动载诱发冲击地压的实验研究

Experimental study on rock burst induced by dynamic load

运用自主研发的冲击岩爆实验系统,进行了动载诱发冲击地压实验研究,提出了一种判别动载是否诱发冲击地压的实验方法。实验采用对加载至500 m深度应力状态下的带圆柱形贯穿孔洞的立方体砂岩试样,在σ_v方向逐级施加扰动波,σ_h保持在恒定应力水平的加载方式,模拟了500 m深度砂岩巷道,由于顶板垮落产生垂直向冲击扰动,由此诱发冲击地压破坏的过程。通过数据采集系统实时采集力和位移数据,获得应力应变曲线;通过图像采集系统实时拍摄动载诱发冲击地压过程,获得颗粒弹射、碎屑剥落等特征现象。实验发现,动载诱发冲击地压过程经历了平静期、颗粒弹射、碎屑剥落和冲击地压剧烈破坏4个阶段。对巷道围岩应力状态进行计算,得出动载诱发冲击地压时巷道围岩最大切向应力大于其单轴抗压强度。对碎屑特征及微观结构分析发现,动载诱发冲击地压产生的碎屑呈现出明显的片状特征,以中、细粒碎屑为主,通过电镜扫描可见穿晶裂纹。计算碎屑块度分形维数表明,动载诱发冲击地压破碎程度较单轴压缩破坏高。

Using the self-developed impact rock burst experimental system of State Key Laboratory for Geo Mechanicsand Deep Underground Engineering,the rock burst induced by dynamic load was experimentally studied,and an exper-imental method for discriminating the occurrence of rock burst induced by dynamic load was presented. The cubicsandstone with circular through hole was loaded to the stress state at the depth of 500 m,and then the dynamic cyclicloading was applied toσ_vdirection,while the constant stress was applied toσ_hdirection. Subsequently,the process ofrock burst induced by dynamic load of roof collapse in the vertical direction in the sandstone roadway at the depth of500 m was simulated. In the experiment,the data of force and displacement were collected by the data collection sys-tem to obtain the stress strain curve of the cubic sample,and the rock burst phenomenon of sandstone sample were re-al-time photographed to obtain the feature of rock burst induced by dynamic load. The experiment revealed that theprocess of rock burst induced by dynamic load experiences four stages including quiet period,particle ejection,spallingand rock burst. When the rock burst induced by dynamic load occurs,the maximum tangential stress of surroundingrock is greater than its uniaxial compressive strength by calculating,and the fragment is medium and the fine grainsmainly show obvious lamellate feature. Tranagranular cracks could be observed by Scanning Electron Microscope（SEM）. And the degree of crushing in rock burst induced by dynamic load is more obvious than that in uniaxial com-pression by calculating the fractal dimensions of fragment.