Non-woven geotextile

Non-woven geotextiles are permeable geosynthetic materials made from synthetic fibers (such as polyester and polypropylene) through non-weaving processes like needle-punching and spunbonding. They possess multiple functions including filtration, drainage, isolation, reinforcement, and protection, and are widely used in hydraulic, transportation, environmental protection, municipal, and other engineering fields.

I. Core functions and working principles

‌1. Filtration (Reverse Filtration) Function‌

When water flows from a fine-grained soil layer to a coarse-grained layer, nonwoven geotextiles allow free passage of water while effectively retaining soil particles, fine sand, and small aggregates, preventing piping and soil erosion, thus maintaining the stability of geotechnical structures.

· ‌Key Indicator‌: The effective aperture (O₉₅) must match the particle size of the protected soil.

‌· Typical Applications‌: Dam slope protection, drainage systems behind retaining walls, and filter layers in blind drains.

‌2. Drainage Function‌

By utilizing the three-dimensional pore structure among fibers, nonwoven geotextiles create internal drainage channels within the soil mass, effectively expelling excess liquids and gases. This reduces pore water pressure and prevents structural instability caused by water accumulation.

· ‌Common Applications‌: Subgrade drainage, slope drainage for artificial lakes, and leachate collection and removal in landfills.

‌3. Separation Function‌

Prevents the intermixing of materials with different physical properties (e.g., soil and gravel, concrete and backfill), maintaining the integrity and independence of each layer and enhancing the overall load-bearing capacity.

‌· Application Examples‌: Separation layer between subgrade and soft foundation, interface between rockfill dam and foundation.

4. Reinforcement and Protection Functions

· Reinforcement: Enhances the tensile strength of soil, improves the stability of slopes or foundations, and reduces differential settlement;

· Protection: Distributes concentrated stresses, prevents soil erosion caused by water flow or damage from external 

forces, and protects waterproofing membranes against puncture.

II. Typical Applications

1. Hydraulic Engineering: internal drainage of dams, filter layers for earth-rock dams, and riverbank slope protection;

2. Transportation Engineering: subgrade reinforcement for highways/railways, reflection crack repair on pavements, and soft foundation treatment;

3. Environmental Engineering: leachate drainage in landfills, filter layers for tailings dams, and auxiliary anti-seepage layers for sewage treatment tanks;

4. Municipal and Landscape Engineering: periphery drainage of underground utility tunnels, filtration layers for constructed wetlands, and drainage layers for green roofs.