基于能量贮存及释放主体的煤矿冲击地压分类

Classification of rock burst in coal mine based on energy storage and release bodies

  • 摘要: 冲击地压研究系统包括发生机理、发生准则及基于机理和准则的预测和防治。因诱发冲击地压影响因素众多,相应的类型多样,传统的研究多集中在机理、监测及防治的独立性研究上,造成现场冲击地压预测和防治的盲目性。为了系统性掌握冲击地压机理,提高冲击地压预测和防治效率,通过调研已有的冲击地压分类方法,从能量贮存及释放主体的角度提出了一种新的冲击地压分类方法;依据扰动响应失稳理论,分析了各类型冲击地压的发生机理;建立各类型冲击地压力学模型,得到了冲击地压发生条件的解析解和发生时释放能量估算公式;并对分类方法在预测和防治中的应用进行了初探。研究结果表明:根据能量贮存及释放主体的不同,冲击地压划分为煤体贮存及释放能量型(Ⅰ)、顶板贮存及释放能量型(Ⅱ)、断层带及围岩贮存及释放能量型(Ⅲ)3种类型;Ⅰ型冲击地压由煤体压缩失稳并释放贮存的弹性能产生,发生条件由煤体固有属性单轴抗压强度σc和冲击倾向性指数K决定,释放能量与冲击倾向性指数K呈反比关系;Ⅱ型冲击地压由顶板-煤层变形系统中顶板断裂失稳诱发,顶板抗拉强度σt越大,冲击的临界采空区跨度Lcr越大,失稳垮断时释放能量也越大;Ⅲ型冲击地压由断层带及围岩系统中断层带岩石在软化阶段失稳产生,失稳条件由断层结构及围岩剪切模量确定,失稳时释放能量与断层落差成正比关系。基于各类型冲击地压的分析,提出了针对Ⅰ型冲击地压临界应力Pcr的监测方法及其调控防治方法,针对Ⅱ型冲击地压顶板的变形监测方法和支撑顶板或诱导垮断的防治方法,针对Ⅲ型冲击地压断层附近应力监测和降低断层处应力集中程度的防治方法。

     

    Abstract: The research system of rock burst includes occurrence mechanism,occurrence criterion and prediction and prevention based on mechanism and criterion. As a result of many and various types of factors affecting rock burst,the traditional research mostly focuses on the research of mechanism,monitoring and prevention inde-pendently,which re- sults in blindness in the prediction and prevention of rock burst in the field. In order to master rock burst systematically and improve the efficiency of prediction and prevention of rock burst,the existing classification methods of rock burst were investigated and a new classification method of rock burst based on energy storage and energy release bodies was put forward. The mechanism of rock burst in various types was analyzed based on the disturbance response insta- bility theory of rock burst. The mechanical models of rock burst in various types were established,and the correspond- ing analytical solutions and the estimating formulas of the energy re-leased during the occurrence were obtained. The application of classification method in prediction and prevention was also discussed. The results show that rock burst can be divided into three types according to different energy storage and release bodies:coal type,roof type,fault zone and surrounding rock type. For coal type,the rock burst is resulted from the storage and release of elastic energy of compressed coal mass,and the occurrence conditions are determined by uniaxial compressive strength σc and impact tendency index K. The release energy is inversely proportional to impact tendency index K. For roof type,the rock burst is resulted from the fracture instability of roof in roof-coal seam deformation system. The larger the tensile strength σt of roof,the larger the critical goaf span Lcr of rock burst occurrence,and the larger the energy released during instability and collapse. For fault zone and surrounding rock type,the rock burst is resulted from fault zone rock instability during softening stage in fault zone and surrounding rock system. The instability condition is determined by the fault structure and shear modulus of surrounding rock. The energy released during instability is proportional to the fault drop. Based on the comprehensive analysis of various types of rock burst,for coal type,roof type and fault zone and surrounding rock type,the methods of monitoring of critical stress Pcr ,deformation monitoring of roof and stress monitoring near faults were put forward to monitor occurrence of rock burst,respectively. Methods of control of critical stress Pcr ,sup- port or induced breakage of roof,reducing stress concentration at fault were put forward to prevent and control rock burst,respectively.

     

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