Segmented Prestressed Tube Section for Subsea Tunnel Adaptability
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Solution Overview
Problem
Existing rigid tube sections in immersed tunnels lack flexibility to redistribute structural internal forces and adapt to complex subsea environments, leading to stress concentration and water leakage risks.
Innovation Solution
A prestressed tube section structure with shear-resistant and water stop systems between segments, along with prestressing tendons partitioned near segment joints, allowing for flexibility and deformability while maintaining overall rigidity, and a construction method involving reinforcement cages, concrete pouring, and prestress tensioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a rigid tube section is used to resist external load with overall rigidity, then the bearing capacity is improved, but the structure cannot redistribute internal forces via flexible deformation and cannot adapt to subsea complicated settling environment
Solution Approach 1:
The tube section is divided into multiple segments connected by segment joints, allowing the structure to combine rigidity within segments with flexibility at joints. This segmentation enables the tube section to resist external loads while accommodating subsea settling through controlled deformation at the joints.
Solution Approach 2:
The segment joints are designed to allow controlled rotation and deformation under load, transforming the static rigid structure into a dynamic system that can adapt to subsea settling conditions. The joints enable the structure to redistribute internal forces through flexible deformation while maintaining overall integrity.
2Adaptability or versatility
If a flexible tube section with segment joints is used to allow deformation under load, then the adaptability to subsea environment is improved, but the shear resistance and water resistance between segments are reduced
Solution Approach 1:
Prestressing tendons are installed and tensioned before the tube section is subjected to service loads, pre-compressing the concrete segments and creating initial friction and normal forces at the segment joints. This preliminary action enhances the shear resistance and water resistance at joints while maintaining the flexibility needed for adaptability.
Solution Approach 2:
The segment joints incorporate multiple materials and mechanisms including concrete, prestressing steel tendons, shear-resistant structures, and water stop systems. This composite approach combines the flexibility of concrete deformation with the strength of prestressing steel and the sealing capability of water stop systems.
3Stability of the object's composition
If prestressing tendons are continuous through segment joints, then the overall rigidity is maintained, but the flexibility and deformability of the tube section is reduced
Solution Approach 1:
The prestressing tendons are segmented to correspond with the tube section segments, with each tendon confined within its respective segment. This segmentation allows each segment to deform independently while the prestressing force maintains local rigidity, enabling overall flexibility through joint deformation.
Solution Approach 2:
The prestressing tendons provide localized compression and rigidity within each segment, while the segment joints remain flexible to allow deformation. This local application of rigidity versus flexibility enables the structure to maintain sufficient stiffness for load resistance while accommodating settlement through joint movement.
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
Enhances shear resistance, watertightness, and adaptability to subsea foundations, improving loading capacity and deformability, and reducing stress concentration and water leakage risks.
Implementation Method 1
multiple prestressing tendons are arranged in the tube section along the circumferential direction of the tube section; and each prestressing tendon is communicated along the longitudinal direction of the tube section
Implementation Method 2
A shear-resistant structure and a water stop system are arranged between two segments
Data Source
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Figure 5
AI summary
The present application discloses a prestressed tube section structure and a construction method thereof. The prestressed tube section structure includes multiple successively connected segments. A shear-resistant structure and a water stop system are arranged between two segments; multiple prestressing tendons are arranged in the tube section along the circumferential direction of the tube section; and each prestressing tendon is communicated along the longitudinal direction of the tube section, and is partitioned into multiple sections at a position close to a segment joint. By the arrangement of the multiple successively connected segments of the present application, the shear-resistant structure and the water stop system are arranged between the two segments, so that a portion between two segments may bear a shear force and have watertightness; the arrangement of the multiple prestressing tendons in the tube section enables the multiple segments to be connected in series and spliced into a whole; in addition, each prestressing tendon is partitioned into multiple sections at the position close to each segment joint, so that the tube section has higher flexibility on the premise of not losing the overall rigidity, and the loading capacity and deformability of each segment are effectively improved; and a proper pressure is applied between two segments, so that the tube section has higher deformability to adapt to a subsea foundation bed.