Study of changes in the stress condition and void ratio of expansive soils subjected to the wetting and drying cycles

expansive soils subjected to the wetting and drying cycles

Abstract

The research included a study of the changes that occur on the expansive soils as a result of multiple cycles of wetting and drying, where one cycle

consisted of a period of wetting that lasted for three days, followed by a period of drying, suitable to achieve the return of the moisture of the samples to the natural water content from the state of complete saturation, and the focus was on Changes in the volumetric deformations, porosity coefficient and strength parameters, as well as the stress situation. Significant results have been reached that the repetition of four cycles of complete wetting and partial drying on the expansive soils leads to reducing the deformations that occur to a value of at least half the value of the deformations that occur in the event that they are not subjected to cycles. But on the other hand, exposing the expansive soils to cycles leads to a decrease in the strength factors, which causes a decrease in their bearing capacity, so a special care must be paid to this phenomenon when studying these types of soils. As for the void ratio taken at the end of the cycles, its values ​​decreased with the increase in the number of cycles applied to the soil, until reaching equilibrium at the fourth or fifth cycle. The stability of deformations of most soils occurred after three cycles, and it was found that the expansive soils that contain percentage of clay greater than 60% need an additional cycle for the occurrence of stability of their deformations. of the soil with the number of turns at each of the applied vertical stresses. The greatest decrease in the tangential stresses was at the lowest vertical load, and with the increase in the applied vertical stress, the effect of multi-cycles decreased