Estimating Consolidation in Fine Grained Soils without Oedometer Test
Estimating Consolidation in Fine Grained Soils without Oedometer Test
(OP)
This is a very broad question, so please go easy on me. I currently work at a geotech firm that mainly uses corrected SPT resistances corresponding with index properties (i.e. atterbergs, moisture contents, gradation, etc.) for giving foundation recommendations. We predominantly practice is the coastal region, so SPT generally will suffice for the coarse grained soils encountered. Sometimes we encounter clays and silts, especially if we venture into the piedmont regions to the west of us. We do not have an oedometer to determine consolidation characteristics of fine grained soils, therefore I generally just look at the atterberg limits and natural moisture contents relative to a structures zone of influence to make judgements. I will also use a pocket penetrometer and a torvane in spoon samples and or test pit walls sometimes as well. Additionally, most clients do not want to pay for consolidation testing for small to medium size commercial projects. I would like to know if there is any way ESTIMATE consolidation without running an oedometer on a shelby sample? Thank you in advance.
J
J





RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test
RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test
RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test
B.K. Hough paper August 1959 ASCE Paper number 2135 of SM 4
“SOIL MECHANICS AND FOUNDATION DIVISION of ASCE”
“COMPRESSIBILITY AS THE BASIS FOR SOIL BEARING CAPACITY”
He set this up based o blow count for most soils. I have used it a lot.
If you can find a copy of the second edition of his text "Basic Soil Engineering", Ronald Press, that has the scoop, but presented more convservatively.
RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test
That then is found by his charts, I did a Google search for BEARING CAPACITY INDEX and many places came up. I down loaded one and I see his method is in it.
http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_r...
RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test
Note: I have no connection with either the book or the sellers. Just have a knack for finding things on the internet.
1. "Basic Soils Engineering", B.K. Hough
2. "Basic Soils Engineering", B.K. Hough
3. "Basic Soils Engineering", B.K. Hough
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test
Su/P can be estimated from the pocket penetrometer (or torvane) and a good guess on density (or the density from a Shelby tube). If your ratio of Su/P is much different than 0.2 or 0.25 you are dealing with some preconsolidation. When you get to the depth that Su/P is close to 0.2 or 0.25, you are likely normally consolidated.
Cc is obtained through correlations to liquid limit. In-situ void ratio is a bit of a problem, but can be estimated through guessing specific gravity and knowing water content - I mean if you are dealing with consolidation, it's mostly likely that the water content will be close to saturation. So, solve the block diagram.
Cr is often 1/10th of Cc. (recall you just got a sense of Pp-Po.)
C-alpha is correlated to water content.
Run the numbers!
f-d
ípapß gordo ainÆt no madre flaca!
RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test
RE: Estimating Consolidation in Fine Grained Soils without Oedometer Test