Modified Spudcan With Optimal Peripheral Skirt for Jackup Stability
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Solution Overview
Problem
Traditional spudcans face challenges in providing maximum fixity in dense sand or hard soil due to conical bottom nature and limited preload, and long skirts can cause issues in soft or hard seabeds, leading to increased frictional resistance, potential damage, and eccentric loading.
Innovation Solution
A modified spudcan with an optimal peripheral skirt where the skirt tip is higher than the central tip, allowing the central tip to predominantly interact with the seabed, minimizing horizontal resistance and eccentric loading, and facilitating full contact and void filling for enhanced stability and fixity across various soil conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional spudcan with conical bottom is used, then penetration into seabed is achieved, but maximum fixity cannot be provided in dense sand or hard soil
Solution Approach 1:
The spudcan is segmented into distinct functional zones: a conical bottom portion for initial penetration and a peripheral skirt portion for providing fixity and bearing capacity. This segmentation allows each portion to optimize its specific function while working together as an integrated system.
Solution Approach 2:
The invention transitions from a two-dimensional conical base to a three-dimensional structure by adding a vertical peripheral skirt that extends downward from the conical bottom. This dimensional addition provides embedment effect and increases fixity without compromising the penetration capability of the conical portion.
2Reliability
If a long peripheral skirt is used to increase fixity, then embedment effect is improved, but frictional resistance and risk of damage increase in soft or hard seabed
Solution Approach 1:
The skirt length is optimized to a specific parameter range (L/D ratio of 0.2 to 0.5) that balances the embedment effect needed for fixity with the frictional resistance that increases with length. This parameter optimization ensures adequate fixity while minimizing harmful frictional effects in various seabed conditions.
3Reliability
If skirt tip is lower than central tip, then embedment is maximized, but eccentric loading and horizontal resistance increase
Solution Approach 1:
The spudcan employs asymmetric geometry where the conical bottom and peripheral skirt are configured with specific angular relationships. The skirt makes contact with the seabed at an optimized angle that provides embedment while minimizing horizontal resistance and preventing eccentric loading during penetration.
4Reliability
If preload is increased to improve fixity, then bearing capacity increases, but the limited preload capability of jackup constrains the solution
Solution Approach 1:
The conical bottom geometry is optimized with specific half-angle parameters that maximize penetration efficiency and bearing capacity distribution. The curved conical surface distributes the limited preload force more effectively across the seabed, achieving adequate fixity without requiring excessive preload that would exceed jackup capabilities.
Data Source
AI summary
A modified spudcan with optimal peripheral skirt for enhanced performance of jackup operations comprises a spudcan top part, a spudcan bottom part, wherein the spudcan bottom has a central tip protruding from the central part of the spudcan bottom; wherein the top and bottom parts are coupled at their peripherals or through a spudcan side wall to form a hull structure, and a peripheral skirt having an upper end being coupled to the spudcan bottom part and a lower end extending downwardly, wherein the tip of the lower end of the peripheral skirt is higher than the distal end of the central tip.