Research on the Mechanical Properties of Hard Rock

Abstract

Large hydropower stations in the western region of China play very important roles in the development of lacal economy, and most of them locate in complex geological conditions, the deeper the rock is buried, the more obvious the geothermal phenomenon is, and the geothermal phenomenon does great damage for the underground construction. In order to study the mechanical properties of hard rock, some tests on granite have been accomplished. Through the uniaxial compression test, the triaxial compression test and the triaxial compression temperature creep test, some mechanical properties are obtained: (1) The peak strength of the granite is 92.9MPa in the uniaxial compression test, 291.0MPa in the triaxial compression test, 260MPa in the triaxial compression test when T = 25°C, 220MPa in the triaxial compression test when T = 50°C, 200MPa in the triaxial compression test when T = 70°C. (2) Compared with the triaxial compression test, when the specimen is broken, the increased percentage of the axial strain of the temperature creep test is respectively 37% when T = 25°C, 53.3% when T = 50°C, 80.6% when T = 70°C. And the value of the lateral strain is respectively 20% when T = 25°C, 59.5% when T = 50°C, 101% when T = 70°C. (3) A threshold exists during the creep of the gneissic granite, which is affected by temperature. The temperature increases the creep deformation of the rock.