Abstract: In order to study on thermal damages of detective granite under temperature effect, an analysis on thermal stress of cracked granite was conducted through applying the theories of thermodynamics and damage mechanics. The critical stress formula of thermal damage of cracked granite was derived, further the influence of high temperature on the variation of the thermal elastic ratio of granite was analyzed, and then the thermal damage evolution equation of granite under temperature was established, finally the possible forms of the stress damage surface of granite under temperature were studied. A numerical simulation of the internal structure, crystal element damage, and stress variation of the Beishan defective granite under temperature was carried out. When the temperature rose to 60℃, a significant thermal damage occurred near the cracks of granite, and the damage was small far away from the cracks. When the temperature rose to 120℃, the shear failure characteristics of granite defects were obvious, the thermal damage near crack increased seriously, and the uninterrupted damages appeared obviously away from the defects. Under 120℃, a sudden change came out for the damage amount, the thermal stress, and the cumulative energy. Thereafter, with the increase of temperature to 200℃, the increment of damage is weak. The results show that there is a direct relationship between the damage and the temperature of Beishan granite with defects.

Key words: defective granite, thermal damage, thermal stress, Beishan,Gansu