Deep grade beam design: Sandbags under SOG has NO active lateral pressure?

[Localeng]

In many cases of constructions, I've seen contractors brought sandbags rather than compacted fill.
At sloped grade, the heights of boundary grade beams vary and sometimes its height can be 4-5 feet.
Do these grade beams not require design as 'retaining wall'?

 

[TehMightyEngineer]

Technically they still have lateral load if they're confined when placing them. However if they're placed such that the fabric of the bag takes the load (keeps the sand from spreading out) then I'd say any lateral load is very small to none. This is apparent as you can build a fairly tall, free standing sandbag wall, one bag thick.

All that said, I would not rely on a burlap or polypropylene bag to last a long time and would highly expect the bag to rupture. This would result in a loss of compaction and increasing lateral loads over time as more and more bags failed. I wouldn't let them put sandbags in, proper backfill only. If you absolutely had to use them then I'd put sandbags down and then fill between the bags and compact the whole layer. Seems like far more work than just placing fill.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

http://www.americanconcrete.com

 

[hokie66]

Where is this practice common? I have never seen it.