Geomembrane is a material made of high molecular polymer with very little water permeability. The permeability coefficient is generally 10-11 ~ 10-12cm/s. Such a low water permeability is an ideal anti-seepage material. Geomembrane products such as composite geomembrane and HDPE geomembrane can be used in the following aspects in water conservancy and anti-seepage projects:

(1) Anti-seepage inclined walls or vertical anti-seepage core walls of dams.

(2) Horizontal anti-seepage paving and vertical anti-seepage walls of dams on permeable foundations.

(3) Anti-seepage bodies of concrete dams, masonry dams and roller compacted concrete dams.

(4) The lining of the channel is anti-seepage.

(5) The culvert and gate are horizontally covered to prevent seepage.

(6) Seepage prevention of buried pipes in tunnels and dams.

(7) Anti-seepage of construction cofferdam.

As a good anti-seepage material, geomembrane has been widely used in earth-rock dams, especially in embankment anti-seepage projects.

The composite geomembrane is used as the main anti-seepage body in the lining of the yellow channel in the middle line of the South-to-North Water Diversion Project, and the cement-soil layer plays the role of secondary anti-seepage. The geomembrane is 900g/m2, two cloths and one membrane, the middle film thickness is 0.5mm, the density is greater than 900kg/m3, the permeability coefficient is less than 10-13, and it is impervious to water for 48 hours under 1.1MPa water pressure. During the construction of the channel lining, the width of the geomembrane is 4.5m, and the TH-1 heat welding machine is used to weld a double-pass weld. The splicing of the two sheets is 10cm, and the lap width is 10cm. The upstream width of the weld is pressed down by the downstream width. Flow direction. For the inspection of the quality of the welds, insert a gas needle into a cavity of about 10mm between the two welds, inflate to 0.15~0.20MPa, wait for 1min, and observe the vacuum gauge. If the air pressure does not drop, it means that there is no leakage. Qualified, otherwise it should be repaired in time. Concrete lining shall be carried out in time when the geomembrane is laid. During the operation period, the water flow condition is good, and the anti-seepage performance of the geomembrane is remarkable.

Geomembrane is used in civil anti-seepage engineering, which has obvious advantages such as simple structure, convenient construction, good anti-seepage effect, saving project cost and speeding up construction period. As long as it is properly designed and carefully constructed, it can ensure safe and reliable operation, which is suitable for vigorous promotion in my country.