Showing papers by "Jyant Kumar published in 2003"

Nγ for rough strip footing using the method of characteristics

Abstract: By using the method of characteristics, the bearing capacity factor Nγ was computed for a rough strip footing. The analysis was performed by considering a curved nonplastic wedge under the foundati...

Seismic bearing capacity of foundations on slopes

Abstract: The effect of pseudo-static horizontal earthquake body forces on the bearing capacity of foundations on sloping ground has been assessed using the method of stress characteristics. Two failure, mechanisms were considered, based on the extension of the characteristics from the ground surface towards the footing base from either one side or both sides. The magnitude of N-gamma based on the both-sides failure mechanism, for smaller values of earthquake acceleration coefficient (alpha(h)), has been found to be significantly smaller than that obtained using the single-side mechanism; however, in the presence of alpha(h) the both-sides mechanism becomes kinematically inadmissible in many cases for higher values of phi. Only the single-side mechanism was found statically admissible for computing the bearing capacity factors N-c and N-q on sloping ground. All the bearing capacity factors reduce considerably with increase in ah for various ground inclinations

Seismic bearing capacity of rough footings on slopes using limit equilibrium

Abstract: For foundations placed on horizontal ground surfaces, incorporating the effects of earthquake body forces, investigations have been performed by using the method of slices (Sarma & Iossifelis, 1990), limit equilibrium (Budhu & Al-Karni, 1993), the upper bound limit analysis (Richards et al., 1993; Dormieux & Pecker, 1995; Soubra, 1997, 1999) and the method of characteristics (Kumar & Mohan Rao, 2002a). For sloping ground surfaces, on the basis of limit analysis Zhu (2000) has reported an earthquake reduction factor for the bearing capacity factor,$ N_{y}$. By using the method of characteristics, Kumar & Mohan Rao (2002b) have established the variation of the bearing capacity factors with changes in horizontal earthquake acceleration coefficient, h, for different ground inclinations. Two different failure mechanisms (single side and both sides) were used in the analysis. It was indicated that, in the presence of \alpha h, only the single-side failure mechanism remains statically admissible for the computation of Nc and Nq. By contrast, in finding$ N_{y}$, for smaller values of \alpha h and _ both mechanisms were shown to remain statically admissible. As compared with the single-side mechanism, the bearing capacity factor $N_{y}$ was shown to become much smaller on the basis of the both-sides mechanism, especially for very small values of \alpha h and _. It was also indicated that the single-side mechanism remains kinematically admissible in all those cases where no slip has been allowed along the footing–soil interface (rough foundations). Although the approach was quite rigorous, however, it was assumed that the ratio of shear to normal stresses along the foundation–soil interface remains constant. Since the limit equilibrium technique does not require this assumption, it was intended to use this method to determine the seismic bearing capacity of rough foundations on sloping ground. It was simultaneously ensured that the solution remains kinematically admissible in all the cases. The results were thoroughly compared with those reported previously.