低温–动荷载耦合作用下砂岩破坏断口的形貌分析  

Fractography analysis of sandstone failure under low temperature-dynamic loading coupling effects

作　　者：闻名[1] 许金余[1,2] 王浩宇[1] 方新宇[1] 郑广辉[1] 

机构地区：[1]空军工程大学机场建筑工程系,陕西西安710038 [2]西北工业大学力学与土木建筑学院,陕西西安710072

出　　处：《岩石力学与工程学报》2017年第A02期3822-3830,共9页Chinese Journal of Rock Mechanics and Engineering

基　　金：国家自然科学基金资助项目(51378497)~~

摘　　要：利用增加了低温补偿装置的大直径分离式霍普金森压杆(SHPB)系统,进行不同负温等级下的砂岩实时动态抗压试验,而后对试件破坏断口进行电镜扫描观察,分析断口形貌特征,并对提取出的微裂隙进行量化处理,得出红砂岩的动态破坏规律。试验结果表明:冻结岩石的动态抗压强度随应变率的增加而提高,随冻结温度的降低而提高,表现出显著的率强化效应与低温硬化效应;低应变率下,断面以胶结物质断裂、脆性断裂为主要断裂模式,耗能普遍偏低;高应变率下,在前2种断裂模式的基础上断面局部出现韧性破坏特征,耗能等级偏高;提取断面裂隙网络,用图像数字处理的方法对断口的孔隙特征进行分析,得出孔隙数量、平面孔隙度、孔隙形状因子的变化规律;将岩石宏观力学性质与断口微观形貌相结合,并立足于微观尺度分析裂纹扩展规律。研究成果对寒区岩体的理论研究与工程实践具有一定参考意义。Dynamic mechanical performance experiments are carried out for red-sandstone specimens in different low temperatures under impact loading,by using the ？ 100 mm split Hopkinson pressure bar（SHPB） with a low temperature compensation device.Then,the scanning electron microscope（SEM） is carried out to study its microcosmic character of failure surface,and dynamic compression failure rules of red sandstone are acquired by the quantitative processing of fracture network.The results indicate that,the peak stress of red sandstone increases with the increase of strain rate,and the peak stress increases with the decrease of temperature.The strengthening effect of strain rate and the hardening effect of low temperature are obvious.In low strain rate,the primary modes of failure surface are cementing material fracture and brittle fracture,with the low energy-consuming.In high strain rate,with the former fracture modes,the surface partially appears ductile damage,while the grade of energy-consuming is pretty high.The quantitatively analysis of fracture network come to the change rules of the pore number,the plane porosity and the pore＇s shape factor.With the combination of experimental results and probability theory,the dynamic failure mechanism of frozen rock is illustrated from a new perspective.The research results have important significance to the theoretical study and engineering practice of the rock mass in cold regions.

关 键 词：岩石力学 冻岩 动态抗压强度 微观结构 SEM图像数字处理 

分 类 号：TU45[建筑科学—岩土工程]