水分与冻融环境下岩石动态拉伸试验及细观分析  

Split tensile tests and mesostructure analyses on red-sandstone under moisture and freeze-thaw conditions

作　　者：闻名[1] 许金余[1,2] 王鹏[1] 刘石[1] 方新宇[1] 刘少赫 

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

出　　处：《振动与冲击》2017年第20期6-11,36,共7页Journal of Vibration and Shock

基　　金：国家自然科学基金资助项目(51378497)

摘　　要：利用直径为100 mm的分离式霍普金森压杆(SHPB)装置与电液伺服压力试验机,进行不同含水率及冻融环境下砂岩试件的动静态劈裂抗拉试验,而后对试件破坏断口进行电镜扫描观察(SEM),立足于细观尺度分析断口形貌特征,并对断口裂隙网络进行量化处理。试验结果表明:饱水、冻融循环处理均会削弱岩样的静动态拉伸强度,其中动态拉伸强度表现出显著的应变率增强效应;基于动态拉伸强度定义软化系数与抗冻系数,该软化系数随应变率的增长近似指数下降,而抗冻系数随应变率的增长近似指数上升;红砂岩破坏断口细观形貌特征主要有3类,分别对应不同的宏观力学性质。以裂隙网络的面积作为损伤变量,探究动态劈拉破坏中的水-应变率效应、冻融-应变率效应对岩石内部损伤扩展的影响,并基于此分析了不同状态下红砂岩的动态劈裂破坏机理,对寒区岩体工程的建设、后期维护具有一定指导意义。By using a hydraulic and servo-controlled pressure testing machine and a split Hopkinson pressure bar （SHPB） with a diameter of 100 mm, splitting tensile tests of sandstone with different moisture contents and cycles of freeze-thaw were carried out to study the static and dynamic mechanical properties of sandstone. Then the mesostructure of fracture was analysed base on microscale by pictures obtained through the scanning electron microscope （ SEM） , tensile failure rules of red sandstone was acquired by the quantitatively processing of fracture network. The results indicate that, the tensile strength of red sandstone decreases with moisture contents and cycles of freeze-thaw, and the dynamic tensile strength exhibits obvious strain rate hardening effect. The softening coefficient and the coefficient of frost resistance of red sandstone are defined with the dynamic tensile strength,the softening coefficient decreases with strain rate,while the coefficient of frost resistance increases strain rate. There are three main fracture microstructure characteristics, corresponding to different macromechanical properties. In the area of the fracture network as damage variable, the rock internal damage extension was analyzed by exploring water-strain rate effect and freeze-thaw-strain rate effect in the dynamic splitting tensile damage. And then the dynamic fracturing mechanism of red sandstone under different conditionswas analyzed.

关 键 词：岩石力学 水岩相互作用 冻融 拉伸特性 细观结构 损伤量化 

分 类 号：TU45[建筑科学—岩土工程]