Improving the performance of circular foundations using structural skirts

This paper presents the results of an experimental study on the behaviour of circular foundations with a structural skirt resting on sand. The structural skirts are fixed to the perimeter of the foundations, and can be used for new or existing shallow foundations. The test results indicate that this type of reinforcement increases the bearing capacity of subgrades and modifies the load-displacement behaviour of the footing. Skirt factors are proposed that take into account the variables that affect the bearing capacity, and they are used within the general bearing capacity equation for shallow circular foundations on sand. Also it was found that the structural skirts reduce the settlement of surface footings compared with footings without structural skirts. At a working stress equal to 50% of the ultimate bearing capacity, the settlement of a surface footing can be reduced to just 11% of that for a footing without a structural skirt.