Effect of Sand Cushion Thickness and Lateral Extension on Heave of Remolded Swelling Soil

Swelling soil is one of the most common problematic soils. Swelling phenomenon can cause severe damage to the overlying lightly loaded structures. Many alternatives have been proposed to mitigate the effects of expansive soil on civil foundations such as pre-wetting, sub-drainage, hydraulic barriers, chemical stabilization, and mechanical treatments. Sand replacement is considered to be one of the most effective and practical techniques that can be utilized for the construction of safe foundations. Experimental study using a large-scale box model is used to investigate the effect of sand cushion on reduce the heave of the expansive soil. In addition, Parametric study was performed to assess the effect of sand cushion thickness and lateral extension on the heave of the footing. The results demonstrated that the use of sand cushion reduces the heave of the footing by increasing the thickness of the sand cushion. Moreover, the rate decrease for sand cushion thickness greater than two-thirds of the footing width. Thus, the optimum thickness of the sand cushion is 2/3 footing width. The footing heave decreases with increasing the lateral extension, Le, of sand cushion, and the rate of reduction of heave becomes negligible when using lateral extension greater than twice thickness of sand cushion.