Laying Method of Subgrade Reinforcing Geotextile

Laying Method of Subgrade Reinforcing Geotextile

1. Pre-construction Foundation Treatment

Clean the subgrade thoroughly: remove sharp stones, tree roots, hard blocks and protruding sundries to prevent puncturing the geotextile.

Level the uneven foundation, fill depressions with graded fine gravel and compact tightly.

For soft soil sections, pre-drain excess surface water to keep the base dry and stable before laying.

2. Unfolding and Laying Requirements

Unroll the geotextile along the road direction flatly, avoid twisting, folding and excessive tension; keep natural slack to reserve deformation allowance for foundation settlement.

Lay rolls sequentially from one side to the other; the geotextile shall cover the full width of the subgrade.

Overlap treatment: horizontal overlap between adjacent geotextile strips is 10–20 cm. For sections with large foundation deformation, increase overlap to 20–30 cm.

The overlapping joint shall face against the reverse direction of filler backfilling to avoid filler wedging into the gap.

3. Fixation Measures

Fix the geotextile edge and overlapping joints with U-shaped steel nails at intervals of 1.5–2.0 m to prevent sliding and displacement during filling and rolling.

For road slope edges, extend the geotextile into the anchor trench at the road shoulder and compact with soil to lock the fabric firmly.

No local arching or empty space between geotextile and subgrade surface.

4. Backfilling and Compacting Rules

Backfill graded gravel or soil filler immediately after laying and fixing geotextile; do not expose the geotextile under sunlight for a long time to avoid UV aging damage.

Backfill from both sides to the middle of the road, avoid direct pushing heavy filler on the geotextile in one direction.

The first layer of filler thickness shall not be less than 15 cm, and compact gently with light rollers first. Heavy compacting machinery is forbidden to roll directly on bare geotextile.

Carry out layered filling and layered compaction strictly according to road design standards after the first layer is stabilized.

5. Special Construction Notes

Construction is prohibited on rainy days; stop laying once ponding appears on the subgrade.

If the geotextile is torn or punctured during construction, cover the damaged area with an extra piece of geotextile with a covering width ≥50 cm.

For widened road sections, lay the geotextile across the joint of new and old subgrade to weaken differential settlement cracks.