基于声发射参数的混凝土循环加卸载动态损伤破坏特性研究

发布时间：2018-01-04 02:04

本文关键词：基于声发射参数的混凝土循环加卸载动态损伤破坏特性研究　出处：《三峡大学学报(自然科学版)》2015年06期 　论文类型：期刊论文

【摘要】：对5种不同几何尺寸与不同配合比的混凝土试件进行了不同加载速率下的单轴压缩试验,同步进行了声发射(AE)数据的采集;在对比分析AE参数与应力应变关系的基础上,进行了不同加载速率下的混凝土损伤机理与破坏机制研究;通过分析不同加载速率下的应力应变全曲线,研究了循环加卸载中的损伤破坏特性的速率效应;构建了基于AE参数的损伤变量模型,并基于该模型进行了动态损伤特性分析.结果表明:混凝土的峰值应力与弹性模量随加载速率的提高而增大,表现出明显的规律性;但峰值应变随加载速率的变化而表现出较大的离散性.峰值应力前的AE能量随加载速率的提高而增加;加载速率越大,上升幅度越大,峰前释放的能量越大,混凝土内部破坏越严重,残余能量不足以维持试件继续承受更多的循环加卸载而直接进入破坏阶段;峰后可完成的循环加卸载次数随着加载速率的提高而减少.在不同加载速率下材料损伤破坏的路径不同,但损伤起点与破坏终点是重合的;随加载速度提高,损伤破坏的路径变短,加载速率差异越大,损伤破坏路径差异越大;混凝土在不同应力阶段的损伤程度及破坏形态与加载速率有较强的相关性.加载速率的提高改变了混凝土的能量释放过程与方式,形成了不同的损伤破坏机制,在不同加载速率下的损伤破坏机理存在较大差异.
[Abstract]:The uniaxial compression tests of five concrete specimens with different geometric sizes and different mixing ratios were carried out under different loading rates. The acoustic emission (AE) data were collected simultaneously. On the basis of comparing and analyzing the relation between AE parameters and stress and strain, the damage mechanism and failure mechanism of concrete under different loading rates are studied. By analyzing the full stress-strain curves at different loading rates, the rate effect of damage and failure characteristics in cyclic loading and unloading is studied. The damage variable model based on AE parameters is constructed, and the dynamic damage characteristics are analyzed based on the model. The results show that the peak stress and elastic modulus of concrete increase with the increase of loading rate. Showing obvious regularity; But the peak strain varies with the loading rate and the AE energy before the peak stress increases with the increase of the loading rate. The higher the loading rate, the greater the rise, the larger the energy released before the peak, the more serious the internal damage of concrete, the less the residual energy is enough to maintain the specimen to endure more cyclic loading and unloading and enter the failure stage directly. The cyclic loading and unloading times which can be completed after the peak decrease with the increase of loading rate. The damage damage paths are different at different loading rates, but the damage start point and failure end point are coincident. With the increase of loading speed, the damage damage path becomes shorter, and the greater the loading rate difference, the greater the damage damage path difference. The damage degree and failure form of concrete in different stress stages have strong correlation with loading rate. The increase of loading rate changes the process and mode of energy release of concrete and forms different damage and failure mechanism. The mechanism of damage failure is different at different loading rates.
【作者单位】：三峡大学三峡地区地质灾害与生态环境湖北省协同创新中心;三峡大学土木与建筑学院;
【分类号】：TU528
【正文快照】： 混凝土结构的破坏是一系列损伤演化并积累的结果.作为一种新型的检测技术,声发射(Acoustic E-mission,简称AE)[1-2]可以在未知混凝土损伤状态的物理参数情况下,了解混凝土内部损伤和裂缝形成、发展的过程,进而实现判定混凝土曾经承受的最大应力历史和动态评估混凝土损伤程度等

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