Grooved Polymeric Shoe Layer for Sliding Subsea Foundations
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional subsea foundations face challenges in supporting heavy structures on soft seabed soils, resisting external loads, and accommodating thermal expansion while minimizing embedment and frictional wear, which can lead to unintended displacement and instability.
Innovation Solution
A sliding subsea foundation with a polymeric shoe layer featuring elongate grooves, made of high-density polyethylene, that provides a low friction angle in the longitudinal direction to allow for thermal expansion while maintaining stability against lateral loads, by engaging the seabed with an array of parallel grooves and lands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional subsea foundation uses a smooth polymeric shoe layer, then frictional wear is high and embedment occurs, but the structure remains stable against lateral loads
Solution Approach 1:
The shoe layer is transformed from a smooth solid surface to a porous material with elongate grooves that extend partially through its thickness. These grooves allow seabed soil to penetrate and interlock with the polymeric material, creating a mechanical anchoring effect that reduces frictional wear and prevents embedment while maintaining stability against lateral loads through the interlocked soil-polymer interface
Solution Approach 2:
The shoe layer is designed with non-uniform local properties: the elongate grooves create regions of different soil interaction characteristics. The grooved regions provide low-friction sliding capability along the length of the grooves, while the raised portions between grooves provide mechanical interlocking with the seabed soil, creating a differentiated interface that simultaneously reduces wear and maintains stability
2Adaptability or versatility
If the foundation allows horizontal movement to accommodate thermal expansion, then the pipeline is less prone to buckling, but the structure may experience unintended displacement
Solution Approach 1:
The foundation transitions from a static, fully fixed configuration to a dynamic system with controlled degrees of freedom. The elongate grooves in the shoe layer enable directional movement along the groove axis to accommodate thermal expansion and contraction of the pipeline, while the interlocked soil-polymer interface at the grooved regions provides resistance to lateral displacement, creating a dynamically adaptive foundation that responds differently to different types of movement
3Reliability
If a large bearing area is provided to minimize embedment, then the foundation is more stable, but cost and installation complexity increase
Solution Approach 1:
Instead of increasing the overall footprint of the foundation to achieve adequate bearing area, the invention creates effective bearing area through porosity in the shoe layer. The elongate grooves allow seabed soil to penetrate and interlock with the polymeric material, generating substantial bearing capacity and embedment resistance from a relatively compact foundation structure, thereby avoiding the cost and complexity associated with oversized foundations
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 reduces frictional wear, allows for cost savings in ballasting and installation time, and maintains structural stability by optimizing the interface between the seabed and the foundation, thereby minimizing unintended displacement and enhancing the durability of the foundation.
Implementation Method 1
the friction angle at an interface between the foundation and the seabed soil may advantageously be lower in a longitudinal direction parallel to the length of the or each groove than in a transverse direction orthogonal to the length of the or each groove
Data Source
Figure 1~3
Figure 4~5
AI summary
A sliding subsea foundation comprises a polymeric shoe layer on the underside of a mudmat or subsea structure. The shoe layer defines a soil-engaging face that comprises an array of parallel grooves. The grooves are shallower than the thickness of the shoe layer such that each groove has a closed top, defined by and integral with the shoe layer, that spans the groove. Where a subsea structure is supported on the foundation with a subsea pipeline attached to the structure, the grooves are substantially parallel to a longitudinal axis of the pipeline.