弱膨胀土浸水变形特性及其预测

Deformation characteristics of weakly expansive soil and its prediction

对取自江苏省淮安市的膨胀土进行了浸水后的膨胀变形和压缩变形试验。在竖向压力25~800 k Pa范围下,研究了不同初始含水率和初始干密度对浸水膨胀变形特性的影响。结果表明：浸水饱和膨胀变形量主要取决于初始干密度,且初始含水率也有一些影响;在相同的含水率下,膨胀变形量随着干密度的增加而增大;在相同干密度条件下,含水率越大,浸水膨胀变形量略微减小。根据各组的固结状态线和浸水饱和膨胀后状态线的交点,得出了介于浸水膨胀和浸水压缩的分界状态线,此线基本上不受初始含水率的影响,进而可以判定不同孔隙比、不同竖向压力下土样处于浸水膨胀还是压缩。最后,基于浸水变形试验结果,提出了一种简便的预测弱膨胀土在不同竖向压力下膨胀变形量的方法。

A series of wetting tests on a weakly expansive soil, taken from Huaian, Jiangsu province, was performed to investigate the swelling and compression deformations. The influences of initial water content and initial dry density were studied under the applied vertical pressures from 25 k Pa to 800 k Pa. It is shown that the swelling deformation due to wetting is mainly affected by the initial dry density, and little affected by the initial water content. At the same initial water content, the swelling deformation increases with the initial dry density increasing. At the same initial dry density, the swelling deformation decreases little with the initial water content increasing. According to the points of intersection of the compression lines on unsaturated state and the saturated state lines with different initial densities, a state line is obtained. The state line is almost not affected by the initial water content. And it can judge whether the expansive soil will swell or compress due to wetting under different void ratios and vertical pressures. Finally,based on the results of wetting tests, a simple method for predicting the swelling deformation of expansive soils due to wetting is proposed.