动静载作用下煤的动力学特性试验研究

Experimental study of dynamic characteristics of coal under static and dynamic loads

为了揭示冲击倾向性煤岩动力破坏过程的载荷响应规律,分别采用声发射系统,霍普金森杆试验装置,研究了不同冲击倾向度、不同动静载组合作用下煤样动力破坏特性.研究结果表明:积聚弹性能的不同,不同冲击倾向度煤样动力破坏过程、形式则不同;强冲击倾向性煤样声发射事件主要集中分布在煤样的中轴线位置,煤样最终以劈裂破坏为主;弱冲击倾向性煤样声发射事件均匀分布在煤样内部,煤样以劈裂和局部剪切破坏为主;无冲击倾向性煤样声发射事件零散分布在煤样中部,煤样发生整体性破坏.静载荷不变的条件下,试件动力学参量随动载荷的增大呈增强趋势,随着动载荷增大,试件达到极限失稳所经历的时间变短;加载动载荷固定不变时,试件动力稳定性、达到极限动力失稳经历时间分别与加载静载荷成正相关关系,但存在临界值,即当加载静载荷值达到煤样强度极限50%时,对试件动力破坏起到加速作用.研究结果为煤矿现场冲击地压发生机理分析提供基础规律指导.

In order to reveal the load response law of dynamic failure process of the impact-tendency coal rock,the acoustic emission system and Hopkinson rod test device are were used respectively to study the dynamic failure characteristics of coal samples under different impact tendencies and different dynamic and static loads combination.Research results show that the dynamic failure process and form of coal samples with different impact tendencies are different under different ability levels of accumulative elastic energy.The acoustic emission events of strong impact coal samples are mainly distributed in the middle axis of coal samples,with coal samples mainly split finally.The acoustic emission events of weak impact coal samples are uniformly distributed inside coal samples,with coal samples mainly splitted and locally shear-destroyed.The acoustic emission events of coal samples with no impact tendency are scattered inthe middle of coal samples,with coal samples wholly destroyed.Under the condition of constant static load,the dynamic parameters of samples increase with dynamic load.Specifically,with the increase of dynamic load,the time taken by samples to reach the limit of instability becomes shorter;when the loading dynamic load is fixed,the dynamic stability of samples and the time of reaching ultimate dynamic instability have a positive correlation with the loading static load.But the critical value exists,that is,when the loading static load reaches 50% of the strength limit of the coal sample,the dynamic failure of samples is accelerated.The research results provide the basic law guidance for the mechanism analysis of coal mine rock burst.