干湿循环下粗粒土回弹模量演变规律及模型预估和修正

Evolution law and model estimation and modification of resilience modulus of coarse grained soil subgrade under wet and dry cycle

借助动三轴试验系统,研究了不同含水率、应力加载路径和干湿循环次数下粗粒土回弹模量的变化规律,采用多种预估模型对模型参数进行统计回归,最终确定Ni模型为粗粒土模量预估模型,并提出了干湿循环修正系数及拟合方程。试验结果表明:回弹模量随含水量的增加呈减小趋势,含水量为4%时对应的回弹模量值最大;当偏应力一定时,围压与回弹模量呈正相关,当围压一定时,偏应力与回弹模量呈负相关;随着干湿循环次数的增加,回弹模量整体呈衰减趋势,且在干湿循环次数N=1、2时衰减幅度最大,N=3、4时衰减幅度减小,当N>4时回弹模量趋于稳定。本文研究成果可为粗粒土路基设计提供参考依据。

With the help of the dynamic triaxial test system, the changes of coarse-grain soil rebound modulus under different moisture content, stress loading paths and dry and wet cycles(N) are studied. A several estimation models are used to determine the Ni model as the estimation model of coarse-grain soil modulus, and the correction coefficient and fitting equation are put forward. The test results show that the rebound modulus decreases with the increase of water content, and the rebound modulus corresponding to 4% water content is the largest. When the partial stress is fixed, the surrounding pressure and the rebound modulus are negatively correlated with the rebound modulus. With the increase of N the rebound modulus has the trend of decay, which reaches the maximum at N=1~2, and the decay is reduced at N=3~4,when N>4, the rebound modulus becomes stable. The research results provide a reference basis for the design of coarse-grain soil subgrade.