Geosynthetics materials are usually made from hydrocarbons and are used with soil or rock in many types of road and trail construction to strengthen weak soil foundations (wetlands). Geosynthetic materials offer alternatives to traditional trail construction and can be more effective in some situations, such as crossing wet soils and stabilizing fill slopes.
Geosynthetics materials come in two forms:
- Two-dimensional sheets. The generic name for these sheets is geofabrics. Geofabrics have the ability to separate, filter, reinforce, and drain soil.
- Three-dimensional structures. Common geosynthetic materials are Geoblocks® or geogrids. These are a series of interlocking, polyethylene paving units that provide vehicular load support. The 20-inch-wide by 40-inch-long by 2-inch-deep sections of geogrids are a commonly used three-dimensional geosynthetic structure. Another three-dimensional structure is a geonet.
The two forms of geosynthetic materials are often used together in conjunction with gravel and perform three major functions:
All these materials become a permanent part of the trail and must be covered with soil or gravel. If the material is exposed, it can be damaged by trail users.
Here are some considerations for using geosynthetic materials for trail construction:
- The installation of Geoblocks® allows construction of trails on steeper slopes.
- Anchors are necessary to hold Geoblocks® in place.
- Geoblocks® sections can be assembled into 15-foot-long sections and then moved to the final location and dragged into place by an excavator.
- Place fine gravel in the Geoblocks® cells for best results.
Maintenance and Management Considerations
- Inspect for exposed synthetics and the loss of cover (soil, gravel, wood fiber etc.). Replace as needed.
- Snow grooming equipment operators need to be careful not to allow their equipment to catch the edges of Geoblocks®. If not, the Geoblocks® can be pulled out of position and lead to failure.
- The US Army Corps of Engineers does not consider Geoblocks® a fill material, so permits are not required.
- Good to use on weak soils and for hardening steep slopes.
- Water flowing across a Geoblocks® installation can wash out the gravel and allow the Geoblocks® to float out of place resulting in failure.
- Cement blocks.
- Native rocks.
- Interlocking pavers.