Stiffness of Rock

[lvkb]

I am trying to model the response of a laterally loaded pile in rock, and to do this I need to know the modulus (E) and the spring stiffness (K) of the rock. I have information from load tests on the rock samples giving values for Uniaxial Compressive Strength. Is there any way of getting a reasonable estimate for E and K from this information?

 

[Ron]

Depending on the type of rock, E will be similar to concrete, likely in the 3x10^6 to 5x10^6 range. It would be good if you could get a stress-strain curve for the rock...you would then be able to solve both. Even a generalized stress-strain curve of the rock type would help.

 

[eric1037]

I would ask the geotechnical engineer to provide that information.

 

[GeoPaveTraffic]

The values will depend on the type of rock as well as the strength. Additionally the type, spacing, and proximity of the joints will affect these values. The direction of loading will also effect these values as most rock is isotropic.

All that said, relative to a latterally loaded pile, the rock is infinity stiff. The joints on the other hand are very soft. Therefore the performance of you pile will depend on the quality, not strength/E/k of the rock.