一种基于统计损伤本构关系的岩石脆性评价新方法

脆性评价对岩石（尤其是深部岩石）的可压裂、开挖损伤及岩爆等特性的研究具有重要意义.为此,总结国内外岩石脆性评价方法,基于现有脆性指数在定量表征岩石脆性程度中的局限性,考虑能够模拟岩石应力-应变全过程曲线的统计损伤本构模型,分析岩石的损伤演化特征,提出一种基于统计损伤本构关系的岩石脆性特征评价新方法,建立脆性指数B_D定量表征岩石的脆性程度,通过模型理论论证和室内三轴压缩试验验证脆性指数的合理性.结果表明:脆性指数B_D能很好地表征岩石的脆性特征,基于统计损伤本构关系的岩石脆性评价方法具有较好的适用性；通过大理岩、花岗岩以及塔木素黏土岩不同围压下的物理实验,验证脆性指数B_D的正确性及相比其他方法的优越性；随着围压的增大,塔木素黏土岩表现出明显的脆性破坏向塑性破坏转变的特征.

A new method for rock brittleness evaluation based on statistical damage constitutive relation

Brittleness evaluation is of great significance to the study of fracturing, excavation damage, and rock burst characteristics of rocks (especially deep rocks). The rock brittleness evaluation methods at home and abroad were summarized. Based on the limitation of the existing brittleness index in quantitatively characterizing the brittleness of rock, the statistical damage constitutive model which can simulate the whole process curve of rock stress-strain was considered, and the damage evolution characteristics of rock were analyzed. A new method for evaluating the brittleness characteristics of rock based on statistical damage constitutive relation was proposed. The brittleness index B_D was established to quantitatively characterize the brittleness of rock, and the rationality of the brittleness index was verified by model theory demonstration and laboratory triaxial compression test. Results show that the brittleness index B_D could well characterize the brittleness of rock, and the rock brittleness evaluation method based on statistical damage constitutive relation had good applicability. The correctness of the brittle index B_D and its superiority compared with other methods were verified by physical experiments of marble, granite, and Tamusu clay rocks under different confining pressures. Moreover, as confining pressure increased, Tamusu clay rocks showed obvious characteristics of transition from brittle failure to plastic failure.