STUDY OF A SOIL WITH SWELLING AND SHRINKING PHENOMENA

Vertisols are deep clayey soils, with more than 45 % clay, dominated by clay minerals, such as smectites, that expand upon wetting and shrink upon drying. The most important physical characteristics of Vertisols are a low hydraulic conductivity and stickiness when wet and high flow of water through the cracks when dry. They become very hard when dry and in all the time are difficult to work. During the rainy season, the cracks disappear and the soil becomes sticky and plastic with a very slippery surface which makes Vertisols in – trafficable when wet. Water movement in soil that change volume with water content is not well understood and management of swelling soil remains problematic. Swelling or shrinking result in vertical displacement of the wet soil, which involves gravitational work and contributes to an overburden component to the total potential of the soil water. Many swelling soil crack and the network of cracks provides pathways for rapid flow of water which prejudice application of theory based on Darcian flow. One – dimensional flow of water in a swelling system requires material balance equation for both the aqueous and solid phases. The analytical data offers some values particle – size distribution, compression, swelling degree and pressure, plasticity index, elastic modulus, triaxial shear, angle of shear and load carrying capacity in order to realize a foundation study for some constructions.