Considerations for the design of retaining walls in reinforced soil

Geogrid-reinforced soil retaining walls are a construction alternative to traditional concrete solutions, which have multiple benefits during the construction process and throughout the service life of the structure.

Nevertheless; To take advantage of this construction alternative, it is necessary to take into account some considerations from the design stage, since these specifications will be decisive for the stability and useful life of the structure.  

Thinking about its importance, in the following video the ing. Civil, Álvaro Gutierrez, delves into the 5 considerations to take into account. Remember that you can also refer to the download link to access the transcript of this video.

 

 

 

 

We show you how geogrid solutions evolved the engineering of three projects. Learn about our success stories here.

 

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VIDEO TRANSCRIPT

Considerations in the design stage of a retaining wall in soil reinforced with geosynthetics

During the design phase it is important to take into account some considerations that, although they seem obvious, will optimize the construction process and will result in an efficient reinforced soil retaining wall. To do this, carefully review:

 

• The study of soils.
• The underdrain.
• The types of geosynthetics.
• The resistance of the design.
• The stability analysis.

 

As a first consideration, keep in mind that, Depending on the magnitude of the project, an adequate exploration plan must be made. Make sure you have the indicated number of perforations to make a good characterization of the soil.

 

• From this characterization it is key to obtain the shear strength parameters, in order to carry out an assertive geotechnical model.

 

• Regarding the forming material, a granular material is recommended where the percentage of fines is below 20%, the plasticity index is less than 12% and the material in the field is compacted to 98% of the

 

As a second consideration, there is the underdrain system. In general, design methodologies do not contemplate a wet condition, but rather a dry condition. Therefore, you must take into account the horizontal, vertical and base elements of the structure, in order to mitigate runoff and infiltration water. 

As for the type of geosynthetic It is recommended, if possible, to work with geogrids since they guarantee a better interaction with the forming material, which, as explained above, is clearly or in a greater proportion granular. (You are interested in: Three advantages of using polyester geogrids in the reinforcement of asphalt layers).

 

According to the design strength You should consider that, although the ultimate resistance value is presented in the geogrid technical data sheets, this is not the resistance that should be used in the designs. The reason? this resistance is the one obtained from a laboratory result, with controlled conditions.

 

• As an alternative, take into account the reduction factors, which, as well expressed in the different bibliographies, are part of the creep issue of installation damage and durability.

• The ultimate strength, affected by the reduction factors, results in the available strength, which is the strength to use in designs.

 

As a final consideration, when the stability analysis It is important to highlight that, as with any containment structure, the pertinent internal, external and global stability checks must be carried out. From each analysis made, it must be rectified that:

 

• Comply with the values of minimum safety factors, established in current regulations.

 

• In these, for internal stability, it is analyzed pull out and reinforcement strength.

 

 

• For external stability, bearing capacity, overturning and direct sliding are checked.

 

• Finally, the global stability condition.