Experimental investigation on the creep behaviour of Beishan granite under different temperature and stress conditions

Based on a series of creep tests performed on MTS815 rock mechanics test system, the influence of temperature and stress condition on the creep properties of Beishan granite is investigated. The experiment data revealed that the creep process of Beishan granite can be divided into three stages: the transient creep, the steady creep, and the accelerated creep, with different strain rate in each creep region. With the employment of 3D acoustic emission monitoring system, a special attention is paid on the cracking process during the creep test. A consistent variation tendency between AE cumulative counts and volumetric creep strain is noticed. Moreover, the variation of recorded AE events is found to be more sensitive to the occurrence of rock failure than rock deformation. Under same confining pressure, it is indicated that the stress level and temperature variation within 90 degrees C have quite limited influence on the critical state of rock failure, while they may accelerate the cracking process and consequently change the time to failure at constant loading condition.