Seismic Bearing Capacity of Shallow Foundations in Anisotropic Non-Homogeneous Soils Under Torsional Waves and Parameter Uncertainty

Abstract

The purpose of the present paper is to investigate the effects of the torsional wave propagation and the soil-earthquake parameter uncertainties on the seismic bearing capacity of shallow foundations in anisotropic non-homogeneous media. A mathematical model of the equivalent seismic bearing capacity factor is derived using the limit equilibrium method with the consideration of the Coulomb failure mechanism. The pseudo-dynamic approach is followed to incorporate the seismic component. A parametric study is carried out showing the impact of the soil parameters, the soil anisotropy, the soil non-homogeneity and the seismic excitation on the seismic bearing capacity factor. The results show that the torsional wave parameters (acceleration coefficient and wavelength) have a significant impact traduced in a decrease in the seismic bearing capacity factor. Furthermore, an increase in the anisotropy of the soil parameters causes a decrease in the seismic bearing capacity factor while an increase in the non-homogeneity of the soil parameters causes an increase in the seismic bearing capacity factor. A reliability analysis, using the Latin Hypercube Sampling method, is also carried out with the aim to incorporate the uncertainties around the main soil and earthquake parameters that govern the seismic bearing capacity of shallow foundations. It is found that the statistical moments and the failure probability of the seismic bearing capacity factor are more influenced by the friction angle uncertainties than by the seismic acceleration coefficient uncertainties. Moreover, the anisotropy and non-homogeneity of soil parameters exert a significant effect on the statistical moments and probabilistic results.