Mohr circle of stress:
The Mohr circle of stress was presented by O Mohr in 1887. According to this cycle within a material at equilibrium the stress at any point can be represented by a circle if the shear stress and the normal stress are plotted using the same scale. Mohr’s circle of stress is the complete representation of the two dimensional state of stress at equilibrium in an element or a point. The above concept of Mohr circle is very useful in geotechnical engineering. Now let’s see how it is used.
While talking about geotechnical engineering, the main area of our interest is the state of stress in the plane that contains the major and minor principal stresses, σ1 and σ3.
The slope of the coulomb’s equation of sheer strength of soil is tanφ, physically which means the coefficient of internal friction of the soil, φ is the angle.