Application of Geomembrane in Hydraulic Engineering
Geomembrane is a new type of engineering material. It has the advantages of light weight, high strength, high elongation, good anti-seepage performance, strong adaptability to deformation, simple construction, easy to ensure quality, and low cost. Therefore, it is widely used in on water conservancy projects. Suizhong is located in the West Liaoning Corridor, and there is a shortage of water resources. The average annual precipitation meter is 620 mm. It seeks to improve the utilization of limited water conservancy resources and reduce the leakage loss of water delivery and water storage projects. It is one of the problems of using Shigong membrane to solve the problem of anti-seepage. Good policy. The traditional practice of anti-seepage in the construction of water conservancy projects is enough to use plastic asphalt to deal with seepage. In the 1990s, with the development of geosynthetic material technology, Shigong membrane was gradually researched and developed and widely used in various anti-seepage projects. At present, our county has widely applied Shigong membrane anti-seepage in projects such as channels, reservoirs, river courses, storage, flood control and flood crossing, and has received good economic benefits and technical effects.
1. Relevant properties of geomembrane
The selection of geomembrane should consider its tensile strength, secondary length and waterproof performance. In addition, there are burst strength and puncture resistance, tear strength, as well as the friction properties of the geomembrane and the membrane and the permeability of the contact interface. Geomembrane is a kind of flexible material, if there is no external disturbance, it is not exposed to the atmosphere, especially if it is used under the protection of rocks, the service life will be longer. Through experimental analysis, the relevant properties of the geomembrane have been obtained.
Application of geomembrane in hydraulic engineering
2.1 Channel anti-seepage
Wangshi Irrigation District, Suizhong County, Liaoning Province was established in the 1970s. The designed irrigation area of paddy fields is 35,000 mu. The soil quality in this area is mostly sandy loam. The irrigation area has serious canal infiltration, and the water utilization coefficient of the canal system is only 0.5. After the seepage, the water utilization coefficient of the canal system is increased to 0.96. The designed water diversion flow of the channel is 9.2m³/S, the normal water level is 0.85m, the geomembrane is fully buried, and the slope ratio of the embankment is 1:1.35, and the setting on it is not less than A 0.35M soil material protection layer is used to enhance the anti-sliding and stability of the geomembrane, and a saw-tooth wall is added at half the depth of the water. Wangshi Irrigation Area uses coated woven cloth to prevent seepage. The canal section is more than 20 kilometers long. After the project is completed, it has received a good effect of preventing seepage and saving water.
2.2 Reservoir seepage prevention
In Suizhong County, a number of earth dams have been built by using geomembrane instead of the clay wall anti-seepage layer, which has achieved obvious economic benefits. The specific construction method is to use geomembrane instead of clay wall, and use a 30cm thick sand protection layer on the top and bottom of the geomembrane. The connection between the geomembrane and the surrounding buildings must be tight and watertight, and the construction should be carried out simultaneously with the dam body. , In the construction of earth dams, the latter not only reduces the cost of the project, but also has a more ideal anti-seepage effect.
2.3 Underground interception
The Jiujiang River in Suizhong County has an area of 180 square meters and a river length of 33 kilometers. It is a seasonal river in the mountainous area. The riverbed of Jiujiang River is sand and pebbles of different sizes, buried underground at a depth of 4-5 meters, and the river section is dry during non-flood season. For comprehensive treatment, a flap-type barrage project was built. The dam was 80m long. Polypropylene coated woven cloth was used for underground interception. When the barrage was built, when the trench was excavated to the impermeable layer, the coated cloth was laid in a U shape. Concrete water stopper is poured in the groove, and then spread from bottom to top along the dam slope to the top of the dam, leaving an overlapping fold part every 2.0m to adapt to the settlement and deformation of the backfill. After the completion of the project, the “Water Great Wall” appeared at the Jiumen Great Wall site where the dam was built to return the water, adding a bright spot to the tourism of the Jiumen Great Wall. At the same time, the water storage of the barrage has played a comprehensive role in flood control and surrounding farmland irrigation.
2.4 Flood control project
The geomembrane soil bag is pressed and cut, and the river bottom protection soft body is generally used for riprap, concrete and other materials, but for plain areas lacking sand and gravel materials, it is safe to use geomembrane to make soil bags to fill soil as river bottom ballast economic effect. The method is convenient to obtain materials locally, has low construction cost, is easy to construct and guarantees the quality of the project, and at the same time, the geomembrane does not have problems such as aging under water. The soil pillows are made of coated woven cloth, pillow bags and soil pillows.
2.5 Cofferdam Project
The construction of the project in the river channel is affected by water during construction, so it is necessary to build a construction cofferdam, and use a 0.2mm thick plastic film as the waterproof layer on the upstream surface. The geomembrane is fixed on the sheet piles driven into the soil, and the backfill is built to resist the water pressure. The temporary cofferdam has a simple structure, convenient construction, easy quality assurance, and ideal waterproof effect.
Geomembrane in Suizhong County has been used for several years. It is recognized by engineers and technicians with the continuous deepening of the application research of geosynthetic materials in hydraulic engineering, superior hydraulic properties and significant economic benefits, and gradually developed. The application range is wider. At present, there are still many dangerous reservoirs in Suizhong County with seepage and channel anti-seepage, and projects such as the repair of water damage projects have yet to be solved. The use of geomembrane for anti-seepage treatment is a simple, feasible, economical and reasonable solution.