Discuss Geosynthetic Clay Liner Permeability and Application Analysis of Hydraulic Engineering
Abstract: This paper introduces the application of a new type of composite geosynthetics, geosynthetics clay mat (bentonite geosynthetic clay liner for sale), in hydraulic engineering, and analyzes the factors affecting the anti-seepage ability of bentonite geosynthetic clay liner factory price. Finally, it points out that high quality bentonite geosynthetic clay liner pays attention to the application of hydraulic engineering. Some questions.
Keywords: bentonite geosynthetic clay liner manufacturers permeability; hydraulic engineering; application
1. Overview
Geosynthetic clay mat is a new type of composite geosynthetic material developed on the basis of compacted clay liners. Most bentonite geosynthetic clay liner for sale sandwich a thin layer of bentonite between two layers of geotextiles, so they combine the advantages of geotextiles and bentonite. Compared with the compacted clay liner, it has a small mass per unit area, high shear strength per unit thickness, GCL geosynthetic clay liner factory price strong resistance to uneven settlement and freeze-thaw cycles, GCL geosynthetic clay liner manufacturers low hydraulic permeability under the same conditions, convenient construction and low installation cost. Advantages; Compared with a general geomembrane, it has the advantages of excellent anti-seepage performance and strong self-healing ability. General hydraulic permeability of wholesale bentonite geosynthetic clay liner:
Under other conditions, the hydraulic permeability coefficient k of the bentonite geosynthetic clay liner factory price product is a function of the compressive stress, which decreases as the compressive stress increases. Generally, under low compressive stress, k is 10-9~10-8cm/s, and under high compressive stress, k is 10-10~10-9cm/s. Under ultra-high stress, its hydraulic power The permeability coefficient will be less than 10-10 cm/s. Hydraulic permeability at the joint of the bentonite geosynthetic clay liner manufacturers product.
2. Discussion on the permeability of geosynthetic clay liner and application of hydraulic engineering
2.1 Understanding of geosynthetic clay liner permeability
The anti-seepage effect of wholesale bentonite geosynthetic clay liner relies on the bentonite after hydration. As the bentonite particles swell and swell, a relatively uniform colloidal system fills the entire space, and the expanded bentonite reaches a certain degree of compactness under the action of limited pressure. Very low water permeability. Therefore, for a certain high quality GCL geosynthetic clay liner, there are two main factors affecting its permeability, the degree of hydration of bentonite and the degree of compaction after hydration. Both of these factors are closely related to the pressure acting on the GCL geosynthetic clay liner for sale.
2.2 geosynthetic clay liner permeability test method
As mentioned above, China still has no national standards and industry standards for bentonite geosynthetic clay liner for sale products and tests. wholesale GCL geosynthetic clay liner manufacturers mostly refer to ASTM standards when conducting osmotic testing on their products. The ASTM standard is an internationally renowned and authoritative standard. It is appropriate to use this standard to test the permeability performance of high quality bentonite geosynthetic clay liner products under uniform conditions. However, due to the practical application conditions of GCL geosynthetic clay liner for sale (especially in water conservancy projects), The test conditions with the side standards may be inconsistent in most cases. Therefore, it is necessary to simulate the actual application conditions to determine the permeability of the high quality GCL geosynthetic clay liner during operation. In view of this, it is necessary to discuss the test method of wholesale GCL geosynthetic clay liner permeability here. The method has the following problems when applied to hydraulic engineering:
(1) As mentioned above, when wholesale bentonite geosynthetic clay liner is applied in water conservancy projects such as channels and basin anti-seepage, the effective pressure of the overlying coating is generally low, about 5kpa (after considering the protective layer at 50cm, the protective layer floats about 10kN). /m3 or so, GCL geosynthetic clay liner manufacturers the effective pressure is about 5kPa), and there is a big gap with the effective pressure of 35kPa in the ASTM5887 standard. The permeability coefficient obtained by this method cannot necessarily reflect the permeability of bentonite geosynthetic clay liner manufacturers in the practical application of hydraulic engineering.
(2) Based on the instruments and methods used in the ASTM 5887 standard, reducing the effective overburden pressure (eg, 5 kPa) and simulating the possible application conditions of bentonite geosynthetic clay liner factory price in hydraulic engineering may cause two problems. One is that the hydration time must change. The fully hydrated test piece of bentonite is effective for about two days under the effective pressure of 35 kPa. Therefore, it is reasonable to select ASTM for 48 hours of hydration time. GCL geosynthetic clay liner factory price if the effective overburden pressure drops to 5 kPa, the hydration time should be adjusted to about 100 hr. Second, the effective overburden pressure when testing with a soft wall permeameter is also the confining pressure around the sample. According to the relevant research, when using the flexible wall permeameter test, it is necessary to have sufficient confining stress to ensure that the rubber film is close to the soil sample. When the effective confining stress is lower than 14 kPa, it is difficult to prevent sidewall leakage. Therefore, if the effective overburden pressure is lowered to 5 kPa, it is difficult to ensure the accuracy of the test results.
