Research on Deformation Mechanism of Underground Chamber Surrounding Rock Based on the Influence of Surrounding Rock Stress Path

Abstract

During the construction of the pumped-storage power station, problems such as the stability of the surrounding rock of the underground chamber of the powerhouse appeared, which put forward higher requirements for the safety of the construction of the project. How to reasonably analyze and evaluate the stability of the surrounding rock of the underground chamber became a constraint to the smooth construction of the project Obstacles to progress. In response to this problem, a typical underground powerhouse chamber of a pumped storage power station was selected, and for the problems caused by the stress unloading of the surrounding rock during the excavation of the powerhouse chamber, field sampling, indoor triaxial unloading test, and numerical analysis were adopted. The stress path test results are applied to the numerical simulation analysis of different types of surrounding rock and different excavation conditions. The calculation analysis shows that the types of surrounding rock and the excavation conditions affect the arches, arch abutments and spans of underground chambers. Key positions such as the intersection of the arch bottom and the side wall have a significant impact. When the surrounding rock grade is the same, the displacement field distribution characteristics and maximum displacement of the two step-by-step excavation schemes are not much different; when the surrounding rock grade changes from type II to type III, the maximum displacements of the arch top and the bottom of the surrounding rock increase doubled.