Foundation Design on Rocks

[ONENGINEER]

I am a soil mechanics engineer but need to design a pad foundation on rock near a slope.

I know rock classification but need to relate my classification results to foundation design parameters. Is there a straight forward methodology for practicing engineers. Thank you.

 

[oldestguy]

A common technique is using a presumptive list of rock types and bearing cap'y for design. Some areas have building code values to use. However, using core borings and unconfined compression tests along with degree of weathering, location of bedding and crack patterns,some of the past experience also come in with shear strength formulas. However, knowing a lot of the discontinuities some degree of engineering opinion also is needed. I think the US Bureau of Reclamation has done large diameter tri-axial compression strength tests to assist in this evaluation.

 

[oldestguy]

Do a Google search.

Try "tri-axial tests on rock cores"

 

[ONENGINEER]

 

[BigH]

Coates wrote a manual that is very good - Coates, D. F. 1970. Rock mechanics principles, D.E.M.R. Mines Branch Mon. 874

 

[racookpe1978]

How much danger is he of having the single "solid rock" crack in sections as he begins to drill in for his foundations and mounts? That would be a function of rock type and the specific local cracks or flaws already in the rock, right?

 

[ONENGINEER]

Thank you for all your feedback.

Also it would be appreciated if on could help m with any minimum width of footings on rock foundations.

The minimum foundation width criteria is better understood for soil foundation but not much for rock.

 

[jayrod12]

If you have adequate bearing you can pour grade beams directly on rock if desired.