Effect of Subway Excavation with Different Support Pressures on Existing Utility Tunnel in Xi’an Loess

Abstract

The interaction between two shield tunnels and the integrated pipe corridor is complicated and still lacks understanding. This paper investigated the influence of the double-track subway construction on the deformation characteristics of the existing comprehensive pipe corridor based on numerical simulation on a case history in Xi’an, China. First, loess is a special kind of clayed soil. In the theoretical calculation of overburden earth pressure of shield tunnel, the loose earth pressure theory under the incomplete soil arching effect can be used for calculation when considering the soil arching effect. Then, in the loess area of Xi’an, the existing comprehensive pipe corridor is affected by the construction disturbance. The vertical displacement of the existing pipe corridor utility tunnel affected by different support pressures which considers the soil arch effect or not was extracted from the FEM. The results indicated that, in the case where the left and right lines are constructed at different times, the vertical displacement of the pipe gallery is affected by different support pressures. If the support pressure is small, the settlement will be large, and the uplift will be diminutive. According to the construction methods and supporting pressures of this article, shield tunnel construction will not damage the safety of the comprehensive pipe corridor.