堆石体在真三轴应力状态下的非共轴性与剪胀特性

Non-coaxiality and dilatancy of rockfill materials under true triaxial stress condition

基于连续-离散耦合分析方法,发展随机颗粒不连续变形分析方法。采用不规则多面体模拟实际堆石颗粒,制备初始各向同性的堆石料数值试样,进行等平均静水压力p、等中主应力系数b应力路径的真三轴数值试验。分析堆石料在真三轴应力状态下的剪胀特性,以及应变增量与应力增量的非共轴性。研究结果表明:刚开始加载时,应变增量与应力增量共轴,随着加载的进行,应变增量的方向发生偏转,偏转量与中主应力系数b有关,在三轴压缩应力路径(b=0)和三轴拉伸应力路径(b=1)时,几乎不发生偏转;对比Rowe,Roscoe,改进的Roscoe以及Lagioia剪胀模型,改进的Roscoe剪胀模型预测的剪胀曲线与数值试验结果较吻合,在改进的Roscoe剪胀模型上引入1个角隅函数,以反映中主应力对剪胀特性的影响。

Based on the combined finite-discrete element method, the stochastic granular discontinuous deformation method was developed. Numerical samples composed of irregular polyhedras were compressed to the isotropical state and then subjected to true triaxial loading with the constant mean stress and the constant intermediate principal stress ratio. The dilatancy of rockfill materials was analyzed, as well as the non-coaxiality of the stress increment and the strain increment. The results show that the strain increment and stress increment are coaxial at first, and then the direction of the strain increment has some deflection which is related to the intermediate principal stress ratio. No deflection is shown in the triaxial compression and extension path. The comparison of the Rowe＇s, Roscoe＇s, modified Roscoe＇s and Lagioia＇s models indicates that the dilatancy curve predicted by modified Roscoe＇s model fits well with the simulated results. A ridge function is introduced to describe the influence of the intermediate principal stress ratio on the dilatancy.