Shear Strength Reduction Method Based On The Hoek-Brown Criterion And Its Numerical Implementation

The finite element strength reduction is one of the most important methods of rock soil mass stability analysis,strength reduction based on linear Mohr-Coulomb criterion has beenwidely developed. But the strength reduction methods based on nonlinearfailure envelope, such as Hoek-Brown, nonlinear Mohr-Coulomb criterion, need further developing and improving.In this paper,Hoek-Brown and nonlinear Mohr-Coulomb criterion were taken as research objects, preliminary study was proceed to which has possibility to be applicable to all.kinds of nonlinear strength criterion of generalized strength reduction method. The specific research contents are as follows:(1) Expressions of Mohr-Coulomb criterion in normal stress a-shear stress τ space, p-q space, principal stress space were summarized. Stress invariant expression and detail derivation process of elastic-plastic theory basic formula based on Mohr Coulomb criterion were introduced.(2) Expressions of Hoek-Brown and nonlinear Mohr-Coulomb criterion in normal stressaand shear stressτ space, principal stress space were introduced.(3) Three kinds of classical soil slopes were picked for stability computation based on conventional strength reduction method of Mohr-Coulomb criterion, the accuracy of the program is verified by contrasting approaches. We have obtained some results by the research work, as follows:(1) Expressions in p and q space,stress invariant and detail derivation process of elastic-plastic theory basic formula based on Hoek-Brown and nonlinear Mohr Coulomb criterion were derived. The existing strength reduction methods based on Hoek-Brown criterion were summarized.(2) Visual interface of geomaterial model visualizer (v1.0) program was developed using Matplotlib program library based on Python, form which people could have comprehensive observations to the yield surfaces of some strength criterions. This interface can be used in teaching and reserch.(3) A new strength reduction method for Hoek-Brown criterion, σci&mb equal proportion reduction method, was proposed, which is based on the normal stress σ and shear stress τ expressionraised by Kumar et al.(4) Computation module for σci&mb equal proportion reduction method had been added to finite element program, σci & s reduction method proposed by Lin was also wrote in the program as authentication scheme. Tow homogeneous rock slopes and a non-homogeneous rock slope analysis examples were applied to numeric calculation, which could indicate that the σc1&mb equal proportion reduction method with clear principle was easy to understand and could obtain reliable safety coefficient in a short period of time.