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预裂效果是低渗透高瓦斯煤层深孔爆破增透技术的关键。采用超动态应变测试系统,实测了单孔起爆和双孔同时起爆作用下有机玻璃板中爆炸产生的应变波,对测试得到的轴向和切向爆炸应变波信号进行了分析。结果表明:单孔起爆产生的裂纹长度有限,双孔起爆由于应力波叠加作用产生的主裂纹长度扩展效果明显;应变波波形包括两个部分,首先以压缩为主的应变作用使裂纹产生,然后以拉伸为主的应变作用使裂纹长度扩展,且拉伸应变峰值是导致裂纹长度扩展的主要原因;双孔同时起爆爆炸拉伸应变峰值是单孔起爆的3~6倍,说明多点爆炸荷载对介质的作用并不是单纯的数值叠加。研究结果为进一步认识爆破破岩机理和爆破预裂技术提供新的试验依据。
The effect of pre-cracking is the key to anti-penetration technology of deep-hole blasting in low permeability and high gas coal seam. The dynamic strain measurement system was adopted to measure the strain wave induced by the explosion in the plexiglass plate under the action of single-hole detonation and double-hole simultaneous detonation. The axial and tangential explosion strain wave signals obtained by the test were analyzed. The results show that the crack length produced by single-hole detonation is limited, and the effect of double-hole detonation is obvious due to the superposition of stress waves. The strain waveform consists of two parts. Firstly, the crack is generated by the compressive strain and then The main effect of tensile strain is to extend the crack length, and the peak value of tensile strain is the main reason that leads to the crack length extension. The peak of tensile strain at the same time of double detonation is 3-6 times that of single detonation, The effect of load on the medium is not simply a numerical overlay. The results provide a new experimental basis for further understanding of blasting and rock breaking mechanism and blasting pre-cracking technology.