and the “volume loss” method were to distribute the earth load to the liner and capture the effect of ground loss, respectively, and the “local strain” method was to reproduce the effect of tunnel advance. The predictions were in reasonable agreement with the field measurements except the tunnel invert where the liner might not be in good contact with the surrounding soil. The principle stress change and rotation were analysed. Parametric studies about the joint number and distribution, ground deformability and rotational stiffness of joint were conducted. The critical angles for the distribution of odd number joint were suggested.