Study of the behaviour of skirted shallow foundations resting on sand

Abstract

The performance of skirted shallow foundations resting on sand bed was investigated using physical modelling. Laboratory tests were performed on small-scale foundation models to study the behaviour of circular, skirted foundations subjected to vertical loads. The effects of foundation diameter, relative density of sand, skirt depth and roughness of the model surface on the bearing capacity and settlement of skirted foundations were studied. The results of the model tests have shown that using skirts improve the bearing capacity and settlement values of skirted foundations compared with shallow foundations without skirt. The improvement in bearing capacity and a reduction in settlement of shallow foundations increase with increasing the skirt depth, roughness of skirt sides and decreasing the relative density of sand. The ultimate bearing capacity of shallow foundations may be increased by up to 5·0 times and the settlement can be reduced to a value of 8% of those of foundations without skirts. On the basis of the obtained results, a series of charts are presented to estimate bearing capacity improvement and settlement reduction in terms of sand relative density, skirt depth to foundation diameter ratio and roughness of skirt sides. Skirted foundations resting on loose sand are more beneficial than those resting on medium and dense sand.