Changes in the mechanical properties of expansive soils under the effect of full wetting-partial drying cycles

Abstract

The double behavior of clays (swelling - shrinking) is one of the most serious problems that we encounter when building on expansive clay soils. Thus it is very important in order to study them to identify changes that may occur in their mechanical properties (axial deformation, cohesion, internal friction angle) as a result of their exposure to repeated cycles. Undisturbed samples of expansive soils were subjected to cycles of full wetting and partial drying. The required time for complete swelling was defined as well as the required time for partial shrinkage for each of the three types of soils used in the study. The results showed that the axial deformation value decreases with the number of cycles. The equilibrium was reached at the end of fourth cycle, and the void ratio decreases at the end of the cycle with the number of cycles. Experiments also have shown a decrease in the values ​​of both cohesion and internal friction angle. The change was clear in the cohesion value, while it was less for the internal friction angle, Therefore, it is necessary to take the effect of multiple cycles into consideration when determining the mechanical properties of expansive soils.