Hi all, Rushan Gizzatullin Stefanos Papavasileiou Dennis Waterman

I have some doubts and correct me if i'm wrong.

01. I have found this equation in Plaxis 2D reference manual 2020 in page number 435. Is this equation correct ?

02. Mobilized shear strength is explained as the "radius of the Mohr stress circle" and maximum shear stress is explained as "maximum shear stress when increasing the circle (keep center constant) until the circle touch the failure envelope", then this shouldn't be the maximum shear strength (only the failure one) {definition as per in the plaxis 2D reference manual 2020). Therefore mobilized shear strength going to give maximum strength and maximum shear stress going to give the shear strength in the failure envlope (not the maximum one) when soil in the stress nearly equal to the failure mohr circle for the give c and phi soil. Then how this equation is correct [as both indicating different points in the same failure mohr cicle (considering relative shear stress is 1)]?

Thanks.