不同干密度下玄武岩残积土土水特征曲线分析

Analysis on soil-water characteristic curve of basalt residual soil considering influence of the different dry densities

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 curves of undisturbed and remolded basalt residual soil with different dry density were tested by combined pressure-plate apparatus of America SOILMOISTRUE. As a result, it was indicated that there were different air entry values in basalt residual soil with different dry densities and the higher dry density samples with the higher air entry value, it is to say that the correlations between suctions and dry densities of samples are positive with the same water content. The variation of water content changes with suction is not obvious and soil-water characteristic curves of undisturbed and remolded samples are approximate parallel when suction is larger than 850kPa. Finally, Van Genuchten model （VG model） , Fredlund tri-parameter model and Fredlund quadr-parameter model were employed to fit soil-water characteristic curve. It was found that VG model could fit to the experimental data better than others. Compared the test data with Fredlund tri-parameter model and Fredlund quadr-parameter model, it is acceptable that the assumption of the residual water content is zero. Three models all could fit well to basalt residual soil, but the VG model is more fitting.