a) In case of footing on sloping ground, the distance of the sloping surface at the base level of the footing measured from the center of footing shall not be less than twice the width of the footing.
ds ≥ 2 x w
ds = distance from center of footing to sloping surface at base level.
W = width of footing.
L = length of footing
Moreover, the minimum distance from the lower edge of the footing to the sloping ground surface should be 90 cm.
b) in case of footings which are in different levels, the distance between the edges of footing shall be such as to prevent undesirable overlapping of structures in soil and disturbance of soil under the higher footing due to excavation of the lower footing.
c) On a sloping site, footing shall be on a horizontal bearing and stepped. At all changes of levels, footing shall be lapped for a distance of at least equal to the thickness of foundation or three times the height of step, whichever is greater. Adequate precaution shall be taken to prevent tendency for the upper layers of soil to move downhill.
* dl ≥ t
* dl ≥ 3 x hs
Where, dl = lapped distance of footing at changes in level.
t = thickness of footing
hs = height of step
The greater value is considered in design.