The FEM And Test Research About Dynamic Pile-soil Interaction

Jack-up platporm was widely used in offshore industry, but because of the complexity of the seabed foundation and the pile-soil interaction, the foundation instability,asymmetric settlement of piles, platform tilt and scour with caving phenomenon were often occured when the pile operated, which brought severe challenges to platform operation safety. According to the current specification, the boundary condition was simplified as constraints under the mud surface somewhere in the structure calculation of jack-up platform. The simplification overlooked the pile-soil interaction, which threatened the platform structure safety. The spudcan model of Shengli NO.3 in Bohai Bay was used to research the dynamic interaction in pile-soil penetration with test and numerical simulation.The correction method in strength and structure design of jack-up, operated inBohai Bay,was provided, which was the purpose of the dynamic resrarch.The main works conducted in this paper are as follows.The FEM method ALE was used to deal with the large deformation in pile-soil penetration. And The soil model of Mohr-Coulomb has the advantage in calculating the bearing capacity. Both the pile and the soil was simplified in the simulation.The mechanisms of the soil flow-back at the spudcan rim and the cavity above the spudcan in processing, development and failure were researched in ABAQUS/ALE. The flowed soil influence of the cavity with the velocity deficit, up and down the spudcan, to the bearing capacity was studied.The spudcan bottom pressure was researched, with the static pressure exerted on the jack-up pile test and ALE numerical simulation, and compared to the ? Rules for the classification and construction of offshore mobile drilling units ? of CCS based on the foundation condition in Bohai Bay. The punch through phenomenon in the composited base was also verified in the static pressure test.An optimized support design on the spudcan was conducted based on the test and numerical simulation in the dynamic pile-soil interaction. The variation of the bearing capacity was the main concern about the optimization.