When and why add water to shear box?

[mntgoat]

If anyone has any info on when to run a direct shear under water, it would be greatly apprefciated. Astm D3080 states that the shear box apparatus should be capable of holding and shearing underwater, but doesn't state when thats applicable. Thank you in advance for your thoughts.

 

[TDAA]

When you need to know the saturated shear strength of soil in water. It is like most other tests that can have variable parameters: you adjust them to get information that is appropraite to what you are engineering.

 

[22222222]

To get effective strength parameters of soil.

 

[dgillette]

22222222:

You're referring to the soil having some capillarity that creates apparent cohesion, and you want to get rid of that by flooding the specimen? (May take a while if the soil has clay in it.)

I've also seen the flooding used to identify collapse or swell potential prior to shearing. (Put the normal stress on, attach a dial gauge or 21st century equivalent, then flood it.)

DRG

 

[22222222]

Dgillette,

I was only talking about the saturated sample of granular material to get effective parameters of soil from direct shear test.

mntgoat
was talking about underwater testing what I understood like saturated condition.
22222222