Study On Bucket Spudcan Penetration Resistance And Influence On Adjacent Pile

The jack-up drilling platform dominate in kinds of mobile drilling platforms because of its reusability,strong adaptability to water depth and good flexibility.The platform requires the penetration of the spudcan into the seabed to support itself.Affected by complex environmental and geological conditions of the sea,the traditional inverted cone spudcan is prone to appear problems of instability and punch-through.What’s more,the penetration and extraction of inverted cone spudcan may impose an adverse influence on the adjacent pile.Fortunately,the new type of bucket spudcan can mitigate these adverse effects.In this investigation,by carrying out small-scale prototype tests in saturated sand,the penetration resistance of bucket spudcan under different penetration rate was studied systematically.Meanwhile,the effects of new-type bucket spudcan and conventional inverted cone spudcan movements on the lateral behavior of adjacent piles were analyzed contrastively.The main contents and conclusions summarized as follows:1.In this paper,the latest development and research of bucket spudcan and inverted cone spudcan have been summarized,and the penetration performance of two kinds of spudcans and their movements on the lateral behavior of adjacent piles were elaborated.2.By carrying out small-scale prototype tests in saturated sand,the influence of penetration speed on the penetration performance of bucket spudcan was studied,and the computational formula for bucket spudcan penetration resistance was put forward based on the bearing capacity.Subsequently,the penetration process of bucket spudcan was simulated by CEL finite element method,and the results were compared with test results.The investigation results show that when the penetration velocity of spudcan is 0.1-0.3mm/s in the model test,the penetration process of bucket spudcan can be regarded as quasi-static process,and the penetration resistance of spudcan varies little.At the same time,the penetration resistance of bucket spudcan in a certain depth can be calculated accurately by using the Hansen formula and Vesic formula.Additionally,the CEL finite element method can simulate the bucket spudcan penetration process exactly,and the simulation results are in good agreement with the test results when the penetration velocity of spudcan is 0.1-0.3mm/s.3.By carrying out small-scale prototype spudcan-pile interaction tests in saturated sand,the effects of new-type bucket spudcan and conventional inverted cone spudcan movements on the lateral behaviour of adjacent piles were studied contrastively.The test took into account the influence of pile diameter,clearance between the spudcan and pile,and pile head condition.Additionally,the soil flow pattern during two types of spudcan penetration and extraction was analyzed by CEL technique.Finite element analyses show that in the process of bucket spudcan penetration,the skirt of bucket spudcan has a constrained effect on the soil inside the bucket spudcan,and reduces the lateral soil squeezing effect.Therefore,during bucket spudcan penetration and extraction,the induced bending moment on a pile and pile head displacement are less than inverted cone spudcan.