Hi Eng-Tips:
A recent failure returned a consultant report. The failure on a typical bridge approach and the work was less than a year or two old. The consultant called the failure, "Shallow, sloughing failure" and told the contractor how to fix it. Contractor and consultant opined, "Well, of...
different soils, different position of the water table, different codes (IBC, AASHTO, etc.). What are the critical soil properties to document the extent to which buried steel will corrode? I know that folks claim 1/4 in! Sure, but. . .
Is it just pH and conductivity? I'm okay getting...
I'm open to discussing the bridge lift. Working for a highway agency, we are all involved in the preliminary engineering for new projects. For the case of an embankment, we may test the strength of foundation soils and the proposed embankment fill. We may assume ground water table and run...
Hi All,
We have an ongoing field exploration and the driller is driving samples with non-a-sized-rod. Maybe N-rod or such? I can certainly get those details in the days to come. My question is whether there are unique terms we'd have to use to normalize the SPT N-values ala N1-(60)?
D6066...
Just to vent. . .
Both ASTM standards for triaxial testing and drained direct shear testing cite the interpretation of friction angle and cohesion as outside the standards (i.e., the're professional services). I'm always receiving laboratory certificates (i.e., non-professional documents) that...
Just heard. Can't quite believe! Checked it out myself and it seems true.
Anybody out there know what's going on? Is there a new standard citation?
f-d
ípapß gordo ainÆt no madre flaca!
ASTM D6032 is the standard for calculating RQD. RQD is measured on, "Sound core." ASTM describes sound core as any core that is fresh to moderately weathered and that has sufficient strength to resist hand breakage.
Separate and unrelated to RQD, FHWA claims any rock that has an UCS...
Please share your experiences. If the embankment is installed and grid is used to support a 1 1/2:1 slope just how practical is it to then drive vertical and battered H-piles. What are the appropriate precautions. Is there any guidance (FHWA, DOTs, AASHTO) that provides some insight?
f-d...
Dear fellows: I'm leaving consulting after 30 years and going to work as a geotechnical engineer for the state transportation department. Yeah, there'll be a culture shift and protocols. Yeah, the spectrum of work may be a bit more focused, but I've always felt the geotechnical aspects of...
Dear Forum:
With limited experience in soil-cement testing I'm wondering about the following:
The Proctor: Do you air dry, mix in the cement, pound the sample and then allow hydration, prior to determining the moisture and density for that sample conditon?
The field density test: Do you...
BigH's thread on "free draining" get's me on my pet peeve. If you want something, take the time to specify it correctly.
The term "SM or Better" is such an ambiguity. Where do you go to find out what soil types are "better" than SM? Sure, folks reference ASTM D-2487 (or 88) but the ASTM...
O.K. for starters, I know nothing about RCC (roller-compacted concrete). What I know is they use it for gravity dams, it has about a zero slump, and it's compacted using a roller (duh). I'm assuming that it's batched on site, as a concrete delivery truck needs some slump to mix and chute from...
Dear All,
Equation 20.4 of my version of Terzaghi & Peck (second edition, 1967) shows the height of capillary rise as follows:
hc=c/(e*D10), where:
hc = height of capillarity rise (cm)
c = empirical coefficient ranging from 0.1 to 0.5 (cm^2 - typical value of 0.3 for granular soils)
e = void...
Here's an architect's perspective on why we have a slope stability failure:
"The soils on the site are sands and clays so sand tends to compact and shift when wet and clay expands when saturated."
So, how then would an embankment dam ever work?
end of rant. . .
f-d
¡papá gordo ain’t no...
John Cephas is dead. He was 78 years old and born in 1930. He and his performing partner, Phil Wiggins were international embassadors of "Piedmont Blues". John played fingerstyle guitar and Phil played the harmonica.
I was luck during 2007 and 2008 to have taken guitar lessons from John in...
Soil nails include a tendon that is enveloped by grout that develops shear along the grout-soil interface. Soil screws include a shaft with helicies (sp) at varying locations. Between the helicies there is limited shear capacity along the shaft-soil interface.
Consider the image below...
Consider an 8-by-8 column footing designed for 2,000 psf and a clay layer 5 to 20 ft below the footing. Run stress distribution beneath the center, edge and corner. Complete the settlement calculations for each stress distribution. You'll get three different results.
Here's my stress...
Somewhere in my past I saw a great photo of an H-pile being installed and an adjacent car being jacked up in the air from the same pile. No doubt the pile hit rock, bent and horse-shoe'd up only to find the underside of a parked car. Does anybody have a copy of that photo? If so, can you post...
Do you consider the blending of flyash, portland cement or lime into a subgrade for a building pad a form of chemical stabilization? Just an informal poll. . . .
f-d
¡papá gordo ain’t no madre flaca!
Dear Folks:
I've been googling for references on the use of coal-combusion byproducts as earth fill for building pads and subbase for slab-on-grade construction. I'm looking for any recent information related to LEED credits and qualities that are known to be favorable for specifying. Here's...
