Inversion analysis of the in-situ stress field in the underground powerhouse of A Pumped-storage Power Station

Abstract

Pumped-storage power stations have been widely adopted in underground powerhouses due to their lower installation elevation. The stability of the surrounding rock of the underground powerhouses directly affects the success or failure of the underground powerhouses. In order to make the calculations in line with reality, it is necessary to combine the results of in-situ stress tests to invert the in-situ stress in the plant area. Taking A Pumped-storage Power Station as an example, the method of inverse analysis of ground stress is introduced. Based on the numerical calculation and simulation results, a regression equation with a better correlation is established. The calculation results shoiv that the main stress value of the underground powerhouse cavern group of A Pumped-storage Power Station increases gradually from top to bottom, and the contour is greatly affected by topographical changes in the shallow layer. The maximum principal stress azimuth angle is about SW1 $\sim 15^{\circ}$, and the angle with the axis of the workshop is about 63$\sim 77^{\circ}$, which is relatively unfavorable to the stability of the side wall of the cavern. According to the results of numerical simulation and linear regression, the initial site of the workshop area is established. The expression of the stress field fitting according to the linear law can be used to generate the initial stress field of the calculation model.