基于真实骨料模型的再生混凝土细观破坏数值分析

发布时间：2018-03-10 07:48

本文选题：再生混凝土　切入点：数值分析　出处：《山东农业大学》2015年硕士论文　论文类型：学位论文

【摘要】：以均匀介质假设为前提的宏观力学方法研究再生骨料混凝土的力学性状,不能深入探究再生混凝土的破坏机理,需要在细观层次上研究再生混凝土内部组分对其宏观力学性能和破坏过程的影响。本文采用基于真实骨料模型的数值分析方法,对再生混凝土破坏过程、力学性能及影响因素等展开了系列研究。应用MATLAB图像处理软件对再生混凝土试件图片进行图形前处理、分段变换、中值滤波除噪、边缘检测和几何矢量转换,建立的再生混凝土真实骨料数值模型。在细观尺度上将再生混凝土分为六相组分:天然骨料、老砂浆、新砂浆、新砂浆和天然骨料界面过渡区、新砂浆和老砂浆界面过渡区、老砂浆和天然骨料界面过渡区。根据再生混凝土各相组分的力学特性,利用自动动态增量非线性分析软件ADINA对再生混凝土单轴拉伸及压缩作用下细观损伤过程和宏观力学性能变化进行了模拟分析。对模拟结果和试验结果进行对比分析,验证了建立的再生混凝土真实细观数值模型的合理性。在此基础上,对再生混凝土进行变参数分析,讨论不同天然骨料、界面过渡区和新老硬化砂浆的力学特性对再生混凝土宏观力学性能的影响。研究结论表明:与混凝土随机骨料细观模型比较,真实骨料模型的模拟结果与试验结果吻合较好,真实骨料模型能更好地模拟荷载作用下的再生混凝土的破坏过程;天然骨料弹性模量较其他各相组分大,对再生混凝土宏观刚度和强度影响较小,在其周边界面过渡区易产生应力集中,影响再生混凝土的破坏过程和裂缝扩展路径;再生混凝土宏观强度和刚度均随新砂浆力学性能的变化而变化,老砂浆性能对再生混凝土宏观性能影响较小;再生混凝土的新老界面处存在拉应力和剪应力集中现象,新老界面强度对再生混凝土宏观力学性能影响较小。本文结论可为再生混凝土结构和构件的力学分析及应用安全等提供技术支持,同时为进一步研究再生混凝土的细微观性能提供参考。
[Abstract]:The mechanical properties of recycled aggregate concrete can not be studied by macroscopic mechanical method based on the assumption of homogeneous medium, and the failure mechanism of recycled concrete can not be deeply explored. It is necessary to study the influence of internal components of recycled concrete on its macroscopic mechanical properties and failure process at the meso level. In this paper, a numerical analysis method based on real aggregate model is used to analyze the failure process of recycled concrete. A series of studies on mechanical properties and influencing factors were carried out. Using MATLAB image processing software, the image of regenerated concrete specimen was processed by image pre-processing, segmental transformation, median filtering and noise removal, edge detection and geometric vector conversion. The real aggregate numerical model of recycled concrete is established. The recycled concrete is divided into six phase components at meso scale: natural aggregate, old mortar, new mortar, new mortar and natural aggregate interface transition zone, new mortar and old mortar interface transition zone, Interface transition zones between old mortar and natural aggregates. Based on the mechanical properties of each phase component of recycled concrete, The microscopic damage process and macroscopic mechanical properties of recycled concrete under uniaxial tension and compression were simulated and analyzed by using the automatic dynamic increment nonlinear analysis software ADINA. The simulation results were compared with the experimental results. The rationality of the real mesoscopic numerical model of recycled concrete is verified. On the basis of this, the variable parameter analysis of recycled concrete is carried out, and the different natural aggregates are discussed. The effect of the mechanical properties of the interfacial transition zone and the new and old hardened mortar on the macroscopic mechanical properties of recycled concrete is studied. The results show that the simulation results of the real aggregate model are in good agreement with the experimental results compared with the concrete random aggregate meso model. The real aggregate model can better simulate the failure process of recycled concrete under load, and the elastic modulus of natural aggregate is larger than that of other phases, which has little effect on the macro stiffness and strength of recycled concrete. It is easy to produce stress concentration in the transition zone of its peripheral interface, which affects the failure process and crack propagation path of recycled concrete, and the macroscopic strength and stiffness of recycled concrete vary with the mechanical properties of new mortar. The properties of old mortar have little influence on the macro performance of recycled concrete, and there are tensile stress and shear stress concentration at the new and old interface of recycled concrete. The new and old interface strength has little influence on the macro mechanical properties of recycled concrete. The conclusion of this paper can provide technical support for mechanical analysis and application safety of recycled concrete structures and members. At the same time, it provides a reference for the further study of the fine properties of recycled concrete.
【学位授予单位】：山东农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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