Scour Prevention Unit with Geotextile Cloth for Offshore Foundations

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Solution Overview

Problem

Conventional scour prevention methods using only crushed stone bags fail to effectively prevent sand infiltration and scouring at offshore windmill foundations, especially in environments with fast tides and high waves, leading to structural instability and increased construction time and cost.

Innovation Solution

A scour prevention unit comprising a bag body housing crushed stone with a fixed cloth below the bag body, preventing sand infiltration by using a woven or knitted fabric with a specific gravity greater than 1.5, integrated with the bag material and secured with hooks or strings to maintain the stone on the seabed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If only crushed stone bags are used for scour prevention, then the structure is simple and construction is fast, but sand infiltration occurs and scouring prevention effectiveness is poor

Engineering Contradiction:
Improvescour prevention effectivenessVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention uses a composite structure combining geotextile fabric and crushed stone. The geotextile layer prevents sand infiltration while the crushed stone provides scour protection weight and stability. This composite material approach resolves the contradiction by integrating the filtering function of geotextile with the protective function of crushed stone, achieving effective scour prevention without excessive structural complexity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The geotextile fabric acts as an intermediary layer between the seabed sand and the crushed stone. It mediates by allowing water flow through while blocking sand particles, preventing sand from infiltrating into and destabilizing the crushed stone structure. This intermediary layer enables the crushed stone to maintain its position and effectiveness without direct contact with sand particles.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If crushed stone is disposed without sand infiltration prevention, then construction is simple and fast, but sand is suctioned from seabed leading to structural instability

Engineering Contradiction:
Improveconstruction speedVSAvoidstructural stability
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The geotextile fabric is laid on the seabed before placing the crushed stone, performing the sand prevention function in advance. This preliminary action ensures that when the crushed stone is placed, sand infiltration is already prevented, maintaining structural stability from the beginning of operation rather than requiring corrective measures later.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The geotextile fabric is a flexible thin film that conforms to the seabed surface and surrounds the crushed stone structure. It provides continuous coverage and adaptation to the underlying terrain, preventing sand infiltration while allowing the structure to maintain its intended configuration without rigid constraints.

Inventive Principle:
Principle #30Flexible shells and thin films

3Stability of the object's composition

If a cloth is added below the bag body to prevent sand infiltration, then sand suction is prevented and stability improves, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improvestructural stabilityVSAvoidstructure complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The combination of geotextile and crushed stone creates a composite scour prevention unit where each material contributes its specific properties. The geotextile provides filtration and separation functions while the crushed stone provides mass and stability. This composite approach achieves enhanced structural stability without requiring complex mechanical structures, as the two materials work together synergistically.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The geotextile is applied specifically where sand infiltration is a problem - at the interface between the seabed and the crushed stone structure. Rather than making the entire structure complex, the solution applies the filtering function locally at the critical interface, maintaining simplicity elsewhere in the structure.

Inventive Principle:
Principle #3Local quality

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

The solution effectively prevents sand suction from the seabed, ensuring structural stability and reducing construction time and costs by maintaining the crushed stone in place, even in sandy environments with fast tidal flows.

Implementation Method 1

a fixed cloth below the bag body, preventing sand infiltration by using a woven or knitted fabric with a specific gravity greater than 1.5

Methodology Applied
Scientific EffectSpecific gravity: Density Gradient

Implementation Method 2

The solution effectively prevents sand suction from the seabed, ensuring structural stability and reducing construction time and costs by maintaining the crushed stone in place, even in sandy environments with fast tidal flows

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3736382B1Erosion prevention unit and erosion prevention method
Publication Date: 2022.11.23 SUMITOMO CORPORATION
  • EP3736382B1 patent drawingFigure 1(A)~2(C)
  • EP3736382B1 patent drawingFigure 3(A)~3(B)
  • EP3736382B1 patent drawingFigure 4~5

AI summary

A scour prevention unit (10) includes a bag body (11) housing block objects (12) in a bag material (13), and a cloth (16) integrated with the bag body (11), wherein the cloth (16) is housed in the bag material (13) and is laid below the block objects (12), or is fixed below the bag body (11) outside the bag body (11) by fixing means.