Abstract

Dynamically Installed Anchors (DIAs) refer to anchors which can embed themselves by free-fall from a specified height above the seabed. They have been widely regarded as the most promising deepwater anchor concept in terms of several advantages over other anchors. First, it is economical because of ease fabrication, quick installation, and no requirement from external source of energy. Second, the installation cost is less depend on the water depth. Finally, the holding capacity is less sensitive to the soil undrained shear strength profile since higher seabed soil shear strength permit less penetration depths and vice versa. However, a degree of uncertainty still exists in relation to predicting the embedment depth and subsequent pull-out capacity especially the inclined pull-out capacity.

The pull-out capacity of DIAs can be dominated by the vertical or horizontal failure mechanisms or a combination of the two. When the combination controls, the DIAs are referred to as being under the inclined pull-out failure. This paper focuses on the inclined pull-out failure of DIAs. A series of finite element analysis on pull-out resistance of DIAs in normally consolidated clay was carried out. First, the numerical results were validated through experimental results and analytical empirical results. A proper method to model the inclined pull-out of DIA is illustrated. Then, a methodology for evaluating the inclined pull-out capacity of DIA is proposed based on the numerical parametric study. This method is capable of predicting pull-out capacity of DIA for various embedment depths and DIA aspect ratios. Finally, the design procedure for DIA is proposed.

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