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对65个直径为68 mm的混凝土圆柱体试件进行试验分析,系统研究了不同初始损伤程度的混凝土试件在冲击荷载作用下的动态抗压特性。通过对混凝土试件预加不同的静态荷载,从而在试件内产生不同程度的初始损伤;利用SHPB设备进行不同速率下的冲击试验,研究初始损伤程度对混凝土动态抗压强度、应力应变关系以及破坏模式的影响。试验结果表明,初始损伤对混凝土动态抗压强度产生重要影响,其影响程度与混凝土试件的初始损伤程度密切相关,损伤程度在阈值以下时对混凝土的动态抗压强度影响较小,超过阈值时影响显著;随应变率增加,带损伤混凝土的动态抗压强度显著提高;含水率的增加降低了带初始损伤混凝土动态抗压性能。基于试验结果,提出了综合考虑初始损伤程度影响和应变速率效应的抗压强度预测模型。
Sixty-five concrete cylinders with a diameter of 68 mm were tested and analyzed. Dynamic compressive characteristics of concrete specimens with different initial damage under impact load were systematically studied. By applying different static loads to prestressed concrete specimens, different initial damage was induced in the specimens. The SHPB equipment was used to carry out impact tests at different rates. The effects of initial damage on dynamic compressive strength, stress and strain of concrete, Destruction of the impact of the model. The results show that the initial damage has an important influence on the dynamic compressive strength of concrete, and the degree of influence is closely related to the initial damage degree of concrete specimens. When the damage degree is below the threshold, the dynamic compressive strength of concrete is less affected. The dynamic compressive strength of concrete with damaged concrete significantly increases with the increase of strain rate. The increase of moisture content decreases the dynamic compressive strength of concrete with initial damage. Based on the test results, a compressive strength prediction model considering the effects of initial damage degree and strain rate effect is proposed.