Fundamental Question 3

[CJJS]

Excuse my lack of knowledge on what is probably a very fundamental soil mechanics question. But, I have looked through my soil mechanics books and searched online, and cannot find a definition of "effective angle of internal friction". Can someone answer this, and what is the difference between this and the "angle of internal friction"? Thanks in advance.

 

[theCorkster]

CJSchwartz;

The answer lies in total and effective. Total stress incorporates the soil response whether partially saturated of fully saturated. Hence, a friction angle from a test run quickly such that the soil cannot drain during shear yields a total stress. Incorporating the effect of pore water response in the soil by either measuring the pore pressure response and subtracting it from the total stress measured, or by running the test sufficiently slow so that no porewater pressure develops (drained test), results in effective stress.

The friction angle measured from a total stress test is the angle of internal friction; the friction angle measured from a test corrected for pore pressure is the effective angle of internal friction.

Check again under total and effective stress and shear strength of soils.

 

[fattdad]

definition of "effective angle of internal friction"

It's the failure envelope when pore pressure is excluded from the forces acting on the shear plane.

Hope this helps.

f-d

¡papá gordo ain’t no madre flaca!