Effect of Footing Roughness on Lower Bound $N_{\gamma }$ Values

The bearing capacity factor $N_{\gamma }$ was computed for a strip footing by considering the variation of footing-soil interface friction angle $\left(\delta \right)$ . The study follows a lower bound limit analysis in conjunction with finite elements and linear programming. The variation of $N_{\gamma }$ with $\delta$ was obtained for different soil friction angles. The magnitude of $N_{\gamma }$ increases significantly with the increase in $\delta$ . For $\delta =0$ , the normal stress along the footing-soil interface was found to increase almost linearly with the increase in the distance from the footing edge. However, with the increase in $\delta$ , the location of the peak normal stress shifts gradually away from the center of the footing. The size of the plastic zone in relation to the footing width becomes gradually larger for greater values of $\delta$ . With respect to variation in $\delta$ , the obtained values of $N_{\gamma }$ were found to be generally smaller than the results available in the literature.