The geotextile plays the role of filtration between the macropore rockfill and the soil under care, in which it also plays the role of filtration, and the filtration effect of geotextile may be evaluated with reliability.

The basic principle of geotextile anti-seepage and anti filtration is that when the velocity of flow from the right to the left of the soil under care flows to the rockfill, some fine soil particles will be carried into the rockfill by the velocity. Near the surface layer of the soil bar on the outside of the soil to be watched, the head of the coarser soil particle is detained, which reduces the water permeability. At the same time, this part of the coarser particle layer will prevent the fine particles in front of it from being taken away by the flow rate in the future. Moreover, the later the fine particles are less likely to shrink by the geomembrane, so a "natural inverted filter layer" is formed on the left side of the geotextile from left to right.

The anti-seepage and anti filtration of geotextile plays an important role in protecting the soil, and the non preservation of geotextile promotes the "catalyst" effect of natural anti filtration layer. This is also the place where geotextiles are widely used in modern existence.

Geotextile is a new type of construction material used to control earth rock and protect slope in construction engineering or pollution control engineering. It is usually composed of polyester or polypropylene fiber, and the manufacturing method can be divided into needling, weaving, nonwovening or thermal bonding according to its application. Geotextile is very strong and durable, and has good water permeability. It can let water pass through and leave soil and rock particles at the same time, so as to achieve the function of fixing and preventing rain erosion. Geotextile is often partially or completely embedded in the rock and soil in use, so it is very important to ensure its wear resistance and tear resistance.

One function of geotextiles is filtration, which is usually used to control pollution. For example, in the construction site, countless soil and dust are stirred during the work. When it rains or there is drainage, the soil can enter the canal and block it. Geotextile can be installed near the construction site to prevent soil erosion. When the geotextile is used for reservoir and roadway treatment, the filtering function can also be used.

Geotextiles can also be used to separate different rock and soil types, as well as for reinforcement. Like embankment or revetment works, soil and rock may slide down during work in progress or during adverse weather trends. We can use Geotextiles to protect dykes and slopes. It can fix the slope with the root system of the plant and provide stable protection.