Hoek-Brown准则高应力条件下断续节理岩体复合损伤本构模型及演化特征

针对岩石损伤本构模型中岩石微元强度采用M-C、D-P等强度准则作为判定依据存在的局限性,基于概率统计理论与连续损伤力学理论,采用应力不变式表示的H-B准则来描述岩石微元强度并假设岩石微元强度服从Weibull分布,认为岩石材料承载能力可以分为弹性和损伤两部分,基于Lemaitre应变等效性假设,推导出基于H-B准则的宏细观复合损伤本构模型,并通过预置裂隙粗晶大理岩试样的三轴试验数据验证了其合理性。结果表明,该模型获得的应力应变理论曲线与试验数据吻合较好,宏细观复合损伤演化过程能反映岩石应力随应变的变化过程,优于同类型本构模型的拟合效果;随着围压的增加,试样强度逐渐增加,峰值应力对应的复合损伤值逐渐增大;在围压一定的条件下,节理岩样的宏细观复合损伤在节理倾角为45°左右时最小,这与节理岩体强度随节理倾角的变化规律相一致。

Compound Damage Constitutive Model and Evolution Characteristics of Intermittent Joint Rock Mass under High Stress Conditions Based on Hoek-Brown Criterion

To overcome the limitation of existing rock damage constitutive models in which the M-C and D-P strength criteria are used as the basis for determining the strength of rock microelements.based on the probability statistics theory and the continuous damage mechanics theory,a macro-meso composite damage constitutive model was proposed and the H-B criterion expressed by stress invariant was employed to describe the strength rock microstructures.For the proposed model,the element strength of rock microelements is assumed to follow the Weibull distribution,and the bearing capacity of rock materials is considered to be divided into two parts.elasticity part and damage part.Then.equations of this model is derived based on the assumption of Lemaitre strain equivalence.The rationality of the constitutive model is fully verified by the triaxial test data of the fractured coarse-grained marble sample.The result shows that the stress-strain theoretical curve obtained by the proposed model agrees well with the experimental data.The macro-meso composite damage evolu-tion process can perfectly demonstrate the change process of rock stress with strain,and it also has higher fitting accuracy than other constitutive models of the same type.With the increase of confining pressure,the strength of the sample grad-ually increases,and the composite damage value corresponding to the peak stress gradually increases too.Under a certain confining pressure,around the inclination angle of 45°,the macro meso composite damage of the joint rock is the smal-lest,which is consistent with the change law of joint rock strength with inclination angle.