多级动荷加载条件下煤岩应力–声发射耦合特性试验

Experimental on coupling properties of stress and acoustic emission during coal and rock fracture under multilevel dynamic loadings

多级动荷加载条件下煤岩应力-声发射耦合特性研究对工程岩体稳定性监测具有重要意义。以揭示多级动荷加载作用下煤岩应力与声发射的关系为目的,采用多级动荷加载煤岩力学特性测试系统,获取得到多级动荷作用下煤岩疲劳损伤的应力与声发射同步数据。研究结果表明煤岩材料的疲劳累积强度始终小于单轴抗压强度。通过分析煤岩疲劳损伤声发射的Felicity效应,得出多级动荷加载诱导损伤裂纹扩展速率加剧,煤岩应力记忆特性的Felicity效应显著,Felicity比值随逐级动荷加载逐渐降低;基于GP算法计算应力与声发射的关联维数,可合理解释Felicity效应的显著程度,应力与声发射耦合特性的分形结构特征愈显著,关联维数越大,声发射的Felicity效应越弱,煤岩材料原先损伤和结构缺陷程度越低,两者关系呈负相关。

It is a significant task for rock mass stability monitoring to study coupling properties of stress and acoustic emission(AE) of coal and rock fracture under multilevel dynamic loadings. This paper is aiming at revealing relations of stress and AE of coal and rock samples under multilevel dynamic loadings. Stress and AE synchronous data has been obtained from mechanic properties testing system of coal and rock samples under multilevel dynamic loadings. The results show that the accumulation stress of coal and rock under multilevel dynamic loadings is obviously less than the maximal compression stress. Then,multilevel dynamic loadings could induce cracks extension according to the felicity effect of coal and rock. Memory characteristic of rock stress shows obvious felicity effect and the felicity ratio presents a decline trending with the larger level dynamic loadings. Also,fractal dimension between stress and AE has been calculated by using of GP algorithm,which could explain the perform of felicity effect reasonably. Coulping properties of stress and AE show more obvious on fractal structure characteristics. The fractal dimension is relatively larger. The felicity effect is not obvious and the fatigue damage and structure defect degree is lower,which show the negative correlation.