What is Hoek-brown criterion in geotechnical engineering?

1. Numerical calculation model of bearing capacity of soft rock foundation based on finite difference analysis (FLAC). In the analysis, the soft rock foundation is regarded as a homogeneous isotropic continuous medium, and the ideal linear elastic-plastic constitutive relation simulation, Hoek-Brown nonlinear failure criterion and uncorrelated flow law are adopted.

2. In order to facilitate numerical simulation, Hoek-Brown nonlinear failure criterion is transformed into Mohr-Coulomb linear failure criterion by tangent method, and the formulas for calculating instantaneous internal friction angle and instantaneous cohesion are derived according to equivalence principle, and a subroutine based on FLAC built-in FISH language is compiled. By using vertical velocity vector, the ultimate bearing capacity of circular foundation with and without rock mass weight is obtained respectively.

2. Compared with the theoretical value and the field load plate bearing capacity test results, Hoek-Brown solution is closer to the measured value than Bell solution, but both of them are conservative, while the numerical calculation results are very close to the measured value, especially when considering the self-weight, the error is only 2%. The results show that it is appropriate to analyze the ultimate bearing capacity of soft rock foundation by FLAC numerical model based on Hoek-Brown nonlinear failure criterion.