E deformation modulus for weathered Sandstone 1

[besatur1]

Does anyone know a typical values of E for a weathered, for a quick calc, finding it very difficult to locate this information.

It would be greatly appreciated

Many Thanks

 

[fattdad]

Need more information. The rock mass modulus will be affected by the primary (i.e., intact weathered rock properties) and secondary rock characteristics (i.e., fracture spacing).

f-d

¡papá gordo ain’t no madre flaca!

 

[besatur1]

Unfortunately I have not got this information. I was after a general figure, say for, 60-200 mm discontinuity spacing with allowable bearing value of less than 750 kPa weathered Sandstone. Have you got an info on typical E values for weathered rock worst and best case? roughly how much MPa?

 

[fattdad]

For an RQD of about 50, I'd use an Efield/Elab ratio of 0.2. Citing bearing value is of little relavance. More important is the unconfined compressive strength of the intact rock mass or the laboratory modulus value (from the stress-strain curve).

Deere (1969) presents a correlation between RQD and rock mass modulus. For RQD in the range of 35 to 50 his correlation would suggest a value of 0.1 to 0.3 GPa. Note that this is fairly arbitrary in that the correlation does not take into account the value of the intact rock mass - it's just based on RQD.

Another item of note: Rock mass behavior is stress dependent. Depending on your anticipated stresses, the modulus value may exhibit strain hardening or strain softening behavoir. There are some data to model strain-softening behavior (hyperbolic modulus values). This may be more than you are asking for right now. . . .

f-d

¡papá gordo ain’t no madre flaca!