REINFORCEMENT : LONG-TERN SEEPAGE TREATMENT IN UNDERGROUND WALKWAY
Seepage sealing reinforcement technology for underground passage
1. Project Background
A pedestrian underpass experienced serious water leakage after being used for a period of time. The maintenance unit installed a water deflector at the location to drain the leaking water.
However, due to blockage by calcium carbonate crystals, this approach did not work, resulting in long-term dampness of the underground passage, frequent damage to the painting surface and internal decoration.
In order to completely solve the water leakage problem, the company was specially entrusted to propose a repair plan for the leakage and plugging work. It was approved, for on-site implementation.
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2. Solution
After accepting the assignment, the company immediately assigned an engineer to the site to conduct a detailed survey, and found 38 structural joints in the underpass that were leaking.
In the earlier installation of the water guide plate, the calcium ions in the leaking water combined with the carbon dioxide in the air to produce calcium carbonate crystals, which caused the drainage outlet of the water guide plate to be almost completely blocked.
In usual weather, water leaked into the ceiling panels near the construction joints and caused mold and peeling paint. In the rainy season, a large amount of water leaked and spilled onto the ground along the edges and bolt holes of the water guide plate, causing the pedestrian pavement to be slippery and potentially hazardous.
The company planned the following solution according to the on-site situation:
(1) Comprehensive inspection of structural damage.
(2) Adopt the resin grouting method for leak-proof reinforcement.
(3) Choose the appropriate grouting material according to the structural characteristics.
(4) Surfaces cleaning and coating of the works area.
(5) Restoration of the site and application for acceptance.
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3. Works Design
The underground passage is a connecting passage between the second underground floors of individual buildings.In order to match structural characteristics, a long-term leak-proof design was proposed as follows:
(1) Remove the original water deflector, remove mold and peeling paint, and confirm the locations of water leakage and structural damage.
(2) The 45-degree oblique hole infusion method to be used with two-stage resin grouting to prevent leakage and reinforce. Use water-swelling polyurethane resin (90” ±10”) for the first stage of temporary water seepage plugging. Fill the original hole with non-expanding polyurethane resin (35″±5″) to bond and seal the cracks to achieve long-term leak-proofing and reinforcement effects.
(3) Because each section of the underpass is an independent structure, in order to prevent the rigid filling from breaking due to differential subsidence and earthquakes, elastic non-expanding polyurethane resin is specially selected as the long-term leak-proof sealing material.
(4) According to the damaged condition of the concrete around the leakage point, use cement mortar or resin mortar to repair the surface.
(5) After the original water guide plate is thoroughly cleaned and repaired, and the water guide design is strengthened, it will be installed back into its original position to provide a second leak-proof function while maintaining the overall coordination of the original design.
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4. Works Process
Because our company had repair experience with many similar underground passages, shared pipelines and underground box culverts, the works process went smoothly. However, during the restoration works, there was a typhoon and very heavy rain, and the underpass was required to maintain normal traffic functions.
The grouting technology and on-site immediate maintenance and cleaning work needed to be fully controlled during the works, and no unexpected phenomena were encountered.
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5. Results
Due to the good construction quality of the original structure of the underground passageway, except for the construction joints where leakage occurred, no shear cracks or serious concrete deterioration were found during the works process.
The company used water-swelling resin and elastic non-swelling resin in combination according to the standard operating procedure from Germany, to effectively seal and bond the construction gaps and maintain sufficient flexural properties between the blocks to obtain a good repair effect.
After works completion, report was made to the relevant unit to send personnel for acceptance, and confirmation was made that the leakage had been completely eliminated, with successful completion of the long-term underground seepage rectification work.
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Long-Term Seepage Treatment In Underground Walkway
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