Failure Characteristics and Treatment Measures of Tunnels in Expansive Rock Stratum

Abstract

During the operation period, disasters caused by the expansion of tunnel surrounding rock often occurs, but the understanding of this problem is still insufficient. This study investigated the disaster that occurred in the tunnel based on numerical simulation on a case in Dugongling, China. First, the main diseases, including lining cracks, pavement uplift and cable trench overturning and so on, of the tunnel were investigated in the field. According to the geological data, the expansion and softening of the surrounding rock was likely to be the main cause of lining cracking. Then, this paper proposed a formula for calculating the expansion force of expansive rock when the water content changes. Based on the expansion force calculation formula, the most severely damaged section was numerically analyzed, and the results were compared with the on-site monitoring data. According to the simulation results, the deformation of the surrounding rock and the stress of the supporting structure were studied. The research showed that the expansion and softening of the surrounding rock led to an increase in the load acting on the lining structure, which intensified the development of disasters. Finally, four reinforcement schemes were proposed and simulated, and the best reinforcement scheme was evaluated. The results of this study can provide a reference for the design and construction of this project and similar projects.

Study of the disaster-causing mechanism and reinforcement measures for soft rock deformation and lining cracking

“…The field investigation showed that the layered structure and fissures in the tunnel site were relatively developed, which facilitated the seepage of groundwater. The water-rock physicochemical reaction intensified, resulting in the strength degradation of the surrounding rock (Yang et al, 2022) and inducing uncoordinated surrounding rock deformation and cracking of the lining. Three cores were drilled in the collapsed tunnel section for laboratory tests to obtain the mineral composition and expansion (Ahn et al, 2021;.…”

Development and application of a borehole stress meter in rocks surrounding the roadway, based on optical-fiber sensing technology

“…The stress state of rock masses is an important issue in engineering rock mechanics. Stress in rock masses is an important parameter for the design and construction of underground engineering, such as in mine roadway design and maintenance and the design of mining working faces (Hao, 2022;Yang et al, 2022a;Yang et al, 2022b). It is also a fundamental force causing excavation deformation and damage in geotechnical engineering, such as in mining Liu and Li, 2022;Wang et al, 2022;Zhou et al, 2022).…”