Soil pressure diagram behind gravity retaining wall 1

[yakpol]

Hello, I have a question for geotechnical engineers. Consider typical reinforced concrete gravity retaining wall, constructed by usual method: 1)excavate behind the heel, 2)construct the wall, 3) Backfill behind the wall.
In case of taller wall (say 15 feet +) and two distinct native soil layers above the footing, would you specify two lateral earth pressure coefficients (and unitweight) or just one. Would it be native soil or backfill parameters.
This is a conceptual question, not based on particular life example.

Thank you for responses!

Yakpol

 

[Panars]

Typically, the active soil wedge is going to be completely in the backfill material, so for this case I usually base the earth pressure on one set of soil parameters. However, I have had situations where I used multiple sets of earth pressure coefficients and unit weights.

 

[yakpol]

Panars, thank you for reply. I guess it's an open field.
Yakpol

 

[GeoPaveTraffic]

In the case you describe, then the geotehncial engineer should provide a pressure diagram since there are just two parameters and the overlying soil unit weight effects the pressure in the lower stratum.

Mike Lambert