MICRO-SEISMIC CHARACTERISTICS AND ITS CHANGE LAWS RESPONDED BY MINING EFFECTS
LEI Wenjie1，WANG Zhaofeng1，HAN Zhenli2，LENG Junfa3，RONG Tao1
(1. State key laboratory cultivation base for gas geology and gas control，Henan Polytechnic University，Henan，Jiaozuo 454000，China；2. Guizhou Institute of Coal Design and Research，Guizou Guiyang 245500，China；3. School of Mechanical and Power Engineering，Henan Polytechnic University，Henan，Jiaozuo 454000，China)
Abstract：According to the theory that the mining stress is the extrinsic impetus for coal and gas outburst，the micro-seismic monitoring system has been constructed to respond to the activities on the coal roadway mining. The process and its main causes of coal caving were analyzed，the characteristics responded by micro-seismic activities on the coal and its roof ruptures were studied. The monitoring system which is combined by sensors with three different levels of sensitivity is aimed to acquaint entirely the change law of mining stress emergence and development. Based on the selection of Wavelet basic function，the total signals which number is 396 activated by mining effects within half an hour were decomposed and reconstructed on the method of Wavelet packet into 4 layers based on the frequency sequence. The micro-seismic signals activated by mining were divided into four categories such as blasting，coal caving，roof and coal wall ruptures signals according to mining sequence and frequency band，and the change tendency of roof and coal wall ruptures events was analyzed on the normalized frequency energy. Coal caving and roof ruptures are caused by blasts；the roof pressure can lead to coal wall ruptures as well. Roof ruptures as well as coal wall ruptures represent the mining stress definitely. Roof pressure in the early stage responds tempestuously，which causes five sections of coal caving within 1.6 seconds after blasting，reached the peak after 1.933 seconds and stabilizes 24.89 minutes later；roof ruptures events are mainly concentrated in the early 2 minutes and its corresponding events rate is 76.2%. Comparatively，coal wall ruptures react with delay of 5.8 seconds relatively to roof pressure，reach the peak after 3.71 minutes and stabilizes 29.217 minutes later；coal wall ruptures events are mainly concentrated on the early 5 minutes and its corresponding events rate is 45.9%. Roof and coal wall ruptures events and the change tendency of its own normalized energy on the dominant frequency band disclose the process of transformation and adjustment of mining stress，and the result that the coal body itself can get stable or not responded by the mining effect can be used to predict and early warn the coal and gas outburst，which needs further thorough research.
俞善炳. 恒稳推进的煤与瓦斯突出[J]. 力学学报，1988，20(2)：97-106.(YU Shanbing. Steady advance of coal and gas bursts[J]. Acta mechanical sinca，1988，20(2)：97-106.(in Chinese))
[4]
周世宁，何学秋. 煤和瓦斯突出机制的流变假说[J]. 中国矿业大学学报，1990，19(2)：1-8.(ZHOU Shining，HE Xueqiu. Rheological hypothesis of coal and methane outburst mechanism[J]. Journal of China university of mining and technology，1990，19(2)：1-8.(in Chinese))
<body>Your browse does not support frame!</body>
2015, Vol. 34 
