加载速率对煤样破坏力学及声发射特征研究

为了研究煤体破坏的加载速率效应,分别从煤岩力学性质、声发射特性和数值模拟角度进行了分析。采用RMT-150 C型岩石力学试验机构成的煤样单轴压缩实验系统,结合DS5型全信息声发射信号分析仪,研究了不同加载速率下煤样力学指标和声发射指标的演化规律,研究结果表明:加载速率由0.2 mm/s降到0.000 2 mm/s,煤样的抗压强度降低了58.7%,弹性模量降低了68.7%;声发射峰值计数降低了71.5%,声发射峰值能量降低了52.3%,声发射累计计数和累计能量却有所升高。从数值模拟结果分析:加载速率由0.2 mm/s降低到0.000 2 mm/s,声发射峰值计数降低了75.8%,声发射峰值能量降低了60.9%;声发射累计计数和累计能量均有所升高;煤样的抗压强度和弹性模量分别降低了62.3%和69.1%。数值模拟结果与实验结果规律相一致。

Study on Failure Mechanics and Acoustic Emission Characteristics of Coal Sample under Loading Rate

In order to study the loading rate effect of coal body failure,this paper analyzed the mechanical properties,acoustic emission characteristics and numerical simulation of coal and rock.The evolution law of mechanical index and acoustic emission index of coal samples under different loading rates was studied by using the uniaxial compression experimental system of RMT-150 C rock mechanics testing machine and DS5 full information acoustic emission signal analyzer.The results show that when the loading rate is reduced from 0.2 mm/s to 0.000 2 mm/s,the compressive strength of coal sample is reduced by 58.7%,and the modulus of elasticity is reduced by 68.7%.When the peak number of acoustic emission decreases by 71.5%,the peak energy of acoustic emission decreases by 52.3%.But the accumulated count and energy of acoustic emission increase.From the analysis of numerical simulation results,when the loading rate is reduced from 0.2 mm/s to 0.000 2 mm/s,the peak count of acoustic emission is decreased by 87.2%,and the peak energy of acoustic emission is decreased by 60.9%.The accumulative count and energy of acoustic emission increases.The compressive strength and elastic modulus of coal samples are reduced by 62.3% and 69.1% respectively.The numerical simulation results are consistent with the experimental results.