基于Hoek-Brown准则的岩石应变软化模型研究  

A strain-softening model of rock based on Hoek-Brown criterion

作　　者：金俊超 佘成学[1] 尚朋阳 JIN Jun-chao;SHE Cheng-xue;SHANG Peng-yang(State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University,Wuhan,Hubei 430072,China)

机构地区：[1]武汉大学水资源与水电工程科学国家重点实验室,湖北武汉430072

出　　处：《岩土力学》2020年第3期939-951,共13页Rock and Soil Mechanics

摘　　要：基于Hoek-Brown(H-B)准则,根据大量试验数据,研究提出一种具有广泛适用性的岩石应变软化模型。利用40种硬岩和软岩三轴试验数据,验证了3参数幂函数型围压函数广泛适用于硬岩和软岩峰后临界塑性应变与围压的关系描述,并将其引入塑性内变量中;其次,比较分析当前基于H-B准则的岩石应变软化模型中软化参数的合理性,明确以GSI作为软化参数的方法最优,拟合结果正确且参数最少。然后,分析岩石峰后GSI随塑性内变量的演化规律,并建立一种普适的非线性演化模型。与其他演化模型相比,所建模型可更准确地描述不同种类岩石峰后H-B强度参数的非线性演化规律,同时参数较少。接着,采用非关联流动法则,将所建GSI演化模型嵌入有限元软件ABAQUS中,实现软化模型的数值求解。最后,对多种岩石的室内试验模拟结果表明,所建模型可正确描述不同围压下硬岩和软岩的峰后应变软化变形及剪胀变形,具备良好的适用性。与定临界塑性应变或定剪胀角的应变软化模型模拟结果相比,所建模型模拟曲线可一致性地与试验曲线接近。A strain-softening model with broad applicability is proposed with respect to the Hoek-Brown(H-B)criterion based on forty triaxial test results of different hard and soft rocks.Firstly,based on the test results,the three-parameter power-type confining pressure function is verified to be correct for describing the relationship between the post-peak critical plastic stain and confining pressure for different types of rocks,and is introduced into the definition expression of the plastic internal variable.Then,the rationality of the different parameters for describing the softening parameters of the strain-softening model based on H-B criterion is compared and analyzed.It is found that the parameter GSI is best suited for the description.Moreover,the evolution of GSI with the plastic internal variable in the post-peak stage is studied,and a widely applicable nonlinear model is established.By comparing it with the other existing models,it shows that the proposed model can describe the nonlinear evolution of strength parameters of H-B criterion in the post-peak stage more correctly with fewer parameters.The model is applied in the software ABAQUS by adopting the non-associate flow rule.Finally,by simulating the different laboratory tests of rocks,it is proved that,with good applicability,the proposed model can correctly characterize the strain-softening and dilation behavior in post-peak stage of hard and soft rocks under different confining pressures.By comparing it with the models of constant critical plastic strain or constant dilation angle,respectively,it is found that the simulated stress-strain curves by the proposed model are more closely in line with the test results.

关 键 词：岩石力学 HOEK-BROWN准则 塑性内变量 应变软化 剪胀 

分 类 号：TU452[建筑科学—岩土工程]