Geomembrane

HDPE membrane, fully known as "High-Density Polyethylene Membrane," offers excellent resistance to environmental stress cracking, low temperatures, aging, and corrosion. It has a wide operating temperature range (-60°C to +60°C) and a long service life (50 years). It is used in anti-seepage projects such as municipal solid waste landfills, solid waste landfill anti-seepage, sewage treatment plant anti-seepage, artificial lake anti-seepage, and tailings treatment.

HDPE Geomembrane Laying Design

1. Before laying the HDPE membrane, there should be corresponding qualified acceptance documents for the civil engineering work.

2. Before cutting the HDPE membrane, accurately measure its relevant dimensions and cut according to the actual size. It is generally not advisable to cut based on the illustrated dimensions. Each piece should be numbered and recorded in detail on a form.

3. When laying the HDPE membrane, strive to minimize the number of welds. Under the premise of ensuring quality, try to save raw materials. This also makes it easier to ensure quality.

4. The overlap width of seams between membranes should generally be no less than 10 cm. Welds are usually arranged parallel to the major slope direction, i.e., along the slope direction.

5. At corners and irregular sections, the seam length should be minimized as much as possible. Unless otherwise specified, avoid placing welds within 1.5 meters of the top slope or stress concentration areas on slopes steeper than 1:6.

6. During the laying of the HDPE membrane, avoid creating artificial wrinkles. When temperatures are low, the membrane should be stretched taut and laid flat.

7. After the HDPE membrane is laid

Laying Process

1. Base Surface Cleaning

The base surface should be cleaned according to design requirements, which is critical for anti-seepage. Remove sharp stones, tree roots, and other debris. The base surface should not have local凹凸 irregularities. The cleaned base surface should be compacted with a rammer or compactor to make it dense and level. During composite laying, ensure the membrane is pressed flat and snug against both the adjacent membrane and the base surface, but avoid over-tightening. Leave a slight looseness, but ensure no air bubbles are trapped under the membrane. Since the geomembrane is thin and lightweight, it can easily be blown by wind before the protective layer is laid. Therefore, the area laid at one time should not be too large. Lay the membrane while simultaneously covering it with protective soil material.

2. Protective Layer

The protective soil layer, 10 cm thick adjacent to the geomembrane, must be sieved. Particles larger than 6 mm are not allowed, as they can puncture the geomembrane. Compact the protective soil layer thoroughly to ensure a dry density of at least 1.5, and take samples for inspection regularly. When backfilling the protective layer and laying block stone revetment, handle materials gently to avoid damaging the geomembrane. Under the block stone revetment, lay a 100 mm thick layer of crushed stone or gravel as a cushion to prevent erosion of the soil protective layer due to water level changes, waves, and other factors. Dry-laid block stones should be placed manually with guidance lines, ensuring stones are tightly interlocked. The individual weight of surface stones should exceed 48 kg, and all gaps should be filled with smaller stones.

3. Perimeter Treatment

The purpose of perimeter joint treatment is to tightly connect the composite geomembrane with the surrounding soil, seal potential seepage entry points, and cut off lateral seepage paths to prevent water from entering beneath the geomembrane and forming blisters that could burst the membrane when the reservoir water level drops. Therefore, a cutoff trench must be excavated around the perimeter, and the geomembrane should be buried within the trench.