Effects of boundary friction and layer thickness on desiccation cracking behaviors of soils

As the layer thickness and interfacial roughness of soils are the most important factors affecting their desiccation cracking, a series of desiccation tests are therefore conducted to investigate the shrinkage and cracking characteristics under various soil thicknesses and interfacial roughnesses. In the tests, nine slurry specimens of initial saturation are prepared and dried under a constant temperature of 30℃ and three different soil layer thicknesses and interfacial roughnesses. The change of water content and surface cracking are kept in a real-time record during the whole process of drying. The image processing technique is employed for quantitative analysis of crack network. The dynamic desiccation cracking process is recorded and the relative parameters are obtained under different soil layer thicknesses and interfacial roughnesses. The results show that: (1) The larger the interfacial roughness, the faster the rate of cracking development, while the greater the thickness of soil layer, the slower the rate of cracking development, and the more significant the effects of integrated shrinkage of soils; (2) The larger the interfacial roughness, the higher the degree of cracking development. However, the increase of soil thickness can restrain the influences of interfacial roughness on cracking development; (3) The influences of interfacial roughness and soil layer thickness on cracking have certain influences on the average water content during the initial cracking of soils. Additionally, the influences of the two factors on cracking development have coupling relationship. Finally, the influence mechanism of the two factors is explored by expatiating the mechanism of soil shrinkage.