非饱和土双应力变量广义土水特征曲线理论模型构建

发布时间：2018-03-31 07:01

本文选题：土壤水分　切入点：应力　出处：《农业工程学报》2017年06期

【摘要】：土水特征曲线(soil-water characteristic curve,SWCC)方程是非饱和土力学中最重要的土性表征手段之一。该文评价当前经典的SWCC方程,指出其未具有包容复杂因素的能力,具有灵活性的优点但却同时具有对试验数据量依赖性高的缺点,不能处理多孔隙尺度集群土体固-液-气共同运动及作用的水力-力学耦合效应问题。建立双应力变量广义SWCC概念图示并定义相对体积含水比,基于Fredlund双应力变量理论及van Genuchten土-水表征方程,构建考虑土体变形及多孔隙分布形态的双应力状态变量的广义SWCC方程。相较于2个参数的Brooks等的方程、3个参数的van Genuchten方程以及4个参数的Fredlund等的方程,广义SWCC方程仅3个参数,其中2个参数在双对数坐标系的"相对体积含水比-吸力"平面中进行最小二乘法线性拟合得到,仅1个参数需非线性最小二乘法拟合得到。该模型可利用不同应力状态下的至少3个土水试验数据点,绘制出1条具有适宜精度的单峰SWCC;方程考虑了多峰孔隙概率密度函数分布及土体变形因素,实现了从应力历史推广到应力状态的广义情况,为定量描述不同孔隙结构土体双应力状态下的持水特性、渗透特性和强度特性提供了一条途径。
[Abstract]:Soil-water characteristic characteristic equation is one of the most important means to characterize soil properties in unsaturated soil mechanics.In this paper, the classical SWCC equation is evaluated, and it is pointed out that it has not the ability to contain complex factors, has the advantage of flexibility, but also has the disadvantage of high dependence on the experimental data.It can not deal with the coupling effect of hydraulic and mechanical interaction between solid, liquid and gas in multi-pore scale cluster soil.Based on the Fredlund double stress variable theory and the van Genuchten soil-water representation equation, the generalized SWCC equation with double stress state variables considering soil deformation and pore distribution was established.Compared with the Brooks et al equation with two parameters, the van Genuchten equation with three parameters and the Fredlund et al with four parameters, the generalized SWCC equation has only three parameters.Two of these parameters are obtained by least square linear fitting in the plane of "relative volume water ratio to suction" in the logarithmic coordinate system, and only one parameter needs nonlinear least square fitting.Using at least three soil-water test data points under different stress states, the model can draw a single peak SWCC with suitable precision, and the equation takes into account the distribution of multi-peak pore probability density function and the deformation of soil.The generalized condition from stress history to stress state is realized, which provides a way to quantitatively describe the water holding property, permeability characteristic and strength characteristic of soil mass with different pore structure under double stress state.
【作者单位】：西南大学工程技术学院;College
【基金】：国家自然科学基金项目资助(11572262) 中央高校基本科研业务费专项资金资助(XDJK2016D016,XDJK2016B006)
【分类号】：TU43

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