Hydraulic Extraction of Offshore Monopiles

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Solution Overview

Problem

Existing methods for dismantling offshore foundation structures with hollow piles are inefficient, requiring extensive cutting and clearing of seabed materials, and often necessitate underwater cutting or welding, which are time-consuming and challenging.

Innovation Solution

A method involving hydraulic extraction of the hollow pile, where the pile is pressurized with a pressure medium to overcome soil resistance and lift the pile out of the seabed, potentially using a drilling fluid to reduce soil permeability and a buoyancy force to counteract the pile's weight, allowing complete removal without cutting tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the hollow pile is cleared out to a certain depth and cut using special tools, then the pile can be removed from the seabed, but the process takes a considerable amount of time and requires complex cutting operations

Engineering Contradiction:

Improvedismantling speedVSAvoidtime for cutting and clearing operations

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The invention extracts the disturbing element (soil and seabed materials) from inside the hollow pile by pressurizing it, causing the materials to be ejected through the leading end opening. This eliminates the need for time-consuming manual clearing and cutting operations, directly resolving the contradiction between dismantling speed and time consumption.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses hydraulic or pneumatic pressurization of the hollow pile to expel the enclosed seabed materials. By introducing a pressure medium through fluid lines connected to the pile, the materials are forced out rapidly, replacing the slow mechanical clearing and cutting processes with a fast fluid-driven extraction method.

Inventive Principle:

Principle #29Pneumatics and hydraulics

2Ease of manufacture

If cutting tools are used to cut off the foundation pile at a defined depth, then the pile can be removed, but special tools and considerable time are required

Engineering Contradiction:

Improvesimplicity of dismantling processVSAvoidcomplexity of cutting tools and operations

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

The invention extracts the soil and seabed materials from the hollow pile through pressurization, causing them to be ejected naturally through the leading end opening. This eliminates the need for complex cutting tools and underwater cutting operations, simplifying the dismantling process while reducing device complexity.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention replaces the mechanical cutting system with a hydraulic/pneumatic pressurization system. Instead of using complex cutting tools to mechanically sever the pile, the system uses fluid pressure to expel the enclosing materials, allowing the pile to be extracted intact and simplifying the overall dismantling operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the hollow pile is extracted hydraulically with complete removal from the seabed, then no residues remain in the seabed, but the weight of the hollow pile must be absorbed by a lifting device

Engineering Contradiction:

Improvecomplete removal without residuesVSAvoidweight of the hollow pile

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The invention uses buoyancy as a counterweight force to offset the weight of the hollow pile. By pressurizing the pile with a pressure medium, buoyant forces are generated that counteract gravity, reducing the effective weight that the lifting device must bear and enabling complete extraction without leaving residues in the seabed.

Inventive Principle:

Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The invention uses hydraulic pressurization to generate the forces necessary for complete extraction. The pressure medium creates both the buoyant forces to counteract weight and the expulsive forces to remove seabed materials, ensuring complete removal without residues while working in conjunction with the lifting device to manage the pile's weight.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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

Enables efficient dismantling of offshore foundation structures by eliminating the need for cutting and underwater operations, reducing the time and complexity of the process while ensuring complete removal of the pile without seabed residues.

Implementation Method 1

pressurizing the hollow pile with a pressure medium provided via the fluid line

Methodology Applied

Scientific EffectPressure Increase: Pressure Increase

Implementation Method 2

a buoyancy force to counteract the pile's weight

Methodology Applied

Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Implementation Method 3

using a drilling fluid to reduce soil permeability

Methodology Applied

Scientific EffectPermeability reduction: Porosity

Data Source

PatentEP3542000B1Method for dismantling offshore foundation structures

Publication Date: 2022.06.01 RWE RENEWABLES GMBH

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AI summary

The invention relates to a method for dismantling offshore foundation structures comprising at least one hollow pile which, at its leading open end, is driven into the subsoil beneath the seabed in such a way that it encloses soil, wherein the hollow pile is hydraulically and/or pneumatically extracted. In particular, the method includes the extraction of the hollow pile in the form of a monopile (1).