Contact Pressure On Saturated Clay

The soil reaction beneath footing produce a upward pressure which is assumed uniform in deriving different relationship for soil-structure interaction problem. This pressure is called contact pressure. 


Flexible Footing

When a footing is flexible, it deforms into shape of bowel, with the maximum deflection at the center. The contact pressure distribution is uniform.

Rigid Footing

When a footing is rigid, the settlement is uniform. The contact pressure distribution is minimum at the center and the maximum at the edges. The stresses at the edges in real soils can not be infinite as theoretically determined for an elastic mass. In real soils, beyond a certain limiting value of stress, the plastic flow occurs and the pressure becomes finite.

Fig: Qualitative contact pressure distribution under flexible and rigid footing resting on saturated clay and subjected to a uniformly distributed load q.