Foundations on Sloping Ground

Foundations on Sloping Ground

To avoid sloping foundation bed or excessive depth of excavation at the top end, stepped foundation is necessary to be provided in a considerably sloping ground. Foundations on Sloping Ground is achieved by cutting the portion of the foundation trench in steps. The steps should not preferably be more than the depth of the concrete bed and each step should be a multiple of the depth of one brick so as to fit in with the brick courses. The lap of concrete at each step should never be less than the vertical thickness of the concrete.

In some cases, the bottom of the footings of different walls of the same structure may be at different levels. The following limitations (as given by I.S.I.) are necessary to be observed in deciding the depth of footings in such circumstances.
(1) The distance between the lower edge of the footing to the sloping surface should not be less than 1 m for soils and 60 cm for rocks.
(2) In clayey soils, the line drawn between the lower adjacent edge of the upper footing and the upper adjacent edge of the lower footing should not have a steeper slope than 2:1 (i.e two horizontal : one vertical).
(3) In granular soils, the line drawn between the lower adjacent edges of adjacent footings should not have a slope steeper thin 2:1 (i.e. two horizontal : one vertical).