undisturbed samples

[tidykiwi]

I was told that core recovered from boreholes using double barrel cores are not suitable for triaxial testing as they are disturbed and as a result usually request "undisturbed" tube samples for this type of testing. Does anyone know if double barrel borehole cores can actually be used for triaxial testing?

 

[fattdad]

You should be able to tell from the test results whether the samples were affected by the sampling method. I feel like any sampling method can include disturbance and it's the engineer's obligation to see whether the test results are adequate to characterize the field conditions.

I know that this is not a direct answer, but I wouldn't think there's any yes or no answer possible - heck, the driller is the largest factor!

f-d

¡papá gordo ain’t no madre flaca!

 

[GeoPaveTraffic]

Are you talking about soil or rock?

Soil would be very iffy, depending on the type of soil.

Rock, unless it is very soft or has a tendency to swell when pressure is released (like some shales), should be just fine.

 

[emmgjld]

Combining fattdad & GeoPaveTraffic replies with my own thoughts and I make the following list -
Material Type & Consistency
Sampling method
Drilling and Sampling personnel experience & care
Laboratory storage & preparation personnel experience & care
Laboratory testing personnel experience & care
Final consideration of results

The direct answer to your question is - possibly, the samples would be suitable for triaxial testing.

Slightly off topic.

ASTM will soon be consistently using the term 'intact samples' rather than 'undisturbed samples' which may be a step forward in discussions such as this.

 

[theCorkster]

tidykiwi;

Also include the diameter of the sample as well. Bureau of Reclamation used 6-inch diameter Pitcher and Dension samplers - even so, samples were radiographed to attempt to reduce the effort in selecting "undisturbed" samples from which test specimens were then trimmed.

All said, this level of effort is well beyond what occurs in most sampling and testing regimens, and fattdad's, GeoPaveTraffic's and emmjgld's considerations are what ultimately determines the value of the test results.







prior to selecting sections for testing.One can check for sample disturbance using radiographs.