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采用美国SOILMOISTRUE综合压力板仪法,测试了原状与重塑玄武岩残积土样在不同密度下的土水特征曲线。试验结果表明:不同干密度下玄武岩残积土的进气值不同,干密度大的土样进气值较小,即相同含水率条件下土样的基质吸力随干密度的增大而增大;当基质吸力超过850kPa后,体积含水率随基质吸力的变化很小,重塑土与原状土土水特征曲线基本平行。进一步地采用Van Genuchten模型(简称VG模型)、Fredlund 3参数模型和Fredlund 4参数模型对试验所测的曲线进行了拟合,结果表明:VG模型能较好地拟合本次试验结果,同时给出了拟合参数,拟合的相关系数均大于0.99;对比Fredlund 3参数模型和Fredlund 4参数模型的拟合数据,可以看出假定残余含水率θr等于0是合理的,三种模型对玄武岩残积土土水特征曲线均具有良好的适应性,但VG模型拟合效果最为良好。
The soil water characteristic curve of intact and remodeled basalt residual soil samples at different densities was tested by the United States SOILMOISTRUE integrated pressure plate method. The experimental results show that the infiltration values of basalt residual soils are different under different dry densities, and the infiltration values of soil samples with large dry densities are small, that is, the matrix suction increases with the increase of dry densities under the same moisture content. When the substrate suction exceeds 850kPa, the change of volumetric water content with the substrate suction is small, and the remodeled soil is basically parallel with the undisturbed soil-water characteristic curve. The Van Genuchten model (VG model), the Fredlund 3 parameter model and the Fredlund 4 parameter model are further used to fit the test curve. The results show that the VG model can well fit the test results, The fitting coefficients were fitted and the correlation coefficients were all greater than 0.99. Comparing the fitted data of Fredlund 3 parameter model and Fredlund 4 parameter model, it can be seen that it is reasonable to assume that the residual water content θr is equal to 0. Soil water characteristic curve has a good adaptability, but the fitting effect of VG model is the best.