Geomembranes cannot be used as load-bearing components. Generally, they are required to be able to adapt to construction stress and slightly larger uneven settlement. However, an important requirement for the function of geomembrane is that it should be impermeable, that is, it should not be punctured and fail under the action of water pressure.
Studies show that the properties of geomembranes under water pressure are closely related to those of the supporting cushion layer beneath them. Simply put, the flatter the cushion layer is and the greater its rigidity is, the less likely the geomembrane is to be damaged.
If the cushion layer is soil, the smaller the particle size of the soil, the better the gradation and the greater the density, the stronger the ability of the geomembrane to withstand water pressure penetration. This is because geomembranes have a very high compressive resistance but limited tensile resistance. If the soil particles in the cushion layer are coarse, their sharp corners can easily puncture the geomembrane. In addition, the large pores formed by coarse particles provide the geomembrane with a relatively large free flexural span. When the span is large, the local geomembrane may undergo strain beyond the allowable limit, causing the membrane thickness to become thinner or even break.
The aging of geomembrane is inseparable from its material properties and is also one of the inherent characteristics of polymer materials. Effective measures can be taken to delay its aging. Specifically, efforts can be made from two aspects:
Anti-aging agents can be added to the raw materials of geomembranes to curb the effects of external factors such as light, oxygen and heat on the materials, for instance, by incorporating an appropriate amount of antioxidants, light stabilizers and dark carbon black, etc.
Protective measures can be taken in the project, such as minimizing the exposure time of materials to sunlight as much as possible, and covering them with rock and soil or deep water, etc.
Geomembranes buried in soil and water can prevent direct ultraviolet radiation. When producing polyethylene films, carbon black can be added to shield ultraviolet rays, which can play a role in blocking direct ultraviolet radiation and thus extend its service life. For the same type of geomembrane, the thicker it is, the more resistant it is to aging.
Due to its excellent performance, geomembrane can not only be used for drainage but also in the construction of waterproof facilities. Delaying aging can enhance its application value.
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