COMPREHENSIVE TESTS AND APPLIED STUDIES OF HYDRAULIC FRACTURING IN THE ROCK MASS OF THE YANGJIANG PUMPING STORAGE POWER STATION

The surrounding rocks of the water tunnel of the Yangjiang pumping storage power plant are required to bear a maximum static pressure of 7.83 MPa; therefore, the state of in-situ stress, dead loadbearing capacity of surrounding rocks and high-pressure permeability are all essential data for the scientific design of the project.The measurement results show that the general characteristics of the present crustal stress field of the project area are as follows:the horizontal principal stress is the maximum principal stress, and the preferred orientation of the maximum horizontal principal stress is NW-WNW, the maximum principal stress of surrounding rocks of the plant buildings and high-pressure branch tunnel area is generally 14.5±0.5 MPa and the minimum principal stress is 9±0.5 MPa; the dead load-bearing capacity of surrounding rocks is 10-14 MPa; and the surrounding rocks are essentially impermeable at high pressures of 8-10 MPa.The results of those measurements of physical-mechanical parameters of surrounding rocks offer a reliable basis for the scientific design of the project.