Soils Report Review
Soils Report Review
(OP)
I received a soils report and the report recommends 2000 psf bearing pressure and a site class of D. I am not a soils engineer but I think the 2000 psf is too much. Blow counts are as low as 3. See attached for the soil boring logs. Should I recommend getting a peer review?





RE: Soils Report Review
I am not a Geotech either, but it seems like pile might be warranted to me.
Mike McCann, PE, SE (WA)
RE: Soils Report Review
RE: Soils Report Review
What are the column and/or wall loads? Did they include a statement in the report recommending densifying the soils to some depth below the base of the foundations? Where was this field exploration performed?
RE: Soils Report Review
Also, if the site class was determined using the SPT blow counts within the investigated depths, should not the site class be "E" as the blow counts are less than 15? or perhaps the geotech is familiar with local conditions and knows that there are denser/stiffer soils within a depth of 100 ft, so the site class can be considered as "D"?
In any case, the borings should have terminated at deeper locations where denser/stiffer soils are located, unless it was a budget problem for the geotech investigations...but even that, I would reduce the number of borings in order to advance deeper borings.
RE: Soils Report Review
RE: Soils Report Review
RE: Soils Report Review
RE: Soils Report Review
RE: Soils Report Review
Seems like the N-values need to be adjusted for the use of the automatic hammer (x1.4 greater than shown).
Seems like all settlement will be related to modulus values and occur immediately.
Unclear whether the 50kip column load is primarily sustained dead load or to what extent the transient live loads are involved in the bearing pressure and settlement forecast.
To the extent that the full extent of variables are considered in the analyses, the use of an engineered subbase could help. Consider an undercut of 4 ft (or so. . . ?) and backfill using an open-graded (i.e., highly frictional) aggregate. The modulus would then be controlled in the zone of highest foundation stress. Below the subbase then you'd have attenuation of the foundation load and limit the settlement forecast.
It's not that 2,000 psf is wrong. It's the presentation in the report doesn't seem address these items of concern.
f-d
ípapß gordo ainÆt no madre flaca!
RE: Soils Report Review