不同含水率红砂岩静动态劈拉试验及细观分析

发布时间：2018-07-03 02:58

本文选题：岩石力学 + 水-岩耦合作用　；参考：《地下空间与工程学报》2017年01期

【摘要】：研究水-岩耦合作用下岩石力学特性及细观结构,对减少由地下水造成的深部岩体工程病害具有重要意义。采用直径为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,分析断口形貌特征,依靠SEM图像数字处理技术,进一步得出红砂岩拉伸破坏规律。试验结果表明:红砂岩的劈拉强度随含水率的增加而降低,有明显的遇水软化现象;相比于静态抗拉强度,动态抗拉强度大幅提升,且有显著的应变率强化效应;随着含水率的提高,砂岩试件拉伸破坏时,碎块数量逐渐增多,尺度逐渐减小;饱水岩样的动态劈裂拉伸破坏相比于干燥岩样表现出一定的塑性特征。对断口微裂隙的面积等信息进行定量化处理,分析动态劈拉破坏中的水-应变率效应,得出水在不同应变率下砂岩试样的动态劈拉破坏裂纹扩展中具有均衡作用;微裂隙数量与面积随应变率的提高有增加趋势,破坏断口细观形貌特征存在应变率相关性。
[Abstract]:It is of great significance to study the mechanical properties and meso-structure of rock under the interaction of water and rock to reduce the deep rock mass engineering diseases caused by groundwater. The split Hopkinson pressure bar (SHPB) device with a diameter of 100 mm and the electro-hydraulic servo pressure tester were used to conduct the static and static splitting tensile tests of sandstone specimens with different moisture content, and then the fracture surface of the specimens was observed by scanning electron microscope (SEM). The fracture morphology was analyzed and the tensile failure rule of red sandstone was obtained by means of SEM image digital processing technology. The experimental results show that the splitting tensile strength of red sandstone decreases with the increase of water content and has obvious water softening phenomenon, and the dynamic tensile strength increases significantly compared with static tensile strength, and has obvious strain rate strengthening effect. With the increase of water content, the number of fragments increases gradually and the scale decreases, and the dynamic splitting tensile failure of saturated rock samples shows certain plastic characteristics compared with dry rock samples. The information of fracture surface area is quantitatively processed and the water-strain rate effect in dynamic splitting failure is analyzed. It is concluded that water plays a balanced role in the crack propagation of sandstone specimen under different strain rates. The number and area of microfractures increase with the increase of strain rate.
【作者单位】：空军工程大学机场建筑工程系;中国人民解放军94940部队;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(51378497)
【分类号】：TU45

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