Analysis On Pile Shaft Soil Pressure Due To Spudcan Penetration

Large diameter spudcan need to be penetrated into seabed to provide bearing capacity when the mobile jack-up work.When spudan penetrated into seabed,adjacent pile could subjected to attached load.In this thesis,the CEL(Coupled Eulerian-Lagrangian)method and model test is used to analysis the soil pressure of adjacent pile shift caused by spudcan penetrating.The efficacy of the CELmethod is proved by comparison with a centrifuge model test.On this basis,the relationship between the soil-pile relative displacement and the soil pressure is analyzed in clay.The results show the resultant pressure increases with the soil-pile displacement.Within 6 times the adjacent pile diameter below the mud surface,the ultimate soil pressure along the pile increases with the depth,and the changing range is 2s_u~7.5s_u(undrained shear strength);when deeper than 6 times the pile diameter,the ultimate soil pressure tends to stabilize at about 7.5s_u.The CEL method is used to calculate the soil pressure on the adjacent pile shaft during spudcan penetration in sand.The results show the resultant pressure increases with the soil-pile displacement.Within 10 times the adjacent pile diameter below the mud surface,the ultimate soil pressure along the pile increases with the depth,and the changing range is 1.5K_pγ’z~5K_pγ’z(Rankine passive earth pressure);when deeper than10 times the pile diameter,the ultimate soil pressure tends to stabilize at about 5K_pγ’z.The CEL method and model test is used to analysis the p-y curves on the adjacent pile shaft during spudcan penetration.The results show the ultimate pressure of adjacent pile is related to the direction of pile head load.When adjacent pile subjected the pile head load face towards to spudcan,the ultimate soil pressure is lager than the ultimate soil pressure of pile subjected the pile head load face back to spudcan.Based on the results of CEL calculation,the p-y curve of adjacent piles is suggested.