Geotextile Application and Solutions

 

Why Contractors and Developers Like Geotextiles

Project owners are under greater constraints when developing or updating building sites. These constraints start with the requirement to comply with strict stormwater controls to protect existing soils. Also, project owners are demanding shorter construction timelines. And when the project is completed, owners want a finished site with long-term stability that won’t require extensive maintenance.

Contractors want to employ building systems that can maximize efficiency while helping to reduce costs. They often face productivity and safety challenges when beginning their site work. These challenges can be caused by poor soil conditions, unexpected concerns about erosion control, and even slope reinforcement. 

Implementing geotextiles when updating or developing challenging building sites can improve or resolve many of these concerns for contractors, developers and building owners.

 

Helping the Environment

Geotextiles also play a key role in reducing a project’s overall carbon footprint. Geotextiles can allow the contractor to reduce the volume of raw materials required on a project. And on many of these applications, geotextiles can decrease a contractor’s amount of material handling. Since geotextiles help preserve soil conditions, they have also create a positive environmental impact long after the project is completed.

Every project starts with the soil

Contractors can often track their jobs by looking at the color of mud on their pick-ups. Each construction site has different ground conditions.

Since all soils aren’t the same, you can use geotextiles to improve soil characteristics to meet acceptable standards before constructing embankments, roads, pipelines and earth-retaining structures.

Soil engineers refer to these differences in terms of boundary conditions (i.e. confining stress and flow conditions) and hydraulic gradients.

Separation

After contractors place geotextiles on the top of a weakened or soft soil layer, they add a layer of coarse aggregate. The fabric prevents the coarse aggregate from intermixing with the material under the fabric for the life of the structure. The fabric’s ability to keep the different materials separate is effective even when the area becomes saturated with moisture. With this stratification, the coarse aggregate particles interlock to form a bridge over the lower layer.  Engineers can calculate the necessary thickness of the coarse material to make the roadway stable, even when the area is subjected to repeated applied loading. This application is effective for creating subbases for roads, pavements, and slabs.

You must match the geotextile to the anticipated loading so that the fabric has a mass per unit area and strength that can resist mechanical stresses. Manufactures offer a wide array of geotextiles that combine thickness and permeability properties, to prevent soil contamination and to allow water flow without compromising structural integrity.

Drainage and Filtration

Engineers often specify geotextiles to enhance drainage and filtration in subsurface structures. These drainage applications are found along highways, within embankments, under airfields, and concrete slabs. These drainage structures work best when they have a properly designed protective filter. The selection must include an estimation of the volume of water transferring through the fabric and a design that protects the fabric from being plugged.

Contractors can use filtration geotextiles for smaller situations as well. These applications include: edge drains, interceptor ("french" or "burrito") drains, wall drains, recharge basins, and relief wells. In these applications, the geotextile should be designed to survive construction, allow the passage of water at high rates, and retain in-situ soil so particles don’t clog the drain. The best design is to place the geotextile filter around the perimeter of a drainage trench, with the pipe encapsulated in stone. Wrapping a pipe with a geotextile, in general, is a poor practice and should not be done unless the soil adjacent to the geotextile is a clean sand or stone.

For many applications, geotextiles are used to filter water as it drains through the soil layers. These applications are often found on landfills. The geotextile permits the liquid to flow on top,  keeping it from entering the lower layer. This is an effective tool when there is a need for water to move in two directions, leading the liquids to a collection point.

 

Road and Railway Stabilization

Road and railway stabilization are probably the most common applications for geotextiles. They reinforce the path of transport to provide constructability, reinforcement, and access over very soft soils.  

Engineered Structures

The growing interest in engineered structures has led to the development of new geotextiles. Geogrids and high strength geotextiles allow contractors to construct slopes, walls, and embankments quickly, and cost-effectively. These products have become integral components in mechanically stabilized earth structures such as retaining walls, slopes, and embankments.

Erosion Control

Geotextiles have been used to prevent erosion during and after construction.

Stormwater management and vegetation regrowth
Geotextiles deliver solutions that provide bare soil retention, vegetation nurturing and high-performance turf reinforcement. Geosynthetics assist with the dissipation of flowing water, and the increased roughness coefficient. Combined with greater light penetration, this creates a nurturing environment in which the grass root system can grow. These products are also suitable for both channel lining and slope/overtopping applications.

Permanent Erosion Control
Filtration geotextiles are often used in the following erosion control applications:  wave protection for shoreline embankments and causeways; scour protection of various small drainage structures and ditches; and cut and fill slope protection for structures such as bridge piers and abutments. As with drainage installations, these applications require that the geotextile be designed to survive installation, plus allow the passage of water while retaining in-situ soil without clogging.