南阳膨胀土土水特征曲线试验研究

摘要

For the study of expansive soil SWCC,the experiment used the pressure plate reader produced by the US Soil moisture company,which the clay plate intake is 15 bar,to research undisturbed samples and remodeling samples. Undisturbed samples were studied under different heights or area series, and remodeling samples were studied under different dry density or moisture content conditions,and using control variables method to draw con-clusions. Research results indicate:①Increasing the area will not affect the water retention characteristics of undis-turbed samples,but undisturbed samples heights will have a great impact on soil water characteristic curve. Height increasing results in water content of soil increasing under the same suction condition, so that the difficulty of dehy-dration increases;②For remodeling sample, under the same dry density condition and low suction force conditions, the moisture content of soil samples increases with the initial moisture content increasing. Starting from a suction value,moisture content decreased with the increasing of suction force. The higher the initial water content is, the lower the suction value is;③Under the same conditions of the initial moisture content and low suction,the lower dry density is, the higher the moisture content is. With the suction increasing, the lower dry density is, the faster water content of soil decreases,and the moisture content of each sample is closed to each other, the final moisture content of the sample under low dry density will converge;④Considering the impact of changing in the volume,we corrected the soil water characteristic curve and did model fitting. The result shows that VG model can simulate SWCC of the undisturbed expansive soil.%为研究南阳膨胀土土水特征曲线，采用美国Soil moisture公司生产的陶土板进气值为15 bar的压力板仪对原状样和重塑样进行了研究；其中原状样进行了不同高度或面积系列下的研究，重塑样进行了不同干密度或含水率系列下的研究；并采用控制变量法来得出结论。研究结果表明：①面积增加对原状试样的持水特性没有影响，但是高度对土水特征曲线的影响很大，高度增加使得在相同吸力下土样含水率增加，脱水难度增大；②对于重塑样，在相同干密度条件下，低吸力条件土样含水率随初始含水率的增加而增加，随着吸力的增加，从某一吸力值开始，含水率随吸力的增加而降低，初始含水率越高，这个值越低；③在相同的初始含水率条件下，低吸力条件干密度越低含水率越高，随着吸力增加，干密度越低，土样的含水率下降的越快，各试样的含水率开始接近，最后低干密度试样的含水率趋于一致；④考虑体积变化的影响对土水特征曲线进行修正并进行模型拟合，最后表明 VG模型能够较好地模拟原状膨胀土的土水特征曲线。