Study on Temperature-Time Effect Characteristics of Hard Rock Under Long-Term Load

In order to reflect effectively the temperature influence on the long-term stability of surrounding rock of deep underground cavern, the triaxial creep tests of deep hard rock under different temperatures were carried out based on an important hydropower station. According to the tests results, under the high temperature and long-term load, the granite has the following creep characteristics: (1) The creep process of granite can be divided into three stages: the transient creep, the steady creep, and the accelerated creep, the higher the temperature, the shorter the creep time. (2) There is a creep stress threshold during the creep of the granite, and the higher the temperature, the lower the creep stress threshold and the shorter the creep failure time. (3) Under the same confining pressure, the compressive strength of the granite decreases with the increase of temperature. (4) The influence of temperature on the deformation of granite is very obvious. The higher the temperature is, the larger the deformation will be within the same time and the greater the change of lateral deformation will be. The granite will be destroyed mainly due to volume expansion.