The size effect ?

[Chen1]

Hello there,

I want to model an underground coal mine, the mine is overlain and underlain by different kinds of rock such as Sandstone, Shale,.......etc. I have the laboratory test results for samples of these rocks, the height of the sampel is 2.0 in and the diameter is 1.0 in

We know from both experience and theory that the strength of the laboratory samples is much higher than than the field rock, It might be 2 or 3 times higher. the reason is the field rock have more defects such as cracks and joints,.....etc.

The question is :
I am using Abaqus Software to simulate that underground mine. how can i overcome that problem, the size effect. You know we input the material properties in Abaqus, which material properties should i input, laboratory material or the field material?

Thanks.

 

[IRstuff]

Simulating to do what?

TTFN
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[Chen1]

Underground mine is similar to superstructure, we cut coal ( make Rooms) and leave some pillars between these rooms, the size of these columns is very big, for instance (60 ft x 60 ft x 8 ft)

my job is to ensure that these pillars are stable and safe.

 

[IRstuff]

How did they do it before you got this newfangled program? Presumably, they did hand calculations using some minimum value of lab measurements coupled with some sort of safety factor.

TTFN
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[MechEng2005]

If I want to know how an aluminum structure will respond to loads, I use the properties of aluminum. If I want to know how the rock in the field will respond, it would only make sense to use the properties of the rock in the field.