ABSTRACT
The working of pile foundations was investigated to study their load-bearing capacity on expansive soils of undisturbed structure before and after wetting, deformation uplift of piles during swelling of soil, uplift forces acting on the pile during heave of soil and deformation of soil around the pile. Experiments were conducted on driven and cast-in-situ piles, piles with an enlarged base as well as a group of piles in regions consisting of various types of clays. The nature of variation of shear forces over the lateral surface of piles during swelling of soils and the data derived from static load tests confirm the statement made earlier that it is not possible to prevent the lift of a pile by increasing the load on it. When the soil expands, its physico-mechanical properties deteriorate, resulting in a decrease in its resistance along the lateral surface and below the enlarged base of the pile.
