基于固定主应力轴假设的砂堆基底应力凹陷的研究

Study of depression of stress on base of sand prism based on fixed principal axes assumption

对砂堆三棱柱的基底应力分布及应力凹陷现象进行了研究,基于固定主应力轴假设(FPA假设)将砂堆分为应力状态已知的I区和应力状态未知的II区,并假设了II区内的多种剪应力分布来求解II区内的应力状态,最后,将不同剪应力分布假设下砂堆中线上的静止土压力系数值与Kulhawy公式计算值对比,可得出如下结论:基底法向应力存在应力凹陷现象,自然休止角越大(砂堆越紧密),应力凹陷程度、应力凹陷范围越大;不同剪应力分布假设下,II区应力分布形态不同,法向应力极小值所在处也不同。剪应力二次方分布假设和三次方假设下砂堆基底应力分布最为合理、最为符合真实情形。

This paper focuses on the basal stress distribution and depression of stress of sand prism. The sand prism is divided into a stress known zone I and a stress unknown zone II based on the fixed principal axes （FPA） assumption. On several shear stress distribution assumptions, the stress state of zone II is available. The values of coefficient of earth pressure at rest on the sand centerline on different shear stress distribution assumptions are compared to the one proposed by Kulhawy. The following results are achieved; there is depression of normal stress on the base of sand prism, and the larger of the friction angle （the denser the sand prism） is, the more the depression of normal stress is; and the larger of the depression range is; the shape of the stress distribution and minimum value of normal stress and the location of the minimum normal stress are different on different assumptions; and the assumption of quadratic distribution and cubic distribution of shear stress are most reasonable.