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为了探求混凝土动态压缩试验入射波形的改善方法,从而进一步研究冲击荷载作用下混凝土动态损伤及力学性能,采用常规的大直径分离式霍普金森压杆(split Hopkinson pressure bar,SHPB)进行混凝土的动态压缩试验。然而入射脉冲的弥散效应和严重的高频震荡现象会对试验结果会产生较大的误差,所以试件在破坏前应力均匀分布要求且保持恒应变率加载是保证试验有效性及试验结果可靠性的关键。通过黄铜整形器改善入射波形以减小试验误差,然后利用理论公式与试验相结合的方式,通过控制变量,进一步研究气压、冲击次数等对混凝土动态损伤的影响。研究结果表明:较薄的小直径实心铜片整形器可以提高试验准确度;随着重复冲击次数的增加,混凝土损伤度逐渐提高,动态弹性模量减小,抵抗冲击的能力减弱。
In order to explore the method of improving the incident waveform of dynamic compression test of concrete to further study the dynamic damage and mechanical properties of concrete under impact load, the conventional large diameter split Hopkinson pressure bar (SHPB) Compression test. However, the dispersion effect of incident pulse and severe high-frequency oscillation phenomenon will produce large errors in the test results. Therefore, the uniform stress distribution of the specimen before failure and the constant strain rate loading ensure the validity of the test and the reliability of the test results key. Through the use of brass shaper to improve the incident waveform to reduce the test error, the influence of pressure and impact on the dynamic damage of concrete is further studied by controlling the variables by the combination of theoretical formula and experiment. The results show that the thinner and smaller diameter solid copper shaper can improve the test accuracy. As the repeated impact times increase, the damage degree of concrete gradually increases, the dynamic elastic modulus decreases and the resistance to impact decreases.