Prefabricated Tunnel Element with Compressible Cavity Layer
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Solution Overview
Problem
Existing tunnel construction methods face challenges in effectively damping ground convergence, particularly during storage and transportation of construction elements, as they tend to agglutinate and lose compressibility, leading to uneven distribution and reduced mechanical properties.
Innovation Solution
A prefabricated construction element comprising an incompressible concrete layer and a compressible layer made from granulates aggregated by a binder with cavities, which secures mechanical damping properties and allows for homogenous tunnel section formation, reducing ground convergence stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compressible layer made from granulates is used to dampen ground convergence, then the mechanical damping properties are improved, but the granulates tend to agglutinate during storage and transportation, losing compressibility
Solution Approach 1:
The compressible layer is pre-formed with cavities created by spherical particles before assembly. This preliminary action ensures the granulates maintain their spaced arrangement and compressibility throughout storage and transportation, preventing agglutination while preserving the mechanical damping properties needed to withstand ground convergence
Solution Approach 2:
The compressible layer incorporates cavities formed by spherical particles distributed within the granulate material. This porous structure allows the layer to maintain its compressibility by providing void spaces that prevent granulate agglutination, while still delivering the mechanical damping properties required for ground convergence resistance
2Reliability
If devices with pass-through holes are injected to create residual volume for damping ground convergence, then the ground convergence damping is improved, but ground elements agglutinate in the delineated space and hamper injection
Solution Approach 1:
The cavities are pre-formed within the compressible layer during manufacturing, before the layer is assembled into the construction element. This preliminary creation of void spaces eliminates the need for subsequent injection operations, avoiding agglutination issues while ensuring uniform distribution of damping structures throughout the layer
Solution Approach 2:
Spherical particles are used as removable templates during manufacturing to create cavities within the compressible layer. These particles are extracted after cavity formation, leaving behind a network of void spaces that provide ground convergence damping without requiring injection of additional devices into the assembled structure
3Reliability
If foam is stuck onto the outer surface of voussoirs to provide compressibility, then the ground convergence damping is improved, but the foam can be damaged during storage or transportation, resulting in loss of mechanical properties
Solution Approach 1:
The compressible layer is constructed as a composite material combining granulates with spherical particles embedded within a binding matrix. This composite structure provides both the compressibility needed for ground convergence damping and the mechanical strength to resist damage during storage and transportation, unlike fragile foam materials
Solution Approach 2:
The compressible layer uses a porous structure formed by spherical particles distributed within granulates. This porous granulate composite provides the necessary compressibility for damping ground convergence while maintaining structural integrity and resistance to damage during handling, storage, and transportation
4Ease of operation
If it is difficult to stick foam to bind it to the voussoir, then the attachment process is simplified, but the compressible layer cannot be securely united to the construction element
Solution Approach 1:
The compressible layer is merged with the construction element by integrating the spherical particle-cavity structure directly into the granulate layer that is already bonded to the voussoir. This merging eliminates separate attachment steps while ensuring secure union through the inherent bonding of the granulate matrix to the construction element surface
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 provides a monoblock construction element that effectively dampens ground convergence by compressing and relaxing stresses, maintaining mechanical properties during storage and transportation, and simplifies the construction process by eliminating the need for additional adhesives and ensuring a homogenous tunnel section.
Implementation Method 1
The cavities enable the ground to converge and to relax the stresses exerted on the first layer
Implementation Method 2
the cavities enable the ground to converge and to relax the stresses exerted on the first layer
Data Source
AI summary
Construction element for creating a tunnel, including an incompressible concrete first layer and a compressible second layer securedly united to the first layer to form a monoblock prefabricated construction element to be integrated in a section of the tunnel, the second layer including a material comprising granulates aggregated by a binder, and cavities sunk into the material.