Technical Requirements and Welding Specifications for HDPE Geomembrane Construction

HDPE (High-Density Polyethylene) geomembrane is widely used in engineering fields such as landfills, water storage tanks, sewage treatment plants, and roadbeds due to its excellent anti-seepage, anti-corrosion, and anti-aging properties. To ensure the anti-seepage effect of the project and meet the construction quality standards, the following details the technical requirements for construction and core welding specifications, presented in both Chinese and English for the reference of overseas engineering practitioners.

I. Technical Requirements for HDPE Geomembrane Construction

1. Construction Process Sequence: Strictly carry out the process in the order of "Geomembrane Paving → Seam Alignment → Welding → On-site Inspection → Defect Repair → Secondary Inspection → Backfilling". It is strictly prohibited to change the construction sequence without authorization.

2. Paving Specifications: Avoid artificial wrinkles during paving to ensure the membrane surface is flat. Combine the local temperature variation range and the performance of HDPE geomembrane to reserve sufficient temperature expansion and contraction deformation; at the same time, reserve a reasonable expansion and contraction margin according to the on-site terrain and actual paving conditions to adapt to foundation settlement or deformation needs.

3. Membrane Surface Protection: After the geomembrane is paved, minimize personnel walking and tool handling on the membrane surface. All objects that may scratch or damage the geomembrane shall not be placed on the membrane surface, and operators shall not carry such objects when walking on the membrane surface to prevent accidental damage to the membrane.

4. On-site Management: All personnel at the construction site are strictly prohibited from smoking, and are prohibited from walking on the membrane surface wearing shoes with iron nails or high-heeled hard-soled shoes; it is prohibited to engage in any operation activities that may damage the integrity of the anti-seepage membrane, so as to avoid the risk of membrane damage from the source.

5. Windproof Fixing: Before the geomembrane is paved and the protective layer is not covered, place one sandbag of 20-40 kg every 2-5 meters at the edge and corner of the membrane to effectively fix the membrane and prevent it from being blown up and displaced, which will affect the subsequent construction.

6. Anchoring Construction: Anchoring operations must be carried out in strict accordance with the design plan. If the project terrain is complex and the construction unit needs to change the anchoring method, it must obtain the written consent of the design unit and the supervision unit in advance before implementing the modified construction.

II. Welding Specifications for HDPE Geomembrane

1. Weld Pre-treatment: Before welding, thoroughly clean the overlapping surface of the weld to ensure there is no dirt, sand, water (including dew) and other impurities on the surface, so as to avoid impurities affecting the welding quality and causing leakage hazards at the weld.

2. Test Welding Requirement: Before the start of welding operations every day (including the start of work in the morning and resumption of work after lunch break), test welding must be carried out at the construction site. Only after the test weld is inspected and qualified can formal welding operations be carried out. It is forbidden to construct directly without test welding.

3. Welding Specifications: Double-track hot-melt welding machine is preferred for HDPE geomembrane welding. Extrusion welding or hot air gun is only used for weld repair, local coverage, or corners and complex parts that cannot be reached by the hot-melt welding machine. After welding, the HDPE membrane at the weld shall be fused into a whole, without defects such as virtual welding, missing welding, or excessive welding; the two overlapping layers of geomembrane shall be flat and smooth, without wrinkles or offset, to ensure tight welding.