关键词: 隧道, 围岩, 稳定性, Hoek-Brown准则, 屈服接近度

Abstract:

In order to build an assessment standard for surrounding rock mass with the Hoek-Brown criterion, firstly, the relationship between Hoek-Brown criterion and Mohr-Coulomb criterion is theoretically analyzed; the yielding approach index (YAI) described by Hoek-Brown criterion parameters is obtained; secondly, the three dimensional calculation for tunnel is founded by FLAC3D, the program of yielding approach index for Hoek-Brown criterion (YAIhb) is compiled; the impacts of material parameters and stress variation to the YAIhb are analyzed, which show that: (1) the areas of YAIhb=1 calculated by the self-compiled program are the same with the plastic areas calculated by FLAC3D, which validates the correction of the self-compile program, and moreover the YAIhb can reflect the yield degree of each element which is superior to the plastic zone distribution standard; (2) with the increase of geological strength index GSI, YAIhb reduces gradually, and the relationship between GSI and YAIhb can be described precisely by the cubic-polynomial equation; with the increase of rock uniaxial strength σci, YAIhb increases gradually in the exponential form; with the damage of element increase, the YAIhb increases gradually, which shows the failure degree of element increases, the relationship between YAIhb and damage index D is in accordance with the hyperbola principle; (3) the increase of maximum principal stress σ1 will lead to the decrease of YAIhb, and their relationship is in accordance with the linear principle; the increase of intermediate principal stress σ2 will lead to the variation of YAIhb in the form of first increase then decrease; and their relationship in accordance with the cubic-polynomial principle; YAIhb increases linearly with the increase of minimum principal stress σ3.

Key words: tunnel, surrounding rock mass, stability, Hoek-Brown criterion, yielding approach index