Stability Analysis of Surrounding Rock in Underground Chamber Excavation of Coral Reef Limestone

The exploitation and utilization of underground space in the coral reef limestone has become more and more important for the development and construction of ocean engineering in the world. Due to the particular composition and development environment of the reef limestone, its surrounding rock stability in underground engineering construction is significantly different from that of other terrestrial rocks. This paper focuses on the stability of surrounding rock in underground chamber excavation of coral reef limestone by physical model experiments and numerical calculation. First, the quartz sand, barite powder, high-strength gypsum, calcareous sand, cement and water are selected as the raw materials to configure the similar materials of reef limestone based on the similarity theory. Second, according to the difference of the lining and span of the chamber, three geological models are designed and the underground chamber excavation experiments of reef limestone are carried out. The change laws of displacement and stress during the excavation are analyzed, and the influence of lining support and chamber span on the stability of the surrounding rock is obtained. Finally, the numerical simulation is used to simulate the excavation of the foundation model, and the physical model experiment is verified by comparing with the numerical calculation results. The results show that: when reducing the lining support or increasing chamber span, the displacement and stress release rate of surrounding rock both increase during the excavation of chamber. The average error of displacement and stress release rate between the physical model experiment results and the numerical simulation results is about 10%, which verifies the accuracy of the physical model experiment results.