一维稳态流下非饱和土主动土压力强度计算模型

Active earth pressure strength model of unsaturated soil

针对均质非饱和土层内含水率沿铅直方向变化的特点,基于总强度指标描述的朗肯主动土压力强度公式,结合非饱和土的重度、总强度指标与含水率之间的关系模型,得到了含水率铅直分布函数,推导出主动土压力系数、上覆土重和黏聚力的铅直分布函数,建立了非饱和土主动土压力强度计算模型。通过算例计算分析入渗、静水和蒸发等不同流动方向下,非饱和粉质黏土层内主动土压力系数和主动土压力强度的铅直分布规律。结果表明:不同流动方向下,主动土压力系数均随距地表深度增大呈现出非线性递减的规律,流动方向为入渗时主动土压力系数最小,静水条件次之,蒸发条件最大;主动土压力系数之间的差异随深度的增大而减小;主动土压力强度随距地表深度增大呈现出非线性递增的规律,流动方向对主动土压力强度的影响较小。

This paper highlights a novel calculation model for the active earth pressure strength in unsaturated soil, which responds to the way the water content in homogeneous unsaturated soil varies along vertical direction. The model is developed by identifying the water content vertical distribution function and the coefficient of active earth pressure and deducing overlying soil heavy and cohesion vertical distribution function, using the Rankine active earth pressure strength formula, coupled with the relationship model between soil gravity density, water content and total shear strength parameters in unsaturated soil layer. The paper is focused on the calculation and analysis of the law underlying the vertical distribu- tion of active earth pressure strength, together with active earth pressure coefficient in unsaturated silty clay layer, when flow directions vary from infiltration to static water to evaporation. The results demon- strate that active earth pressure coefficient behaving in different flow direction exhibits a nonlinear de- crease with an increasing depth; the minimum coefficient occurs in the active earth pressure when the flow direction is infiltration, followed by hydrostatic condition and the evaporation condition is maximum; the decreasing differences in active earth pressure coefficient depends on the increasing depth; the active earth pressure strength is governed by a nonlinear increase due to an increasing depth, and the flow direc- tion exerts a smaller effect on active earth pressure strength.