Experimental study on the behavior of strip footing on sandy soil bounded by a wall

Structural skirts are walls fixed to the edges of shallow foundations to improve their bearing capacities. Sometimes, the shallow foundation is bounded by a close obstruction like a wall. The presence of this wall has an effect on the bearing capacity of footing, whose behavior in this case can be similar to a skirted foundation in which a structural skirt is located at one side of the footing. The present study investigates the behavior of model footings bounded by a wall of different depths and located at different distances from the footing resting on sandy soil. Different parameters are considered such as relative density of sand, distance from the wall to the edge of footing, h, width of footing, B, and ratio and depth of wall, d, to width of footing. Test results show that the presence of the wall affects remarkably the bearing capacity, leading to improvement in the bearing capacity with different percentages according to the distance of the wall from the edge of footing and depth of wall, due to the increase in the soil confinement underneath the footing. In loose sand, the largest improvement in bearing capacity for strip footings bounded by walls reaches about 37 %, at h/B = 0.5 and d/B = 2. In medium sand, the largest improvement in bearing capacity for these footings bounded by walls reaches about 25 %, at h/B = 0.5 and d/B = 2, while in dense sand, the largest improvement in bearing capacity for strip footings bounded by walls reaches about 59 %, at h/B = 0 and d/B = 2. The presence of the wall mitigates the vertical settlement; the largest reduction in the vertical settlement ranges from 5 to 160 % in all tests depending on the wall depth and its distance from the footing. In loose and medium sand, the maximum effect of the wall on the value of bearing capacity is when the distance between the wall and the footing edge, h/B, is 0.5 in all shapes of footings.