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| EXPERIMENTAL STUDY OF RELATED LAWS OF ROCK THERMAL CRACKING AND PERMEABILITY |
| (1. Institute of Mining Technology，Taiyuan University of Technology，Taiyuan，Shanxi 030024，China；2. School of Mining Engineering，China University of Mining and Technology，Xuzhou，Jiangsu 221008，China；3. Faculty of Architecture and Civil Engineering，Huaiyin Institute of Technology，Huai¢an，Jiangsu 223001，China；4. School of Geology，Hebei Vocational College of Geology，Shijiazhuang，Hebei 050081，China；5. School of Quality and Safety Engineering，China Jiliang University，Hangzhou，Zhejiang 310018，China) |
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Abstract Thermal cracking of rock is a very common natural phenomenon in engineering. The experiments on acoustic emission(AE) characteristics and permeability evolution of sandstone and granite were carried out at temperature ranging from room temperature(RT) to 600 ℃ by using 600 ℃ 20 MN servo-controlled rock triaxial testing machine with high temperature and high pressure (HTHP)；and it reveals the related features between thermal cracking law and induced permeability. The results show as follows：(1) There exists a thermal-cracking threshold value in the heating process from RT to 600 ℃ as a result of thermal effect. According to AE characteristics induced by rock thermal cracking，the cracking threshold temperature of granite from Pingyi，Shandong Province in China is 65 ℃ and the one of fine-grained sandstone from Yongcheng，Henan Province in China is 170 ℃，respectively. (2) The behavior of rock thermal cracking is discontinuity and multi-period from RT to 600 ℃ with temperature rising over the threshold temperature. It neither increases nor reduces monotonously in the heating process；and there exist more than two peak value areas. (3) The rock permeability appears multi-peak value area because of the multi-period of thermal cracking with temperature increasing. The relative lowering permeability lag occurs after the quietude of AE in the peak value area of permeability. But the permeability remains in a high level and it is more and more high with the increasing happening times of AE drastic period.
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Received: 01 April 2010
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2010, Vol. 29 
