论文部分内容阅读
为探讨含水煤样动静组合加载下的力学特征,利用改进split Hopkinson pressure bar(SHPB)和RMT–150试验系统对自然和饱水7 d煤样进行了三维动静组合加载、三维静载对比试验。结果表明:三维静载试验中,自然煤样峰值强度变化幅度为10.49%,饱水7 d煤样峰值强度变化幅度为59.98%,饱水强度软化系数为0.81;三维动静组合加载试验中,轴压强度低于单轴静载煤样强度的55%时,饱水7 d煤样的动态强度高于自然煤样动态强度,饱水7 d煤样比自然煤样动态强度分别提高了7.85%~18.44%(围压4 MPa)和8.71%~19.84%(围压8 MPa);不同围压相同轴压试验中,自然和饱水7 d煤样的动态强度随着围压增大均呈增大趋势,饱水7 d煤样动态强度增加幅度比自然煤样动态强度增加幅度大,表明饱水煤样对围压变化的响应较强。揭示饱水对煤样的强度影响较显著,但应变率起到控制作用,中或高应变率条件下裂隙水与裂隙耦合形成较大刚度,三维动静组合加载饱水煤样动态强度呈增高特征。
In order to investigate the mechanical characteristics of hydrous coal samples under static and dynamic loading, three-dimensional static and dynamic load tests and three-dimensional static load tests were carried out on natural and saturated 7-day coal samples with the improved split Hopkinson pressure bar (SHPB) and RMT-150 test systems. The results show that in the three-dimensional static test, the change range of the peak intensity of natural coal samples is 10.49%, the peak intensity of coal samples in saturated water samples is 59.98%, and the softening coefficient of saturated water intensity is 0.81. In the three-dimensional dynamic and static loading tests, When the compressive strength is lower than 55% of the uniaxial static coal sample strength, the dynamic strength of the 7d saturated coal sample is higher than that of the natural coal sample, and that of the saturated coal sample increases by 7.85% ~ 18.44% (confining pressure 4 MPa) and 8.71% ~ 19.84% (confining pressure 8 MPa) respectively. In the same axial compression tests with different confining pressures, the dynamic intensities of natural and saturated 7 d coal samples increased with increasing confining pressure The trend of increase of dynamic intensities of coal samples during 7 days of water saturation is larger than that of natural coal samples, which indicates that the response of saturated coal samples to confining pressure is strong. It is found that the saturated water has a significant effect on the strength of coal samples, but the strain rate plays a controlling role. Under medium or high strain rate, the fissure water and fractures are coupled to form larger stiffness, and the dynamic strength of the three-dimensional dynamic and static loading saturated coal samples increases .