One of my latest projects is to provide shoring for an enclosure that is about 15’x20’, but is about 60’ deep. I have a 100psf surcharge at the surface. Large section steel soldier piles and larger steel walers. The soil is highly plastic clay. The backfill against the lagging is fine sand and filter fabric to keep it from seeping through. The construction is temporary.
For shallower excavations I’ve simply used the Kp*(the surcharge) as a uniform load full height. I find it difficult to imagine that the effect of the surcharge would have an effect at the full depth. Does anyone have any comments about reducing the effects of the surcharge?
There is no geotekkie on this project, and, I’ve done these before; I’m just wondering if I’m being too conservative.