漳村煤矿两种尺度煤样单轴压缩声发射特征的试验研究

Research on acoustic emission characteristics of Zhangcun coal samples in two sizes subject to uniaxial compression

利用RMT-150B岩石力学试验系统,对潞安漳村煤矿3号煤层两种尺度煤样进行单轴压缩声发射试验。标准煤样为50 mm×100 mm,大煤样为155 mm×155 mm×125 mm,两种尺度煤样含有原始节理,裂隙等缺陷存在差异,表现出单轴压缩试验过程的变形、强度和声发射参数有所不同。试验结果表明:大煤样单轴压缩试验过程的变形、强度参数明显低于标准煤样,单轴抗压强度、弹性模量、变形模量的降幅依次19.7%,35.7%和55.4%;两种尺度煤样单轴压缩过程中可分为压密、弹性、屈服和破坏4个阶段,4个阶段均产生不同强度和数量的声发射事件,于此对应可分为平静期、过渡期、活跃期和衰减期,活跃期可作为煤体破坏前兆信息;大煤样产生声发射事件的强度和数量明显高于标准煤样,瞬时最大能量、累计能量分别提高16.6倍和6.4倍;瞬时最大计数、累计计数分别提高11.1倍和8.1倍;瞬时峰值计数和累计峰值分别提高7.4倍和6.6倍;标准煤样的声发射特征值作为煤与瓦斯突出及冲击地压等煤岩动力灾害预测、预报偏于保守,采用大煤样的声发射特征值更加合理。

Acoustic emission characteristics of coal samples in two sizes from the No.3 coal seam in Lu＇an Group Zhangcun Coal Mine under uniaxial compression were studied by the servo-controlled testing machine RMT-150B.The sizes of standard and large block coal samples are Φ50 mm×100 mm and 155 mm×155 mm×125 mm,respectively.Both samples contain different original bedding planes and fissures,and exhibit different deformation,strength and acoustic emission when subject to uniaxial compression.The experimental results show that deformation and strength in large block coal sample are obviously lower than that of the standard samples,and the decreases in amplitude of uniaxial compression strength,modulus of elasticity and modulus of deformation are 19.7%,35.7% and 55.4%,respectively.There are different acoustic emissions corresponding to the four stages of the uniaxial compression process for the two coal samples.These acoustic emissions can be divided into four stages in the following order quiet,transition,active and decay stages.The active stage can be used as a predictor for coal breakage.The strength and quantity of acoustic emissions in large block coals are obviously higher than those in the standard samples.The maximum and accumulative energies in large block coals are enhanced by 16.6 and 6.4 times,respectively.The maximum count of sample failure and the cumulated count are enhanced by 11.1 and 8.1 times;the peak number of sample failure and the cumulated count are enhanced by 7.4 and 6.6 times,respectively.It is conservative to predict coal and gas outburst,rock burst and other dynamic disasters of coal and rock using acoustic emission data of standard coal samples;it is better to use the ones of large block coal samples.