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利用10 MN大型多功能液压伺服静动力三轴试验系统和SAEU2S声发射信号采集系统,研究了单轴循环荷载作用下混凝土强度变化及声发射特征。结果表明:混凝土在单轴循环荷载作用下,其抗压强度与回弹值的比值随应变速率的增加而增大,通过线性拟合发现混凝土抗压强度与回弹值的比值率效应表现明显;混凝土在单轴循环加卸载过程中,声发射定位研究揭示了混凝土开裂位置及发展状况,并将混凝土变形分为4个阶段进行研究,结合每个阶段声发射累积定位数情况,分析了混凝土损伤变化;对循环加卸载过程中声发射累积定位数的分析发现,卸载后再次至最大历史应力水平前大量声发射信号产生说明混凝土不满足Kaiser效应;基于声发射定位数与应力随时间变化关系的研究认为,混凝土强度与应力水平有关,与内部结构也有关。
Using 10 MN large-scale multi-functional hydraulic servo static and dynamic triaxial test system and SAEU2S acoustic emission signal acquisition system, the concrete strength changes and acoustic emission characteristics under uniaxial cyclic loading were studied. The results show that the ratio of compressive strength and rebound value of concrete increases with the increase of strain rate under the uniaxial cyclic loading. The ratio effect of compressive strength and rebound value of concrete is obvious by linear fitting Acoustic emission positioning study reveals the location and development of concrete cracking in uniaxial cyclic loading and unloading process, and the concrete deformation is divided into four stages to study, combined with the cumulative number of acoustic emission at each stage of the situation, the analysis of the concrete The analysis of the cumulative number of acoustic emission during cyclic loading and unloading showed that a large number of acoustic emission signals before unloading again to the maximum historical stress level showed that the concrete did not satisfy the Kaiser effect. Based on the relationship between the number of acoustic emission and stress with time The study suggests that the strength of concrete is related to the stress level and to the internal structure.