How to estimate Intact strength form Geophysical Log? 1

[t291291]

Dear All,
Can anyone briefly provide me on how to estimate the field intact strenth of material(MPa or KPa) from open hole drilling and gephysically logged (i.e. available data only: SD and GR_).
I am currently reviewing the drill log data that only show the Gama Ray (GR) and Specific Density (SD) magnitude and its graphs for typical coal mine stratigraphy - consists of Claystone, Siltstone, Sandstone, and Coal. What I want to know is how to get the estiamte intact strength form Geophysical Log (SD & GR)? Is there any simple reference?

Many thanks.

 

[BigH]

Please don't double post - you'll have one of them removed. It is highly frowned on and most geotechs read all the geotechnical type forums.

 

[dgillette]

I wouldn't touch that with a ten-foot (three-meter) pole. No reason to expect any kind of good correlation between qu and either SD or GR.

 

[Mccoy]

+1 on dgillettes' answer.

Correlations between failure parameters and your geophysical parameters? No way, dude.

You can have some correlations between elastic parameters and velocity of shear or compression waves.

Over here some guys even correlate Vs to Su and phi-c, but that's totally uncool (technically unsound). A ruse not to pay for geotechnical investigation.

Anyone has valid and recognized literature references on that, I'm going to fast on Christmas day.