October 23, 2018

Best Practices for Zero Retaining Wall Failures - Compaction and Soil Considerations

For tall walls design parameters of compaction and wall rock usage should be increased.  Select/structural fill should be specified for the minimum bottom 1/3 to 1/2 of the reinforced fill.  The use of additional select/structural fill should extend to the entire length of the reinforcement.  

Also consider how much potential settlement will impact structures above the reinforced soil mass. For tall walls consider increasing compaction requirements from 95% to 98% of standard proctor to minimize settlement where essential to the application.

As walls get taller the internal stresses increase and depending on the soils used, can cause lateral loads pushing on the back of the facing. To minimize internal lateral loads on the Allan Block facing, it is recommended to expand the depth of the wall rock column behind the facing, See Section 8.2.b for more information.

In addition to the compaction and wall rock parameters, tall walls require the design engineer to evaluate the overall stability of the soil structure and the subsoils beneath the wall. The reinforced soil structure should be evaluated for internal settlement which may require additional select fill to mitigate.  (ref. BP, Chapter 8.3)

Allan Block is working to achieve our industry initiative of Zero Wall Failures. With our Best Practices Manual and experience in the industry we are trying to expand the knowledge base for the design of segmental retaining walls (SRW's) by communicating and educating the professionals in the industry.  To see the full Best Practices Manual, visit allanblock.com to download today and keep an eye out for more industry Best Practice recommendations here.

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