Roger Turk wrote:
It has been only in the last couple of years that I have heard the term,
"at-rest" pressure. None of my soils books (Spangler, and Peck, Hanson &
Thornburn in particular) have the term.
I'm almost as "experienced" as you are, and I've been using "earth pressure
at rest" for basement wall design for as long as I can remember. Designing
restrained walls for active earth pressure is clearly unconservative! My
trusty old 1968 edition of "Foundation Analysis & Design" by Joseph E.
Bowles clearly defines earth pressure at rest in Section 6-2, on Page 267:
"Earth pressure at rest is the concept associated with the forces acting on
the retaining structure before any movement takes place either into or away
from the backfill mass."
Bowles further defines the usual range of lateral earth pressure
coefficients for "at rest" conditions as 0.4-0.6 for cohesionless soils and
0.4-0.8 for cohesive soils.
I hope that this helps you catch up on those lost decades. Perhaps, next
week, we can discuss life after DOS!
Stan R. Caldwell, P.E.
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