冻融循环下砂岩的动态劈裂特性与应变演变机理  

Study on dynamic splitting and evolution mechanism of sandstone under freeze-thaw cycle

作　　者：杨国梁[1] 尚卓 邹泽华 毕京九 董智文 YANG Guoliang;SHANG Zhuo;ZOU Zehua;BI Jingjiu;DONG Zhiwen(School of Mechanics and Civil Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China)

机构地区：[1]中国矿业大学(北京)力学与土木工程学院,北京100083

出　　处：《矿业科学学报》2024年第2期199-208,共10页Journal of Mining Science and Technology

基　　金：国家自然科学基金(51934001)。

摘　　要：为了研究冻融循环条件下砂岩的动态拉伸力学性能,利用分离式霍普金森压杆(SHPB)试验系统并结合高速数字图像相关技术(DIC),对冻融循环0次、10次、20次、40次的砂岩试件进行不同冲击速度下的动态劈裂试验,研究分析了不同冻融循环次数下冻结砂岩在动态拉伸应力下的强度特征、变形过程与破坏形态。结果表明:不同冻融循环作用下冻结砂岩与普通砂岩的动态拉伸曲线有着相似的应力发展特点,分为低速增长段、高速增长段、峰值平台段和降低段;冻岩的拉伸峰值应力与应力加载速率呈线性关系,与冻融循环次数之间呈现出先增大后减小的趋势;在相同打击强度下,4种冻融循环次数(N)的冻岩试件中心处拉伸应变大小依次为40次、20次、0次、10次,具有一定的冻融循环效应。This study attempts to investigate the dynamic tensile mechanical properties of sandstone under freeze-thaw cycle by using the split Hopkinson pressure bar(SHPB)test system to perform dynamic splitting tests on sandstone samples with freeze-thaw cycle 0,10,20 and 40 times at different impact speeds.Also adopting the high-speed digital image correlation(DIC),we observed the dynamic tensile failure process of the specimen,where we analyzed the strength characteristics,deformation process and failure form of frozen sandstone under dynamic tensile stress in different freeze-thaw cycles.Results show that 1)the dynamic tensile σ-t curves of frozen sandstone and ordinary sandstone exhibit similar patterns of stress variation under different freeze-thaw cycles,which can be divided into four stages:low speed growth section,high speed growth section,peak plateau section and decreasing section;2)the peak tensile stress increases linearly with the increase of stress loading rate;3)the peak tensile stress of frozen rock has a certain freeze-thaw cycle effect,and there is a strong correlation between the peak tensile stress and the number of freeze-thaw cycles.The dynamic tensile strength of frozen rock increases first and then decreases as the number of freeze-thaw cycles increases.Under the same impact pressure,the frozen rock specimen shows certain freeze-thaw cycle effect as the tensile strain at the center shows N=40>20>0>10 under 4 kinds of freeze-thaw cycles.

关 键 词：冻融循环 应力加载速率 SHPB 应变率效应 动态拉伸 DIC 

分 类 号：TU521[建筑科学—建筑技术科学]