土-水特征曲线滞后阻塞模型

基于Young-Laplace方程利用土-水特征曲线估算孔隙分布，借鉴非饱和渗流统计模型，建立了土-水特征曲线的滞后模型。在某一基质吸力下对应的毛细半径上限的毛细水对更大孔隙半径的毛细水具有阻塞作用，阻塞概率与孔隙分布函数直接相关。孔隙分布函数自身属性体现了土体孔隙空间分布的非均匀性。该模型显示：在高基质吸力与低基质吸力阶段，脱湿曲线与吸湿曲线趋近相等；中等基质吸力阶段，脱湿曲线饱和度高于吸湿曲线饱和度，两者的差值存在一个明显的峰值。并采用实例验证了该模型的可靠性，发现该模型对中、细粒土预测效果较好，而砂类土因孔隙分布不符合假设，导致存在较大误差。对于砂类土等特征尺寸较大的土质，引入阻塞概率修正系数，发现最佳修正系数与土-水特征曲线半对数坐标下的土-水特征曲线最大斜率呈反比例关系。

Hysteresis model of soil-water characteristic curve

Based on the Young-Laplace equation, the relationship between pore size distribution and soil-water characteristic curve is estimated. The lagging model of soil-water characteristic curve is established by referring to the statistical model of unsaturated seepage. The capillary water corresponding to the upper limit of the capillary radius under a certain suction of the substrate has a blocking effect on the capillary water of larger pore radius. The probability of obstruction is directly related to the pore distribution function. The pore size distribution function reflects the heterogeneity of spatial distribution of soil pores. The model shows that the desorption curve is almost identical to the absorption curve when the substrate is in high or low matric suction. The water content in the middle section of desorption is higher than that of the absorption curve, and there is a clear peak. The results show that the model works well for medium and fine granular soil, but the sandy soil porosity is beyond the model hypothesis and resulting large errors. For sandy soils, the introduction of blocking rate correction coefficient shows that the best correction factor and SWCC half log under the SWCC maximum slope inversely proportional relationship.