硬脆性玄武岩破裂变形特征研究

为了深入研究白鹤滩坝址区杏仁状玄武岩的破裂变形特征,重新整理室内单轴和三轴压缩试验成果,获取杏仁状玄武岩的应力应变曲线、破坏特征和强度特征,结果表明,杏仁状玄武岩的脆性特征显著,试件最终形成贯穿的从左上延伸到右下的倾角约70°的大裂缝。采用连续非连续的数值分析方法CDEM进行细观数值模拟,确立杏仁状玄武岩的应力应变曲线、破坏特征和裂纹演化特征,结果表明,随着围压增大,试件逐渐从拉剪破坏过渡为剪切破坏。同时利用CDEM模拟圆形洞室开挖过程中的破裂现象,研究成果表明,连续非连续的数值分析方法CDEM在模拟硬脆岩石的渐近破坏方面具有一定优势,数值模拟结果与室内试验结果具有较好的一致性,为进行下一阶段工程尺度的数值模拟奠定基础。

Study on Fracture Deformation Characteristics of Hard Brittle Basalt

In order to deeply study the fracture deformation characteristics of almond-shaped basalts in Baihetan dam site, indoor uniaxial and triaxial tests results were reorganized to obtain the stress-strain curves, failure characteristics and strength characteristics. The results show that almond-shaped basalt has typical brittle characteristics and finally formed a big crack with dip angle of about 70° extending through the specimen from the upper left to the lower right when it failed. Microscopic numerical simulations were carried out by using continuous discontinuous numerical analysis method CDEM to establish the stress-strain curves, failure characteristics and crack evolution characteristics of almond-shaped basalts. The results show that as the confining pressure increases, the specimens gradually change from tensile-shear failure to shear failure. At the same time, the rupture phenomenon during the excavation of circular cavern was simulated by using CDEM. The research results show that the continuous and discontinuous numerical analysis method CDEM has certain advantages in simulating the asymptotic failure of hard brittle rocks. The numerical simulation results are in good agreement with the indoor test results, laying the foundation for the next stage of engineering scale numerical simulation.