The reason why geomembrane can have good waterproof performance is mainly due to its material characteristics and structural design.

Material properties: Geomembranes are typically made from synthetic materials such as high-density polyethylene (HDPE), polypropylene (PP), or polyvinyl chloride (PVC). These materials have good waterproof properties and can effectively resist water penetration. They have high density and low permeability, and under normal use and appropriate thickness, can effectively prevent moisture from penetrating into the area beneath the geomembrane.

Barrier Effect: The primary function of a geomembrane is to form a physical barrier that prevents moisture and other liquids from penetrating into the underlying soil or structure. The geomembrane layer is usually continuous without pores and cracks, thus preventing the passage of moisture.

Seam treatment: Geomembranes are usually laid in rolls, and the treatment of seams is very important. Proper handling of joints can ensure the continuity of the geomembrane and prevent moisture from penetrating through the joints. Common seam treatment methods include hot melt welding, chemical welding, mechanical fixing, etc.

Chemical corrosion resistance: Geomembrane materials usually have certain chemical corrosion resistance and can resist the erosion of some chemicals in groundwater. This allows the geomembrane to maintain its waterproofing properties in harsh underground environments.

To sum up, the waterproofing of geomembrane is mainly due to the anti-seepage performance of its material and the blocking effect of its structural design. However, in practical applications, it is still necessary to select appropriate geomembrane materials based on specific engineering needs, environmental conditions and the quality of the geomembrane, and to correctly construct and maintain them to ensure their long-lasting and reliable waterproof performance.