花岗岩和混凝土在单轴冲击压缩荷载下的动态性能比较

COMPARISON OF DYNAMIC CAPABILITIES OF GRANITE AND CONCRETE UNDER UNIAXIAL IMPACT COMPRESSIVE LOADING

采用黄铜波形整形器改进后的分离式Hopkinson压杆装置,分别对花岗岩和混凝土试件进行不同应变率(101～103)s-1下的单轴冲击压缩试验,有效地减少传统Hopkinson压杆试验中,岩石类脆性材料在内部应力达到均衡之前过早破坏以及输入波的高频震荡给试验数据带来的波动性。试验结果表明,应变率不仅影响这2种岩石类材料的强度,而且也影响材料的破碎程度和破碎形式,但对材料的初始弹性模量、破坏应变以及能量吸收率影响不大。从花岗岩和混凝土材料的微观结构特征和能量吸收能力等方面,对比分析这2种材料动态性能的共同特点和相互差异,合理地解释试验现象。该方法与结论对其他类型的脆性材料的动态性能研究具有一定的参考价值。

Experiments with strain rate varying from 10^1 s^-1 to10^3 s^-1 on granite and concrete under uniaxial compressive loading are conducted with the modified split Hopkinson pressure bar（SHPB）.It can ensure the symmetrical stress in the specimens before fracture and avoid the fluctuation of test data due to input shaky stress pulse by adding the copper wafer as the pulse shaper.The experimental results show that the compressive strength and the fragment numbers of rock-like materials increase with the strain rate.The fragment size decreases with the strain rate.The initial elastic modulus,the failure strain and the ratio of the energy absorption of granite and concrete can be seen no relations with strain rate under condition that strain rate ranges from 101 s-1 to 103 s-1.The stress-strain curves,the energy absorbency-time curves and the ratio of the energy absorption-time curves of granite and concrete are compared.It is illustrated that the microstructure characteristic,impedance,compression deformation capability of rock-like materials are crucial factors influencing the characteristics of dynamic fracture.The research method and conclusions can be used to analyze the dynamic behavior of the other brittle materials.