Calculating the collapse potential under embankment using finite element method

Collapsible soil is known as problematic soil, which possess considerable strength when dry and loses its strength when submerge experiencing excessive settlements. The collapse potential increases with time due to soaking and leaching which is attributed to the dissolution and washing out of gypsum. In this paper, a embankment of granular sub - bas with (2 m, 3 m, 4 m) height and side slope equal (1:1.5), (1:1), and (1:0.75) respectively, is assumed to be constructed on gypsouse soil with dimensions (20 m) in width and (10 m) in height. A footing with width equal to (2 m) was placed in position on the surface of the embankment. The problem was analyzed for each embankment at different water table levels from the ground surface (at surface, 2m, 5m and at b ottom), by the finite element program Giostudio (SIGMA/W). It is noticed that the bearing capacity of the footing decreases with decrease of the water table depth due to the dissolution of the cementing gypsum causing high softening of soil and the colla pse potential increases when the water content of the soil increases due to the dissolution of cementing gypsum which is accompanied by collapse of soil structure. A mathematic relationship was determined between the collapse potential and the height of embankment and water table depth, and anther mathematical relationship was obtained between the bearing capacity and the height of the embankment.