Experiment research on the fracturing characteristics of mudstone with different degrees of water damage
YANG Jianfeng1,2,LIANG Weiguo1,2,CHEN Yuedu1,2,LI li1,2,LIAN Haojie1,2
(1. College of Mining Engineering,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;2. Key Laboratory of In-situ Property-improving Mining of Ministry of Education,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China)
Abstract:In order to study the effect of water damage on the characteristics of fracturing of mudstone,three-point bending test was carried out to the semi-circular bend(SCB) mudstone specimens that have been soaked in water for different durations. The real-time monitoring with PCI–2 type acoustic emission system was conducted on the fracturing process of the mudstone specimens. The results show that fracturing behaviors of the mudstone is significantly influenced by water-rock interaction. The peak load of the mudstone specimens decreases with the soaking time increases. After being soaked for 200 minutes,the fracture toughness of mudstone from pure mode I to pure mode II decreased respectively to 53%,56.5%,61%,64%,64.7% and 67.6% of those of the intact specimens,and the failure characteristics of mudstone was changed from brittle to ductile. The length of fracture process zone(FPZ) of the mudstone SCB specimens soaked for different durations was confirmed by the acoustic emission(AE) positioning. As the soaking time increases,the length of FPZ decreases and the accumulative number of acoustic emission events increases. The experimental ratio of Keff/KIC and the theoretical ratio based on the modified maximum tangential stress(MMTS) criterion that takes into account the T-stress matched well when the mudstone SCB specimens are not soaked or only soaked for a short time. However,as the soaking time increases,the experimental results of SCB specimens diverge from the theoretical values gradually. When the soaking time reaches 200 minutes,the deviation becomes very distinct.
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YANG Jianfeng1,2,LIANG Weiguo1,2,CHEN Yuedu1,2,LI li1,2,LIAN Haojie1,2. Experiment research on the fracturing characteristics of mudstone with different degrees of water damage. , 2017, 36(10): 2431-2440.
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