摘要: |
为了探究岩石循环动力学特性及其尺寸效应,本文采用分离式霍普金森压杆对高径比为0.5、0.67、1.0的花岗岩试样开展循环冲击试验,并对试验结果进行了对比分析。结果表明:同一弹速下,随着试样高径比的减小,最后一次冲击曲线的峰后破坏阶段更显著;随着高径比增加,循环冲击过程中试样峰值应变整体减小;试样的峰值应变与循环冲击次数之间呈正相关;峰值应力下降随高径比增加而变缓;高弹速下,不同高径比试样的峰值应力下降幅度比低弹速下更显著;累积比能量上升趋势随着高径比增加逐渐变弱;弹速一定,不同高径比试样的累积比能量随冲击次数的增加线性增加;在相同弹速条件下,随着高径比增加,试样循环冲击破坏后破碎程度降低,宏观上表现为破碎块度增大、破碎块数减小;低弹速下试样出现纵向贯通裂纹,呈现轴向劈裂破坏模式,高弹速(9.9 m/s)下,由轴向劈裂转变为边缘仅少量剥落。研究结果对实际工程中能量的利用以及损伤的防控等方面均具有指导意义。 |
关键词: 花岗岩 循环冲击 高径比 动力学特性 破坏模式 |
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基金项目:国家自然科学基金项目(面上项目,重点项目,重大项目) |
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Study on size effect of mechanics characteristics of granite under cyclic impact loading |
Zhang Hang, Wang zhiliang, Lu Zhitang, Xiong Feng, Wu Xutao
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HFUT
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Abstract: |
To explore the dynamic characteristics of rock cycle impact and its size effect, the cyclic impact tests of granite specimens with height-diameter ratios of 0.5, 0.67 and 1.0 are carried out using the split Hopkinson pressure bar, and test results are compared and analyzed. Results show that under the same striking velocity, the post-peak failure stage of the final stress-strain curve is more significant when the height-diameter ratio increases; with the increase of the height-diameter ratio, the peak strain of the specimen decreases overall during the cyclic impact process; the peak strain of the specimen is positively correlated with the number of cyclic impacts; the peak stress decreases with the increase of the height-diameter ratio; under the high striking velocity, the decreasing range is more significant than that under the low striking velocity; the increasing trend of cumulative specific energy gradually weakens with the increase of height-diameter ratio; the cumulative specific energy of specimens with different height-diameter ratio increases linearly with the increase of impact times when the striking velocity is constant; under the same striking velocity, the degree of fracture of specimens decreases with the increase of height-diameter ratio, and the volume of fragments increases at macro level while the number of fragments decreases; under the low striking velocity, the longitudinal through crack appears, which presents the mode of axial splitting failure. At high striking velocity (9.9 m/s), the failure mode changes from axial splitting to only a small amount of spalling at the edge. The research results are of guiding significance for the utilization of energy as well as the prevention and control of damage. |
Key words: Granite Cyclic impact Height-diameter ratio Dynamic characteristics Failure mode |