Comparative Study of Dynamic Response Analysis of Shallow Foundation on Layered Soils

Abstract

Dynamic response analysis of shallow foundation in time-varying motion is very much essential in the present days. As the seismic events are unpredictable, it draws the attention of researchers towards the response of the soil foundation system against dynamic loading. Hence, in the present study, an attempt has been made to investigate the dynamic response of a shallow foundation (continuous footing) resting on different layered soil deposits subjected to seismic loadings. The layered soil deposits considered for the analysis are weak clay underlain by stiff clay (case I) and loose sand underlain by stiff clay (case II). In addition, comparative studies have been made considering the parameters like layered soil types (case I and II), water table effects (dry and partially saturated) and seismic loadings (Bhuj earthquake: Mw—7.7 and Nepal earthquake: Mw—7.8) conditions. The modelling of the soil foundation system has been carried out using two-dimensional finite element software CyclicTP. The response of the dynamic analysis of shallow foundation on layered soils is presented in the form of peak acceleration; horizontal and vertical displacement; shear stress versus shear strain; and excess pore pressure variations at different locations. The results of the analysis indicate that the peak acceleration, horizontal and vertical displacements are more in both the cases (I and II) under the excitation of Nepal earthquake than the Bhuj earthquake motion. Also, it is observed that the response in terms of peak acceleration, horizontal and vertical displacement is more in partially saturated state than in dry state for both the earthquake motions.