关键词: 岩石脆性指标, 锦屏II级水电站, 铁路隧道, 全应力?应变曲线, 应力变化速率

Abstract: As an important mechanical index of rocks, brittleness is of great significance for deep rock mass behavior assessment and disaster prevention. The stress-strain curve of rock can well represent rock brittleness. Considering that most of the existing brittleness indicators based on stress-strain curves only analyze a part of the curve, and few indices can be accurately applied to the rock II type curve, lack of overall consideration may lead to the inadequate adaptability and reliability in engineering application. In order to solve those problems, such as the unclear physical meaning and the discontinuous relationship between the evaluation results and rock brittleness of the existing brittleness indices based on the complete stress-strain curve of rock, the influences of pre-peak stress rising rate, post-peak stress falling rate and peak strain on rock brittleness were analyzed, and a method of rock brittleness index with clear physical meaning, monotonous and continuous relationship between calculation results and rock brittleness was proposed. The commonly used brittleness indices were selected to compare the brittleness evaluation of the marble of Jinping II hydropower station and the granite, metamorphic sandstone and gneiss of a railway under uniaxial compression conditions, which verified the applicability of the index proposed. This novel brittleness index was further applied to the brittleness evaluation of marble under conventional triaxial test conditions. The results showed that this index could not only quantify and classify the brittleness characteristics of different rock types, but also characterize the confining pressure inhibition behaviors of rock brittleness.

Key words: rock brittleness index, Jinping II hydropower station, railway tunnel, complete stress-strain curve, stress change rate