MohrCoulombin

MohrCoulombin is not a standard term in geotechnical engineering or materials science. It appears to be a concatenation of the Mohr and Coulomb names or a misspelling of the Mohr-Coulomb criterion, which is a widely used model for the shear strength of soils and rocks. When encountered in literature or software, it most likely refers to the Mohr-Coulomb failure criterion in some abbreviated or variant form.

The Mohr-Coulomb criterion describes the shear strength on a plane within a material as a linear function of the normal stress on that plane. The classic equation is tau = c + sigma_n tan(phi), where tau is the shear stress at failure, sigma_n is the normal stress on the plane, c is the material’s cohesion, and phi is the internal friction angle. This relationship yields a straight-line failure envelope in shear-normal stress space. In effective stress terms, c and phi are replaced by c' and phi' to account for pore pressure in saturated soils.

In practice, the Mohr-Coulomb criterion is calibrated from laboratory tests, such as unconfined compression, direct shear, or triaxial tests, to obtain c' and phi'. It is widely used in geotechnical design for assessing slope stability, bearing capacity of foundations, underground excavations, and earth dam performance. The criterion provides a simple and intuitive framework but has limitations: it assumes isotropy, rate independence, and a linear envelope that may not capture nonlinear or time-dependent behavior in some soils, particularly clays or materials under cyclic loading.

See also: Mohr circle, Coulomb friction, shear strength, effective stress.