气爆卸压增透防治井筒揭穿煤层突出的数值模拟研究

Numerical Simulation on Outburst Prevention by High Pressure Gas Shock Technology for Shaft Coal Uncovering

爆破震动卸压增透抽采瓦斯是消除井筒揭穿低透气性煤层煤与瓦斯事故的根本措施。采用有限差分数值模拟的方法,研究了气爆冲击震动卸压范围对井筒揭穿煤层卸压增透防突效果的影响。结果表明:当冲击震动卸压范围较小时,井筒揭穿卸压煤层后,煤层无支承压力增高区的出现;当卸压范围较大时,则依次出现支承压力三区,且支承压力增高区的宽度有随卸压范围的增大而增加的趋势;冲击震动卸压存在一临界卸压范围,当卸压范围超过该临界范围时,煤层支承压力曲线由单峰特征转变为内外双峰特征,且外峰值小于内峰值,内峰值还明显小于无卸压和不超过该临界范围卸压范围时支承压力单峰值,还能使支承压力增高区向煤岩体深部转移,显著降低井筒揭穿瓦斯煤层发生煤与瓦斯突出动力灾害发生的频度及强度,为气爆冲击卸压防治井筒揭穿煤层突出的工程应用提供参考。

Blasting to enhance the permeability and to decrease the ground pressure is the important method to control coal and gas outburst as a shaft excavated through an outburst prone coal seam. Effects of pressure relief zone on the outburst prevention for a shaft coal uncovering are studied by conducting several numerical simulations. The results show that no high-pressure zone exists once the range of destressed zone is small; however, the high-pressure zone starts to appear as the range of relief zone extends to a certain range and the thickness of high pressure zone increases along with the relief zone increasing. When the destressed zone exceeds a critical range, two peak points appear in the abutment pressure curve. The outer peak value near the shaft surface is smaller than the inner peak value far from the excavated surface. Both the inner and outer peak values are also smaller than the abutment pressure peak value of the cases with either no blasting or small relief zone. Simultaneously, the high-pressure zone of coal seam moves inside, which dramatically reduces the strength and frequency of outburst.