不同加载方向条件下堆石料剪胀特性试验研究

剪胀方程描述的是塑性应变增量比例大小的变化规律，是构建弹塑性模型的重要组成部分。然而目前堆石料的剪胀方程大都是根据等围压 路径得到的，这些剪胀方程是否能反映不同应力路径条件下堆石料的剪胀规律还尚不明了。开展了等围压 、等轴向力 、等平均主应力p、等主应力比 共4种应力路径下的堆石料大型三轴试验，研究了应力路径对堆石料剪胀规律的影响。试验表明：不同路径的剪胀比 和应力比 均呈近似线性关系，但剪胀比与应力比不存在一致的关系，表现出明显的应力路径相关性；在 - 空间中，剪胀线随着应力增量方向的变化会发生平移和转动，其斜率 和截距参数 均随 ( )的增大而增大；目前的剪胀理论不能较好地描述剪胀的应力路径相关性，提出了一个考虑应力增量方向影响的修正剪胀方程并对其进行了试验验证。

Stress dilatancy of rockfill material under different loading directions

Dilatancy, representing the plastic flow direction of granular material, is an important part in elastic-plastic constitutive model. So far, the dilatancy equation of rockfill is mainly obtained by the conventional triaxial test, and it is not clear whether these dilatancy equations can reflect the dilatancy law of rockfill under different stress paths. In this paper, tests with four different stress paths, including constant confining pressure , constant axial stress , constant mean effective stress p, and constant principal stress ratio are conducted to study the influence of stress paths on the dilatancy. The results show that: the dilatancy ratio is linearly associated with the stress ratio under different paths, but there is no consistent relationship between the dilatancy ratio and the stress ratio; the dilatancy line translates and rotates with the stress increment direction in the - space, and the slope parameter and the intercept parameter are increased with the increase of ; the existing dilatancy equations cannot well describe the dilatancy relationship under different stress paths, and a modified dilatancy equation considering the stress increment direction is proposed and verified.