Abstract
In order to investigate the influence of the intermediate principal stress on the stress and displacement of surrounding rock, a novel approach based on 3D Hoek-Brown (H-B) failure criterion was proposed. Taking the strain-softening characteristic of rock mass into account, the potential plastic zone is subdivided into a finite number of concentric annulus and a numerical procedure for calculating the stress and displacement of each annulus was presented. Strains were obtained based on the nonassociated and associated flow rule and 3D plastic potential function. Stresses were achieved by the stress equilibrium equation and generalized Hoek-Brown failure criterion. Using the proposed approach, we can get the solutions of the stress and displacement of the surrounding rock considering the intermediate principal stress. Moreover, the proposed approach was validated with the published results. Compared with the results based on generalized Hoek-Brown failure criterion, it is shown that the plastic radius calculated by 3D Hoek-Brown failure criterion is smaller than those solved by generalized H-B failure criterion, and the influences of dilatancy effect on the results based on the generalized H-B failure criterion are greater than those based on 3D H-B failure criterion. The displacements considering the nonassociated flow rule are smaller than those considering associated flow rules.
Highlights
A reasonable assessment of plastic failure scope and its deformation is the key to evaluate the safety and stability of tunnel
Yu et al [1, 2] presented a nonlinear unified strength criterion for rock material, which took the effect of intermediate principal stress into account
On the basis of this, elastic-brittle-plastic solutions based on the Mohr-Coulomb and Hoek-Brown (a = 0.5) failure criteria were proposed by Carranza-Torres [3, 4]
Summary
A reasonable assessment of plastic failure scope and its deformation is the key to evaluate the safety and stability of tunnel. Zou and Su [14] presented an analytical solution of the surrounding rock based on the generalized Hoek-Brown failure criterion and elastic-brittle-plastic model, and this solution is compared with Wang et al [11] to verify its correctness using the method of parameter transformation. Lee and Pietruszczak [19] proposed a numerical procedure for calculating the stresses and radial displacements around a circular tunnel excavated in a strain-softening Mohr-Coulomb or generalized Hoek-Brown media. In this approach, the potential plastic zone is divided into a finite number of concentric rings and it is assumed that all the strength parameters are linear functions of deviatoric plastic strain. The results are compared with those based on generalized Hoek-Brown failure criterion to find differences between the two methods
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