Q3原状黄土变形过程中的应变速率效应

The strain rate effects of Q3 original loess during deformation

为揭示应变速率对黄土体变形过程的影响规律,以兰州Q3黄土为对象,在不同含水率和围压条件下,系统开展黄土体应变速率效应的三轴试验研究,且以应力-应变曲线、抗剪强度、孔隙压力作为关键要素进行分析。结果表明:应力-应变曲线存在应变软化效应,高应变率促使应变软化的产生,但高含水率、高围压抑制应变软化的产生;应变速率对抗剪强度有显著影响,抗剪强度随应变速率的增大呈现先增大再减小的规律,黏聚力的变化规律与之相同,应变速率对内摩擦角的影响规律与之相反;应变速率对孔隙压力的增长趋势几乎没有影响,但孔隙压力峰值受应变速率的影响显著,且含水率和围压不同,其变化规律存在差异。Q3原状黄土变形过程中存在明显的应变速率效应,其对黄土地区工程应用和丰富黄土力学具有积极的意义。

In order to reveal the influence law of strain rate during deformation of loess.Taking Lanzhou Q3 loess as an object of study,the triaxial tests of strain rate effect of loess are carried out under different water content and confining pressure conditions,and the stress-strain curve,shear strength,and pore pressure are analysed.The results show that there is strain softening effect in stress-strain curve,and high strain rate promotes the strain softening,however,high water content and high confining pressure restrain strain softening.The shear rate has a significant effect on the shear strength,and with the increase of the strain rate,the shear strength increases first and then decreases,the change law of cohesion is same as that of shear strength,but the influence of strain rate on the internal friction angle is opposite to the shear strength.The strain rate has little effect on growth trend of pore pressure,however,the peak pore pressure is significantly affected by strain rate.But,the variation rule is different with different water content and confining pressure.In a few words,there is a significant strain rate effect in deformation process of Q3 original loess,which is great significance to engineering application in loess area and rich loess mechanics.