考虑吸应力非线性非饱和的无粘性土主动土压力模型

挡土墙背后的填土往往是非饱和土。在稳态流条件下,非饱和土含水量铅直分布呈现非线性变化规律。通过对库仑土压力理论基本假设进行补充,采用条分法划分土楔体,在忽略条间力的前提下,利用静力平衡条件,结合抗剪强度公式、基质吸力铅直分布公式等辅助条件,建立考虑吸力非线性分布的无粘性土主动土压力计算模型,并对模型进行检验与计算。结果表明:库仑土压力公式是将整个土楔体视为单一土条推导得到的,是本文所建立模型的一个特例;无粘性土主动土压力随比流量和地下水埋深的增大均呈现先递减后增大的变化趋势。

Active Earth Pressure Model of Unsaturated Cohesionless Soil Considering the Nonlinear Distribution of Suction Stress

The fillbehind the retaining wall is usually unsaturated soil. In the steady flow conditions, the vertical distribution of the water content in unsaturated soil presents nonlinear variation. The basic assumptions of Coulomb's earth pressure theory were firstly extended, and then the slice method was used to divide soil wedge. On the basis of the ignored inter-slice force, the static balance condition, the shear strength formula, as well as the verticle distribution formula for matrix suction were all utilized. The active earth pressure model of unsaturated cohesionless soil, with the consideration of the nonlinear distribution of suction stress, was established. Meanwhile, the model in this paper was verified for calculation. The results show that the Coulomb's earth pressure formula is derived from considering the whole earth wedge as a single soil strip, which is a special case of the model established in this paper. The active earth pressure of the unsaturated cohesionless soils decreases first and then increases with the increase of specific flow rate and the groundwater depth.