抛掷型岩爆震源体能量动态释放机制与几何尺度特征  

Dynamic energy release mechanism and geometric scale feature of ejection rockburst source

作　　者：向鹏[1] 纪洪广[1] 蔡美峰[1] 张月征[1] 

机构地区：[1]北京科技大学城市地下空间工程北京市重点实验室,北京100083

出　　处：《岩土力学》2018年第2期457-466,共10页Rock and Soil Mechanics

基　　金：国家重点研发计划资助(No.2016YFC0600801);国家自然科学基金重点项目资助(No.51534002)~~

摘　　要：为了进一步理解岩爆的机制并解释岩爆发生的过程,通过对抛掷型岩爆能量来源、去处及大小的分析,提出了抛掷型岩爆的震源两体模型。抛掷型岩爆本质上是释能体-岩爆体相互作用下岩石裂纹动态扩展和能量快速释放的过程。从岩爆体张拉断裂机制出发,采用脆性内聚裂纹阵列扩展动力学模型分析了裂纹间距与应变率对岩爆体能量释放速率的影响。据此得出释能体对岩爆体的作用可归结为应变率效应,释能体能量释放速率越大,对岩爆体的动态加载速率就越大,使得岩爆体能量释放速率加快。岩爆体破裂能量释放速率越大,作用于释能体的动态卸载速率就越大,又使得释能体的能量释放速率增大,两体相互作用形成的动态加、卸载效应构成了岩爆能量释放的正反馈机制。基于上述理论推导得出岩爆震源体的几何尺度是岩爆体的几倍到几十倍,理论结果与现场实际监测分析基本吻合。To investigate the mechanisms of rockburst and to explain the process of rockburst occurrence, a two-body model of the ejection rockburst source was proposed by analysing the sources, the dissipation and the magnitude of the released energy. The rockburst is essentially a process of brittle crack growth and rapid energy release in rocks under the interaction between energy- release-body and rockburst-body. Based on the tensile fracture mechanism of rockburst-body, the influence of crack spacing and strain rate on the dynamic energy release rate was analysed by using a dynamic model of brittle cohesive crack-array growth. The role of energy-release-body for rockburst-body can be attributed to loading strain rate effect. It can be found that a higher energy release rate of energy-release-body results in a greater dynamic loading rate and energy release rate of rockburst-body. Meanwhile, a higher energy release rate of rockburst-body leads to a greater dynamic discharge rate and energy release rate of energy-release-body. Dynamic loading and unloading effect caused by the interaction between two bodies constitutes a positive feedback mechanism of rockburst energy release. Based on the above theory, it is concluded that the geometrical scale of the rockburst source is almost several to dozens of times larger than rockburst-body, which is consistent with the field monitoring results.

关 键 词：抛掷型岩爆 两体系统 裂纹动态扩展 能量释放速率 应变率效应 几何尺度 

分 类 号：TD45[矿业工程—矿山机电]