中文摘要：

干湿循环引起膨胀土裂隙开展,进而对土体的土水特性产生重要影响.首先进行了不同干密度、含水率状态下均质无裂隙试样的导电性能试验,认为试样电导率与干密度、含水率呈线性关系,可采用多元线性函数进行拟合.用远距离光学显微镜观测了膨胀土裂隙发生发展过程,利用图像灰度熵评价裂隙形态,试验过程中同时测定了试样的含水率和电导率,获得了干湿循环下土体灰度熵-含水率-电导率的关系.结果表明：随着含水率的降低,灰度熵逐渐增大,电导率逐渐减小;含水率对电导率的贡献逐渐降低,裂隙对电导率的贡献逐渐增大.当失水到一定程度时,裂隙对电导率的贡献几乎不变,此时表明裂隙已开展稳定;浸水过程中,裂隙部分闭合,灰度熵减小,电导率增大.经历多次干湿循环的试样,灰度熵和电导率均有所降低,表明土体结构产生了不可逆的改变.

英文摘要：

The soil-water characteristics of expansive soil are influenced by cracks caused by drying-wetting cycles. Electrical conductivity tests were carried out to obtain the soil conductivity without cracks and electrical conductivity had a linear positive correlation with soil dry density and water content. A linear multivariate function was obtained to describe their relationships. A long-distance microscope system was used in observing the crack growth of the expansive soil dynamically under the conditions of drying-wetting cycles and the gray level entropy of image with the cracks was used to evaluate the crack shape. The soil water content and conductivity were obtained and the gray level entropy-water content-conductivity relationship of soil was established under the conditions of the drying- wetting cycles. The gray level entropy increased and conductivity decreased with the crack growth due to water loss. The impacts of water content on the soil conductivity decreased and impacts of cracks on the soil conductivity increased gradually. The impacts of cracks on the soil conductivity kept constant under drying to a certain degree, and the shape of cracks remained stable; the cracks were closed partially due to water absorption. The gray level entropy decreased and the soil conductivity increased. The gray level entropy and the soil conductivity decreased to some extent under the drying-wetting cycles. It was shown that the soil structure was changed irreversibly.