From the GMA Techline
Subject: Geogrid use behind rigid concrete walls I was wondering if you can provide some information or guidance regarding the use of geogrid reinforcing behind rigid concrete retaining walls. My main questions are: How much can the use of geogrid reduce the lateral earth pressures acting on the retaining wall? How much does the geogrid have to deflect/deform for it to be in tension to support the applied loading? (Joe, New York)
Reply: Nice question and following is my answer. One can construct a wraparound geotextile reinforced wall to the effect that 100% of the lateral load is carried by it and zero goes to the concrete, which now acts as a facing. In fact, this is precisely what the Japanese railroad system does and it has proved excellent under static and seismic conditions. Walls for their bullet train are constructed in this manner. That said, they do require a period of about one year (depending on the type of backfill soil) to allow for compaction and settlement of the wraparound structure before anchoring the concrete facing to it. Regarding your question as to the amount of deformation needed, it depends on the type of backfill soil and its in-situ conditions.
Here in the U.S., we have done similar constructions sometimes with “tilt-up” wall facing panels acting as the permanent facing material for more than 15 years. Go to it!