Offshore Jacket Foundation Leveling via Three-Point Bearing
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Solution Overview
Problem
Constructing offshore jacket foundations with four or more support legs is challenging due to static overdetermination during the curing of grouting compounds, leading to instability and increased costs for leveling and load transfer.
Innovation Solution
The method involves loading and tilting the jacket to ensure a statically determined position by transferring the load over three support legs, with one leg relieved of its load, and using ballast to compensate for buoyancy forces, particularly on the leeward side, and employing brackets and spacers for precise leveling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the jacket is supported on all four support legs during grouting, then the structure appears stable, but the position becomes statically overdetermined and unstable due to tolerances in foundation piles and manufacturing tolerances
Solution Approach 1:
The patent extracts one support leg from the load-bearing system during the grouting process. By deliberately relieving one support leg (typically the windward leg) from carrying load, the system transitions from a statically overdetermined four-point support to a statically determinate three-point support. This extraction eliminates the instability caused by tolerances while maintaining apparent stability through the remaining three legs.
Solution Approach 2:
The patent applies preliminary anti-action by preemptively relieving the windward support leg before grouting begins. This prevents the potential instability that would arise from trying to maintain all four legs in load during grouting. The ballast arrangement is designed in advance to counteract buoyancy forces and ensure the windward leg remains unloaded throughout the critical grouting period.
2Manufacturing precision
If shim plates are used for leveling the jacket on all four support legs, then leveling can be achieved, but the cost increases and clear load transfer cannot be guaranteed
Solution Approach 1:
The patent removes the need for expensive shim plates by extracting one support leg from the leveling problem. With only three support legs bearing load, the jacket naturally achieves stable positioning through three-point contact, eliminating the need for costly precision leveling components on all four legs.
3Stability of the object's composition
If ballast is added to support legs to compensate for buoyancy, then the jacket can achieve stable three-point bearing, but the device complexity increases
Solution Approach 1:
The patent uses ballast as a counterweight to compensate for buoyancy forces acting on the relieved support leg. By adding mass (ballast) to the leeward support legs, the system creates a downward force that counteracts the upward buoyancy force, ensuring the jacket maintains stable three-point bearing on the grouted legs without floating or becoming unstable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach simplifies the construction process, ensures stable three-point bearing, and reduces the complexity and cost of leveling, while maintaining structural integrity during grouting and after hardening of the grouting compound.
Implementation Method 1
the support legs are fixed in the foundation piles with a hardenable grouting compound
Implementation Method 2
The mass of the ballast can be selected in such a way that the ballast just compensates for the buoyancy force that the support foot in question would experience after settling down when a wave passed
Data Source
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AI summary
The method involves attaching a jacket comprising four supporting legs (2a-2d) which are anchored in the foundation piles, to a subsoil. The jacket is issued on the foundation piles under load transfer in the subsoil. The supporting legs are set with a curable casting compound in the foundation piles. The jacket is leveled before and/or balanced during the casting. The load transfer in the subsoil is carried out for relieving a fourth supporting leg before curing the grout. : An independent claim is included for a jacket foundation of an offshore structure. USE : Method for constructing jacket foundation of offshore structure. ADVANTAGE : The construction of the offshore structure in the form of jacket foundation, is simplified. The position of jackets which are not fully clamped during hardening of the grout is simply determined statically, since the supporting leg is completely relieved. DESCRIPTION OF DRAWINGS : The drawing shows a top view of the jacket foundation. 2a-2d : Supporting legs 9 : Center of gravity.