穿层爆破中控制孔对裂隙扩展作用机理试验研究

为研究控制孔在穿层爆破中对裂隙扩展的作用机理，在实验室内进行穿层爆破相似模拟试验。研究表明:煤岩体试块上表面产生了贯穿炮孔和控制孔的裂隙，侧面生成了多条不规则的裂隙，试块内部出现了包括沿控制孔方向发展的多个断裂面；炮孔和控制孔连线上产生了较高拉应力，炮孔和控制孔连线方向上拉应变峰值是炮孔45°方向上的拉应变峰值的1.12倍；爆破产生的压缩应力波P和在控制孔处反射生成的反射横波Sr、反射纵波Pr在控制孔附近的煤岩体上产生应力叠加，造成煤岩体损伤，最终形成贯穿裂隙。穿层爆破中控制孔对爆生裂隙的扩展起到导向作用，但由于穿层爆破中煤岩交界面的存在，使得应力波出现复杂的反射、透射、叠加效应，造成煤层内裂隙无序发育，工程现场应予以重视。

Experimental study on action mechanism of control holes on cracks propagation in cross-seam blasting

In order to study the action mechanism of control holes on the cracks propagation in the cross-seam blasting,a similar simulation test was carried out in the laboratory.The results showed that the crack running through the blast hole and the control holes was generated on the upper surface of the test block of coal and rock mass,and several irregular cracks were generated on the side.There were multiple fracture surfaces including the development along the direction of control holes in the test block.The higher tensile stress was generated on the line connecting the blast hole and the control holes,and the peak tensile strain in the direction connecting the blast hole and the control holes was 1.12 times as that in the 45° direction of blast hole.The compressive stress wave generated by the blasting,the reflected transverse wave and reflected longitudinal wave rgenerated by the reflection at the control holes produced the stress superposition on the coal and rock mass near the control holes,which caused the damage of coal and rock mass and eventually formed the penetrating crack.The control holes played a guiding role in the propagation of the blasting cracks in the cross seam blasting.However,due to the existence of the interface between coal and rock during the cross seam blasting,the stress waves presented the complex reflection,transmission and superposition effect,resulting in the disorderly development of cracks in the coal seam,and the attention should be paid in the engineering site.