单轴压缩下薄喷裂隙红砂岩力学性质与裂纹扩展特征分析

Mechanical properties and crack propagation behavior of flawed red sandstone coated with a thin spray-on liner under uniaxial compression

选取红砂岩为研究对象,采用水泥基薄喷材料,制作完整和裂隙红砂岩薄喷岩石试样,研究在单轴压缩条件下薄喷材料对完整和裂隙红砂岩强度、变形和能量演化特征的影响;采用颗粒流PFC3D软件,分析薄喷材料对不同裂隙倾角试样裂纹扩展特征的影响。结果表明:薄喷红砂岩试样的峰值强度和应变较无薄喷红砂岩均有提高,裂隙试样的提升系数高于完整试样;峰后阶段薄喷岩石试样内部岩石发生破坏,表面薄喷材料出现拉伸裂纹,但整体未松散。薄喷红砂岩在破坏时的总能量、弹性应变能和耗散能均高于无薄喷试样,且薄喷材料使外部输入的总能量更多转化为破坏过程所需的耗散能。PFC3D模拟结果表明,薄喷材料增强了不同倾角的裂隙试样的起裂应力和峰值强度。薄喷材料对不同裂隙倾角试样的破坏模式影响程度不同,当裂隙倾角为15º,薄喷材料可以限制峰后拉伸裂纹扩展;但当裂隙倾角为75º,有无薄喷试样的裂纹扩展模式大致相同。该研究可为薄喷材料在工程应用提供一定的参考。

Taking red sandstone as the research object,the intact and flawed red sandstone specimens coated with liner were made using a cement-based thin spray-on liner.The study examined how the thin spray-on liner affected the strength,deformation,and energy evolution of intact and flawed red sandstone under uniaxial compression.Furthermore,the study analyzed how the thin spray-on liner influenced the crack propagation characteristics of sandstone with different inclination angles through particle flow PFC3D software.The results indicate that red sandstone coated with the thin spray-on liner exhibited higher peak strength and strain compared to uncoated specimens.Moreover,the improvement coefficient for flawed sandstone exceeded that of intact specimens.In the post-peak stage,the internal rock of specimens with the thin spray-on liner was damaged,resulting in the formation of tensile cracks on the liner’s surface,although the specimens did not fully collapse.The total energy,elastic energy,and dissipation energy of specimens with a thin spray-on liner are greater than those of uncoated specimens.Moreover,a greater amount of input total energy is converted into dissipation energy post-coating.The PFC3D simulation results indicate that applying a thin spray-on liner can increase the initiation stress and peak strength of crack specimens at different inclination angles.The influence of a thin spray-on liner on the failure modes of specimens with varying crack angles.Specifically,at a 15º inclination angle,the thin spray-on liner hinders the propagation of tensile cracks in the post-peak stage.Conversely,at a 75º inclination angle,the crack propagation behavior of specimens,whether coated or uncoated with a thin spray-on liner,is similar.These research findings can provide a reference for the application thin spray-on liners in engineering applications.