Steel Monopile Foundation with Adjustable Precast Concrete Interface
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Solution Overview
Problem
The challenge lies in accurately positioning and adjusting a precast concrete part on top of a steel monopile for offshore structures, such as wind turbines, where tight geometrical tolerances and the absence of a pile cap complicate the alignment and adjustment of the monopile, leading to construction errors and increased construction time.
Innovation Solution
A method involving a support structure with radially extending rods inside the monopile, pre-stressing tendons, and embedded supporting columns to ensure precise alignment and adjustment of the precast concrete part, allowing for horizontal and vertical adjustments within restricted tolerances, while embedding the structure in concrete for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single steel monopile is used without a pile cap, then the foundation structure is simplified and more suitable for offshore applications, but the geometrical tolerances for positioning the precast concrete part become more restricted and difficult to work with
Solution Approach 1:
The connection plug is segmented into multiple functional components: supporting columns for load transfer and positioning adjustment, a connection body for structural integration, and tendons for pre-stressing. This segmentation allows each component to address specific tolerance issues independently, enabling the precast concrete part to be positioned accurately despite monopile construction variations.
Solution Approach 2:
The invention uses pre-stressable tendons that can be tensioned to adjustable levels, and supporting columns with adjustable lengths, to compensate for horizontal position errors, height variations, and tilt angle deviations. By changing the pre-stress parameter and column length parameter, the system adapts to different construction tolerances and ensures proper alignment.
2Adaptability or versatility
If adjustment capacities are added to cope with construction errors, then the positioning flexibility is improved, but the duration of the whole construction process may be extended
Solution Approach 1:
The support structure, including supporting columns and tendons, is prepared and positioned within the connection plug before the precast concrete part is installed. This preliminary arrangement allows for quick adjustment and alignment during installation, reducing on-site adjustment time and accelerating the construction process while maintaining positioning flexibility.
Solution Approach 2:
The connection plug acts as an intermediary element between the monopile and the precast concrete part. It absorbs and compensates for construction tolerances through its adjustable components, eliminating the need for time-consuming field adjustments of the precast concrete part itself and streamlining the installation process.
3Manufacturing precision
If the precast concrete part is positioned with tight tolerances, then the structural alignment is improved, but the ability to accommodate construction errors is reduced
Solution Approach 1:
The connection plug incorporates dynamic adjustment capabilities through pre-stressable tendons and adjustable supporting columns. These components can be modified after the monopile is installed to achieve the required alignment precision, allowing the system to adapt to actual construction conditions while maintaining high alignment standards.
Solution Approach 2:
The invention replaces rigid mechanical positioning with a pre-stressed tendon system that provides both positioning and load transfer functions. The tendons, when tensioned, create a constrained but adjustable connection that maintains precise alignment while accommodating minor construction variations through elastic deformation and adjustable pre-stress levels.
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 method enables the precast concrete part to withstand mechanical loads and accommodate construction errors, ensuring precise alignment and reducing the construction time by allowing for adjustments that maintain the structural integrity and alignment within the specified tolerances.
Implementation Method 1
arranging tendons between the support structure and the precast concrete part and tensioning the tendons to pre-stress the supporting columns
Data Source
AI summary
The invention relates to a method of building a foundation (1) comprising a steel monopile (2) and a precast concrete part (3) on top of the monopile (2), comprising:—arranging a support structure (12) inside the monopile (2), the support structure (12) having a plurality of rods (16) extending radially with respect to a longitudinal axis of the monopile; —bringing the concrete part (3) above the monopile (2), with supporting columns (13) interposed between the support structure (12) and the concrete part (3), wherein reinforcement bars (14) protruding from a bottom surface (9) of the precast concrete part (3) extend downwardly beyond the support structure (12) by passing between the rods (16) of the support structure (12); —arranging tendons (15) between the support structure (12) and the concrete part (3) and tensioning the tendons (15); and—pouring concrete into an upper part of the monopile (2).