气动力脉冲-水力耦合冲击预裂破岩试验研究

Experimental investigation on pre-cracking by aerodynamic pulse hydraulic coupling impact

为解决深部矿井地层体积压裂难的问题,通过构建深孔超前气动预裂破岩试验装置,并以大尺寸混凝土为压裂对象,开展气动力脉冲-水力耦合冲击破岩试验,探究了气动力脉冲-水力耦合冲击波在钻孔管道中的传播衰减规律,及其在含裂隙岩体中的破岩效果。试验结果表明:初始气动力脉冲压力越高,耦合脉冲在管道中的衰减系数越低,当压力达到35 MPa以上时,衰减系数小于0.1,并推导得出100 MPa压力下的衰减系数仅为0.0648;低压气动力脉冲对于岩石的致裂效果不明显,而在40 MPa以上高压气动力脉冲作用下,混凝土试块裂纹数量增多,隙宽增加,其中最大裂纹宽度达1 cm。该研究成果可为进一步探索深层矿井在高地应力下的岩体破裂及其他相关工程领域提供基础。

To address the challenges posed by high geo-stress in deep coal mines below one kilometer in China and achieve safe and efficient coal seam unloading as well as pre cracking for enhanced permeability,a deep-hole pneumatic pre-cracking and rock breaking system was independently developed using large-sized concrete as the fracturing object.Tests were conducted to investigate the attenuation law of pneumatic pulse pressure during propagation and its rock-breaking effect under the condition of pre-existing cracks.The experimental results showed that the higher the initial air pressure,the lower the attenuation coefficient of pressure after propagating a certain distance.When the pressure exceeded 35 MPa,the attenuation coefficient was less than 0.1,and the attenuation coefficient under 100 MPa pressure was only 0.0648.Low-pressure gas pulses had no significant fracturing effect on rocks,while under the action of high-pressure gas pulses above 40 MPa,the number and width of cracks in concrete specimens increased significantly,with the maximum crack width reaching 1 cm,accompanied by a large amount of high-pressure water vapor ejected from the cracks.The research findings may serve as a preliminary basis for further exploration of rock fragmentation and related engineering fields in deep mines where high stress conditions prevail.