Permeable Grout Plug for Suction Pile Decommissioning
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Solution Overview
Problem
After installation, a gap between the soil plug and the closed suction pile top can be filled with a grout plug that obstructs the development of overpressure during decommissioning, making it difficult to remove the suction pile from the seabed.
Innovation Solution
A grout plug is made fluid-permeable by incorporating fluid channels or a permeable tube, allowing fluid flow from a pump to press out the suction pile during decommissioning, facilitating easier extraction by equal distribution of overpressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a rigid grout plug is used to fill the gap in the suction pile, then the structural stability is improved, but the ease of removal deteriorates due to obstruction of overpressure development
Solution Approach 1:
The grout plug is made porous with fluid channels extending through it, allowing fluid to flow through while maintaining structural stability. This porous structure enables overpressure to be transmitted to the soil plug during removal, solving the contradiction between stability and ease of removal.
Solution Approach 2:
The permeable grout plug acts as an intermediary between the fluid injection system and the soil plug. It transmits the fluid pressure while maintaining its structural position, enabling the removal process without compromising the structural stability during operation.
2Strength
If a rigid grout plug is used to fill the gap, then the load bearing capacity is improved, but the difficulty of extraction increases due to fluid flow obstruction
Solution Approach 1:
The grout plug incorporates fluid channels that allow fluid to pass through while maintaining its load-bearing structural integrity. This porous structure eliminates the harmful effect of fluid flow obstruction during extraction while preserving the load bearing capacity.
Solution Approach 2:
The grout plug can be viewed as a composite structure combining rigid load-bearing material with fluid-conducting channels, achieving both strength and permeability requirements simultaneously.
3Stability of the object's composition
If the gap is filled with grout to prevent soil collapse, then the stability is improved, but the ability to generate overpressure for removal is reduced
Solution Approach 1:
The permeable grout plug with fluid channels allows overpressure to be transmitted through it to the soil plug, maintaining the ability to generate removal forces while providing structural stability during operation.
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 fluid-permeable grout plug enables reliable and efficient extraction of the suction pile by allowing fluid flow through the grout plug, overcoming the obstruction caused by the rigid grout and ensuring equal distribution of overpressure, thus simplifying the removal process.
Implementation Method 1
A grout plug (provided after the suction pile penetrated the seafloor to its end depth) is provided such that it is fluid (i.e. gas and/or liquid) permeable
Implementation Method 2
vacuum or suction can be generated by removing water from within the suction space such that a resulting force tends to force the suction pile deeper into the subsea floor
Implementation Method 3
the suction pile can easily be removed by creating an overpressure within the suction space, e.g. by pumping in (sea) water
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
Marine structure comprising a foundation with one or more suction piles installed in the seafloor to operate as a foundation or part of it to support an offshore structure resting onto the seafloor, the suction pile having internally below the top bulkhead a grout plug, which grout plug is fluid permeable to provide a fluid connection between the suction pile inner spaces above and below it, e.g. wherein a fluid flow channel extends through the grout plug.