What should we pay attention to when laying geotextile to protect geomembrane?

What should we pay attention to when laying geotextile to protect geomembrane?

When geotextile is used as a protective layer for geomembrane, the following key points shall be observed during installation:

1. Substrate treatment

The base surface must be smooth, free of sharp stones, roots, broken concrete and protruding hard objects that may puncture the geomembrane. Fill and compact pits and sharp protrusions in advance.

2. Laying sequence

Arrange the geotextile on both sides of the geomembrane as required: the lower protective geotextile goes first, then the geomembrane, followed by the upper protective geotextile. Do not lay the geomembrane directly against rough rock or crushed stone without geotextile cushion.

3. Laying tension & wrinkles

Lay the geotextile loosely with moderate slack, avoid excessive stretching. Do not pull it tight, which may cause displacement or local stress concentration after filling. Smooth out obvious wrinkles.

4. Overlap / seam requirements

Reserve sufficient overlap width (normally 20–30 cm for non‑woven geotextile). If sewn, use durable polyester thread; avoid sewing needles piercing the underlying geomembrane. Do not weld geotextile together with HDPE geomembrane.

5. Avoid sharp construction damage

Construction machinery, shovels and steel tools shall not directly scrape or stab the geomembrane through the geotextile. No heavy vehicles shall run directly on the composite structure before backfilling.

6. Backfilling control

Backfill material cannot contain angular sharp aggregates. Place fill gently and compact in thin layers; forbid high‑throwing dumping. Keep the upper covering soil in time to prevent ultraviolet aging of both geotextile and geomembrane.

7. Connection at anchor trenches and corners

At slope toes, anchor trenches, pipe penetrations and curved corners, lay extra geotextile for reinforcement. Ensure the protective layer fully wraps the geomembrane without exposed membrane.

8. Inspection & repair

Check after laying: if the geotextile is torn or displaced, repair it promptly. If the geomembrane is accidentally punctured, perform leak detection and patch before proceeding.