硬岩应力–应变曲线真三轴仪研制关键技术研究

基于茂木式岩石真三轴试验原理,介绍真三轴试验机设计中的岩石体积变形测量、端部摩擦效应、应力空白角效应以及真三轴条件下的峰后行为捕捉关键试验技术。此试验系统具有高刚度、大吨位及高响应等特点,能获得真三轴条件下多种硬岩的全应力–应变曲线。同时,利用该试验系统,对不同减摩方案下的摩擦系数进行测试,并评估端部摩擦效应对岩石变形的影响。结果表明:硬脂酸和凡士林混合物具有较好的减摩效果,真三轴试验中,建议采用此减摩方案。端部摩擦往往造成岩石变形的不均匀分布,且对岩石的变形模量和强度有所提高。

Key technology in development of true triaxial apparatus to determine stress-strain curves for hard rocks

Based on the testing principle of the Mogi Type rock true triaxial apparatus,the key technology that the measurement of volumetric deformation of rock,the end friction effect,the loading gap and the capture of the complete stress-strain curves are introduced in terms of the principle for designing. The test system realizes the measurement of the stress-strain curves for hard rocks under the condition of true triaxial compression with high rigidity,large loading capacity as well as fast response. The friction coefficient under different anti-friction conditions and the influence of end friction effect on rock deformation were studied. It is shown that the mixture of stearic acid and Vaseline has good anti-friction effect and is thus recommended to be used in the true triaxial experiments. Meanwhile,the end friction often results in the uneven distribution of rock deformation and the deformation modulus and strength of rock to increase.