Research On Pile Group Analysis Method Of Jacket Offshore Platform

With the development of the deepwater jacket offshore platform, the pile groupfoundation becomes an important jacket offshore platform foundation. This paperpresents the further research and discussion on the jacket offshore platform pile groupanalysis method.Firstly, the method to determine the p-y curve of pile group is analyzed, whichdiscusses the differences between the P-factor and Y-factor. The calculation resultsshow that different correction factor is needed to use when the pile spacing is different,if the pile spacing is less than three times the pile diameter, the P-factor should beused to determine the p-y curve of pile group, when the pile spacing is greater thanthree times the pile diameter, the Y-factor should be used to determine the p-y curveof pile group.When determing the pile group effect of jacket offshore platform underhorizontal loads with the group pile head as elastic constraints, the article uses Winkerfoundation beam pile group model iterative algorithm to determine the p-y curve ofpile group with elastic pile head constraints, the results shows that the iterativealgorithm is reasonable.Secondly, for the modified Poulos method cannot consider the effect of soilnonlinear interaction between soil and pile, finite element analysis is used to get thep-y curves of pile group. The article gives the corresponding calculation methods, anddiscusses how to select the parameters for the calculation, and also determines theapplicability by contrast with the the modified Poulos method.Then, the article uses the finite element method to determine the t-z curve ofpile group under vertical loads during the pile group settlement calculation, thismethod can reflect soil nonlinear and the pile-soil interaction influence, which reflectsthe rationality of the finite element method by contrast with the the modified Poulosmethod.For the selection of the pile group efficiency coefficient, the article uses the finiteelement method to evaluate pile group efficiency in clay, sand and layered soil, whichdiscusses the rules of the pile group efficiency.Finally, considering the influence of the penetration and extracting of pile shoeof drilling ship completion of jacket offshore platform to the load-bearingcharacteristics, the article respectively analyzes the influence of the pile penetrationpit with different depth to the horizontal load-bearing characteristics and verticalcharacteristics of the platform, and gets the p-y curve and t-z curve of the pile groupwith the effect. Then, the article analyzes the influence of extracting of pile shoe and back flow in the penetration to the horizontal characteristics and verticalcharacteristics of the platform, and the p-y curve and t-z curve will be proposed.