Undrained Shear Strength
Undrained Shear Strength
(OP)
What are some common undrained shear strengths (in psf) for over-consolidated clay till soils, with varying N60 values 20-70 BPF?
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RE: Undrained Shear Strength
For clay till, Hegedus E. and J. Peterson "Penetration Resistance and Shear Strength of Cohesive Soils" in Proc 1st Int. Symp. on Penetration Testing, Orlando, 1988.
In 1960, USBR published a correlation referenced to field vane; as I recall, it predicts higher strength than the others do. The report is pretty obscure. Most of their results, in psi, were between [2 + 0.95 N] and [6.5 + N], with N up to 16. No depth or energy adjustments were applied to N. I don't know what type of hammer they used at that time, probably donut. Much of the testing was done at a cemetery here in town (not filled up with bodies at that time) by an old friend of mine, who is now buried there. I suppose that's appropriate.
RE: Undrained Shear Strength
RE: Undrained Shear Strength
RE: Undrained Shear Strength
Great Lakes area? I think H&P's data came from along south shore of Lk. Erie. (The paper shows H&P as being from Cleveland.)
RE: Undrained Shear Strength
You could make an estimate of undrained sher strength using Su=0.05*N-value (tsf).
I usually reduce the value even further by about 2/3.
Good luck!