HDPE geomembrane, as a high-performance impermeable material, is widely used in numerous engineering fields. Its laying quality directly affects the impermeability and service life of the project, and reducing wrinkles and improving overall flatness are key points in the laying process.
Before laying, the treatment of the base layer is crucial. The base layer must be firm, flat, and free of sharp objects, debris, and obvious unevenness. If the base layer has unevenness, it should be repaired. For soil base layers, compaction is required to ensure that the compaction degree meets the design requirements, providing a stable foundation for the geomembrane laying. At the same time, the slope of the base layer should meet drainage requirements to avoid long-term soaking and erosion of the geomembrane by accumulated water, affecting its flatness and impermeability.
Determining a reasonable laying direction and sequence is an important step in reducing wrinkles. Generally, it should be laid along the slope, extending from the lower point to the higher point. This reduces the number of joints and lowers the possibility of wrinkles. When laying HDPE geomembrane on slopes, it is advisable to proceed from top to bottom, with the membrane unfolding direction generally parallel to the maximum slope line. This ensures better adhesion of the geomembrane to the base layer and avoids wrinkles caused by improper laying direction. For large-area laying, it can be done in sections, unfolding from the center outwards to ensure an orderly process.
During the unfolding of the HDPE geomembrane, extra care should be taken to avoid dragging and damage to the membrane. Unfold slowly, keeping the membrane surface flat and wrinkle-free. Simultaneously, adjust the position of the geomembrane promptly to ensure tight adhesion to the base layer. For corners or complex areas, appropriate trimming can be made according to the actual situation to ensure complete coverage and reduce wrinkles caused by localized misalignment. During unfolding, sandbags or other heavy objects can be used to temporarily fix the geomembrane to prevent displacement. The spacing between fixing points should be determined based on the site's wind force and slope, generally not exceeding five meters.
The overlapping treatment between adjacent geomembranes also affects the overall flatness. The overlap width should meet design requirements, generally not less than a certain value, to ensure seepage prevention effectiveness. When overlapping, ensure the two geomembrane sheets are aligned and aligned to avoid misalignment. Longitudinal joints should not be placed on the same horizontal line; they should be staggered by a certain distance to distribute stress and reduce wrinkles. Simultaneously, longitudinal joints should be located at a certain distance from the dam toe and bends, on a flat surface to ensure joint stability.
During installation, the impact of temperature changes on the HDPE geomembrane must also be considered. Due to the thermal expansion and contraction properties of geomembranes, experience suggests that the geomembrane should be stretched taut in cold weather and appropriately loosened in hot weather, but excessive looseness should be avoided to prevent wrinkles and water accumulation. It is also advisable to choose to install in the morning or evening to allow for expansion and contraction, adapting to temperature changes and reducing wrinkles caused by thermal expansion and contraction.
Using specialized tools to assist in installation can also effectively improve flatness. For example, using a rolling mill during installation can help the geomembrane adhere better to the base layer, expel air, and reduce wrinkles. When rolling, apply force evenly to ensure that all parts of the geomembrane are in close contact with the base layer. Furthermore, when cutting the geomembrane, use a professional cutter to ensure clean edges and avoid wrinkles during installation due to irregular cuts.
