Pseudo-Static Limit Equilibrium Method for Bearing Capacity of Footing on Slope and Seismic Uplift Capacity of Horizontal Strip Anchor

Abstract

Seismic bearing capacity for a shallow strip footing embedded in a sloping ground is derived along with seismic uplift capacity of horizontal strip anchors. c-ϕ soil medium is used with limit equilibrium method of analysis. A planar failure mechanism has been adopted. The seismic bearing capacity is determined in the form of a single pseudo-static bearing capacity coefficient (N γe ) in association with unit weight, surcharge and cohesion, which becomes more practical to simulate the actual field problem. The seismic forces are considered to act both on the footing and on the soil below the footing. The effects of soil friction angle, soil cohesion, wall friction angle, horizontal and vertical seismic accelerations are taken into account to evaluate the seismic bearing capacity of the foundation. Also seismic uplift capacity factors for horizontal strip anchors is found. The factor is determined as a function of embedment ratio, angle of internal friction of soil, angle of wall friction, cohesion of soil and seismic acceleration coefficients. The uplift capacity factors have been determined for the simultaneous resistance of cohesion and unit weight of soil. Effect of the vertical seismic acceleration coefficient has been found to always reduce the uplift capacity factor whereas the effect of horizontal seismic acceleration coefficient has also been found to reduce the uplift capacity factor in maximum cases. The results obtained from both the cases has been compared with existing literature and the effect of parametric variations discussed.