Woven Geotextile for Embankment Slopes

Embankment slopes are generally built with soil fill, and woven geotextile for slopes is often used to keep them stable. Soil fill has different slope angles depending on the type of soil used. Regardless of the material, failure can occur when the embankment is loaded. For this reason, the safety factor in such cases should generally be 1.5 or higher. The safety factor of an embankment can be determined by trial runs with software that performs slope analysis.

The following parameters were used in the slope analysis trial:

1. Surcharge load of 15 kN/m³
2. Subgrade (sand):
3. Unit weight: 18 kN/m³
4. Cohesion: 0 kPa
5. Friction angle: 35^o

• Embankment fill (gravel-sand-clay):
• Unit weight: 22 kN/m³
• Cohesion: 1 kPa
• Friction angle: 32^o

NB: These parameters can be adjusted to site conditions, soil type and laboratory test results.

Below are the software trial results for the embankment slope without geosynthetics:

Woven geotextile for embankment slopes

The trial results show that without geosynthetics the safety factor is below 1.5. A value below 1.5 makes the condition critical, with a high potential for failure (landslide). Geosynthetics can therefore be used to reinforce the structure.

Below are the software trial results for the embankment slope with geosynthetics:

Woven geotextile for embankment slopes

The trial used woven geotextile with a tensile strength of 50 kN. The woven geotextile was placed every 1 metre of fill. The trial shows 5 layers of geotextile, each 6 metres wide. Installed geosynthetics generally lose some strength during installation, typically with a reduction factor of 1.5. With the woven geotextile installed, a safety factor of 1.704 was obtained. A value above 1.5 is considered ideal, with a low potential for failure (landslide).

The woven geotextile installation parameters can be adjusted in terms of tensile strength, number of layers and installation width. The values can be lower or higher than in the trial. The values used require technical judgement to achieve the most effective result and avoid going over budget on geosynthetics or other materials.