ABSTRACTSemi-deep skirted foundations are now considered to be a viable foundation option for a variety of onshore and offshore applications. The capacity under combined vertical, horizontal, and moment loadings must be found to ensure their capability and stability. In this study, undrained bearing capacity subjected to vertical loading, as part of combined loading is determined through stress characteristics and finite element analyses. Circular skirted foundations with different soil strength and geometries considering embedment depth effects have been studied. Stress field, kinematic mechanism accompanying failure, and bearing capacity factors for various embedment ratios are investigated. Acquired vertical failure mechanism has demonstrated the transition from a general shear to a punch shear failure. Comparisons with different research works including conventional methods, upper and lower bound, finite element analyses, physical modeling, experimental, and centrifuge tests have indicated the underestimation of conventional approaches and accuracy of proposed methods in determining bearing capacity. Furthermore, differences between predicted bearing capacities and the results of this study increased with D/B ratio due to ignoring the significant role of skin friction in larger embedment circumference.
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