可变形土中孔径分布函数的模拟

Simulation of the pore size distribution function for a deformable soil

为了获取一种可变形土孔径分布函数(PSDF)的间接估测方法,用传统土-水特征曲线(w-SWCC)函数和收缩曲线(SC)函数作为初始输入函数.w-SWCC曲线函数给出在不同土吸力条件下土体中的水分含量,SC曲线阐释了在不同含水量土样的孔隙比.选取w-SWCC曲线中的10个点作为初始状态,转换计算得到10个以饱和度和土吸力表征的土-水特征曲线组(S-SWCC).基于毛细定律,将土-水特征曲线组转换得到孔径分布函数组,每一个PSDF曲线都对应着不同的孔隙比.从该理论计算模型发现:可变形土在干燥过程中PSDF曲线可能会由双峰型转向单峰型转变.选取Chataignier黏土作为该理论计算模型的验证对象,与压汞孔试验(MIP)实验数据对比,发现模型计算结果与实验结果较为相符.同时分析了该理论计算模型结果与MIP实验结果在孔径数值的分布间隔和孔径密度峰值之间存在一定差异的原因.

In order to obtain an indirect estimation method of the pore size distribution function(PSDF)for a deformable soil,both the soil-water characteristic curve in the form of gravimetric water content(w-SWCC)and the shrinkage curve(SC)are used as the input parameters.The w-SWCC defines the relationship between the gravimetric water content and soil suction.The SC illustrates the variation of the void ratio with respect to different water contents.10 points in the w-SWCC were selected as initial conditions.By adopting different void ratios,a group of soil-water characteristic curve in the form of the degree of saturation(S-SWCC)can be obtained.Based on Kelvin's capillary law,the S-SWCCs can be converted into a group of PSDFs.In the group of PSDFs,each PSDF represents the geometric pore space in soil corresponding to a given void ratio.From the proposed methodology,it is observed that a bimodal PSDF can be gradually changed into a unimodal PSDF when the soil is compressed.The Chataignier clay is selected as the verification and it shows that the simulation results agree well with the measured results from the mercury intrusion porosimetry(MIP)test.In addition,the discrepancies between both direct measurement data using the MIP test and the indirect estimated results from the proposed method are also discussed.