(3) Although the flexible wall permeation instrument has many advantages, the equipment is expensive and complicated, and the test operation is complicated, and the application is inconvenient. To this end, the author makes the following recommendations for the test standards and method points of the bentonite geosynthetic clay liner for sale used in hydraulic engineering: a. The ASTM standard is still used as the material performance test standard to meet the versatility and uniformity of the test indicators. Starting from the accuracy and simplicity required to meet the actual needs of water conservancy projects, the following methods were used to test the application performance of high quality GCL geosynthetic clay liner. b. The test instrument is recommended to use the commonly used vertical permeation instrument and can be modified slightly. The size of the test piece is 20cm or 30cm. The larger size sample can effectively reduce the influence of the edge of the sample, and the large size test piece is easy to install and seal. According to the author’s experience, the method of applying the prepared bentonite to the wall of the sample can be sealed according to the author’s experience. Although this method has a certain influence on the permeability coefficient, it is sufficient for the project. Precision. A piston pressure rod is arranged at the center of the vertical permeator, and the pressure on the sample is controlled by the pressure rod. The permeable stone should be used instead of the permeable plate as the protective layer and support layer of the GCL geosynthetic clay liner for sale. The main reason is that the pore size of the permeable plate is too large, which may cause the bentonite powder to be lost and the sample to be damaged due to excessive deformation of the underlying geotextile of the high quality bentonite geosynthetic clay liner sample. c. Using the vertical permeation test, GCL geosynthetic clay liner manufacturers it is not possible to use the backpressure for saturation according to the ASTM standard, but it can be applied to the installed sample after the application of the predetermined vertical pressure by the combination of drip saturation and suction saturation. The test is saturated to hydrate the bentonite. d. When using vertical penetrator to measure the permeability of bentonite geosynthetic clay liner manufacturers, the vertical pressure applied to the sample should be determined according to the actual engineering conditions. When the actual engineering conditions cannot be determined, effective restraining stress of 5 kPa is recommended. The hydration time is preferably 100 hr.
2.3 geosynthetic clay liner attention to problems when applied to hydraulic engineering
GCL geosynthetic clay liner factory price has strong resistance to dry-wet cycles, freeze-thaw resistance, and low permeability. It has a large application prospect in the anti-seepage of channels (especially in northern China), GCL geosynthetic clay liner factory price reservoir basins and artificial lakes and pools. The following issues should be noted in these engineering applications:
(1) Due to excessive water pressure, high quality GCL geosynthetic clay liner may cause hydraulic breakdown damage. Therefore, it should be checked whether the hydrostatic pressure of wholesale GCL geosynthetic clay liner meets the requirements of the actual engineering operation head. The author suggests that the wholesale bentonite geosynthetic clay liner hydrostatic pressure should be greater than the actual maximum permeate head. L.1 times or more.
(2) In the channel anti-seepage project, the overlying protective layer of bentonite geosynthetic clay liner factory price mainly consists of cast-in-place concrete lining and precast concrete blocks. Since the thickness of the protective layer is generally thin and insufficient to resist the expansion force of the GCL geosynthetic clay liner manufacturers water swell expansion, attention should be paid to the deformation problem and stability of the concrete lining board during use.
(3) When used in projects with high anti-seepage requirements such as lake bottom and bottom of the reservoir, GCL geosynthetic clay liner for sale can only exert its anti-seepage effect after it is completely hydrated. Therefore, if the high quality bentonite geosynthetic clay liner is not fully hydrated after the completion of construction, it will start to store water. , in the beginning, there will inevitably lead to effective leakage, and attention should be paid to controlling the storage rate.
3. Enhance quality awareness
In the process of construction of water conservancy projects, a key factor in ensuring the quality of construction projects during the selection of materials must strengthen the supervision of materials and, in addition, strengthen the details. (1) Test data. During construction, GCL geosynthetic clay liner factory price it is necessary to strengthen the analysis of all materials and engineering conditions, and obtain more accurate data, such as the type of anti-seepage materials, the impact on the quality of the materials after use, etc., through scientific experiments to obtain data, master the project The key to construction is to invest in construction. (2) Deformation joints. In this stage of construction, due to its strict technical requirements, coupled with a large number of engineering procedures, it is necessary to pay attention to its continuity, to ensure that after the project is processed, it can form an effective whole.
4. Conclusion
wholesale GCL geosynthetic clay liner is used for anti-seepage engineering with high efficiency, low cost, and good anti-freezing performance. It can be promoted in water-deficient areas in northern China. There is still a big gap between the promotion and application of geosynthetics in China compared with developed countries. We can learn from the experience of developed countries in the application of new materials to serve China’s economic construction.