双向静载约束条件下动力冲击对煤岩的损伤影响

The damage of dynamic impact on coal and rock under bidirectional static load constraint

利用自行研制的约束式摆锤冲击动力加载装置,对煤样进行双向静载约束条件下动力冲击试验,在不同静载约束条件下,研究了恒定冲量循环冲击与递增冲量循环冲击对煤样损伤演化的影响规律。基于超声波检测对不同静载约束条件下试样受冲击作用的损伤程度定量化表征,并对不同静载约束条件下煤岩表面的裂纹扩展规律进行了分析。研究发现在不同静载约束条件下煤岩产生损伤的冲量阈值不同,并且煤岩在不同冲击方式作用下的损伤量均随累计冲量的增加而增大,当累计冲量相同并且每次冲击产生的冲量均大于煤岩产生损伤的冲量阈值时,恒定冲量冲击对煤岩的破坏效率更高。在静载约束条件下,裂纹尺度和数量以及分岔频率均随静载约束比的增加而增加,即随着静载约束比的增加,煤岩的破坏形式趋于复杂化发展。

The dynamic impact test of coal samples under bidirectional static load constraints was carried out with the self-developed dynamic loading device of pendulum impact.The effects of constant impulse and incremental impulse on the damage evolution of coal samples were studied under different static load constraints.Based on the quantitative characterization of the damage degree of samples subjected to impact under different static load constraints,the crack propagation law of coal rock surface under different static load constraints has been analyzed.It has been found that the impulse threshold of coal and rock damage is different under different static load constraints,and the damage amount of coal rock under different impact modes rises with the increase of accumulative impulse.When the cumulative impulse are the same and each impact generated by each impact is greater than the threshold value of coal and rock damage,constant impulse impact is more efficient to destroy coal and rock.Under the condition of static load constraint,the size and number of crack and the bifurcation frequency increase with the static load constraint ratio,that is,as the static load constraint ratio increases,the failure mode of coal rock tends to be complicated.