Seismic Bearing Capacity of a Strip Footing Over an Embankment of Anisotropic Clay

K Krishnan,Debarghya Chakraborty,Koushik Halder

doi:10.3389/fbuil.2019.00134

Abstract

The present study adopts lower bound finite element limit analysis technique in association with non-linear optimization to compute the seismic bearing capacity of a strip footing placed over an embankment of anisotropic clay. The influence of seismic loading is incorporated in terms of a horizontal seismic acceleration coefficient. The bearing capacity factor Nc of the strip footing is obtained for various combinations of (i) slope angle, (ii) footing setback distance, (iii) horizontal seismic acceleration coefficient, and (iv) anisotropic strength ratio of clay. The bearing capacity factor of the strip footing increases with the increasing setback distances. However, beyond a certain setback distance, hardly any influence is found. For a particular footing position and constant value of horizontal seismic acceleration coefficient, the magnitude of bearing capacity factor increases with the increase in anisotropic strength ratio. However, the percentage increment in the bearing capacity reduces when the value of anisotropic strength ratio becomes greater than one. In addition, the bearing capacity reduces with the increasing slope angle and horizontal seismic acceleration coefficient. Failure patterns are obtained to understand the failure mechanism.

Highlights

In recent times, shortage of construction land compels the people to build structures on the embankment; even on its edge or side face
The objective of the present study is to determine the bearing capacity factor Nc of a rigid, rough and surface strip footing of width B placed over an embankment of anisotropic clay, in the presence of horizontal earthquake acceleration using the lower bound finite element limit analysis method
The variation of bearing capacity factor Nc is presented as a function of slope angle (β), setback distance of footing (S), seismic coefficient, and anisotropic strength ratio (b/a)

Summary

INTRODUCTION

Shortage of construction land compels the people to build structures on the embankment; even on its edge or side face. With the consideration of all the parameters mentioned above, the present study computes the bearing capacity of a strip footing situated over an embankment of anisotropic clay. The objective of the present study is to determine the bearing capacity factor Nc of a rigid, rough and surface strip footing of width B placed over an embankment of anisotropic clay, in the presence of horizontal earthquake acceleration (khg) using the lower bound finite element limit analysis method. After a particular setback distance of footing, there is no further increment in the value of bearing capacity factor The reason behind this is the reduction in the influence of plastic zone over the slope when setback distance is increased.

CONCLUSIONS

Findings

DATA AVAILABILITY STATEMENT