Immersed Tunnel Final Joint Inverted Trapezoid Prefabrication
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Solution Overview
Problem
The construction of final joints in immersed tunnels, particularly in open sea ultra-long tunnels, faces challenges due to geographical and weather conditions, requiring a method that enhances precision, reduces construction time, and minimizes project risks.
Innovation Solution
A final joint with tilted end surfaces forming an inverted trapezoid structure, combined with water stop systems and shear keys, allows for precise control and alignment during installation, reducing the risk of collision and enabling quicker assembly, while prefabrication in a land factory and transportation for installation reduces exposure to harsh weather conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional weir enclosing method or water stop plate method is used for final joint installation, then the joint can be constructed, but the construction period becomes long (3-4 months) and quality control becomes difficult due to weather and wave current conditions
Solution Approach 1:
The final joint structure is prefabricated on land with all connection surfaces, water stop systems, and internal components prepared in advance under controlled conditions, then transported and installed as a complete unit, eliminating the need for prolonged underwater construction operations
Solution Approach 2:
The final joint integrates multiple functions into a single prefabricated structure including connection surfaces for tube sections, water stop systems, shear keys for lateral restraint, and internal reinforcement, all prepared together before installation
2Ease of operation
If diving work is used for final joint installation in open sea, then the joint can be assembled, but the construction is limited by weather and wave current conditions, making project timeline and quality hard to control
Solution Approach 1:
All installation准备工作 is completed on land before transportation, including fabrication of connection surfaces, installation of water stop systems, placement of shear keys, and reinforcement positioning, eliminating the need for complex underwater operations
Solution Approach 2:
The patent replaces manual diving operations with mechanical prefabrication and positioning systems, using cranes and positioning equipment to install the pre-assembled final joint structure
3Length of moving object
If KEY tube section method is used with 100m long tube sections, then the tunnel can be constructed, but the installation and control become extremely difficult to meet precision requirements
Solution Approach 1:
The final joint is divided into manageable components (connection surfaces, water stop systems, shear keys, reinforcement) that are fabricated and assembled in sections on land, then combined into the complete structure, avoiding the need to handle extremely long tube sections as single units
Solution Approach 2:
All precision work for connection surfaces, water stop systems, and internal components is completed on land under controlled conditions before transportation, ensuring high precision without the difficulties of underwater alignment
4Manufacturing precision
If V-shaped block method is used for final joint, then the joint can be constructed, but high measurement precision and jointing deviation control are required, increasing complexity
Solution Approach 1:
The final joint is prefabricated with all connection surfaces, water stop systems, and positioning features already in place on land, eliminating the need for complex measurement and adjustment operations during underwater installation
Data Source
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AI summary
The present application discloses a final joint of an immersed tunnel, a prefabrication method and an installation method, wherein the final joint includes two end surfaces connected with installed adjacent tube sections; the two end surfaces are both tilted surfaces, so that the longitudinal profile of the final joint along an installation direction is of an inverted trapezoid structure; and the final joint further may be of a structure with a tube section I and a tube section II which are connected with each other. The final joint of the immersed tunnel is simple in structure, convenient to control and relatively high in precision, thereby reducing lots of open sea diving work and lowering a risk of installation quality defects; as prefabrication procedures are simple, the final joint may be prefabricated in a land factory and then transported to the site, thereby reducing influence of weather conditions on construction; a body structure of the final joint is prefabricated in the factory, and then the overall final joint is transported to the site for installation; water stop systems realize quick water stop, thus forming a dry construction environment; and therefore, the influence of weather and tidal current conditions on a project may be reduced, and a quality risk may be lowered.