砂浆试样破坏过程声发射试验研究

发布时间：2018-07-22 13:36

【摘要】：砂浆是建筑中最常用的一种材料,其性能的优劣直接影响着构筑物的安全。从构筑物的材料入手,研究砂浆材料变形破坏过程中的力学性能,利用声发射监测技术这一先进的技术手段监测砂浆材料破坏过程中声发射信号,探究其损伤机制,进而预防或减少砂浆材料对构筑物的危害有重要的理论意义和实用价值。本文以声发射监测机理、损伤理论为理论基础,采用理论分析与室内试验相结合的方法,对砂浆试样变形破坏过程中声发射特性进行了系统的研究,主要研究成果如下:(1)预制不同配比的砂浆试样,开展单轴压缩试验,同时采用声发射监测系统进行监测,研究了砂浆配比、加载速率与砂浆试样强度之间的关系,研究表明砂浆试样峰值强度随加载速率增大而增大,砂浆试样峰值强度随水泥与砂质量比的增大而增大;将砂浆试样变形破坏全过程声发射分成三个阶段,初始压密弹性阶段、屈服上升阶段和破坏残余阶段;结合声发射试验数据,提出了一种预测指标K,K值变化情况出现明显的“回弹”现象,预示着砂浆试样即将破坏。(2)预制铸铁、松木两种夹芯材料的夹芯砂浆试样,采用声发射监测技术监测其单轴压缩过程中声发射信号,得到了配比与夹芯砂浆试样的强度关系,夹芯砂浆试样峰值强度均随水泥与砂质量比的增大而增大,同一配比下的铸铁夹芯砂浆试样的峰值强度大于松木砂浆试样的峰值强度;夹芯砂浆试样的声发射事件计数特征与声发射能量特征变化趋势相同;K值变化情况出现明显的“回弹”现象,也能预测夹芯砂浆试样破坏。(3)根据声发射能量值重新定义损伤变量,利用二参数威布尔分布理论给出砂浆试样损伤演化方程,确定了各参数,并对损伤演化方程进行修正,最终建立了砂浆试样本构模型,理论结果与试验结果吻合。
[Abstract]:Mortar is one of the most commonly used materials in buildings, and its performance directly affects the safety of structures. Starting with the materials of the structure, the mechanical properties of mortar materials during deformation and failure are studied. The acoustic emission monitoring technology is used to monitor the acoustic emission signals during the destruction of mortar materials, and the damage mechanism is explored. Therefore, it has important theoretical significance and practical value to prevent or reduce the harm of mortar material to the structure. Based on the theory of acoustic emission monitoring and damage theory, the acoustic emission characteristics of mortar samples during deformation and failure are studied systematically by means of theoretical analysis and laboratory test. The main results are as follows: (1) the uniaxial compression test was carried out for prefabricated mortar samples with different ratios, and the relationship between mortar ratio, loading rate and strength of mortar samples was studied by acoustic emission monitoring system. The results show that the peak strength of mortar specimen increases with the increase of loading rate, the peak strength of mortar specimen increases with the increase of cement to sand mass ratio, and the acoustic emission of the whole process of deformation and failure of mortar specimen is divided into three stages, the initial compaction elastic stage. In combination with the acoustic emission test data, an obvious "springback" phenomenon is proposed to predict the change of K value, which indicates that the mortar sample is about to be destroyed. (2) prefabricated cast iron, Acoustic emission monitoring technique was used to monitor the acoustic emission signals of the core mortar samples of two kinds of pine core materials during uniaxial compression, and the relationship between the ratio and the strength of the sandwich mortar samples was obtained. The peak strength of core mortar increased with the increase of cement to sand mass ratio, and the peak strength of cast iron sandwich mortar sample with the same ratio was higher than that of pine mortar sample. The change trend of acoustic emission event counting and acoustic emission energy is the same as that of core mortar. The phenomenon of "springback" appears in the change of K value. It can also predict the failure of sandwich mortar samples. (3) according to the energy value of acoustic emission, the damage evolution equation of mortar specimen is given by using the two-parameter Weibull distribution theory, and the damage evolution equation is modified. Finally, the constitutive model of mortar specimen is established, and the theoretical results are in agreement with the experimental results.
【学位授予单位】：山东科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ177.6

【参考文献】