混凝土冲击破坏动力特性及能耗规律研究

Dynamic characteristics and energy consumption laws of concrete impact failure

为探究冲击速度和骨料率对混凝土动力特性及能量传递规律的影响,设计了骨料率为0、32%、37%和42%的混凝土试样,利用SHPB装置进行了速度为5、6和7 m/s的冲击压缩试验。系统分析了冲击速度和骨料率不同时混凝土动态变形、动强度增长及能量转化规律,并利用双因素方差分析法研究了冲击速度和骨料率对动强度的影响程度。结果表明:冲击压缩作用下,混凝土试样主要以拉伸劈裂破坏模式为主。混凝土动强度随骨料率和冲击速度的增大而增大,而且相较于骨料率,冲击速度对动强度的影响程度更大。冲击速度介于5~5.8 m/s时,DIF随骨料率的增加而增加;冲击速度介于5.8~7 m/s时,DIF随骨料率的增加而减小。混凝土试样透射能随冲击速度和骨料率的增大而增大,而反射能、吸收能和吸能占比均随冲击速度的增大而增大,随骨料率的增大而减小。

Impact compression tests on concrete specimens are conducted using a split Hopkinson pressure bar(SHPB)device,with impact velocities of 5,6 and 7 m/s and concrete aggregate volume ratios of 0,32%,37%and 42%,to explore comprehensively the influence of these two factors on the dynamic characteristics and energy transfer laws of concrete.We study the variations in dynamic deformation,dynamic strength growth,and energy transformation of concrete with the two factors,and examine their influence on the dynamic strength using two-factor variance analysis.The results indicate that under impact compression,concrete specimens are subjected to failure dominated by the tensile splitting mode.Aggregate content imposes a great influence on dynamic elastic modulus,while impact velocity affects little.Concrete dynamic strength increases as aggregate content or impact velocity increases,and impact velocity has a greater effect on dynamic strength than aggregate content.With an increasing aggregate content,the dynamic increasing factor(DIF)increases in the impact velocity range of 5 to 5.8 m/s,while it decreases in the range of 5.8 to 7 m/s.The transmitted energy increases with impact velocity or aggregate content;the reflected energy,absorbed energy,and the ratio of absorbed energy to incident energy all increase with impact velocity but decrease with aggregate content.