循环荷载作用下黄土边坡变形研究

 通过室内不排水动三轴试验，研究列车循环荷载长期作用下，Q3黄土的动强度以及动应力–动应变关系。结果表明，Q3黄土动应变随动应力及振动次数的增加而增大，动弹性模量随动应变增大逐渐减小，动强度随循环次数的增加而降低。在此基础上，建立黄土边坡的动力分析模型，分析机车振动荷载作用下边坡的变形规律。结果表明，边坡位移随时间的增大而增大，下边坡的变形量要远远大于上边坡的变形量，边坡位移表现为一个非稳定的变形过程；由于机车荷载的作用，黄土的动强度下降，从而造成边坡的稳定性降低，相对于上边坡而言，下边坡更易失稳。

STUDY ON DEFORMATION OF LOESS SLOPE UNDER CYCLIC LOAD

By collecting loess samples in typical slope along Zhengzhou—Xian passenger special line，the dynamic shear strength and dynamic stress-dynamic strain relationship of Q3 loess acquired by loess undrained dynamic triaxial test under cyclic load are discussed. The results show that with the increase of cycle number，the strain of Q3 loess develops. When the dynamic load is less than preliminary consolidation pressure，the dynamic strain increases in several initial cycles，and strain rate decreases after cycle number with that strain curve becomes flat；once exceeding preliminary consolidation pressure，the strain increases rapidly and eventually leads to soil damage. Dynamic elastic modulus with increasing strain gradually decreases，and this relationship can be described as hyperbolic form. The dynamic shear strength lower than static shear strength decreases with cycle number. Based on these results，the loess slope dynamic model is established，and the slope deformation rules are studied. The rules show that the instability process is an unstable one as stress，displacement，velocity and acceleration of slope change with time. The lower slope has great displacement and becomes instable more easily than the corresponding upper one. Subjected to train vibration load，the dynamic shear strength of loess decreases，which leads loess slope stability to decrease. Compared with the upper slope，the lower slope is apt to be instable easily.