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分别利用RMT-150C和多功能分离式霍普金森压杆(SHPB)试验系统对砂岩进行了不同应变率下的单轴压缩、三轴压缩和拉伸试验。结果表明,在围压为0或围压一定的情况下,应变率低于102s-1时,抗压强度的增加与应变率的量级呈正比;在应变率高于102s-1时,岩石的抗压强度增加趋势与应变率的1/3次方呈正比。拉伸强度也存在类似规律。针对101~102s-1应变率范围内缺少岩石动态强度准则这一现状,根据上述试验规律,结合Mohr-Coulomb准则、Hoek-Brown准则和Griffith准则的原理,给出了不同应变率范围内动态Mohr-Coulomb准则和动态Hoek-Brown准则的具体表达形式。研究结果表明,在低应变率情况下,动态Mohr-Coulomb准则和动态Hoek-Brown准则均适用,但Griffith准则判别结果误差很大。在高应变率情况下,动态Mohr-Coulomb准则比较适用,Griffith准则仅适用于评估高应变率单轴抗压强度和抗拉强度之间的关系。
Sandstone was subjected to uniaxial compression, triaxial compression and tensile tests under different strain rates by using the RMT-150C and the multi-functional split Hopkinson pressure bar (SHPB) test system respectively. The results show that when the confining pressure is 0 or the confining pressure is constant, the increase of compressive strength is proportional to the magnitude of strain rate when the strain rate is lower than 102s-1. When the strain rate is higher than 102s-1, The compressive strength increase trend is proportional to the 1/3 of the strain rate. Tensile strength there is a similar law. According to the above experimental law and the principle of Mohr-Coulomb criterion, Hoek-Brown criterion and Griffith criterion, a dynamic Mohr model with different strain rates is presented in view of the lack of rock dynamic strength criterion in the strain rate range of 101 ~ 102s- -Coulomb criteria and dynamic Hoek-Brown criteria specific expressions. The results show that the dynamic Mohr-Coulomb criterion and the dynamic Hoek-Brown criterion are applicable at low strain rate, but Griffith’s criterion has great error. The dynamic Mohr-Coulomb criterion is more applicable at high strain rates. The Griffith criterion applies only to assess the relationship between high strain rate uniaxial compressive strength and tensile strength.