Geomembrane was initially a high molecular polymer obtained from petroleum asphalt. This material encompassed the essence of technology at that time. With the development of the petroleum industry, many new materials extracted from petroleum have also found new uses, giving petroleum more uses. Throughout the process, various indicators of geomembrane have gradually developed, laying a solid foundation for the development of geomembrane. The service life of new geomembranes has been improved, and the tensile capacity has also been improved, all of which provide convenience for practical engineering. Between 1930 and 1940, humans first used polyvinyl chloride membranes in swimming pool anti-seepage. This stage was basically the beginning of people's widespread application of geosynthetic materials. In 1953, in channel anti-seepage, people borrowed the successful experience of Japanese swimming pool anti-seepage and again used polyvinyl chloride membranes for anti-seepage treatment. After the 1850s, the use of plastic film materials for anti-seepage in projects such as channels, reservoirs and earth-rock dams has become a common phenomenon. Generally speaking, geomembranes are roughly divided into two categories: asphalt geomembranes and polymer geomembranes. To ensure that geomembranes do not cause engineering accidents in engineering applications, they are usually treated with reinforcement and non-reinforcement or combination. There are many raw materials for manufacturing geomembranes, which can be divided into the following categories
(1) Chemical mixing: mixing two or more polymers, such as chlorosulfonated polyethylene (CSPE).
(2) Producing asphalt and epoxy resin, such as modified asphalt and polysulfone resin, etc.
Composite geomembrane is a new product that combines traditional geomembrane with geotextile. The manufacturing method of composite geomembrane is usually to press single-layer cloth and single-layer membrane together, or to composite single-layer cloth and single-layer membrane to form two layers. The form is one cloth one membrane. Similarly, if two layers of cloth and single-layer membrane are composited to form three layers, then this form is two cloth one membrane. Composite geomembrane has excellent anti-seepage, deformation adaptability and aging resistance. Therefore, in practical engineering applications, the anti-seepage ability, durability and anti-aging ability of composite geomembrane are more valued. Composite geomembrane is made by combining traditional geomembrane materials with geotextiles. Its engineering characteristics have the following advantages compared with traditional single materials:
(1) The tensile and puncture resistance of composite geomembrane is much stronger than that of single-layer geomembrane.
(2) Under the same stress conditions, the extension length of composite geomembrane is smaller than that of single material.
(3) Composite geomembrane is more isotropic, which can prevent changes in one direction when the physical environment changes and temperature changes.
(4) Composite geomembrane can improve the friction resistance between geomembrane and soil, thereby improving its stability.
Since composite geomembrane is composed of two types of materials: geomembrane and geotextile, its mechanical properties have both the characteristics of membrane and cloth. Therefore, the tensile strength and puncture resistance of composite geomembrane are significantly improved compared with single-layer geomembrane. When composite geomembrane receives tensile stress, or when geotextile completely ruptures, both composite geomembrane and geotextile have consistent stress-strain curves; after geotextile is damaged, due to the good extensibility of the concrete layer, the geomembrane and concrete layer at this time have consistent stress-strain curves. The level of roof leakage of composite geomembrane mainly depends on the ductility of the concrete layer, and is not limited by the strength of the concrete layer.
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