EXPERIMENTAL RESEARCH ON EFFECTS OF BEDDING PLANE DIRECTION ON COAL ACOUSTIC EMISSION CHARACTERISTICS UNDER UNIAXIAL COMPRESSION
ZHANG Zhaopeng1，2，ZHANG Ru1，2，LI Hegui1，2
(1. State Key Laboratory of Hydraulics and Mountain River Engineering，Sichuan University，Chengdu，Sichuan 610065，China；2.College of Water Resources and Hydropower，Sichuan University，Chengdu，Sichuan 610065，China )
Abstract：Bedding has a great influence on the macroscopic and microscopic mechanical properties of coal. In order to explore damage evolution and AE characteristics of coal with different bedding plane direction during the deformation and failure，coal samples are prepared as two types，i.e. axis parallel to bedding plane direction and vertical to bedding plane direction. Experiments on acoustic emission characteristics of full-regime failure of samples under uniaxial compression，are carried out by the MTS815 rock mechanics and the PAC AE testing system in laboratory. Effect of bedding plane direction on characteristics of AE time parameters and energy release，AE location distribution and AE amplitude distribution are revealed. The results show that compared to the samples with axis vertical to bedding plane direction，AE ringdown count and energy release of samples with axis parallel to bedding plane direction are stronger during the whole loading process，while AE ringdown count and energy release in unit time are smoother. Coal samples with axis vertical to bedding plane direction present the fiercer energy release characteristics；A mount of AE events are produced at lower stress level in the samples with axis parallel to bedding plane direction，where AE location distribution are more homogenous，and there are no nuclear phenomena；For the samples with axis parallel to bedding plane direction，during the deformation and failure ，the variation of AE amplitude distribution is smaller，b value is greater and proportion of big AE events is smaller. To a certain extent，experimental results show bedding plane direction has an obvious effect on AE features of working face and overlying coal during process of mining，and also provide the references for monitoring the state of surrounding rock by AE technique in the field.
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2015, Vol. 34 
