地震应变率下水饱和度对混凝土动力压缩效应的影响

Influence of water content on dynamic compressive properties of concrete subjected to seismic strain rate

为揭示地震应变率下不同含水量混凝土的力学性能变化规律,采用真空饱水设备快速制备不同水饱和度混凝土试件以消除水泥进一步水化对试验结果的影响;进行了3种应变率下(10-5s-1、10-4s-1、10-3s-1)的单轴压缩试验,测试分析了应变率和水饱和度对混凝土的应力应变曲线形态、抗压强度、弹性模量以及峰值应变的影响规律与影响机理。研究结果表明,随着应变率增加,混凝土动态抗压强度增大、弹性模量增加、而峰值应变减小;随着水饱和度增加,混凝土在静载以及动载下的抗压强度绝对值减小,但动载作用时动力强度增长因子增大;应变率越高混凝土峰值应变随水饱和度增大而减小的趋势越明显。综合考虑应变率效应以及水饱和度的影响,提出了混凝土力学性能指标的经验计算公式,与试验结果有着较好的吻合度。

To clarify the influence of water contents on the mechanical properties of concrete subjected to seismic strain rate,a vacuum water-saturated equipment was used to prepare concrete specimens with different water contents rapidly. The effect of cement secondary hydration on the rest results can be minimized by this method. Uniaxial compression tests were carried out at strain rates of 10-5,10-4 and 10-3 s-1. The effects of strain rate and water content on the stress-strain curves,compressive strength,elastic modulus and critical strain of concrete are analyzed. The obtained results show that the compressive strength and elastic modulus increase with the increase of strain rate,while the critical strain of concrete decreases. At a same strain rate,increasing water content lowers the compressive strength,but increase the dynamic increase factor under dynamic loading. Critical strain decreases more significantly with the increase of water content especially at higher strain rates. Empirical formula for the mechanical properties of concrete are proposed in this study considering the effect of strain rate as well as the water content,which has a good agreement with the test results.