On infiltration enhancement mechanism of shaped charge blasting in high gas and low permeability coal seam

被引：0
|
作者：
Li X. [1 ,2 ]
Zheng J. [2 ]
Song Y. [2 ]
Guo D. [3 ]
Ma H. [2 ]
Wang J. [1 ]
机构：
[1] China Coal Research Institute, Beijing
[2] School of Mechanics and Civil Engineering, China University of Mining & Technology (Beijing), Beijing
[3] School of Emergency Management and Safety Engineering, China University of Mining &Technology (Beijing), Beijing
来源：
Baozha Yu Chongji/Explosion and Shock Waves | 2023年 / 43卷 / 05期
关键词：
coal seam permeability enhancement; gas drainage; shaped charge blasting; stress wave propagation;
D O I：
10.11883/bzycj-2022-0164
中图分类号：
学科分类号：
摘要：
In order to improve the permeability of coal seam with high gas and low permeability and effectively control the disaster of coal and gas outburst, the mechanism of permeability enhancement of coal seam by shaped charge blasting is studied. Firstly, the comparative experiments of concrete cracking caused by shaped charge blasting and conventional blasting were carried out, and the sizes of concrete crushing area and fracture area after blasting were compared. Meanwhile, the strain data of the strain bricks with time were collected by the super dynamic strain gauges. Then, ANSYS/LS-DYNA is used to reproduce the whole process of the formation, migration and penetration into concrete of shaped energy jet. The stress wave propagation characteristics of shaped charge blasting and conventional blasting are compared and analyzed. Finally, the coal seam antireflection tests were carried out in Pingmei No. 10 mine, and the gas volume fraction of the extraction hole after blasting was compared. The results show that after shaped charge blasting, the crack width of concrete in the direction of energy accumulation and in its perpendicular direction was 1.1 cm and 0.4 cm, respectively; while the width of four main cracks formed in concrete after conventional blasting was 0.3 cm. Comparing the strain peaks measured from strain gauges at the same distance, it is found that the strain gauge in the direction of energy accumulation is the maximum, followed by the perpendicular direction, and the strain at the diagonal direction is the minimum. In addition, the strain peak value in the direction of energy accumulation is much larger than that under conventional blasting, and the strain peak value in the perpendicular direction is basically equal to that of conventional blasting, while the strain peak value of the diagonal direction is smaller than that under the conventional blasting. The numerical simulation results show that the crushing region of concrete after shaped charge blasting is of “dumbbell type”, and the area of crushing region is smaller than that under conventional blasting. While the fracture region is of “spindle type”, the fracture is better developed. The field test shows that the gas volume fraction of the extraction hole after shaped charge blasting is significantly higher than that under conventional blasting. It is seen that shaped charge blasting can effectively improve the permeability of coal seam with high gas and low permeability. © 2023 Explosion and Shock Waves. All rights reserved.
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