Sliding Subsea Mudmat Foundation With Embedded Rock Support
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Solution Overview
Problem
Conventional subsea foundations for heavy pipeline accessories on soft seabed soils are limited by size constraints due to cost, weight, and installation challenges, particularly in deep-water environments, where large mudmats are difficult to install and may not provide sufficient support, leading to instability and potential buckling of pipelines.
Innovation Solution
The method involves embedding discrete masses of rocks in the seabed, such as using gabions filled with rocks, to create a support structure for a sliding mudmat foundation, allowing for a reduced footprint and increased load-bearing capacity while enabling horizontal movement to accommodate thermal expansion and contraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large mudmats are used to support heavy accessories on soft seabed, then load-bearing capacity and stability are improved, but installation difficulty and cost increase significantly
Solution Approach 1:
The invention divides the large mudmat into multiple smaller modular units that can be independently handled and installed. Each module contains a foundation element with bearing plates that distribute loads to the seabed, achieving the required load-bearing capacity through distributed support rather than a single large structure. This segmentation makes the components manageable for installation while maintaining structural integrity.
Solution Approach 2:
The invention transitions from a two-dimensional large-area mudmat to a three-dimensional modular structure with vertical bearing plates extending into the seabed. The bearing plates provide depth dimension for load distribution, allowing smaller surface footprints to achieve the same load-bearing capacity as much larger flat mudmats.
2Ease of manufacture
If mudmat size is reduced to ease installation, then installation cost and complexity decrease, but load-bearing capacity and stability are insufficient
Solution Approach 1:
The invention concentrates load-bearing capacity at critical local points through bearing plates positioned at specific locations on each modular unit. Rather than distributing load uniformly across a large area, the bearing plates provide localized high-strength contact points with the seabed, allowing small modules to support heavy accessories through strategically placed support elements.
Solution Approach 2:
The modular foundation elements combine different materials and structural features - the mudmat body material with separate bearing plate elements that have optimized contact properties with the seabed. This composite approach allows each component to be optimized for its specific function while working together to achieve overall load-bearing capacity.
3Device complexity
If heavy accessories are used to reduce the number of components, then device complexity decreases, but the required foundation size and installation difficulty increase
Solution Approach 1:
The invention segments the foundation system into standardized modular units that can be combined in different configurations to support various accessory sizes and weights. Each module is a complete, self-contained unit with integrated bearing plates, allowing the system to scale with accessory requirements without increasing individual component complexity or installation difficulty.
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
This approach enables the use of smaller mudmats or heavier accessories, reduces installation complexity and costs, and maintains stability by distributing loads effectively through rock columns, minimizing the risk of embedment and buckling, thus enhancing the efficiency of pipeline installation and operation.
Implementation Method 1
The support comprises at least one rock column embedded in the seabed
Implementation Method 2
mudmats can be designed to slide horizontally across the seabed, for example to accommodate thermal expansion and contraction that causes a supported pipeline to lengthen and shorten due to temperature fluctuations
Data Source
AI summary
A method of constructing a sliding subsea foundation includes embedding at least one mass of rocks in seabed soil and placing a sliding mudmat on the seabed over the or each mass of rocks. The rocks can be lowered into a cavity in the seabed by dumping the rocks into the cavity or when contained within a gabion that is inserted into the cavity. Alternatively, a gabion containing the rocks can penetrate the seabed soil, driven by self-weight or additionally by a deadweight bearing on the gabion. The gabion can be lowered toward the seabed suspended from the deadweight. The deadweight can be removed and recovered after the gabion has been embedded in the seabed. The mass of rocks is embedded within an area of excursion of the mudmat to ensure that the mudmat will lie directly above the mass of rocks at any position within the area of excursion.