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About UsZHONGTAI HENGBANG Engineering Technology Co., Ltd. is located in the Academician Entrepreneurship Base of Tai'an National High-Tech Industrial Development Zone, Shandong Province. The company is a comprehensive service provider specializing in engineering consulting and design, materials R&D and manufacturing, as well as operations and maintenance. With strong technical expertise and robust R&D capabilities, its products are primarily applied in critical areas such as water conservancy infrastructure projects, transportation infrastructure initiatives, and environmental protection solutions for isolating and preventing leakage from urban waste and highly hazardous industrial solid waste.
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ProductsZHONGTAI HENGBANG Engineering Technology Co., Ltd. boasts production lines sourced from countries including Germany, Italy, Denmark, Belgium, and Switzerland, adhering to rigorous quality management systems and testing standards. We are equipped with advanced testing equipment capable of evaluating tensile strength, creep resistance, UV protection, water permeability, flame retardancy, antistatic properties, chemical corrosion resistance, and oxidation performance.
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Application CasesThe product is primarily used in hydraulic infrastructure projects, transportation infrastructure projects, and environmental protection applications—including the isolation and impermeability of municipal waste and highly hazardous industrial solid waste.
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What is the minimum overlap width required for laying EVA waterproof sheets in Sichuan?
Release date:
2020-09-18
In highway engineering tunnel construction, what is the minimum overlap width required for laying and joining Sichuan EVA waterproof membranes?
(1) Sichuan Leshan EVA Waterproof Board The lining should be laid ahead of the secondary lining construction by 1 to 2 lining sections. After alignment, it must maintain a safe distance from the excavation face—specifically, beyond the blast safety zone. Lining installation must be carried out using dedicated scaffolding units, with precise layout and marking performed beforehand to define trial placements. This ensures the accurate determination of the dimensions for each EVA waterproofing sheet in the Sichuan Leshan section, while minimizing the number of joints as much as possible. Sichuan Leshan EVA Waterproof Board Wood screws or nail-free installation should be used, with adequate overhangs left in place, and the surface must be smoothly rounded.
(2) Base Surface Treatment
Sichuan Leshan EVA Waterproof Board Before construction begins, the centerline position and elevation should be rechecked, and section dimensions verified to ensure that the lining thickness and clear space after lining installation meet both code requirements and design specifications.
Sichuan Leshan EVA Waterproof Board The main contents of the substrate inspection and treatment to be carried out before laying include:
1. The initial support surface must be smooth, free from hollow sounds, cracks, or crumbling areas. Any exposed rigid elements on the initial support surface—such as anchor bolt heads or rebar mesh ends—should be completely removed by electric or oxy-welding, followed by smoothing with a 1:2 cement mortar to prevent puncturing the drainage board.
For the two areas with local irregularities, chipping and shotcrete application should be performed to ensure a smooth surface. Additionally, for sections with significant over-excavation, mesh installation followed by shotcrete anchoring is required.
Three key areas of surface water should be pre-equipped with blind drains for drainage. For extensive seepage above the tunnel roof, a solution could be implemented using Sichuan Leshan EVA Waterproof Board Coordinate with the blind pipes to channel and drain water into the temporary drainage ditches.
(1) Sichuan Leshan EVA Waterproof Board The lining should be laid 1 to 2 lining sections ahead of the secondary lining construction, maintaining a safe distance from the excavation face—specifically, beyond the blast safety zone. Lining installation must be carried out using a dedicated gantry system, with precise layout performed beforehand. After marking the standard lines, a trial placement should be conducted to ensure proper alignment and positioning. Sichuan Leshan EVA Waterproof Board Each ring should be sized appropriately, and joints should be minimized as much as possible. Sichuan Leshan EVA Waterproof Board Wood screws or nail-free installation should be used, with adequate overhangs left in place, and the surface must be smoothly rounded.
(2) Base Surface Treatment
Sichuan Leshan EVA Waterproof Board Before construction begins, the centerline position and elevation should be rechecked, and section dimensions verified to ensure that the lining thickness and clear space after lining installation meet both code requirements and design specifications.
