Anisotropic Boundary Elements for Buried Pipeline Deformability
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Solution Overview
Problem
Buried pipelines face catastrophic failures due to ground movements from geological or environmental phenomena, as existing solutions with homogeneous, isotropic mechanical behavior are inadequate in accommodating pipe displacements without being crushed by soil pressure.
Innovation Solution
An anisotropic mechanical system with collapsible elements positioned near and distant from the pipe, allowing the pipe to move while resisting soil pressure, comprising collapsible near elements and protective distant elements that are stiff in one direction and collapsible in orthogonal directions, facilitating longitudinal, lateral, and vertical movements without straining the pipe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If homogeneous, isotropic mechanical boundary elements are used to allow pipe movement, then the pipe can deform under ground movement, but the boundary elements are crushed under soil pressure and cannot accommodate sufficient displacement
Solution Approach 1:
The patent applies asymmetry by designing boundary elements with different mechanical properties in different directions: they are stiff in the direction perpendicular to pipe movement to resist soil pressure, and collapsible in the direction of pipe movement to accommodate displacement. This anisotropic mechanical behavior resolves the contradiction between needing strength against soil pressure and adaptability for pipe deformation.
Solution Approach 2:
The patent implements local quality by creating boundary elements with spatially varying mechanical properties: the elements have stiff regions oriented to resist soil pressure while having collapsible regions that allow pipe movement. This local differentiation of mechanical properties enables simultaneous resistance to soil pressure and accommodation of pipe displacement.
2Strength
If pipelines are designed with high strength to resist ground movements, then the pipeline can withstand internal forces, but the pipeline cannot deform to distribute displacements and avoid critical strain concentrations
Solution Approach 1:
The patent applies inversion by reversing the conventional approach: instead of designing the pipeline itself to be extremely strong to resist ground movement forces, the solution makes the boundary conditions anisotropic and collapsible in the movement direction. This allows the pipeline to deform and distribute displacements while maintaining integrity, resolving the contradiction between strength and deformability.
3Adaptability or versatility
If soft boundary constraints are used to accommodate pipe displacement, then the pipe can move under ground movement, but the soft boundary elements cannot resist soil pressures and are crushed
Solution Approach 1:
The patent resolves this contradiction by making boundary elements asymmetric in their mechanical response: they provide soft, collapsible constraints in the direction of pipe movement to accommodate displacement, while maintaining stiff, strong resistance in the direction perpendicular to movement to withstand soil pressures. This directional differentiation enables simultaneous pipe movement capability and soil pressure resistance.
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 system enhances pipe deformability, distributing displacement over longer distances, reducing strain concentrations and accommodating maximum displacements, thereby increasing pipeline reliability and safety by modifying boundary conditions to resist soil pressures and absorb ground movements effectively.
Implementation Method 1
a set of elements with an anisotropic mechanical behaviour which are stiff in the direction along which the soil pressure is applied, and is collapsible in the direction along which the pipe moves
Data Source
AI summary
A system is provided that increases the deformability of buried pipelines to accommodate combinations of vertical, lateral and longitudinal displacements and subsequent curvatures caused by ground movements. Installation of this system prevents concentration of deformations which may cause catastrophic failures such as buckling, yielding, rupture, and weld failures. The assembly includes an element provided adjacent a pipeline and collapsible in two orthogonal directions; one, the longitudinal direction of the pipe, and two, a direction of expected lateral movement of the pipe. The collapsible element is configured to resist soil pressure in a direction orthogonal to the first two directions, and further provided is a supporting backing element adjacent an end of the collapsible element opposed to the pipeline, to prevent exposure of the collapsible element to soil pressure in one of the two orthogonal collapsible directions. The size and configuration of the installation depends on the soil and pipe properties, and type/magnitude of expected displacements.