中文摘要：

加载速率效应是岩石材料力学特征的一个重要性质。通过对锦屏Ⅱ级水电站硬脆性大理岩T2b开展单轴抗拉强度特性的加载速率效应试验，获得以下5点试验规律：（1）在巴西圆盘劈裂试验中，岩样的破坏过程基本可以归纳为应力集中区出现、应力集中区扩展、破坏面形成和岩样破坏4个阶段；f21岩样的峰值抗拉强度随着加载速率的提高而呈对数增大；（3）应力峰值对应的平均垂直应变随着加载速率的增大而增大，而平均侧向应变随着加载速率的增大而减小；（41对岩样电镜扫描图进行断口学分析表明，在较低的加载速率（0．000255MPaJs）下，岩样的破坏面中张拉破坏区域（即镜面区）所占的比例较大，剪切破坏区域（即锯齿区）所占的比例较小，且锯齿区分布均匀规则，而在较高的加载速率f2．55MPa／s）下，岩样的断口中镜面区比例较小，锯齿区所占的比例较大，且锯齿区剪切脆断痕迹明显；（51在0．000255MPa／s的加载速率下，岩样一般劈裂成2块，岩石破坏所消耗的能量较小，而在2．55MPa/s的加载速率下，岩样破碎成多块，岩样破坏所消耗的能量较大。本文通过宏细观两方面的分析，并引入断口形貌学的分析方法，揭示了硬脆性岩石力学特性加载速率效应的试验特征和内在机制，为岩石破坏机制研究提供一条新的途径。

英文摘要：

The loading rate effect is an important property of rock materials. The research of the Brazilian splitting test at different loading rates on the hard brittle marble in depth in Jinping II hydropower station shows five characteristics： （1） The failure processes can be almost divided into four steps regarding the loading rates, i.e. stress concentration zones, expanding of the stress concentration zones, shaping of the failure and failure. （2） The peak stress in the Brazilian splitting test logarithmic increases with the increase of the loading rate. （3） The loading rate is higher, the average vertical strain is greater, but the average lateral strain is smaller. （4） According to thefractography, the analysis of the microcosmic fracture surfaces shows that the area of mirror district at the rate of 2.55 MPa/s is less than that a of 0.000 255 MPaJs and the shear failure is dominant; furthermore, the sawtooth district of the 0.000 255MPa/s is regular. （5） At the rate of 2.55 MPa/s, the sample breaks into more pieces and the failure is much more violent than that at a lower loading rate. The energy of sample failure at the rate of 2.55 MPa/s is greater than that at the rate of 0.000 255 MPa/s when calculation. The test result is analyzed in view of macroscopic and microscopic studies; and fractography is utilized to explain the mechanism of the rock failure at different loading rates. The analysis method is helpful for the understanding the loading rate effect and its mechanism.