Sichuan Leshan EVA Waterproof Board The main contents of the substrate inspection and treatment to be carried out before laying include:
1. The initial support surface must be smooth, free from hollow sounds, cracks, or crumbling areas. Any exposed rigid elements on the initial support surface—such as anchor bolt heads or rebar mesh ends—should be completely removed by electric or oxy-welding, followed by smoothing with a 1:2 cement mortar to prevent puncturing the drainage board.
For the two areas with local irregularities, chipping and shotcrete application should be performed to ensure a smooth surface. Additionally, for sections with significant over-excavation, mesh installation followed by shotcrete anchoring is required.
Surface water in the three base areas should be diverted in advance using blind drains. For extensive seepage above the tunnel roof, the Sichuan Leshan EVA waterproof membrane can be used in conjunction with blind drains to channel the water efficiently into temporary drainage ditches.
4. The initial support surface must meet the following flatness requirements: at the arch spring, D/L ≤ 1/6; and at the arch crown, D/L ≤ 1/8. (Here, D refers to the distance between two adjacent convex points on the initial support surface, while L represents the depth of the concavity between these two convex areas.)
(3) Sichuan Leshan EVA Waterproof Board Front-mounted spot welding
Based on the estimated area to be covered outside the tunnel, cut 2 to 3 narrower-width rolls of Sichuan Leshan EVA waterproof sheets. Then, lay these sheets flat on the ground and weld them together into larger, continuous panels that are easier to transport and install on-site. This approach minimizes the number of weld seams required during in-tunnel operations, ultimately enhancing the quality of the Han joints. Sichuan Leshan EVA Waterproof Board Joints should be minimized.
Sichuan Leshan EVA Waterproof Board Splicing is performed using a heat-sealing machine with double weld seams, requiring an overlap width of at least 100 mm. It's crucial to carefully control the temperature and speed of the heat-sealing machine to ensure high-quality welds. The weld seams must be tightly sealed, with each individual seam having an effective overlap width of no less than 12.5 mm. Before splicing, the surfaces of the joining plates should be thoroughly cleaned. Additionally, the optimal heat-sealing temperature and speed must be determined through testing, based on the material being used. During the splicing process, avoid issues such as incomplete welding, false welding, overheating that causes burning, or even weld penetration.
The longitudinal length of the waterproof layer laid in a single pass along the Sui Road should ideally exceed the current secondary lining construction length by about 1.0 meter, ensuring seamless connection with the next cycle's waterproofing layer. At the same time, this approach helps offset the waterproof layer joints by approximately 1.0 meter relative to the lining concrete joints, which is beneficial for preventing water leakage at concrete construction joints.
(4) Laying and Hanging Sichuan Leshan EVA Waterproof Board
To ensure Sichuan Leshan EVA Waterproof Board The quality of the paving should first be assessed through a trial layout and positioning.
Control of fixed-point spacing: Use a measuring tool for inspection. The spacing between fixed points should be 0.5 to 0.7 meters at the arch section and 1.0 to 1.2 meters along the sidewalls. At concave or convex areas, adjust by adding extra fixing points as needed, ensuring even distribution.
Song Chi-lü: Sichuan Leshan EVA Waterproof Board The spacing of the suspension rings must be determined based on their required longitudinal and transverse deflection. Typically, the empirical value for circumferential deflection is set at 10 percent, while the longitudinal deflection is usually taken as 6 percent. Adjustments should also be made according to the initial support surface’s smoothness, ensuring that the formwork plate closely adheres to the sprayed concrete surface during concrete placement.
(5) Follow-up paving
Sichuan Leshan EVA Waterproof Board "Seamless continuation" refers to two large-format images connected end-to-end. Sichuan Leshan EVA Waterproof Board The connection between the sections should first be made using a hot-welding machine to create a circular weld along the seam. During construction, ensure that the surfaces of the two panels to be welded are thoroughly cleaned and properly aligned, maintaining the required overlap length. Carefully control both the welding temperature and the machine’s travel speed, ensuring consistent, smooth contact between the welder and the seam throughout the process. After welding is complete, conduct a thorough inspection—particularly focusing on any areas where welding may have been missed—and use an electric soldering iron to carefully re-weld those spots. For T-joints, which can be particularly challenging to weld fully or prone to insufficient strength due to incomplete fusion, reinforce the joint by applying additional weld adhesive in the form of patches.
