Study on permeability enhancement by deep-hole shaped-charge controlled blasting of deep soft and high gas coal seam floor
This study is targeted at problems associated with deep-hole pre-split blasting in enhancing the permeability of deep soft coal seams with a high gas content.To address these problems,a method for permeability enhancement by floor blasting was proposed here.First,a state-of-the-art bidirectional loading gas-solid coupling and blasting similar simulation experimental system was developed in the labo-ratory.With the aid of this experimental system,a series of comparison experiments involving ordinary-charge blasting,shaped-charge blasting,and controlled-hole blasting were performed.The results show that ordinary charge blasting predominantly impacts the floor rock,resulting in excessive damage to the floor,but it cannot effectively induce cracks in the overlying coal.In contrast,controlled-hole blasting leads to a notable increase in peak tensile strain,generating a significant number of tensile cracks in the coal and corresponding to an expanded overall damage range.Moreover,shaped-charge blasting indicates an elongated duration of static load action,accompanied by intensive expansion of cracks in the shaped-charge direction.After the application of shaped-charge blasting,the damage to the floor is re-duced by 26.67％,and the damage to the coal is promoted by 167％.This approach proves effective in cracking the coal while minimizing damage to the floor.Furthermore,the blasting effects of ordinary charge and shaped charge coupled with controlled-hole blasting was comparatively analyzed using AN-SYS/LS-DYNA software.The results indicate that,in comparison to ordinary charge,shaped charge coupled with controlled-hole blasting forms an"inverted-triangle-shaped"stress concentration region a-long the line connecting the blast hole and the controlled hole.The coupled blasting method raises the damage to the coal by 85.37％and decreases the damage to the floor by 32.07％,boasting noticeably improved blasting effectiveness.The research results have certain reference significance for directional blasting for enhancing the permeability of deep soft coal seams with a high gas content.
deep soft coal seams with a high gas contentdeep hole blastingpermeability enhance-mentshaped chargecontrolled hole
万方数据
维普
