Research On Penetration And Uplift Mechanism Of Spudcan In Jack-up Drilling Platform

As the supporting structure of self-elevating platform,the stability of pile boots is closely related to the safety of the platform.At present,most domestic and foreign scholars use numerical simulation to analyze the pile boots.Because the establishment of numerical simulation is based on the adjustment of parameters,the operation results are accurate.Sex is open to question.To this end,this paper studies the displacement mechanism of the soil on the side of the pile when the pile shoe penetrates through the transparent soil model test.Secondly,the compressive and uplift bearing model tests of pile boots are established to study the bearing characteristics of pile boots and the law of load transfer along the pile body,and to deduce the calculation formulas of load settlement curves under uplift and download conditions respectively.The specific contents are as follows As shown:(1)The model pile boots were penetrated into transparent soils with different relative densities(0.231,0.665,0.821,0.930).When the pile boots penetrated into soils with different densities,the displacement field of the soil on the side of the piles was changed.The results showed that: When the penetration depth of the shoe is shallow,the soil on the pile side is offset diagonally upward to both sides,forming a cavity above the pile shoe;as the penetration depth increases,the soil on the pile side returns and the cavity disappears;as the soil body With the increase of the relative density,the influence range of the displacement and offset of the soil particles on the side of the pile decreases;in the vertical direction,as the depth increases,the displacement of the soil particles decreases;in the horizontal direction,as the pile distance increases,The displacement of the soil particles gradually decreases.(2)In the compressive model test of pile boots,the load-settlement changes of pile boots with different tip angles and equal-diameter piles under different loads and the change of the axial force of the pile body are measured.The results show that: under the same load,the pile boots The settlement of the pile is less than that of an equal-diameter pile;the settlement of the pile shoe decreases with the increase of the pile tip angle;under static load,due to the presence of the pile shoe,the axial force of the pile end decreases suddenly.(3)In the pull-up model test of pile boots,the pull-out characteristics(load-uplift displacement curve)and pile body shaft transfer law of pile boots of different structures and equal-diameter piles under different loads were measured.The results showed that: The antipulling characteristics are better than equal-diameter piles.At the same time,the structure of the top of the pile boot affects the anti-pulling characteristics of the pile boot.The flat round top surface is superior to the round table structure.(4)According to the elastic model theory of the pile body,the circular hole expansion theory,and the iterative algorithm of segmented displacement,the load-displacement change law of the pile shoe uplift and the static load is derived respectively,and the model test results are used to verify.The test results are highly consistent and have a certain accuracy,which can provide a reference for related projects.