uniaxial compressive strength vs bearing pressure
uniaxial compressive strength vs bearing pressure
(OP)
I have a foundation system that I need to provide anchors across the concrete/rock interface. I am concerned with the grout-to-rock bond strength since the rock is weathered fractured limestone with an allowable bearing capacity of 8000psf. (Yes, that is correct...only 8000 pounds per square foot.) I saw an article that recommends that the grout-to-rock ulitmate bond strength could be estimated as one tenth the uniaxial compressive strength.
The geotechnical report that is available makes recomendations on the bearing capacities but does not address the uniaxial compressive strength. Are these realted in any way to each other? Other than performing additional tests, is there any method to determine the uniaxial compressive strength?
The geotechnical report that is available makes recomendations on the bearing capacities but does not address the uniaxial compressive strength. Are these realted in any way to each other? Other than performing additional tests, is there any method to determine the uniaxial compressive strength?





RE: uniaxial compressive strength vs bearing pressure
A contractor who installs anchors in your project area would be a good resource (presuming you can't contact the geotech who wrote the original report).
RE: uniaxial compressive strength vs bearing pressure
RE: uniaxial compressive strength vs bearing pressure
Fracture limestone - is that even a proper location for the bond zone? You might have to pump a lot of grout. On the other hand pumping a large amount of grout could fill some of the voids and seal the fractures, and ultimately improve the pull-out capacity of the anchor.
Concerning the tests, I always believe a few more tests are cheaper than the cost of failure.
You may want to check the compressive strength of massive rock, not weathered fractured rock. For preliminary you should fine range of strength of competent rock in NAVFAC, but the local contractor is preferred.
RE: uniaxial compressive strength vs bearing pressure
The foudnations is for a conveying system for a material handeling project. To complicate matters, the location is on the toe side of a client owned access roadway embankment and is right next to and possibly partway into a state owned creek. When it rains, it pours...hopefully not, that could just casue even more problems. LOL. Because of site conditions, we are limited with the access and availability of equipment to get in to excavate/drill for the foundations.
With all the concerns, we want back to the drawing board and reconfigured the conveying system so that the foundations in question is away from the creek and embankment toe. With the new location of the foundaions, the geotechnical engineer has said we can use 25psi as the rock-to-grout interface shear strength.
RE: uniaxial compressive strength vs bearing pressure
RE: uniaxial compressive strength vs bearing pressure
That's your correlation.
When dealing with rock mass, this is meaningless as you can't depict defects in the rock mass when doing an unconfined compressive strength test in the laboratory.
There are all sorts of ways to look at the strength of a rock mass. I refer you to my thesis for more information (and citations to better references then my actual thesis - ha).
http://home.comcast.net/~fatt-dad/thesis.pdf
f-d
¡papá gordo ain't no madre flaca!