Yol Mühendisliğinde Geomembran Uygulamaları

Core Value of Geomembranes in Road Engineering

Geomembranes, made from high-molecular-weight materials such as HDPE or PVC, geomembrane form a physical barrier with an extremely low permeability coefficient (as low as 1×10⁻¹⁷ cm/s).

effectively preventing water infiltration and mitigating subgrade softening. In road engineering, their functions extend beyond impermeability: ‌

Separation:‌

Prevents mixing of different soil layers, reducing uneven settlement caused by material interpenetration. ‌

Reinforcement:‌

Composite geomembranes (e.g., two-layer fabric with a membrane core) enhance tensile strength and improve slope stability. ‌

Environmental Protection:‌

A 1.5mm thick HDPE geomembrane around landfill access roads can block leachate from contaminating groundwater.

Typical Applications and Material Selection

1‌. Soft Subgrade Treatment‌ ‌Issue:‌ Low-bearing capacity of soft soil leads to pavement collapse. ‌

Solution:‌ Lay 0.75–1.0mm thick HDPE geomembrane as a separation layer, combined with sand drainage layers to improve subgrade uniformity. In cold regions, select materials with a low-temperature brittleness point below -40°C.

2. ‌Slope Protection‌ ‌Issue:‌ Erosion from rainwater causes slope instability. ‌

Solution:‌ Use textured HDPE geomembranes (friction coefficient ≥0.6) with geotextile composites. Bury the top edge ≥0.8m deep and secure it with anchor trenches.

3. ‌Impermeable Systems‌ ‌Issue:‌ Leakage in roadside drainage ditches exacerbates soil erosion. ‌

Solution:‌ Line ditches with 0.5mm thick PVC geomembranes, using thermal welding for seams with a overlap width ≥10cm.

Construction

1‌. Subgrade Preparation‌ Remove sharp objects; ensure surface flatness deviation ≤50mm and compaction ≥90%.

2. ‌Laying Specifications‌ Allow 3–5% natural relaxation to avoid wrinkles;

place the fabric side up and the membrane side down for composite geomembranes.

3. ‌Welding & Inspection‌ Use dual-track thermal welding at 280–320°C with a speed of 1.5–2.0m/min;

perform air pressure testing at ≥0.15MPa for 5 minutes without leakage.

4. ‌Acceptance Standards‌ Conduct peel tests on one weld per 500㎡, requiring ≥80% of the parent material strength;

use spark testing at 15kV with no breakdown points.

‌Common Issues & Countermeasures‌ ‌

Membrane Damage:‌ Repair with thermal welding using same-material patches, extending edges by 15cm beyond damage. ‌

Seam Failure:‌ geomembrane Reweld seams and apply waterproof sealant before covering with soil. ‌

Sliding Risk:‌ Add anti-slip teeth on slopes and compact fill material in layers (≤30cm per layer). ‌

Economic & Environmental Benefits‌ ‌Cost Comparison:‌ HDPE geomembrane impermeable layers reduce costs by 40% compared to concrete lining and cut construction time by 50% for instance. ‌

Lifespan:‌ HDPE geomembranes with carbon black additives last up to 50 years with minimal maintenance at least. ‌

Eco-Friendliness:‌ Recyclable geomembranes align with green construction practices.