Use of SPT's in V.Soft Soils and Peats
Use of SPT's in V.Soft Soils and Peats
(OP)
I'm trying to compare Geotechnical Properties derived from In-situ Testing and Lab Testing to determine how reliable/comparable the respective methods are.
The main two properties I'm looking at are Undrained Shear Strength (Cu) and Coefficient of Volume Compressibility (Mv)for some very soft Alluvial Clays and Peat.
SPT's, CPT's and Lab Testing have been carried out on a site. Calculating parameters for the latter two methods is not an issue. However the problem is for the SPT's many of the "N" Values are recorded as Self Weight (SW/0) or 1. Making deriving parameters impossible or parameters that have no variation across the site.
Are there any papers out there that detail the derivation of Geotechnical Parameters in soft soil? (I have used Google). Or that show that using SPT's on soft soil is unreliable?
Thanks
The main two properties I'm looking at are Undrained Shear Strength (Cu) and Coefficient of Volume Compressibility (Mv)for some very soft Alluvial Clays and Peat.
SPT's, CPT's and Lab Testing have been carried out on a site. Calculating parameters for the latter two methods is not an issue. However the problem is for the SPT's many of the "N" Values are recorded as Self Weight (SW/0) or 1. Making deriving parameters impossible or parameters that have no variation across the site.
Are there any papers out there that detail the derivation of Geotechnical Parameters in soft soil? (I have used Google). Or that show that using SPT's on soft soil is unreliable?
Thanks





RE: Use of SPT's in V.Soft Soils and Peats
RE: Use of SPT's in V.Soft Soils and Peats
RE: Use of SPT's in V.Soft Soils and Peats
RE: Use of SPT's in V.Soft Soils and Peats
I'm not aware of any correlations to compressibility, but luckily I don't have to work in peat areas.
Good luck.
Mike Lambert
RE: Use of SPT's in V.Soft Soils and Peats
Su for normally-consolidated clay correlates to sigma V'
Peat is pretty frictional, but the settlements!
f-d
ípapß gordo ainÆt no madre flaca!
RE: Use of SPT's in V.Soft Soils and Peats
RE: Use of SPT's in V.Soft Soils and Peats
Assume that there is no soil at all. For example, if you improve this soil, do not add any bearing capacity at all from the soil. Assume all loads are carried by rigid inclusion. (Or you can try wick drains if you have time.)
What I wonder is how did site crew obtained samples from a peat that has 0 SPT value? It does not seem logical. And they tested it! What did you obtain from the lab? I would question the reliability of one of the results, SPT or lab results.
RE: Use of SPT's in V.Soft Soils and Peats
http://www.eng-tips.com/viewthread.cfm?qid=79209