If indeed there is an old slide on the slope, then inherently there is at least one surface or layer that isn't horizontal, and it also happens to likely be the most critical with respect to future stability.
Depending on the degree of weathering at the surface (i.e. time), knowledge of local...
"With typical pile depth of 20' bgs (36' total, 7' rock embedment)"
From the photo provided (and the apparent size of the landslide), the slide plane would seem to be much deeper than 13' below grade. Am I correct in assuming that the photo was taken near the middle of the slope failure...
With regards to the option of removing and recompacting the existing fill, is there not a soil profile at the top of the native glacial till? If so, that is a particularly easy way to verify you are through the fill and into the native below.
As a geologist, I enter test pits and large-diameter borings all the time. BigH is correct, though I don't know about the term microstructure... The test pit and large-diameter boring (24" or greater) is critical as an investigative tool in many of the areas where I work, where large...
As an engineering geologist, frankly I'm reading some of these questions and cringing. It's pretty obvious you should get some input from a geologist, preferrably the one that put the geologic map together. If you are using a regional geologic map for your geology information, this data is...
The assessment of air photos and topographic maps is invaluable in the process, IMHO. Not enough people look at these, and I don't know why.
Also, do not get into the all too familiar habit of simply looking at the subject property. If the site is on a large slide, the ground at the site may...
With all due respect to the soils folks on these boards, rocks are often described as "soft". A good reference for this and other rock questions / issues is the USBR's "Engineering Geology Field Manual", which is available for download online at http://www.usbr.gov/pmts/geology/geoman.html...
moe333,
My bad, I thought perhaps you might have been thinking of drilling via a method (air rotary, ODEX, etc.) other than coring and subsequently doing the camera work.
I don't know which method takes less time. The video method provides output which is nice to include in a report and, it...
Why not do both? Seems like you would want the core for shear strength testing along the discontinuities and all the usual visual classifications. I reviewed a project where they cored and then subsequently lowered a down-hole camera into the borehole.
Might want to talk with a company called...
Well, this is kind of the "standard" used in many universities at the undergraduate level these days:
Engineering Geology: An Environmental Approach (2nd Edition)
by Perry H. Rahn (Author)
However, if you are focused in on a particular topic or topics there may be better options.
As an engineering geologist, I would strongly suggest getting ahold of both an engineering geology and a geomorphology text to familiarize yourself on these matters.
Stego1 provides some good advice for a recent slope failure or one that is currently moving. But, how do you begin to figure out...
If you are drilling on "steep" slopes, I assume you will be encountering bedrock, of varying hardness, at some depth. A geoprobe or tripod rig will be of no help, they are intended for softer materials.
You will most likely need to core. There are rigs available, but they are few and far...
Perhaps the strength values you, and your jurisdiction, are looking for are "ultimate", rather than residual.
Unless your fill slope has a pre-existing failure, why would you use residual strenghts?
Too add to the previous post...
So, you are a "good" geotech engineering firm that is already leary of litigation associated with single family residence work. Now, you are asked to work on a job that has a pretty good chance of ending up in in court...
What you need is a geotech expert who...