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Large rectangular cross-section tunnel undercrossing urban road by micro pipe jacking and joint assembly structure
Jia Zou1, Xiongyao Xie2, Biao Zhou1
1Department of Geotechnical Engineering, College of Civil Engineering, Tongji University, Shanghai, 200092, China.
A new micro pipe jacking and joint assembly structure (MPJ & JAS) method offers a trenchless solution for urban ultra-shallow tunnels. This innovative approach enables cost-effective, rapid construction of large-diameter tunnels with enhanced structural reliability.
Area of Science:
- Civil Engineering
- Geotechnical Engineering
- Trenchless Technology
Background:
- Urban infrastructure development leads to numerous
- dead end roads
- requiring new undercrossing tunnels.
- Existing trenchless methods are often unsuitable for ultra-shallow overburden in urban environments.
Purpose of the Study:
- To introduce and validate a novel micro pipe jacking and joint assembly structure (MPJ & JAS) method for urban ultra-shallow tunnels.
- To address the need for cost-effective, time-efficient, and flexible trenchless construction solutions.
Main Methods:
- Design and mechanical testing of a CT-shaped integrated joint.
- Bending tests and finite element (FE) analysis to evaluate tunnel structure reliability and performance.
- Development of a theoretical design method for predicting bending strength.
- Engineering of specialized equipment and techniques for MPJ & JAS construction.
Main Results:
- Tensile tests verified the mechanical performance of the CT-shaped integrated joint.
- FE analysis confirmed the structural reliability, failure modes, and load-deflection behavior of the MPJ & JAS tunnel.
- A theoretical design method accurately predicts bending strength ( < 10% error).
- Optimized construction technologies, including micro pipe jacking machines and guidance systems, were developed.
Conclusions:
- The MPJ & JAS method is a viable and reliable trenchless solution for urban ultra-shallow tunnels.
- The developed integrated joint and design methodology enhance structural integrity and predictability.
- The supporting construction technologies ensure accurate and efficient tunnel installation.
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