基于微震监测的矿山开挖扰动岩体稳定性评价

Stability evaluation of excavated rockmass in mines based on microseismic monitoring

基于已有的微震监测资料,借助有限元数值模拟手段,分析深部矿山开挖条件下围岩裂隙损伤演化机制,同时探寻微震监测数据与应力场变量之间对应关系。研究结果表明:微震监测系统可以有效的识别围岩微破裂孕育机制并圈定岩体潜在失稳区域;结合数值模拟与微震监测结果发现3363号矿房围岩出现潜在失稳主要是由于矿房上覆岩层内部存在高水压含水层,在高水压力和开采扰动作用下,含水层与采空区之间形成条形的应力集中带,诱发微破裂的萌生、扩展和贯通,最终产生潜在失稳区;微震监测数据(累积事件数、累积能量、累积应力降)与应力场变量存在很好的对应关系,根据微震监测数据的时空分布规律可以对高应力区域的转移进行描述,并验证定量分析不同区域的应力状态的可能。研究结果为揭示复杂地质条件下深部矿山开挖岩体失稳机制及微震活动规律提供依据,指导矿山现场短期或者长期开采工艺的选择。

Crack damage evolution mechanism of surrounding rock in deep mines was analyzed under excavation disturbance based on the results of microseismic monitoring data recorded and numerical simulation using realistic failure process analysis（RFPA） approach.The qualitative relations between microseismic variable values estimated from mine microseismic monitoring systems and the stress estimates provided by numerical models were explored.The research results show that microseismic monitoring system can effectively identify evolution mechanism the microcracks of surrounding rock and help to locate potential instability area of rockmass.The generation of potentially instability area insurrounding rock of No.3363 stope was mainly due to existed high water pressure aquifer in overlying rock strata of stope.The stress concentration zone was formed between aquifer and goaf under the effect of high water pressure and excavation disturbance,induced micro-fractures initiation,growth and expansion in deep rock masses,and formed potential instability area.There are good corresponding relations between microseismic variable values（cumulative events number,cumulative energy,and cumulative stress drop） estimated from mine microseismic monitoring systems and the stress estimates provided by numerical models.The shift of high stress area can be described based on tempo-spatial distribution regularity of microseismic events.It was possible by using microseismic variable values to quantitative analysis of the stress state of different regions.The research results provide important the basis for understanding instability failure mechanism of deep rock mass and microseismic activity law in complex geologic condition and be used to eventually impact both short-and long-term mine design decisions.