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.
Highlights
In recent years, with the vigorous development of a large number of construction projects, there have been varying degrees of disasters, such as deformation, lining cracking or leakage, in tunnel engineering during the construction or operation period
According to the damage phenomenon of the Dugongling tunnel of the Changping Expressway in Shanxi Province, China, this study evaluated the disaster of the expansive rock tunnel during the operation period
This paper proposed a formula for calculating the expansion force of expansive rock when the water content changes
Summary
With the vigorous development of a large number of construction projects, there have been varying degrees of disasters, such as deformation, lining cracking or leakage, in tunnel engineering during the construction or operation period. Tunnel engineering disasters caused by expansive surrounding rock have been very common. According to the geological data, the expansion and softening of the surrounding rock was likely to be the main cause of lining cracking. Through the analysis of the geological conditions of the diseased holes and the drilling exploration results, it was considered that the main causes of the disease in the expansion rock tunnel are the following: 1) groundwater. Under the long-term action of groundwater, softening of marl, softening and expansion of gypsum and anhydrite destroy the lining of the surrounding rock, which is the main cause of disease. 1) Numerical simulation is carried out for the support structure of the tunnel and expansion softening process of the surrounding rock from geometric and mechanical aspects. The value for the minimum difference between the numerical analysis result and the detection result is 5%
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