The characteristics of the protected soil have an impact on the anti-filtration performance. The geotextile mainly acts as a catalyst in the anti-filtration layer, which promotes the formation of an overhead layer and a natural filter layer in the upstream of the geotextile. The natural filter layer plays a role in anti-filtration. Therefore, the properties of the protected soil have an important impact on the characteristics of the inverted filter. When the particle size of soil is equal to the pore size of geotextile, it is most likely to block in the geotextile.
Geotextiles mainly play a catalytic role in the inverted filter
The nonuniformity coefficient of soil represents the nonuniformity of particle size, and the ratio of the characteristic pore size of geotextile OF to the characteristic particle size DX of soil should follow the nonuniformity coefficient C μ Increase and decrease, and soil particles with particle size less than 0.228OF cannot form overhead layer 20. The shape of soil particles will affect the soil retention characteristics of geotextile. The scanning of electron microscope shows that the tailings have obvious long and short axis characteristics, which cause the overall anisotropy of tailings. However, there is no clear quantitative conclusion on the influence of particle shape. The protected soil which is easy to cause the failure of the inverted filter has some general characteristics.
Geotextiles mainly play a catalytic role in the inverted filter
The German Society of Soil Mechanics and Basic Engineering divides the protected soil into problem soil and stable soil. The problem soil is mainly the soil with high silt content, fine particles and low cohesion, which has one of the following characteristics: ① the plasticity index is less than 15, or the clay/silt content ratio is less than 0.5; ② The content of soil with particle size between 0.02 and 0.1m is more than 50%; ③ Uneven coefficient C μ Less than 15 and containing clay and silt particles. The statistics of a large number of geotextile filter failure cases found that the geotextile filter layer should avoid the following soil types as far as possible: ① non-cohesive fine-grained soil with a single particle size; ② Broken-graded cohesionless soil; ③ The dispersive clay will disperse into separate fine particles with time; ④ Soil rich in iron ions. Bhatia study believed that the internal instability of soil caused the failure of geotextile filter. The internal stability of soil refers to the ability of coarse particles to prevent fine particles from being carried away by water flow. Many criteria have been formed for the study of soil internal stability. Through the analysis and verification of 131 typical criteria for soil attribute data sets, more applicable criteria have been proposed.
Post time: Jan-12-2023