Geotextile fabrics from Landplan Engineering Supplies

Geotextile fabrics perform four basic functions;
Filtration
Geotextiles function to restrict the migration of fine soil particles from a soil mass while remaining permeable to water movement at least greater than, or equivalent to, permeability of the protected soil.

Drainage
Water is conveyed vertically or horizontally along the plane of the geotextile and thence to an outlet. Drainage is related to the role of filtration, and is a function of the permeability of a geotextile and its pore opening size.

Separation
Prevents two distinct soils of different materials from intermixing. The key factors for a geotextile to satisfy this function are porosity, toughness and strength.

Reinforcement
This function involves stabilisation of a soil mass by provision of tensile strength of the soil-fabrication system.