Seismic bearing capacity of foundations incorporating excess pore water pressure generation during an earthquake

Abstract

Considering the occurrence of an earthquake, the bearing capacity of a strip footing placed on a saturated cohesive-frictional soil mass has been computed by performing a pseudo-static rigorous analysis incorporating the existence of (i) excess pore water pressures, and (ii) additional seismic- tractions and body forces. The analysis has been carried out by using lower and upper bounds finite elements limit analysis (FELA) in conjunction with the second order cone programming (SOCP) using the Mohr-Coulomb (MC) yield criterion. The generation of the excess pore water pressure in the event of an earthquake has been incorporated by defining a pore pressure coefficient $r_u$ − a ratio of the excess pore water pressure to the total vertical overburden stress at any point. The analysis has revealed that the bearing capacity reduces considerably with an increase in the magnitude of horizontal earthquake acceleration. For a given magnitude of earthquake acceleration, the bearing capacity reduces extensively further with an increase in the value of r_u. All the computational results have been presented in a non-dimensional manner, and for the validation purpose, necessary comparisons have also been made. The study will be useful for designing foundations in a seismically active zone.