Thanks, Professor! There is another application for the UCS strength rather than using it as a simple index of strength? I guess that in this type of test we are measuring the intrinsic strength of the rock matrix, is not it?
Dear Jubier, As you say, UCS tells you the strength of the rock matrix. However, small cracks invisible to the naked eye or rock hetereogeneity can make the term "rock matrix" subjective or length scale-dependent. A longer explanation here: Section 4.1 dnicolasespinoza.github.io/
It means it's the end of the example. There is typo there, the last equal sign should be deleted. The equation should finish with (1+sin phi)/(1-sin phi).