(6) Weld Seam Inspection
Sichuan Leshan EVA Waterproof Board The joints must be free of bubbles, wrinkles, and gaps; they should be securely fastened, and the weld strength must meet or exceed that of the base material, as verified through sampling tests.
Sichuan Leshan EVA Waterproof Board The quality of the lap seam welds is inspected using the "inflation method": inflate until the pressure reaches 0.25 MPa, then stop inflating and maintain the pressure for 15 minutes. If the pressure drop remains within 10 percent during this time, the weld quality is deemed acceptable.
(7) Finished Product Protection
When the lining closely follows the excavation, the front edge of the lining Sichuan Leshan EVA Waterproof Board Protective measures must be implemented to prevent bao from breaking and causing flying rocks to damage the EVA waterproof panels in Leshan, Sichuan. Excavation and installation are also required. Sichuan Leshan EVA Waterproof Board When the lining and three other components are worked on simultaneously, the section where the waterproof layer is laid should be no less than the minimum safety distance from the excavation face—and ensure proper implementation during construction. Sichuan Leshan EVA Waterproof Board Protecting the EVA waterproof membrane in the paving and shaping section of Leshan, Sichuan: When tying reinforcing bars, equip the bar ends with protective sleeves; during han jointing of reinforcement bars, ensure proper safety measures are in place at the han-jointing work area. Sichuan Leshan EVA Waterproof Board Install protective panels between the areas; after the waterproof layer is installed, drilling or making holes in it is strictly prohibited. When vibrating the concrete, the vibrator must not come into contact with anything. Sichuan Leshan EVA Waterproof Board 。
Before pouring the secondary lining concrete, the quality of the waterproofing layer installation and the Han joint quality should be inspected. If any damage is found, it must be addressed immediately.
Sichuan Leshan EVA Waterproof Board When repairs are needed, the patch used to mend the waterproof layer must not be too small. The patch should be cut into rounded corners, avoiding sharp angles like rectangles or triangles. After repairing the waterproof layer, a vacuum testing method is typically employed for inspection.
(8) Lay down a waterproof layer with full protection and documentation.
The section where the waterproof layer is laid should be no less than the minimum safety distance from the excavation face. During secondary lining installation, the waterproof layer must not be damaged.
The waterproof layer should be treated as a concealed work, and its quality must be inspected before the secondary lining is applied. Be sure to carefully complete the quality inspection records.
ZHONGTAI HENGBANG Engineering Technology Co., Ltd. is a comprehensive service provider integrating engineering consulting and design, material R&D and manufacturing, as well as operations and maintenance. With robust technical expertise and strong R&D capabilities, our products are prominently applied in environmental protection fields such as hydraulic infrastructure projects, transportation infrastructure initiatives, and the isolation and anti-seepage solutions for urban waste and hazardous industrial solid waste management. The company boasts advanced production lines sourced from Germany, Italy, Denmark, Belgium, Switzerland, and other countries, adhering to stringent quality management systems and testing standards. We are equipped with cutting-edge testing equipment capable of evaluating critical properties—including tensile strength, creep resistance, UV resistance, permeability, flame retardancy, antistatic performance, chemical corrosion resistance, and oxidation stability—ensuring superior product quality. Furthermore, ZHONGTAI HENGBANG has successfully obtained certifications such as CRCC, ISO 9001, ISO 14001, OHSAS 18000, and MA certificates, along with inspection reports from China’s Ministry of Railways and Ministry of Water Resources, the EU CE certification, and approvals from specialized laboratories in Russia, Australia, and the United States. We are dedicated to delivering top-quality geosynthetic materials and comprehensive services tailored to a wide range of projects, including reinforced soil retaining walls, soft ground stabilization, land reclamation and embankment construction/maintenance, hydraulic engineering, slope remediation and landscaping, road construction, and mining projects.
Consultation Phone: 13953856388
Contact: Mr. Zhang
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