Upper bound solution for the bearing capacity of two adjacent footings on rock masses

Abstract

In this paper, the effect of the adjacency of two strip footings on bearing capacity of rock masses was investigated using the upper bound analysis and finite element method. The modified Hoek-Brown nonlinear failure criterion was used for the rock mass. The effect of various parameters such as the distance between the two footings, Hoek-Brown parameters, surcharge pressure and unit weight of the rock mass on the ultimate bearing capacity of rock masses were also investigated. The results show that if the distance between the two footings is significant, the failure lines occur beneath each footing will not interfere with the failure lines beneath the other adjacent footing and each footing behaves as a single one. The maximum distance for which the two footings affect each other can be obtained from the charts presented in this paper. By reducing the distance between the two footings, the bearing capacity will increase firstly and then decrease. Finally, when the two footings touch each other, the ultimate bearing capacity of the two footings will be equal to the ultimate bearing capacity of a single isolated footing with a width twice the width of each footing.