超临界CO_2气爆煤体致裂规律模拟研究

Simulation research on law of coal fracture caused by supercritical CO_2 explosion

为研究超临界二氧化碳气爆应力波和爆生气体致裂煤体的规律,通过实验确定了不同温压条件下气爆喷嘴压力时程曲线,反演得到了爆生气体Jones-Wilkins-Lee(JWL)状态方程参数,建立了超临界二氧化碳气爆致裂煤体的冲击动力学模型,应用光滑粒子流体动力学方法对不同压力的超临界二氧化碳气爆煤体过程进行了模拟计算,揭示了粉碎区和裂隙区的破坏规律和形成机理,得到了气爆过程中爆破压力的分布.结果表明:煤体破坏形貌与实验结果一致;超临界二氧化碳气爆产生的冲击载荷超过爆孔周围煤体的动态抗压强度形成粉碎区,粉碎区外的介质在应力波作用下产生径向位移,形成环向拉应力,连同爆生气体的气楔作用使得环向拉应力超过煤体动态抗拉强度发生开裂形成裂隙区;裂隙扩展范围和密集程度与超临界二氧化碳气爆压力正相关.

To investigate supercritical carbon dioxide explosion stress wave and coal fracture laws which were caused by detonation gas,pressure history curves of the nozzle were determined by the method of experiments at different temperature and pressure,and parameters of Jones-Wilkins-Lee state equation were inverted.An impact dynamics model of coal fracture was established and the simulation of supercritical carbon dioxide explosion process was carried out based on smoothed particle hydrodynamics.The distribution of explosion pressure was obtained in the process of gas explosion.The destruction rule and formation mechanism of crushing zone and fracture zone was revealed.The results show that the fracture morphologies were consistent with experimental results.Smash area was formed around the blast hole,caused by impact load exceeds dynamic compressive strength in the process of supercritical carbon dioxide explosion.The medium outside smash area have a radial displacement under the effect of stress wave which cause the circumferential tensile stress,combined with the effects of gas wedge exceeds dynamic tension strength of the coal,forming fracture zone.Fracture extent and intensity are positively correlated with supercritical carbon dioxide explosion pressure.