三种岩石巴西劈裂及单轴压缩试验对比研究

Comparative Research of Brazilian Splitting and Uniaxial Compression Tests on Three Kinds of Rock

利用RMT-150C岩石力学试验机,对取自雅砻江两河口水电站坝址的砂板岩、三峡库区的砂岩和宜昌城区的泥岩进行巴西劈裂和常规单轴压缩试验。结果表明:1 3种岩样的抗拉强度之比为1∶0.42∶0.16,劈裂破坏时,砂板岩和砂岩表现出脆性,泥岩表现粘性。2 3种岩样应力-应变曲线峰前变形特征相似,力学性态稳定,峰后砂板岩和砂岩应力跌落迅速,脆性特征明显,而泥岩在峰后还保持较高的强度,属于塑性破坏。3 3种岩样各自的抗拉强度、抗压强度和变形参数均存在离散性。4 3种岩石单轴抗压强度远大于抗拉强度,且抗压强度分别为各自抗拉强度的7.438、14.867和8.38倍,且巴西劈裂条件下的弹性模量、泊松比远小于单轴压缩条件下的。

The Brazilian split and conventional uniaxial compression tests are carried out for the sand slate rock from Lianghekou Hydropower Station dam site in Yalong River, the sandstone rock in Three Gorges Reservoir area and the soft rock in Yichang City area by using RMT-150-C testing machine. The results show that： a） under the condition of splitting, the tensile strength ratio of three kinds of rock is 1 ： 0.42： 0. 16, and the sand slate rock and sandstone rock show brittleness and the soft rock shows viscosity when they are failed; b） under the condition of uniaxial compression, the stress-strain curve and deformation characteristics of three kinds of rock are similar before peak strength and the mechanical properties are stable, the stress of sand slate and sandstone fall rapidly after reaching peak strength and the brittle characteristic is significant, while the soft rock still maintains high strength after peak strength and belongs to plastic failure; c） the tensile strength, compressive strength and deformation parameters of three kinds of rock are discrete; d） the uniaxial compressive strength is much greater than tensile strength with a magnitude of 7. 438, 14. 867 and 8. 38 times to tensile strength respectively, and the elastic modulus and Poisson ratio under the condition of Brazilian splitting are far less than that under the condition of uniaxial compression.