Structural Stability Monitoring of Model Test on Highway Tunnel with Lining Backside Voids Using Dynamic and Static Strain Testing Sensors

Abstract

Voids behind a lining may develop due to insufficient backfilling, poor workmanship, water erosion or gravity. They affect the interaction between the surrounding rock and lining and even cause instability of the lining structure. To ensure the safe operation of tunnels, it is very important to study the influence of voids behind the lining of the lining structure. In this paper, a laboratory model of a tunnel lining was established by taking the voids behind the lining of the Wushan Tunnel as an example. By changing the position and size of the voids, the corresponding stress variation law of the lining was obtained, and the influence of the voids behind the lining on the structural stability of the highway tunnel was analyzed. The experimental results showed that the voids behind the lining led to an increase in the stress near the voids, especially the voids at the vault. The circumferential stress and axial stress increased with increasing void depth and length, and the increase was greater with increasing void depth than increasing length; that is, the void depth had a greater effect on the lining stress. When the vault void depth was 30 mm, the axial tensile stress of the vault was 0.281 MPa, and the maximum increase was 178.2% compared with that without voids. The safety factors at different lining positions, from large to small, are: arch foot > spinner > arch top > arch waist. In the processes of lining operation and maintenance, special attention should be given to the treatment of voids behind the lining, especially deep voids.

Research on Excavation Method for Soft Rock Tunnel Based on Stress Release Rate

“…In order to further explore the displacement deformation and mechanical characteristics of surrounding rock under different excavation methods of soft rock tunnels with high ground stress, this paper uses a model test to carry out further research. The traditional model test often uses the model box to realize the in-situ stress loading through the loading system and excavates the model soil according to demand to simulate the actual tunnel excavation [28,33,34]. This test method can better restore the construction process of the tunnel, but there are still some shortcomings.…”

Investigation into the Time-Dependent Characteristics of Stress and Deformation of Weak Surrounding Rock and Lining Structure in Operational Tunnels: Model Test

“…In terms of experimental research, Du et al [13] considered the impact of the postlining cavity on the interaction between the surrounding rock and lining and conducted an indoor modeling test in the case of the Wushan Tunnel, analyzing the position and size of the post-lining cavity on the structural stability of the tunnel. Xu et al [14] conducted research and development as well as the formulation of similar materials for surrounding rock and lining, on the basis of which they conducted research on the cracking mechanism of tunnel lining crack damage and the characteristic law of the physical field response of the tunnel surrounding rock and lining structure.…”