为了提高水射流破煤岩性能和卸压增透效果,通过理论分析建立了高压气液两相射流的冲击动压模型,推导出影响其破煤岩性能的关键参数体系。采用自主研发的高压气液两相射流破煤岩试验系统,研究了关键参数对气液两相射流的破煤岩特性的影响规律,结果表明:与纯水射流相比,气液两相射流破煤岩压力阈值降低约50%,破碎深度增加25%,破碎坑直径是纯水射流的2倍,破煤岩效率提高80%以上。煤岩体破碎是气-液-固三相耦合作用的结果:气体的掺入改变射流的结构,产生局部脉动作用,强化了射流破岩能力;高压液相脉动冲击作用激发裂纹起裂,高压气相的多级溃灭作用促进裂纹扩展;气相多级溃灭与液相脉动冲击交替作用,最终使煤岩体裂隙贯通、破坏。

In order to improve the coal rock-breaking capacity of water jet and pressure-relief and permeability effect, by establishing the impact dynamic pressure model of high pressure gas-liquid two-phase jet,the key parameters were obtained which affected the capacity of coal rock-breaking. Experimental tests about the characteristics of impacting coal rocks were conducted by self-designing rock breaking test system of high pressure gas-liquid two-phase jet. The results showed that the rock breaking threshold pressure was reduced by 50% ,the breaking depth increased 25% ,the diameter was 2 times and the efficiency increased about 80% by comparing with pure water jet. The coupling between the gas-liquid-solid three phases resulted in breaking coal:the structure of jet was changed and formed local impulse by mixing gas,which strengthened coal rock-breaking ability;cracks were motivated under high pressure liquid pulsa- tion,which promoted by multilevel collapsing of tiny gas phase. By the multilevel alternation of liquid pulsation and gas phase,the coal rock was broken finally when the original cracks were connected.