Cases from our journey
Tunnel Joint Experts.
Selectieve Onttrekking, Salt barrier
Period
2021-2024
Author
Joel van Stee
Role
Technical lead and supervision
Client
Van Hattum en Blankevoort; Trelleborg
Engineers & Contractors
Problem Statement
The “Selectieve onttrekking -Salt barrier” project began with
a complex challenge: stabilizing the installed barrier gates
within a confined space, requiring materials that could
withstand high pressure and significant deformation.
Traditional installation methods were not feasible given the
constraints of the environment and the necessary tolerances
and hardening criteria.
Engineers & Contractors
Solution
The solution involved developing a unique injectable laminated bearing capable of withstanding high pressures and deformations while accommodating installation tolerances within a limited space. A meticulously designed injection system was created to ensure precise filling of the bearings using a custom-mixed polyurethane (PU) material that cured quickly and could handle high compressive strength. The finished bearing still has a high degree of deformability reducing the stresses in the barrier gates.
Engineers & Contractors
Design
The design focused on ensuring consistent filling of the bearings without air pockets and with guaranteed preload pressure. The system included specifically engineered distribution and control panels, pump units, and controlled mixing systems designed to accurately regulate pressure throughout the injection process. Notably, the design accounted for the fact that no control mechanism was available during the injection, meaning the process had to be first-time-right.
Engineers & Contractors
Testing and Validation
Extensive testing was conducted in a controlled environment to validate the functionality and durability of the system. The testing programs included pressure tests, vacuum tests, and hardening tests of the PU materials under simulated loads. Every stage was documented to verify the effectiveness of the design decisions and ensure the system’s readiness for field implementation.
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Implementation
After successful validation, the system was implemented on the project site. The installation of the injection systems and laminated bearings was meticulously performed according to the designed specifications. Preparations included assembling the injection equipment, calibrating sensors, and checking all connections to ensure everything was set for operation.
Engineers & Contractors
Injection Methodology and Equipment Design
The injection methodology was designed to maintain uniform fill levels and pressure. The system was equipped with sensors and valves to continuously monitor and control pressure. A step-by-step approach was employed, injecting section by section to ensure even distribution of the material. The custom-mixed PU was formulated specifically for this application, ensuring optimal performance under the required conditions.
Engineers & Contractors
Verification and Testing of the Injection Methodology
Prior to execution, extensive tests were conducted on the injection methodology to confirm its functionality. This included injecting dummy blocks, checking pressure levels, and validating fill rates and hardening. Results confirmed that the methodology met all design criteria, emphasizing the need for a first-time-right approach due to the absence of a control mechanism during injection.
Engineers & Contractors
Construction of the Injection System
The injection system was built with custom distribution panels, vacuum units, and pumps. Construction was conducted under controlled conditions, where each component was tested for functionality. After assembly, the systems were prepared for transport and installation at the project site.
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Implementation Testing
Following installation, the system was tested on-site to ensure all components functioned correctly. These implementation tests included integrity checks of connections, pressure trials, and a final assessment of the system’s responsiveness. All tests were aimed at confirming readiness for the critical injection process.
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Testing of PU Material
Samples of the custom-mixed PU material were tested for compressive strength and curing time to ensure compliance with ULS load requirements. Tests confirmed that the PU material had adequately hardened and showed no significant deformation, indicating high reliability and durability, meeting the stringent demands of the project.
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Injection
The injection process itself was executed with a strict protocol, meticulously monitored at each step. The system ensured that the laminated bearings were consistently filled without air pockets and maintained the required pressure levels. Injection times and pressures met the predefined expectations, with the custom-mixed PU delivering optimal performance.
Engineers & Contractors
Post-Implementation Care and Inspections
After the injection, comprehensive inspections were conducted to verify the quality and integrity of the filled bearings. Visual inspections and pressure measurements were performed to validate the results. Additionally, system components were cleaned and prepared for future use, with detailed documentation of all measurements and any observed deviations.
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