Offshore steel jackets are commonly supported by large diameter open ended steel piles located in a group called pile cluster at the jacket legs. The number of piles and diameter at each pile cluster depend on the loading on the jacket and the specific soil condition at the jacket site. The piles at the pile cluster are connected to the jacket in the pile sleeves by the grout connection. The grouted pile connection shall be then designed to satisfactorily transfer the design loads from the pile sleeve to the pile. The diameter of pile in the pile group usually varies from 84 in (2.134 m) to 108 in (2.743 m), and the number of piles vary usually from 2 to 6 piles. To increase the characteristic interface transfer strength for grout steel interface against large torsional moments, it is recommended to introduce shear keys transverse to the direction of the interface shear stress. The focus of this paper is to study the effect of pile diameter on the torsional moment distribution in a pile group and propose a procedure for the design of shear keys to increase the pile to pile sleeve grout capacity against torsional moments.
Tewodros H. Tefera
Keywords: Torsion, grout, shear key, pile sleeve, jacket
Publisher: DFI