Helical Cut Foundation Pile Extraction
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Solution Overview
Problem
The dismantling of foundation piles, particularly hollow piles, is complex and often incomplete, with existing methods only partially removing the upper part, leaving the lower part permanently in the seabed due to high static friction.
Innovation Solution
A helical cut is made along the outer lateral surface of the foundation pile, reducing static friction by causing the pile to taper as it is lifted, allowing for complete removal with minimal effort by decreasing the diameter and elongating the pile, which loosens the contact with the ground, enabling the pile to be pulled out in one piece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the foundation pile is extracted directly without any modification, then the extraction force required is extremely high due to static friction, but the pile can be removed in one piece; if the pile is cut into segments, then the extraction force is reduced, but the pile cannot be removed completely in one piece
Solution Approach 1:
The foundation pile wall is severed along a helical dividing line, creating a continuous cut that segments the wall structure while maintaining the pile's overall integrity. This segmentation reduces the contact area with the surrounding soil, thereby reducing static friction and enabling complete extraction with feasible forces.
Solution Approach 2:
The dividing line is configured as a helical curve rather than a straight line. This curved path creates a tapered effect during extraction, where the pile diameter gradually decreases, loosening the contact between the pile and ground, which significantly reduces extraction resistance and enables complete removal.
2Ease of operation
If the foundation pile is cut along a helical dividing line, then the static friction is reduced and complete extraction becomes possible, but the wall of the foundation pile must be completely severed which requires complex cutting operations
Solution Approach 1:
The cutting tool is designed with multi-functionality, capable of both rotating around the pile's longitudinal axis and moving axially along the pile. This combination of rotational and axial movements allows a single tool to create the complex helical cut pattern required for effective extraction, reducing the need for multiple specialized tools.
Solution Approach 2:
The cutting tool employs dynamic motion control, alternating between rotation around the longitudinal axis and axial advancement. This dynamic operation pattern enables the tool to trace the helical dividing line efficiently, creating the necessary wall severance while maintaining operational flexibility and reducing overall system complexity.
3Force
If the foundation pile is extracted without clearing the interior, then the extraction process is simpler, but the static friction on the inner pile shell remains high; if the interior is cleared, then the inner friction is reduced to nearly zero, but additional time and resources are required
Solution Approach 1:
The interior of the foundation pile is cleared of sediment and debris before the extraction process begins. This preliminary action removes the source of internal static friction, ensuring that the inner pile shell experiences minimal resistance during extraction. By performing this clearing operation in advance, the overall extraction force requirement is significantly reduced.
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 helical cut significantly reduces static friction, allowing the foundation pile to be completely lifted out of the ground with less effort, overcoming the challenge of partial dismantling and residual parts in the seabed.
Implementation Method 1
reducing the static friction on the outer lateral surface in order to be able to pull the hollow pile out of the ground in one piece
Data Source
Figure 1a
Figure 1b
Figure 2
AI summary
Method for dismantling a foundation pile comprising cutting the foundation pile starting from its inner wall and lifting the cut foundation pile, characterized in that the cutting is carried out along a separation line extending tangentially and axially to the inner wall.