水分与冻融环境下岩石动态拉伸试验及细观分析

发布时间：2018-03-20 09:03

本文选题：岩石力学　切入点：水岩相互作用　出处：《振动与冲击》2017年20期 　论文类型：期刊论文

【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。
[Abstract]:The split Hopkinson pressure bar (SHPB) with a diameter of 100 mm and an electro-hydraulic servo pressure tester were used to conduct the static and static splitting tensile tests of sandstone specimens under different moisture content and freezing and thawing environment. Then the fracture surface of the specimen was observed by scanning electron microscope (SEM), based on the meso-scale analysis of the fracture morphology and the quantitative treatment of the fracture network. The test results show that the fracture surface is saturated with water. The static and dynamic tensile strength of rock samples is weakened by freeze-thaw cycle treatment, in which dynamic tensile strength shows a significant strain rate enhancement effect, and the softening coefficient and freezing resistance coefficient are defined based on dynamic tensile strength. The softening coefficient decreases approximately with the increase of strain rate, while the frost resistance coefficient increases with the increase of strain rate. Taking the area of fracture network as the damage variable, the effects of water-strain rate effect, freeze-thaw strain rate effect and freeze-thaw strain rate effect on the damage propagation of rock are studied. Based on this, the dynamic splitting failure mechanism of red sandstone under different conditions is analyzed, which has certain guiding significance for the construction and later maintenance of rock mass engineering in cold region.
【作者单位】：空军工程大学机场建筑工程系;西北工业大学力学与土木建筑学院;
【基金】：国家自然科学基金资助项目(51378497)
【分类号】：TU45

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