Abstract: Brazilian splitting tests were conducted on Beishan granite (the potential host rock for China’s high-level radioactive waste repository) at different temperatures (25 ℃,60 ℃,90 ℃,120 ℃,200 ℃,and 300 ℃).The cracking process of granites was investigated using acoustic emission (AE),section analysis and particle flow code (PFC).Results reveal that:1) Temperature at 120℃ has a significant strengthening effect on granite,while the strength of granite at other temperatures is lower than that at 25 ℃.2) The AE data shows that the number and size of cracks in granite both increase with rising temperature in mild temperature range (60 ℃~120 ℃),which consumes more energy produced by loading and gradually improves the strength of granite.(3) Affected by the differences in thermodynamic properties of feldspar,quartz and mica,cracks of granite tend to propagate along the boundary of feldspar with the increase of temperature between 25 ℃ and 120 ℃.When temperature is higher than 120 ℃,the proportion of cracks at the boundary of non-feldspar particles begins to rise.(4) PFC^2D model was established based on the distribution of minerals on granite surface,and the simulation suggest that temperature could reduce the bond strength between mineral particles and makes the rock more prone to fracture.

Key words: Beishan granite, Brazilian splitting test, temperature, cracks, acoustic emission, K-means clustering, PFC^2D