扰动诱发高应力岩石动力响应及岩爆灾变机制

Dynamic response law of high-stressed rock triggered by dynamic loading and mechanism of rockburst occurrence

为揭示深部矿山岩爆发生机制,以硬质红砂岩为研究对象,利用岩石动静组合加载试验系统开展了无轴向静压及4个轴压条件下的不同入射能冲击试验,获得了纯动载及动静组合加载下岩样的力学行为与破坏特征。结果表明:试样最终形态分为完整、轴向劈裂、表面剥离、即时型粉碎和滞后型粉碎五类,其中,表面剥离和滞后型粉碎两类破坏模式表现出“岩爆”特征,即Ⅰ型应力−应变曲线、峰后释放能量、岩石自身静应变储能驱动碎片弹射、明显压剪破坏面;根据碎片弹射与动力加载的相对时间,进一步将表面剥离与滞后型粉碎破坏分别对应深地工程中的“即时型”和“滞后型”岩爆;动力扰动是岩爆的关键诱发因素,触发岩爆的临界扰动能随轴压比升高而逐渐降低。

To reveal the occurrence mechanism of rockburst in deep mines,we took a hard red sandstone as the research object,and conducted series of impact tests with different incident energy under no axial static pressure or four axial pre-stress levels by using the coupled static-dynamic rock testing system.The mechanical response and damage characteristics of red sandstone samples subjected to pure dynamic loading and coupled static-dynamic loading were obtained.The results show that the final patterns of samples after tests can be divided into five categories:intact,axial splitting,surface spalling,instant pulverization and delayed pulverization.The modes of surface spalling and delayed pulverization exhibit the characteristics of“rockburst”,includingⅠtype of stress-strain curve,energy release at post-peak,the static strain energy stored in the sample driving the ejection of fragments,obvious compressive-shearing failure planes on rock fragments.According to the relative time of fragment ejection and dynamic loading,the surface spalling and delayed pulverization failure modes respectively correspond to the instant and delayed rockburst in actual engineering.Dynamic disturbance is the key inducement factor of rockburst occurrence.The critical disturbance energy to trigger rockburst decreases gradually with the rise of axial stress ratio.