高压脉冲作用下岩石的击穿特性与物理力学参数关系试验研究

Experimental Study on Relationship Between the Breakdown Characteristics and Physical and Mechanical Parameters of Rocks Under High Voltage Pulses

高压脉冲提供了一种非常具有应用前景的新型破岩技术。为了研究高压脉冲作用下岩石的击穿破裂特性,并掌握击穿场强与物理力学参数之间的关系,开展了不同岩性岩石的电击穿试验。借助扫描电子显微镜分析了高压脉冲击穿后岩石的微观破裂机制,比较了不同岩性岩石在刚好击穿时的破裂模式,研究了岩石物理力学参数对击穿场强的影响。微观分析结果表明:等离子体通道附近区域呈现高温灼烧特征,晶粒表面光滑且出现孔洞;冲击波作用下裂纹区主要为沿晶断裂和穿晶断裂;过渡区则表现出高温和冲击波共同作用的特征。此外,岩石的击穿场强与密度、波速、弹性模量之间的相关性较弱;而与抗压强度及抗拉强度之间具备一定的量化关系,击穿场强随着抗压强度和抗拉强度的增大呈指数型增长。

High voltage pulse provides a new rock breaking technology with great application prospect.In order to study the fracture characteristics of rock breakdown by high voltage pulses,and clarify the relationship between breakdown field strength and physical and mechanical parameters,electric breakdown experiments on different lithological rocks were conducted.The microscopic fracture mechanisms of rocks after breakdown were analyzed with the aid of a scanning electron microscopy,and the rupture patterns of different lithological rocks at just breakdown were compared.Besides,the influence of physical and mechanical parameters on the breakdown field strength of rocks was studied.The results of microscopic analysis show that:the region near the plasma channel shows high-temperature burning characteristics with smooth grain surface and holes;The crack region presents intergranular and transgranular fractures under shock waves;The transition area shows the joint action of high temperature and shock waves.In addition,there is little correlation between the breakdown field strength and the density,wave velocity,and elastic modulus.However,a good quantitative relationship can be established between the breakdown field strength and the compressive and tensile strengths of rocks,which increases exponentially with the increase of these two parameters.