模量指数评价煤的冲击倾向性的实验研究

为研究模量指数评价煤的冲击倾向性的可行性,选取4组冲击倾向性强弱不同的煤样试件,测定各组煤样试件的模量指数、冲击倾向性评价指标和声发射信号,分析模量指数同其它冲击倾向性评价指标和评价结果的相关性,模量指数对煤加载过程中内部能量释放特征的影响。研究结果表明:模量指数同其它冲击倾向性评价指标具有相关性,同单轴抗压强度之间的相关性最强;各组冲击倾向性相同的煤样,各试件模量指数大小的变化范围较小。各组冲击倾向性不同的煤样,各试件模量指数大小的变化范围很大。煤样模量指数的大小和煤的冲击倾向性强弱相关,煤的冲击倾向性越强,模量指数越大。依据模量指数评价煤的冲击倾向性的结果,同其它评价指标的评价结果具有一致性;不同冲击倾向性煤样的软化模量是决定煤的模量指数大小的关键因素,弹性模量对模量指数大小的影响较小;煤样内部能量的释放特征和模量指数的大小相关。模量指数小的煤样在全程加载过程中声发射事件频繁出现,模量指数大的煤样在破坏前后阶段没有明显的声发射事件出现,但在临近载荷曲线峰值的冲击破坏阶段集中出现高能量的声发射事件。模量指数可用于评价煤的冲击倾向性,模量指数对煤样能量释放的影响规律可用于指导现场监测。

Experimental study on the evaluation of coal burst tendency utilizing modulus index

In order to study the feasibility of evaluating the bursting tendency of coal by modulus index,the modulus index,bursting tendency evaluation indexes and acoustic emission signal of four group coal specimens with different bursting tendency strengths are determined.The correlation between the modulus index and the other evaluation indexes of the bursting tendency and the valuation results of bursting tendency are analyzed.The influence of the modulus index on the internal energy release characteristics of coal is analyzed according to acoustic emission signal.The results show that the modulus index is related to other evaluation indexes of the bursting tendency.The correlation between coaxial compressive strength is the strongest.For the coal specimens with the same bursting tendency,the change range of modulus index of each specimen is small.For the coal specimens with the different bursting tendency,the change range of modulus index of each specimen is large.The magnitude of modulus index of coal is related to the bursting tendency of coal.The stronger the coal bursting tendency is,the larger the modulus index is.The results of evaluating the coal bursting tendency according to the modulus index are consistent with the evaluation results of other evaluation indexes.The softening modulus of different bursting tendency is the key factor to determine the modulus index of coal,and the influence of elastic modulus on modulus index can be ignored.The release characteristic of internal energy of coal specimens is related to the magnitude of modulus index.The acoustic emission events occur frequently during the whole loading process of coal with large modulus index,while acoustic emission events releasing high-energy centrally occur in the coal with small modulus index at the peak load moment.The modulus index can be used to evaluate the coal bursting tendency,and the influence of modulus index on coal energy release can be used to guide on-site monitoring.