Foundation Practices & Rehabilitation of Structures on Expansive Soils

Vijayawada : Expansive soils popularly known as Black cotton soils in India are highly problematic, as they swell on absorption of water and shrink on evaporation thereof. Because of this alternate swell and shrinkage, distress is caused to the foundations of structures laid on such soils. Extensive research is going on to find the solutions to black cotton soils. The present paper reviews innovative solutions along with conventional foundation practices to counteract the dual problem of swelling and shrinkage posed by expansive soils. Besides, the present paper throws a light on causes of distress in lightly loaded structures founded on expansive soils and also various measures to rehabilitate the distressed structure founded on them.

The problem is more in case of light structures; those cannot counteract the upward thrust posed by expansive soils. The damage will be apparent, usually, several years after construction. The soil below will exert swelling pressure both upwards and laterally. As a result, the floor slab is lifted up, leading to cracking of floor. Cracking is normally evident at the corners of window and door openings. These usually assume in the form of diagonal cracks-a consequence of differential settlement in the wall.