Hoek-Brown准则在岩石强度各向异性评价中的应用

Application of Hoek-Brown Criterion in the Evaluation of Rock Strength Anisotropy

完整岩石强度随非连续界面角度发生变化而变化,因此具有各向异性。修正的Hoek-Brown准则可以对岩石的强度各向异性特征进行合理预测。通过对沉积岩及变质岩两大岩类、共23组岩样单、三轴测试结果进行分析,获取相应强度各向异性参数Kβ及Rc,结果表明:岩石各向异性强弱与原岩类型、压实和胶结等沉积成岩作用、微裂隙发育程度及变质作用等因素有关。对于结构完整的沉积岩石,煤岩的各向异性最强,其次为页岩,而砂岩、泥岩和灰岩的各向异性相对较低。变质岩中板理发育的板岩各向异性最强,片麻岩次之,片岩和大理岩的各向异性相对较低。K_(min)与Rc间满足幂指数关系,K_(90)/K_(min)与Rc间满足线性关系,建立了各向异性岩石K_(min)分类标准。最后利用Londe转换和σcβ预测效果验证了修正的Hoek-Brown准则方程具有较高预测精度,结果可靠,从而为岩石强度各向异性更深入研究提供参考和依据。

The strength of intact rock changes with the discontinuous interface angle. The modified Hock- Brown criterion can forecast the strength of anisotropy rock. In this paper, we analyze two large sedimen- tary and metamorphic rocks, the uniaxial and triaxial test results of a total of 23 groups of samples, and obtain the corresponding anisotropic parameter Kp and Re. The result shows that the rock anisotropy is correlated with the original rock type, sedimentary diagenesis such as compaction and cementation, the de- gree of micro crack development, and metamorphism. For the intact sedimentary rock, the anisotropy of coal is strongest, followed by shale, while the anisotropy of sandstone, mudstone and limestone is rela- tively low. The anisotropy of slate in the metamorphic rock develops most, followed by gneiss, while the anisotropy of schist and marble is relatively low. The parameter I＇~min determined by the modified H-B crite- rion has a power relationship with Re, and there is linear relationship between K90/Kmin and Rc, and the rock anisotropic classification standard of Kmin is established. Finally, the study validates that the modified H-B criterion has high prediction accuracy by using Londe transformation and σcβ prediction result. The re- suits are reliable, and can provide reference and basis for more indepth study of the rock anisotropy.