Bearing capacity of foundation on rock mass with weak layer

This paper deals with a strip surface footing on a rock mass with a weak layer. The calculations of the bearing capacity were performed simultaneously by two computer programs using the finite element method and the finite difference method with independent development of the models. The calculation was performed for different widths of the footing according to the width of the layer. The axis of the layer was placed on the edge of the footing and in the center of the footing, with different inclinations from a vertical In the iteration procedure used in the calculation, special attention was paid to the stepping up (load increase) in the determination of "local" and 'global" failures in the subgrade. The results show a significant decrease in the value of the bearing capacity for some widths and positions of a weak layer, as well as an important influence of a differential settlement (between the edges of the footing) on the determination of the collapse loads. The analyzed problem is illustrated by an example of a bridge footing (a bridge over Rijeka Dubrovacka, Croatia).