非贯通裂隙岩体损伤演化率相关性及变形特征

Rate correlation and deformation of damage evolution of non-penetrating fractured rock masses

含非贯通裂隙岩体是自然界中岩体的主要赋存形式,其裂隙几何特征对岩体的强度及变形均产生显著影响。应变率对岩体的损伤演化及黏滞效应也具有显著的率相关性。首先,运用模型元件的方法,将非贯通裂隙岩体动态破坏过程视为具复合损伤、静态弹性特性、动态黏滞特性的非均质点组成,对黏弹性响应的Maxwell体进行改进,将细观损伤体与裂隙损伤演化的宏观损伤体根据等效应变假设并联组成宏细观复合损伤体,构建综合考虑岩体宏细观缺陷的动态损伤模型;其次,基于断裂力学及应变能理论,对岩体宏观裂隙动态扩展的能量机制进行分析,综合考虑初始裂隙应变能、裂隙动态损伤演化过程应变能、裂隙闭合应变能,得到裂隙岩体宏观动态损伤变量计算公式;最后,将模型计算结果与实验结果进行比较,模型计算结果与实验结果吻合较好,证明了模型的合理性,同时利用模型讨论了裂隙倾角、应变率、岩石性质对岩体变形特征的影响规律。

The non-penetrating fractured rock mass is the main form of rock mass in nature, and the geometric features of its fractures play a remarkable role in its strength and deformation. Its strain rate also has a significant rate dependence on its damage evolution and viscous effects. Firstly, using the model element method, we treated the dynamic failure process of non-penetrating fractured rock mass as a heterogeneous point with composite damage, static elastic properties and dynamic viscous properties, and improved the Maxwell body that responds to viscoelasticity. Then we combined the meso-damaged body and the macroscopic damage body of fracture damage evolutions into a macro-microscopic composite damage body following the equivalent strain hypothesis and constructed a dynamic damage model considering the macroscopic and microscopic defects of the rock mass. Furthermore, based on the fracture mechanics and strain energy theory, we analyzed the energy mechanism of the macroscopic fracture dynamic expansion of rock mass and obtained the calculation formula of the macroscopic dynamic damage variable of the fractured rock mass, with the initial fracture strain energy, the strain energy of the crack dynamic damage evolution process and the fracture closed strain energy, taken into consideration. Finally, we compared the results from the model calculation with those from experiment and found them in good agreement, thereby proving the rationality of the model. At the same time, we also discussed the influence of fracture inclination, strain rate and rock properties on rock mass deformation characteristics using the model.