Geomembranes: Innovative Applications and Prospects for Sustainable Development

1.1 Research background
As an important engineering material, geomembrane plays a key role in many fields such as water conservancy, environmental protection, transportation and construction. In water conservancy engineering, it can be used for seepage control of reservoirs, dams, canals, etc. In the field of environmental protection, it is widely used in landfills, sewage treatment plants, etc., to prevent pollutants from leaking. Its importance is self-evident, not only can effectively protect water resources, prevent soil pollution, but also improve the stability and durability of the project.
Currently, with the increasing awareness of environmental protection and the continuous promotion of infrastructure construction, the market demand for geomembranes is growing. The global geomembrane market is expanding and is expected to reach nearly 100 billion USD by 2025. Meanwhile, technological innovation is also driving the development of the geomembrane industry, with new materials and intelligent applications emerging. However, the geomembrane industry is still facing some challenges, such as uneven product quality and fierce competition in the market. Therefore, it is of great practical significance to conduct in-depth research on geomembranes.
1.2 Research purpose
This study aims to deeply analyze the performance, application and development trend of geomembranes, and provide scientific guidance for engineering construction.
Geomembrane has many excellent properties. First of all, its seepage control performance is excellent, which can effectively prevent liquid infiltration and is widely used in environmental protection, water conservancy and other fields. For example, in landfills, geomembranes can prevent leachate leakage and protect the soil and groundwater environment; in reservoirs, aqueducts and other water conservancy projects, they can reduce the seepage loss of water resources and improve the efficiency of water resources utilization. Secondly, geomembrane has good chemical stability, resistant to acid, alkali, oil and other corrosion, adapting to a variety of complex engineering environments. In addition, it also has high anti-aging performance, and can still maintain stable performance under long-time outdoor exposure environment.
In terms of application, geomembrane covers a wide range of fields. In the field of sanitation, such as landfills, sewage treatment plants, etc., play an important role in waste isolation and seepage control; in the field of water conservancy, it can be used for embankment, dams before the horizontal seepage control paving, leakage plugging, reinforcing, etc.; in the municipal engineering, the subway, building basement works, tunnel seepage control lining can not be separated from the geomembrane; in the garden, petrochemical, mining, transportation facilities, agriculture, aquaculture and other fields are also widely used.
From the development trend, the geomembrane will pay more attention to the future of green environmental protection, the use of environmentally friendly materials and production processes to reduce the impact on the environment. At the same time, high-performance geomembranes will continue to emerge to meet the needs of high-end engineering, improve seepage control performance and weather resistance. With the development of Internet of Things technology, intelligent geomembranes will also become an important direction for future development, improving the safety and reliability of the project by monitoring the use of geomembranes in real time.
To summarize, in-depth study of the performance, application and development trend of geomembranes is of great significance for promoting the sustainable development of engineering construction.

II. Types and characteristics of geomembranes
2.1 Classification of geomembranes
2.1.1 Classification by material
HDPE (high density polyethylene) geomembrane has excellent mechanical strength and chemical corrosion resistance, high seepage coefficient, up to 1 × 10-17 cm / s, the use of environmental temperature of high temperature 110 ℃, low temperature -70 ℃, can resist strong acid, alkali, oil corrosion, is a good anticorrosive material, has a strong tensile strength and elongation at break, to adapt to the geological strain of uneven settlement is strong, the use of the ground is good. It has a long service life of more than 50 years and is widely used in landfills, sewage treatment plants and other places.
LDPE (low-density polyethylene) geomembrane relative to HDPE geomembrane has better tensile strength and flexibility, mainly polyethylene, ethylene, vinyl polymer polymerization and other materials, in the absorption of the previous geomembrane on the basis of flexibility, increased the good extensibility, adapt to deformation and other capabilities, greatly increasing its waterproof seepage control capacity. It is corrosion-resistant, low-temperature resistant, lightweight, tear-proof ability, etc., low cost, high quality and low price, is widely used in construction, water conservancy, chemical industry, transportation, subway, garbage disposal site and other projects.
LLDPE (Linear Low Density Polyethylene) geomembrane combines some of the characteristics of HDPE and LDPE, has good flexibility and seepage control, commonly used in reservoirs, artificial lakes, irrigation systems and other fields.
2.1.2 Classification according to process
Smooth surface of glossy geomembrane has good seepage control performance and low friction coefficient, which is suitable for projects with high seepage control requirements and low friction resistance, such as landfills and sewage treatment plants.
Rough surface of rough geomembrane increases the friction between it and soil body, which is suitable for projects with complicated terrain and better stability required such as slopes.
Column point geomembrane has raised column points on the surface, which not only increases the friction, but also improves the drainage performance, which can be applied to some projects that need drainage function.
Composite geomembrane is produced by geotextile and geomembrane composite together, in which geotextile mainly plays the role of protecting geomembrane, and geomembrane mainly plays the role of anti-seepage. A cloth a membrane is mainly used in construction conditions in the project, such as roadbed seepage control project, airport seepage control project, etc.; two cloth a membrane on the top and bottom are composite geotextile, can be used for a variety of complex field seepage control project, such as river seepage control project, ditch seepage control project and so on.
2.2 Performance characteristics of geomembrane
2.2.1 Physical properties
The mass per unit area of geomembrane usually fluctuates within a certain range, for example, the mass per unit area of common HDPE geomembrane is generally between 700g/m² and 2500g/m². The mass per unit area of geomembranes varies from one type of geomembrane to another, and the mass per unit area of geomembranes has a direct impact on the performance and application of geomembranes.
Thickness is also one of the important physical indicators of geomembranes. Generally speaking, the thickness of HDPE geomembranes is usually between 0.2mm and 2.0mm, while the thickness of LDPE geomembranes is relatively thinner and may be between 0.15mm and 1.5mm. The choice of thickness depends on the specific requirements of the project, e.g. projects with high impermeability requirements may require a thicker geomembrane.
The pore size of a geomembrane has a significant impact on its impermeability. High-quality geomembrane pore size is very small, can effectively prevent the infiltration of liquid and small particles. In general, the aperture of HDPE geomembrane can reach micron level, which greatly reduces the risk of seepage.
2.2.2 Mechanical properties
In terms of tensile performance, HDPE geomembrane has high tensile strength and can withstand large tensile force without rupture. According to relevant data, its tensile strength can be as high as 25MPa or more, and the tensile strength of LDPE geomembrane is relatively low, but it can also meet the needs of many projects, generally around 15MPa. This high tensile strength enables the geomembrane to adapt to the deformation and stretching of the soil body in the project, ensuring the stability of the seepage control system.
Tear performance is also one of the important mechanical indexes of geomembrane. In the actual project, the geomembrane may be affected by factors such as the puncture of sharp objects or the uneven settlement of the soil body, which is easy to produce tearing. Therefore, geomembranes need to have good tear resistance. For example, some high-quality geomembranes can have tear strengths of several hundred Newtons or more under specific test conditions.
Top-break performance is also critical for geomembranes. In some projects, such as landfills, there may be heavy or sharp objects that exert top pressure on the geomembrane. Geomembranes need to have sufficient top breaking strength to resist this pressure and prevent damage. Generally speaking, the top breaking strength of HDPE geomembranes is as follows