摘要
Static and dynamic splitting tests were conducted on ring marble specimens with different internal diameters to study the tensile strength and failure modes with the change of the ratio of internal radius to external radius （ρ） under different loading rates. The results show that the dynamic tensile strength of disc rock specimen is approximately five times its static tensile strength. The failure modes of ring specimens are related to the dimension of the internal hole and loading rate. Under static loading tests, when the ratio of internal radius to external radius of the rock ring is small enough （ρ〈0.3）, specimens mostly split along the diametral loading line. With the increase of the ratio, the secondary cracks are formed in the direction perpendicular to the loading line. Under dynamic loading tests, specimens usually break up into four pieces. When the ratio ρreaches 0.5, the secondary cracks are formed near the input bar. The tensile strength calculated by Hobbs’ formula is greater than the Brazilian splitting strength. The peak load and the radius ratio show a negative exponential relationship under static test. Using ring specimen to determine tensile strength of rock material is more like a test indicator rather than the material properties.
对不同内径的大理岩圆环试样进行静态和动态劈裂试验,研究其在不同加载速率下的抗拉强度和破坏模式随内外径比值(ρ)的变化规律。结果表明:圆盘试样的动态抗拉强度约为其静态抗拉强度的5倍。圆环试样的破坏模式与试样内径大小以及加载速率有关。在静载试验条件下,当试样内外径比较小(ρ<0.3)时,试样以沿加载径向劈裂破坏为主,而随着内外径比的增大,在垂直加载方向上产生次生拉伸裂纹。在冲击荷载作用下,圆环破裂成4块,且当试样内外径比为0.5时,次生裂纹靠近入射杆。采用Hobbs公式计算的抗拉强度均比巴西圆盘的劈裂强度大,且静态劈裂试验的峰值荷载和圆环试样的内外径比呈负指数变化规律。利用圆环试样确定的岩石抗拉强度更像是材料的一种试验指标而不是材料属性。
基金
Project(2015CB060200)supported by the National Basic Research Program of China
Project(51474250)supported by the National Natural Science Foundation of China
Project(2015JJ3166)supported by the Natural Science Foundation of Hunan Province,China
