Evaluation of undrained bearing capacities of skirted foundations

Investigating the response of skirted foundations to uniaxial vertical, horizontal and moment loading as well as under the combinations of these loads is key feature in their designing procedure. Naturally the offshore loads take place under undrained conditions and the short term response of a foundation in undrained soil is most critical. Therefore investigating the foundation response in undrained condition is conservative. In this paper, a series of three-dimensional finite element analyses are performed to investigate the response of skirted foundations in undrained uniform soil under uniaxial vertical and horizontal loads. Uniaxial ultimate vertical and maximum horizontal bearing capacities are presented for different embedment ratios “0 ≤ L/D ≤ 1”, where L is the embedment length and D is the caisson diameter. The maximum horizontal capacity corresponds to purely horizontal translation where the rotation degree of freedom is constrained. The results show a growing trend for uniaxial bearing capacities with an increasing embedment ratio; however this increasing trend dropped for roughly L/D ≥ 0.6. Moreover, the accuracy of the obtained results is validated by comparing the uniaxial bearing capacity factors with other published data.