Research on Dynamic Characteristics of Hydraulic Fracturing in Coal Body Containing Gas

摘要： 为了研究煤体水力压裂的破裂机理及动态变化特征，本文以平煤集团十二矿为例建立了相关数学模型，通过数值试验和现场实验，获得了水力压裂过程中裂隙起裂及扩展过程的动态变化特征，即：应力积累→微裂纹稳定扩展→局部破坏带形成→局部破坏带扩展与贯通→裂隙失稳扩展；结合现场实测数据及含瓦斯煤体水力压裂动态变化影响因素分析，建立了煤体埋深、瓦斯压力和水力破裂压力三者耦合模型，研究结果对现场实践具有重要指导意义。

关键词: 水力压裂, 破裂机理, 动态特征, 数值模拟

Abstract: To study the hydraulic fracturing mechanism and its dynamic characteristics，taking 12th mine of Pingdingshan Coal Group as example，a related mathematic model was built，and the dynamic characteristics of fracture initiation and extension were gained in the progress of hydraulic fracturing by numerical simulation and field test，which is described as: stress cumulating →micro-cracks steadily developing →partially destroyed area forming →partially destroyed area extension and coalescence →cracks unsteadily developing．Combined with the analysis of onsite measured data and influencing factors of hydraulic fracturing dynamic changes of coal body containing gas，the coupling model which is composed of coal seam depth，gas pressure and hydraulic fracturing pressure is fitted．The results have an important significance to the field practice．

Key words: hydraulic fracturing, fracture mechanism, dynamic characteristics, numerical simulation