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| Thermal shock factor measurement and its evolution in granite under conduction heating |
| XI Baoping1，2，HE Shuixin1，CHENG Zepeng1，LI Xiaoxue1，DONG Yunsheng1，YANG Xinxin1，XIN Guoxu1#br# |
(1. College of Mining Engineering，Taiyuan University of Technology，Taiyuan，Shanxi 030024，China；2. Key Laboratory of Insitu Property Improving Mining of Ministry of Education，Taiyuan University of Technology，Taiyuan，Shanxi 030024，China)
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Abstract Heat transfer，meso-fracture and macro-mechanical properties are closely related to each other during the thermal damage of rocks. Thermal shock factor is an important physical quantity that can quantitatively characterize the strength of thermal damage to rocks，based on which the dynamic thermal stress in rock at a certain moment can be calculated to determine the time and degree of thermal damage. In order to study the evolution of the thermal shock factor during the heat transfer process，the temperature field，temperature gradient and thermal shock factor in granite under conductive heating were experimentally determined. The results show that granite undergoes three stages of rapid temperature increase，slow temperature increase and relatively stable temperature under constant heat source conduction heating，that the temperature gradient closely related to the temperature of the heat source and time changes greatly during the heating stage and the changing rate of the temperature gradient per unit time is different，and that the thermal shock factor in granite is heterogeneous and irregular in distribution and sensitive to rock mass structure and the peak of the thermal shock factor in the conduction heating process is dynamically mobile. The essence of the granite damage caused by cyclic heating is that mineral particles are separated under the dynamic thermal stress and cracks gradually present，expand and penetrate through the rock mass. The experimental determination of the thermal shock factor and the study of its evolution law，as well as the calculation of the dynamic thermal stress and the criterion of rock thermal damage based on the thermal shock factor，can promote the development of rock thermal damage theory.
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2020, Vol. 39 
