含裂隙岩石微裂纹起裂扩展及损伤演化分析

Analysis of Microcrack Initiation,Propagation and Damage Evolution in Fractured Rock

为探究含有不同裂隙类型(张开、闭合)、裂隙倾角和裂隙长度岩样的微裂纹起裂扩展及损伤演化规律,基于PFC 2D构建了含裂隙岩样模型并进行单轴压缩数值试验,从细观角度解释了不同裂隙倾角和裂隙类型岩样的起裂及破坏特征差异,并从能量角度对岩样进行损伤分析。结果表明,随着裂隙倾角α的增大,张开型峰值强度呈正相关,闭合型则先减小后增大,弹性模量与峰值强度变化规律一致。当30°≤α≤60°时,两种含裂隙岩样多从裂隙尖端起裂;当60°≤α≤90°时,两种岩样破坏路径相似;基于胶结破坏能定义损伤变量和修正系数,建立了演化模型,分别从裂隙类型、倾角和长度三个角度验证了模型的合理性。研究结果可为进一步了解含裂隙岩体受载后的损伤演化过程提供理论基础。

In order to explore the microcrack initiation,propagation and damage evolution of rock samples with different crack types(opening and closed),inclination and crack length,based on PFC 2D,the fractured rock sample model was constructed and the uniaxial compression numerical tests were carried out.The initial crack and failure characteristics of rock sample under different crack obliquity and type were explained from the perspective of mesoscopics.The damage analysis of rock samples was carried out from the perspective of energy.The results are as follows.With the increase of crack inclination angle,the peak strength of the open type is positively correlated,while that of the closed type decreases first and then increases.The elastic modulus is consistent with the change of peak strength.When 30°≤α≤60°,the microcrack initiation characteristics of the two kinds of fractured rock samples are consistent.When 60°≤α≤90°,the failure paths of the two rock samples are similar.The damage variable and correction coefficient were defined based on the energy of cementation failure,and the evolution model was established.The rationality of the model was verified from the perspectives of fracture type,inclination angle and length.The research results can provide a theoretical basis for further understanding the damage evolution process of fractured rock mass after loading.