A cloth and a film
1) Characteristics of composite geomembrane
Composite geomembrane is made of plastic film and non-woven fabric. Its anti-seepage performance mainly depends on the anti-seepage performance of plastic film. At present, polyvinyl chloride (PVC) and polyethylene (PE) are the main anti-seepage plastic films at home and abroad. They are a kind of high molecular chemical flexible materials with small proportion, strong extensibility, high adaptability to deformation, corrosion resistance, low temperature resistance and good frost resistance. The main mechanism is that the water leakage channel of earth dam is separated by the impermeability of plastic film, which can bear the water pressure and adapt to the deformation of dam body with its large tensile strength and elongation; and the non-woven fabric is also a kind of short polymer fiber chemical material, which has high tensile strength and extensibility through needle punching or hot bonding. After it is combined with plastic film, it not only increases the tensile strength of plastic film Because of the rough surface of the nonwoven fabric, the friction coefficient of the contact surface is increased, which is beneficial to the stability of the composite geomembrane and the protective layer. At the same time, they have good corrosion resistance to bacteria and chemical action, and are not afraid of acid, alkali and salt erosion.
The service life of composite geomembrane is mainly determined by whether the plastic film loses the function of anti-seepage and water-proof. According to the national standard of the Soviet Union, the service life of the polyethylene film with the thickness of 0.2m and stabilizer can reach 40-50 years under the condition of clean water and 30-40 years under the condition of sewage. Therefore, the service life of composite geomembrane is enough to meet the service life of dam seepage control requirements.
2) Determination of film laying range
The dam of Zhoutou reservoir was originally a core wall dam, but due to its collapse, the upper part of the core wall was disconnected. In order to solve the problem of seepage control in the upper part, the anti-seepage inclined wall was added. According to the safety demonstration and analysis of Zhoutou reservoir dam, in order to solve the leakage weak surface and dam foundation leakage caused by multiple landslides of the dam, in the vertical seepage prevention, the bedrock curtain grouting, the contact surface grouting, the backfill curtain of flushing and grabbing well and the high-pressure jet grouting impervious plate wall are adopted. The upper inclined wall is covered with composite geomembrane for anti-seepage, and the lower part is connected with the vertical anti-seepage wall. The upper part reaches the elevation of 358.0m (0.97M higher than the check flood level). See the design drawing for specific location and quantities.
3) Selection of composite geomembrane
There are one cloth one film, one cloth two film, two cloth one film, two cloth two film and many cloth multi film. The models are 200g / m2 ~ 2000g / m2, and the width is 1-6m.
Composite geomembrane is made of plastic film and non-woven fabric. Its anti-seepage performance mainly depends on the anti-seepage performance of plastic film. At present, polyvinyl chloride (PVC) and polyethylene (PE) are the main anti-seepage plastic films at home and abroad. They are a kind of high molecular chemical flexible materials with small specific gravity, strong extensibility and high adaptability to deformation,. Corrosion resistance, low temperature resistance, good frost resistance. The main mechanism is that the water leakage channel of earth dam is separated by the impermeability of plastic film, which can bear the water pressure and adapt to the deformation of dam body with its large tensile strength and elongation; and the non-woven fabric is also a kind of short polymer fiber chemical material, which has high tensile strength and extensibility through needle punching or hot bonding. After it is combined with plastic film, it not only increases the tensile strength of plastic film Because of the rough surface of the nonwoven fabric, the friction coefficient of the contact surface is increased, which is beneficial to the stability of the composite geomembrane and the protective layer. At the same time, they have good corrosion resistance to bacteria and chemical action, and are not afraid of acid, alkali and salt erosion.
The service life of composite geomembrane is mainly determined by whether the plastic film loses the function of anti-seepage and water-proof. According to the national standard of the Soviet Union, the service life of the polyethylene film with the thickness of 0.2m and stabilizer can reach 40-50 years under the condition of clean water and 30-40 years under the condition of sewage. Therefore, the service life of composite geomembrane is enough to meet the service life of dam seepage control requirements.
