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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。
The static and dynamic splitting tests of marble rings with different inner diameters were carried out to study the variation of tensile strength and failure mode with the ratio of inner diameter to outer diameter (ρ) under different loading rates. The results show that the dynamic tensile strength of disc specimen is about 5 times of its static tensile strength. The failure mode of the ring specimen is related to the sample inner diameter and the loading rate. Under the static load test conditions, when the inner and outer diameter of the sample is relatively small (ρ <0.3), the specimen is mainly fractured and broken along the radial direction of loading, and it is generated in the vertical loading direction as the ratio of inner diameter to outer diameter increases Secondary stretch cracks. Under the action of impact load, the ring breaks into 4 pieces, and when the inner-outer diameter ratio is 0.5, the secondary cracks are close to the entrance rod. The tensile strength calculated by Hobbs formula is larger than that of Brazil disc, and the negative exponential change of the peak load of static splitting test and the inner-outer diameter ratio of ring specimen is negative. The tensile strength of a rock, determined using a ring specimen, is more a test indicator of the material than a material property.