Non-penetrating Fastener for Tunnel Lining Sealing
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Solution Overview
Problem
Existing tunnel lining systems in unstable rock face challenges with water leakage through anchor threads and inadequate sealing, leading to ice formation and corrosion, especially under high-pressure conditions from train traffic, which compromises tunnel integrity and safety.
Innovation Solution
The development of non-penetrating fasteners with a socket and adapter system that closes all openings, including capillary holes, and uses a mandrel to clamp the foil seal without piercing, ensuring a secure and watertight connection between the tunnel lining and rock, even in curved surfaces, and employing adjustable threaded rods and sleeves for optimal alignment and load distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If anchors with threaded rods are used to fasten the foil seal, then the connection strength is improved, but water infiltration occurs through the thread openings
Solution Approach 1:
A sealing element (intermediary component) is introduced between the threaded rod and the foil seal to block water infiltration through the thread openings. The sealing element acts as a mediator that maintains the water-tight barrier function while allowing the mechanical connection to remain intact.
Solution Approach 2:
The harmful function (water infiltration through threads) is extracted and separated from the useful function (mechanical connection). The sealing element specifically addresses the water infiltration issue without compromising the connection strength provided by the threaded rod.
2Reliability
If the foil seal is pierced by anchors, then the fastening is secured, but the sealing integrity is compromised
Solution Approach 1:
A sealing element is positioned at the interface between the anchor and the foil seal to prevent water infiltration through the piercing point. This intermediary component restores the sealing integrity that would otherwise be compromised by the anchor penetration.
Solution Approach 2:
The sealing element is pre-positioned to prevent water infiltration before it can occur through the anchor piercing. The sealing function is established in advance to counteract the potential harmful effect of the piercing.
3Ease of manufacture
If plastic roundels are used for fastening, then the installation is simplified, but the load-bearing capacity is insufficient under high-pressure conditions
Solution Approach 1:
The fastening system combines different materials and components: the plastic roundel provides simplified installation and sealing, while the steel threaded rod provides high load-bearing capacity. This composite approach integrates the advantages of both materials to satisfy multiple requirements simultaneously.
4Ease of manufacture
If the anchor threads are exposed, then the assembly is simplified, but corrosion and ice formation occur
Solution Approach 1:
The foil seal acts as an intermediary barrier that covers and protects the exposed anchor threads. This sealing element prevents water contact with the threads, thereby eliminating the conditions for corrosion and ice formation while maintaining assembly simplicity.
Solution Approach 2:
The foil seal, originally intended only for water drainage, is utilized to also protect the anchor threads from water contact. The same component that performs the primary sealing function also provides secondary protection against corrosion and ice formation.
Data Source
Figure 1~2
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AI summary
Construction has a seal secured at the outer side against traversing water or a anchor isolation against corrosion or a film with rough surface or a claw mat or an agent for spraying concrete with enclosed plastic foam particles. The film is held by means of sealing elements at the anchoring elements.