基于不同强度等级混凝土的动力学特性研究

基于TAW-2000D电液伺服岩石三轴仪和直径75 mm的霍普金森压杆试验装置，得到了C25，C35和C45混凝土在静、动载荷作用下的应力-应变曲线，探讨了混凝土强度等级、动态峰值强度、峰值应变和应变率之间的变化规律。结果表明:混凝土准静态应力-应变曲线和动态应力-应变曲线在形态上存在明显差异，动态应力-应变曲线的峰值点随应变率的增大向右上方移动，线弹性阶段各曲线斜率变化不明显；动态峰值应力、动态弹性模量和峰值应变均存在不同程度的率相关性，并且混凝土材料的应变率敏感性随其强度等级的提高而增强；混凝土C45的各力学指标对应变率的敏感性最强，C35次之，C25的应变率敏感性最弱；推导了应变率与强度等级和冲击速率之间的经验公式，三者之间存在非线性变化规律。

Study on dynamic characteristics of concrete based on different strength grades

Based on the TAW-2000D electro hydraulic servo rock triaxial apparatus and the 75 mm diameter Hopkinson pressure bar test device,the stress strain curves of C25,C35 and C45 concrete under the static and dynamic loads were obtained,and the change laws of concrete strength grade,dynamic peak strength,peak strain and strain rate were studied.The results showed that the quasi static stress strain curve and the dynamic stress strain curve of concrete had obvious difference in morphology.The peak point of dynamic stress strain curve moved towards the upper right with the increase of strain rate,and the slope change of each curve in the linear elastic stage was not obvious.All the dynamic peak stress,dynamic elastic modulus and peak strain had the rate dependence with different degrees,and the strain rate sensitivity of concrete material enhanced with the increase of its strength grade.It was found that each mechanical index of concrete C45 had the strongest sensitivity to the strain rate,followed by C35,and the strain rate sensitivity of C25 was the weakest.The empirical formula between the strain rate and the strength grade and impact velocity was derived,and there was a nonlinear variation law between them.