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The characteristics of the protected soil have an impact on the performance of the inverted filter. The geotextile mainly acts as a catalyst in the inverted filter layer, prompting the protected soil upstream of the geotextile to form an overhead layer and a natural filter layer. The natural filter layer acts as the inverted filter. Therefore, the properties of the protected soil have an important impact on the characteristics of the inverted filter. When the soil particle size is equal to the pore diameter of the geotextile, it is most likely to be blocked inside the geotextile.
What are the main functions of geotextile in inverted filter
The geotextile mainly acts as a catalyst in the inverted filter
The non-uniformity coefficient of soil indicates the non-uniformity of particle size, and the ratio of the characteristic aperture OF of geotextile to the characteristic particle size DX of soil should follow the non-uniformity coefficient C μ The soil particles with the particle size less than 0.228OF can not form the overhead layer 20. The shape of soil particles will affect the soil conservation characteristics of geotextile. Scanning with electron microscope, it is found that the tailings have obvious long and short axis characteristics, which cause the overall anisotropy of tailings, but 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.
The geotextile mainly acts as a catalyst in the inverted filter
The German Society of Soil Mechanics and Foundation Engineering divides the protected soil into problem soil and stable soil. The problem soil is mainly the soil with many silt particles, fine particles and low cohesion, which has one of the following characteristics: ① plasticity index is less than 15, or clay/silt content ratio is less than 0.5; ② The content of soil with particle size between 0.02~0.1m 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 should avoid the following soil types as far as possible: ① non cohesive fine grained soil with single particle size; ② Broken graded cohesionless soil; ③ Dispersive clay will disperse into individual fine particles over time; ④ Soil rich in iron ions. Bhatia studies that the internal instability of soil causes 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.