中应变率下石英砂岩循环冲击破坏特性研究Study on Cyclic Impact Failure Characteristics of Quartz Sandstone under Medium Strain Rate
王军祥,马宝龙,李树昊,李林,寇海军,孙港
摘要(Abstract):
利用落锤冲击试验设备对石英砂岩进行循环冲击加载,在0.3~0.6 m各冲击高度下均选取3个试样,每个试样进行8次循环冲击,应变率分别选取为26.33 s~(-1)、29.7 s~(-1)、32.03 s~(-1)和35.17 s~(-1),研究中应变率下石英砂岩受循环冲击加载下的力学性能。通过对试验数据进行分析总结,讨论循环加载次数对石英砂岩动态抗压强度、弹性模量和能量效率的影响以及中应变率下石英砂岩的破坏过程。结果表明:不同中应变率条件下,第8次循环冲击加载作用下试件的动态抗压强度均较第一次循环冲击减小约13 MPa,抵抗变形能力减弱,同时弹性模量明显降低,试件动态抗压强度与弹性模量表现出正向相关关系;从能量角度研究,在8次循环冲击加载后,试样耗散能、能量效率、单位体积耗散能均有提高,其中在冲击能为70.27 J效果最为明显,岩石耗散能提高6 J、能量效率提高8.8%、单位体积耗散能增幅50%;从破碎分形角度进行研究,中应变率下岩石破碎形态有劈裂破坏、边缘崩落破坏、块状破坏和粉碎破坏,当应变率由26.33 s~(-1)增大至35.17 s~(-1)时,试样碎块块度平均粒径特征值由24.49 mm减小到21.15 mm;分形维数由1.07增加至1.75,岩石分形维数呈线性增大趋势。
关键词(KeyWords): 中应变率;循环冲击;破坏特性
基金项目(Foundation): 国家自然科学基金(No.51974187);; 辽宁省自然科学基金(No.2019-MS-242);; 辽宁省教育厅重点攻关项目(No.LZGD2020004)
作者(Author): 王军祥,马宝龙,李树昊,李林,寇海军,孙港
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