Study on Stress Characteristics of Multi-arch Tunnel Lining under Weak Surrounding Rock Conditions Based on Field Measurement

Abstract

Considering the complexity of stresses on multi-arch tunnel structures under conditions of shallow depth, unsymmetrical pressure and weak surrounding rocks and the actual geological exploration of the Xiaojian Mountain Multi-arch Tunnel, the cross-sections in strongly-weathered section were selected for embedment of monitoring and measurement equipment to monitor in real time the stress of support structures during tunnel construction. In addition, the finite difference software FLAC3D was adopted to study the surrounding rock deformation during the excavation of the multi-arch tunnel. As a result, the stress state and deformation characteristics of the support structures under unsymmetrical pressure and construction disturbance were obtained. Based on the analysis of monitoring data, it can be concluded that under conditions of shallow depth and unsymmetrical pressure, reduction of stress imbalance on the support structures is of utmost importance to the structural stability of a multi-arch tunnel and that the method of cross-validation between monitoring & measurement and numerical simulation enables more accurate analysis of stability of tunnel structure and better guidance for construction.