Structural Strength Assessment Of Jack-up Platform Considering Nonlinear Action Of Spudcan And Soil

The interaction between spudcan and soil provides the supporting force and anti-sliding force needed for the jack-up platform to stand,and at the same time bears the bending moment transmitted from the upper structure.In the process of structural strength evaluation,the previous spudcan-soil boundary treatment method simplifies the constraint of foundation on spudcan boots excessively,and can not guarantee the accuracy of the analysis.Based on the in-depth study of spudcan-soil non-linearity of jack-up platform,a finite element model considering the non-linearity of spudcan shoe and soil is proposed in this paper.The model can reflect the actual working state,supporting state and corresponding environmental conditions of the structure,and then evaluate the structural strength of the platform,so as to accurately predict the in-situ working performance of the platform.This paper mainly carries out the following research work:(1)The bearing capacity of foundation under spudcan-soil interaction of jack-up platform was analyzed.Using the small deformation finite element method,considering the interaction between spudcan and soil,the whole process of spudcan stably penetrating into different kinds of foundation was studied.The interaction between spudcan and soil and the variation law of foundation bearing capacity in this process were obtained,and the non-linear characteristics of foundation bearing capacity in the process of spudcan-soil interaction were clarified.Based on Winkler foundation model,a method of replacing the non-linear spring in the bearing capacity of jack-up platform foundation was proposed.(2)The finite element numerical model of the platform considering the non-linear action of spudcan and soil was established.Firstly,a three-dimensional finite element model of jackup platform was established by using ANSYS structure modeling technology,which could rationally simplify the relevant structures and reflect the actual stress characteristics while avoiding stress concentration.Secondly,according to the analysis results of spudcan-soil bearing capacity of jack-up platform,the nonlinear spring element was used to simulate the vertical reaction of foundation to spudcan boots,and the spudcan was accurately reflected spudcan Foundation Model of Nonlinear Soil Action.(3)Structural strength evaluation of jack-up platform under storm self-sustaining condition was carried out.The various loads on the platform were analyzed and determined,and the loads were loaded in different ways.The structural strength of the jack-up platform was evaluated under the condition of storm self-storage by using the proposed calculation model and considering the non-linear effect of spudcan and soil,and the evaluation results meeted the safety requirements.The structural static response characteristics of the jack-up platform under the condition of storm self-storage were obtained by structural strength evaluation.Stress Distribution and Maximum Stress Location of Supports and Bearings of Jack-up Platform were defined,and the overall performance of the jack-up platform againstthe ultimate environmental load was obtained.