Seismic bearing capacity of strip footings adjacent to slopes using pseudo dynamic approach

Determining of the seismic bearing capacity has a great importance for foundations located near sloping ground in geotechnical earthquake engineering. In this paper a new formulation based on the pseudo-dynamic method is presented to calculate the seismic bearing capacity of strip foundations resting on C-φ soil which are adjacent to slope using limit equilibrium method. The seismic bearing capacity coefficient Nγe for the simultaneous resistance of surcharge, unit weight and cohesion is calculated considering two-sided composite rupture surface which is the combination of a logarithmic spiral and planar surfaces. This failure mechanism comprises of two slip surfaces which are assumed that a realistic failure surface occurs on the side of slope and the resistance mobilization is taken into account on the side without slope. Using the presented approach a parametric study is conducted to study the effect of various parameters such as soil cohesion, soil friction angle, slope angle, horizontal, and vertical seismic coefficients. Results show the bearing capacity coefficient increases by approximately 176 and 264% when β increases from 10 to 20° and from 20 to 30°, respectively. The results of this study are compared with the few pseudo-static results available in the literature. Present procedure give lower amount of bearing capacity of strip footings in comparison with the results of pseudo-static analysis.