BEARING CAPACITY OF ECCENTRICALLY LOADED FOOTINGS ON COHESIONLESS SLOPES

Abstract

In some situations foundations are required to be placed on slopes, near the top edge of a slope or near a proposed excavation. These may be subjected to moments, as it normally happens, in addition to vertical loads. In such situations it is necessary to obtain the maximum value of bearing capacity (a) from foundation failure (b) and from the overall stability of slopes. In case of cohesionless soils, the bearing capacity will always be governed by the foundation failure, while it may not be so in case of cohesive soils. Many theories are available to compute the ultimate bearing capacity of foundations on slopes subjected to vertical loads without eccentricity. The objective of this dissertation is to estimate the ultimate bearing capacity of eccentrically loaded shallow'footings near the soil slope. A review of literatureindicated that several theories are available to find the ultimate bearing capacity of centrally loaded footings on slopes and eccentrically loaded footings on level ground (Meyerhof, 1957), (Mizuno et al, 1960), (Sokolovski, 1960), (Saran, 1969), (Sivareddy, Mogaliah, 1975), (Kusakabe et al, 1981), (U.K. Sud, 1984). The theory proposed by Sud takes into account the effect of slope rationally and has the merit of estimating foundation settlements in a simple way. Saran (1969) developed bearing capa-city factors for determining ultimate bearing capacity of shallow foundations placed on level ground and subjected to moments: In the present case, the ultimate bearing capacity of footings has been found by limit equilibrium analysis, when the eccentricity of load is towards the side of the slope. it It has been assumed that the failure surface is a log spiral and the failure occurs on the side of the slope. The resistance mobilised on this side is full passive and that on the other it is partial. Bearing capacity factors N , Nq have been obtained considering two cases separately (i) c = q = 0, (ii) y = c = 0. The total bearing capacity is then obtained by superposing the limit stresses obtained in the above two cases