Mobilization mechanism and calculation method of embedded chain axial resistance in sand

For the mooring chain embedded in seabed, the axial resistance greatly influences the chain load transfer. For calculating chain axial resistance, effective width parameter Et is adopted to reflect its characteristic dimension. However, the mobilization mechanism of chain axial resistance in sand is unrevealed at present. In this paper, the large deformation simulation based on a Coupled Eulerian-Lagrangian (CEL) approach was carried out to reveal the chain-sand axial interaction mechanism. Then, a calculation method based on the mechanism was proposed to divide the chain axial resistance into three parts, i.e., sand-sand friction, chain-sand friction and passive resistance. A series of chain axial loading tests were conducted and the results were taken as the comparative data. Compared with the test data, a reduction factor a was introduced to modify the chain passive resistance due to stress release of the front chain link. Large deformation simulation result shows that soil near the chain straight bar moves with chain, but the soil in front of the link has outward movement because of chain end resistance. By introducing a reduction factor, the proposed method can be adopted for calculating the chain axial resistance. At last, the resistance contribution and mobilization order were assessed.

Automated summary

This paper conducts a large deformation simulation to study the axial interaction mechanism between mooring chain and sand. A calculation method for chain axial resistance is proposed based on this mechanism. The method is validated and shows good accuracy in predicting chain behavior.