Fracture angle of Hoek-Brown materials

The fracture angle (defined as the angle between the normal vector of the fracture plane and the first principal stress) of Mohr-Coulomb is 45 degrees +& phi;/2, which plays a crucial role in soil mechanics. However, for the non-linear Hoek-Brown criterion, the fracture angle cannot be derived as easily as Mohr- Coulomb. Based on the physical evidence that there is no parallel plastic strain in the shear zone, the fracture angle of Hoek-Brown materials, is derived as tan-1 & RADIC;1 + m(2 & RADIC;s + m & sigma;3/& sigma;c). The experimental data of marble and granite and numerical results demonstrate that the obtained theoretical fracture angles agree well with the experimental and numerical fracture angles. & COPY; 2023 Elsevier Ltd. All rights reserved.

Automated summary

The fracture angle of Mohr-Coulomb is 45 degrees + φ/2, which is important in soil mechanics. However, the fracture angle of the non-linear Hoek-Brown criterion is not as easily derived. Using physical evidence of no parallel plastic strain in the shear zone, the fracture angle of Hoek-Brown materials is derived as tan-1√1 + m(2√s + mσ3/σc). Experimental and numerical results confirm the agreement between the theoretical and observed fracture angles.