【作者】 王丽；

【导师】 岳强；

【作者基本信息】 山东农业大学 ， 岩土工程， 2015， 硕士

【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。更多还原

【Abstract】 On the premise of hypothesis of homogeneous medium,the macro test can not further study the RC, at meso-level the research is in need on the impact of RC internal components on RC macro mechanical properties.In the paper, a numerical analysis method is used to study the failure process of recycled concrete, mechanical properties of recycled concrete and the influence factors.Using MATLAB the image processing software, and combining the image predisposing, image segmentation transformation, median filtering noise, morphological image processing, the edge detection and geometry vectorization algorithms, the real aggregate numerical model of recycled concrete can be established. At meso-level, the RC be regarded as a heterogeneous six-phase composite material: natural aggregate,the old mortar,the new mortar, the interface transition zone of new mortar and natural aggregate(ITZ1), the interface transition zone of new mortar and old mortar(ITZ2), the interface transition zone of old mortar and natural aggregate(ITZ3). According to the mechanical properties of each phase material in RC and by using the automatic dynamic incremental nonlinear analysis software, the meso damage process and the macro mechanical properties of RC specimens can be simulated and analyzed under uniaxial tension/compression.By contrasting the simulation results and the test results, the established RC real meso model is verified reasonable. The parameters of RC is changed to find the influence on RC macro mechanical properties from the different mechanical parameters of natural aggregate, interface transition zone and the new/old hardened mortar.The study in this paper shows that the real aggregate model can more truly simulate the damage process of RAC under external loads compared with other meso-mechanical models, such as a random aggregate model, and can more accurately describe the macro-properties of heterogeneous concrete.the results of the real aggregate model are in a better agreement withthe experimental data. The natural aggregate has great influence on the damage process and damage path, but less influence on elastic modulus and strength of concrete. If the natural aggregate elasticity coefficient is oversized, the stress concentration phenomenon is even more obvious. The strength and rigidity of RAC linearly change with the changed mechanical properties of new hardened mortar. The old hardened mortar has little effect on the macroscopic mechanical properties of RAC. The concentration of tensile stress and shear stress appear in new and old ITZs, and the strength of ITZs has little effect on the macro mechanical properties of RAC. This paper can provide technical supports for the engineering practice of RAC and provide references for further study on meso properties of recycled concrete.更多还原