Seismic Bearing Capacity of Shallow Strip Footing Resting On C Layered Soil

Abstract

The problem of bearing capacity of the shallow foundation is one of the earliest subjects in newlinegeotechnical engineering and several methods have been widely applied to this problem. These newlinemethods may be performed analytically, numerically or experimentally. The bearing capacity newlineproblem is more disputing when complicated cases are coming across. For instance, when the newlinefoundation width becomes large in comparison to the top soil thickness or when the soil profile is newlinenot homogeneous upto the desired depth. In reality, soil strength parameters may vary either with newlinedepth or two/more distinct layer may exist beneath the footing. The aim of the present study is to newlinedetermine the seismic bearing capacity of shallow strip footing resting on c and#61485;and#61542; layered soil. In newlinethe thesis, seismic bearing capacity is analyzed by limit equilibrium and limit analysis principles newlineusing Pseudo-static, Pseudo-dynamic and modified Pseudo-dynamic methods. At first, Pseudostatic method is adopted where seismic inertia forces is converted into equivalent static forces. newlineThen Pseudo-dynamic analysis which takes into account the effect of time and phase difference newlinefor both shear and primary waves has been used. Later, modified Pseudo-dynamic method has newlinebeen introduced which considered the damping properties of soil and the soil is considered as newlinevisco-elastic. Different types of failure mechanisms are adopted such as linear, non-linear and newlinecomposite (Punching) failure mechanisms. The analysis is performed to formulate the seismic newlinebearing capacity with single coefficient ( Nand#61543; and#61602;and#61602;) for the simultaneous resistance of unit weight, newlinesurcharge and cohesion. A wide range of variation of parameters have been considered such as newlineangle of internal friction, angle of wall friction, ratio of thickness of top layer to width of footing, newlineratio of cohesion in two layers, slope inclination, mobilization factor, seismic acceleration newlinecoefficients etc. newlineIn next stage, numerical analysis is performed using finite element software PLAXIS-2D. In newlinenumerical analysis, two soil layer