Tests for control hole&rsquo;s enhanced permeability mechanism under blasting load

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Journal of Vibration and Shock ›› 2017, Vol. 36 ›› Issue (24) : 213-219.

Tests for control hole’s enhanced permeability mechanism under blasting load

ZHANG Shuchuan1，2，LIU Zegong1，2，LIU Jian1，2，LI Zhongqing1，2，LIU Bingqian1

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Abstract

In order to study the enhanced permeability mechanism of control hole under blasting, an analog test system of blasting in a laboratory was built. A test model with control hole and other one without control hole were designed. Two models with sizes of 300mm×300mm×300mm were built based on coal engineering classification and coal physical and mechanical characteristics. The blasting analog tests were conducted on the two models, their crack initiation, propagation, perforation and destruction processes were recorded using a high-speed camera. The strain signals of coal seam were monitored with a super dynamic strain gauge. The electrical resistivity changes of the models before and after blasting were inverted with a network parallel electrical instrument. The models’ crack propagation, dynamic and electrical parameters characteristics were analyzed under blasting load. The actions of control hole in deep-hole control blasting, pressure relief and permeability enhancement were further revealed. The results indicated that blasting load produces reflected compression waves at the fixed end (hard materials) and they are reflected into tension waves at a control hole; two models produce two main waveforms under the combined action of shock wave, stress wave and detonation gas; the measured point’s radial strain peak value is close to its tangential strain peak one; coal rock resistivity has an abnormal change before and after blasting, the mean abnormal coefficient before and after blasting is 6~9; the results can be used to prevent coal and gas outburst with the deep-hole control blasting technology in engineering practices.

Key words

enhanced permeability of coal blasting / control hole / deep borehole blasting / fracture / resistivity

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ZHANG Shuchuan1，2，LIU Zegong1，2，LIU Jian1，2，LI Zhongqing1，2，LIU Bingqian1. Tests for control hole’s enhanced permeability mechanism under blasting load[J]. Journal of Vibration and Shock, 2017, 36(24): 213-219

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