考虑中间主应力Hoek-Brown强度准则及其适用性

为考虑中间主应力对岩石极限破坏强度作用，在广义Hoek-Brown强度准则幂率项中添加定量表征中间主应力项，构建新的三维Hoek-Brown强度准则。该准则在主应力空间是通过3个角点外接Hoek-Brown准则包络面的曲六面体，在 空间包络线是幂律型曲线。通过与Hoek-Brown准则、Drucker-Prager准则和Mogi准则分别对4组真三轴压缩强度试验数据的拟合对比分析，探讨其反映中间主应力效应的适用性。结果表明，修正的Hoek-Brown强度准则拟合试验数据效果总体最好，Mogi准则次之，Hoek-Brown准则和Drucker-Prager准则较差。从而修正的Hoek-Brown强度准则最适用于粗面岩、大理岩和花岗岩等硬脆性岩石的真三轴强度预测及中间主应力影响规律描述。

A new three-dimensional Hoek-Brown strength criterion considering effect of intermediate principal stress and its applicability

To evaluate the effect of the intermediate principal stress on the ultimate strength of rock, a new three-dimensional (3D) Hoek-Brown failure criterion is established by adding a quantitative representation of the intermediate principal stress to the power-law item of the generalized Hoek-Brown failure criterion. The new failure criterion in principal stress space is a curved hexahedron circumscribing the envelope of the Hoek-Brown failure criterion through three angular points. It is a nonlinear power-law curve in the plane. Comparative study with three different rock failure criteria i.e. Hoek-Brown criterion, Drucker-Prager criterion, and Mogi (1971) criterion is conducted by fitting the triaxial test data of four different rocks. Then the applicability of four failure criteria is discussed on describing the effect of intermediate principal stress. The results show that the new 3D Hoek-Brown failure criterion fits the triaxial strength data best, followed by the Mogi (1971) criterion, whereas the Hoek-Brown criterion and the Drucker-Prager criterion have a relatively poor performance. Therefore, the new 3D Hoek-Brown failure criterion is the most suitable to predict the true triaxial strength and to describe the effect of the intermediate principal stress on trachy, marble, granite and other hard brittle rocks.