Benefits of geogrids for the construction of retaining walls in reinforced soil

For the development of retaining walls in soil reinforced with geosynthetics, it is important to understand the benefits offered by uniaxial geogrids, compared to geotextiles.

Geotextiles are generic materials developed for engineering works in different applications; however, not specifically for the formation of retaining walls in reinforced soil. On the other hand, geogrids have mechanical and hydraulic properties that make them suitable for reinforcing soils in this type of structure.  (Read: Recommendations for implementing walls in reinforced soil).

For this reason the civil engineer and technical director of Geomatrix, Omar Torres, will tell you in the next video benefits of geogrids  and the aspects that differentiate them from geotextiles. Remember that you can also refer to the transcript of this video at the bottom of the post.

  

 

 

 

We show you how we apply a cost-effective solution in real projects. Learn about our success stories here.

 

---

VIDEO TRANSCRIPT

Benefits of geogrids versus geotextiles for retaining walls in reinforced soil

Although geosynthetics are making their way into the engineering sector as a viable alternative for the construction of retaining walls in reinforced soil, geogrids have some advantages over geotextiles. The nature of the product, the differences in terms of behavior and the benefits in its use, are some of the aspects that differentiate them, and which we will delve into below.

 

1. About the nature of the product

Geotextiles were created to fulfill the functions of separation, filtration and later reinforcement, with the advancement of the technique. Nevertheless; This same advance has given rise to the generation of uniaxial geogrids, more precise materials for soil reinforcement, and therefore, for the construction of retaining walls in reinforced soil.

 

2. Differences between geogrids and geotextiles

Mechanical and hydraulic capabilities are a big differentiator between one and the other. Each one specifically impacts the behavior of retaining walls in reinforced soil, as follows:

 

mechanical behavior

• Friction or interaction with the ground. Geotextiles interact with the soil through the mechanism of friction. This, through the confinement made by the soil particles on the plane of the geotextile.

 

 

• When you use geogrids, you not only have that friction mechanism, but also that of passive resistance. In what cases does it occur? when soil fractions are damaged in the openings of the geogrid, creating a higher efficiency in the reinforcement capacity.

 

The difference between one and the other can be measured through the pull-out resistance test, better known as pull out, referenced under STMD6706. The result of this test is, fundamentally, the scale factor that has to do with the overall deformability when geogrids or geotextiles are used.

 

• When geogrids are used, the value of the scale factor is of the order of 0.8.

• When it goes to geotextiles, that value is reduced to 0.6, that is, a reduction of the order of 25 percent is presented.

 

 

In this way, the development of resistance in the calculations reflects an increase in the anchorage length, which in the case of geotextiles is above geogrids. This produces a natural consequence, changing from one material to another.

 

Hydraulic behavior

The differences in terms of hydraulic behavior have to do with the ability to allow the passage of water through the soil.

 

• For the case of geogrids. The size of the opening of the geogrid does not mean an interference in the ability to allow the flow of water. 

• On the contrary, for the case of geotextile, it can become so because the size of the pore opening is of the order of tenths of a millimeter. When working with soils with considerable plastic fine infractions, this can generate a certain clogging or plugging effect in the long term, as well as excess pore pressure with the consequent decrease in resistance. 

• As a consequence, there would be an increase in deformations and loss of stability. Geogrids guarantee the stability of the structure, in the long term.

 

3. Benefits of geogrids

Although geotextiles are an alternative, geogrids have some significant advantages, such as: 

• The ability of the geogrid to interact with the ground reduces the reinforcement length behind the failure plane. Additionally, it guarantees the stability of the structure.

• As a consequence, there will be less consumption of geogrid for the construction of the wall, and this, in turn, will present less deformability.

• The volume of material is not only palpable in the amount of geogrid, but also in the amount of soil since it will have a more slender structure.

• This optimizes construction time and, in general, increases the efficiency of the structure, both in the construction process and in performance throughout its useful life.

 

---

Note that changing from geotextiles to geogrids means a 25% loss in strength, resulting in an increase in anchor length, behind the failure plane defined for the wall. If you want to know more information about it, we invite you to consult our specialized library.

In Geomatrix we have the indicated engineering solutions for the development of retaining walls in soil reinforced with geonsynthetics, in addition, you will find the advice you need. Discover our success stories and how they turn your construction project into our next challenge.