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云南高海拔地区沥青混合料性能仿真研究 云南高海拔地区沥青混合料性能仿真研究 High-altitude Areas in Yunnan Asphalt Mixture Performance Simulation【中文摘要】 云南高海拔地区,在气候特征上属于湿润温带-寒温带气候,而青藏高原多属于半干旱和干旱-高原寒带季风性气候,其降雨量远远高于青藏高原。由于气候条件的不同,使得其筑路条件也就不同,在青藏高原筑路面临的主要问题是多年冻土问题,而云南高海拔地区则没有多年冻土问题,筑路面临的主要是季节性冻融问题。就冻融问题而言,云南高海拔地区的冻融问题远比我国北方地区冻融问题严重,主要表现在其冻融期较长(最长达300天),且冻融变化频繁。因此,在云南高海拔地区筑路,即不能套用青藏高原地区相关筑路经验,也不能套用北方地区解决冻融问题的经验,而必须根据云南高海拔地区的具体特点,有针对性的研究开发其筑路技术。随着云南高海拔地区公路建设的发展,近年来由于当地季节性冻融原因即其特殊的气候环境,使得路面修筑过程中出现的工程问题及使用期的早期破坏现象越发明显。当前的沥青混合料级配组成设计基本上仍是沿用传统的实验-观察的现象学经验方法,应用先进的计算手段、力学分析工具,定量地分析微观或细观尺度沥青混合料的力学特征,对深刻理解沥青混合料的力学机理与改进沥青混合料组成设计方法有重要意义。当前研究工作在数字图像获取与处理技术、虚拟力学计算软件、分形原理等方面得到了迅速发展,这些技术的发展已被认为是道路工程界非常有潜力的一些研究发展方向。由于特殊的地理及气候条件,云南高海拔地区沥青路面病害较其他更为复杂,为了研究云南高海拔地区特殊气候条件下沥青混合料的力学性能,本文在借鉴国内外相关研究成果的基础上,结合云南高海拔地区特殊的气候条件,建立适用于模拟沥青混合料真实相互作用的离散单元模型进行计算机虚拟试验,通过实验结果和数值模拟结果对比分析,建立宏观与细观参数之间的关系。在室内试验结果分析总结的基础上,在获得科学数据的基础上进行理论分析和评价,探讨PFC2D模拟沥青混合料大粒径的可行性分析。 【英文摘要】 Yunnan,high-altitude areas, belong to the climatic characteristics on humid temperate - cold temperate climate, and the Qinghai-Tibet Plateau belong to semi-arid and dry - cold plateau monsoon climate, its rainfall is much higher than the inghai-Tibet Plateau. Because of different climatic conditions, making it different from the onditions of its roads, and roads in the Qinghai-Tibet Plateau are the main problems facing the permafrost problem, and high-altitude areas in Yunnan there is no permafrost problems, the main roads are seasonal freeze-thaw problem. Question on freezing and thawing, the Yunnan high altitude than the problem of freeze-thaw Freeze-thaw in northern China the problem is serious, mainly reflected in its freeze-thaw for long periods of time (up to 300 days), and the frequent freezing and thawing Change. Therefore, high-altitude areas in Yunnan, and roads, that is, should not apply the relevant construction experience in the Qinghai-Tibet Plateau region, and should not be applied to solve the northern region experience freeze-thaw problem. And must be based on high-altitude areas in Yunnan specific characteristics, targeted research and development of its road construction technology.With the high-altitude areas of Yunnan highway construction development, in recent years because of local reasons for the seasonal freezing and thawing that is, its special climate and environment, making road construction projects arising in the course of questions and use the early phase of situation all the more obvious damage. The current asphalt mixture gradation component design is still a traditional experiment - observe the phenomenon of the experience of study methods, the application of advanced computing tools, mechanical analysis tools, quantitative analysis of micro-or meso-scale asphalt mixture mechanical characteristics on a deep understanding of asphalt mixture mechanical mechanism and improve the composition of asphalt mixture design method has important significance. Current research work in the digital image acquisition and processing technology, virtual mechanics calculation software, and so on fractal principle has been the rapid development of these technologies has been the development of road engineering are very think there is some potential for research and development direction.Because of special geographical and climatic conditions, high-altitude areas in Yunnan Asphalt Pavement more complex than the other, in order to study high-altitude areas in Yunnan special climatic conditions of asphalt mixture mechanical properties, in this paper draw on relevant research results at home and abroad on the basis of combination of high-altitude areas in Yunnan special climatic conditions, set up for asphalt mixture Analog real discrete element model of the interaction of the virtual computer experiments, through the experimental results and numerical simulation results of comparative analysis, the establishment of macro-and micro-parameters of the relationship between. Analysis of laboratory test results at the basis of summing up, in access to scientific data based on theoretical analysis and evaluation 【中文关键词】 高海拔地区; 离散元; 三轴试验; 剪应力 【英文关键词】 high-altitude areas; discrete element; triaxial test; shear stress 【毕业论文目录】摘要 3-4 ABSTRACT 4-5 第一章 前言 9-20 1.1 引言 9-11 1.2 研究的背景和意义 11 1.3 沥青混合料微观结构的国内外研究现状 11-14 1.3.1 沥青混合料的细观结构识别 11-13 1.3.2 沥青混合料的微观结构特性的数值模拟 13-14 1.4 离散单元法在国内外研究概况及在沥青混合料结构分析中的应用 14-18 1.4.1 离散单元法在国外的发展状态 15-16 1.4.2 离散单元法在国内的发展状态 16-18 1.4.3 离散单元法在沥青混合料微观结构分析中的应用 18 1.5 本文的主要研究内及技术路线 18-19 1.6 工程背景及研究意义 19-20 第二章 离散单元法的基本原理及PFC2D 程序简介 20-39 2.1 离散单元法基本思想 20 2.2 离散单元法的数值求解 20-21 2.3 PFC2D 简介 21-24 2.3.1 PFC2D 的发展概况 21-22 2.3.2 PFC2D 方法的特点 22-23 2.3.3 PFC2D 基本理论 23 2.3.4 PFC2D 模拟步骤 23-24 2.4 颗粒离散单元法模型假设及思路 24-26 2.5 计算循环 26-34 2.5.1 力-位移关系法则 27-31 2.5.2 运动定律 31-33 2.5.3 计算方法动态松弛法 33-34 2.6 边界条件和初始条件 34 2.6.1 以墙为边界条件 34 2.6.2 以颗粒单元为边界条件 34 2.6.3 初始条件 34 2.7 相对滑动模型 34-35 2.8 计算参数的确定 35-38 2.8.1 时步的确定 35-36 2.8.2 机械阻尼的确定 36-37 2.8.3 刚度及摩擦系数的选取 37-38 2.8.4 微分密度因子 38 2.9 本章小结 38-39 第三章 云南高海拔地区沥青混合料仿真分析模型 39-57 3.1 引言 39-41 3.2 沥青混合料的强度机理 41-45 3.3 沥青混合料细观结构模型的基本假设 45 3.4 沥青混合料数值结构力学模型 45-56 3.4.1 结构离散化产生离散单元 45-46 3.4.2 离散单元接触模型 46-53 3.4.3 构造离散元计算模型 53-54 3.4.4 构造离散元计算模型 54-56 3.5 沥青混合料细观结构模型特点 56-57 第四章 云南高海拔地区 pfc2d 数值模拟及结果分析 57-88 4.1 数值分析涉及的参数 57-69 4.1.1 关键参数选取及相应的PFC2D 命令 57-58 4.1.2 PFC2D 中一些参数及相应的确定方法 58-68 4.1.3 伺服控制机制 68-69 4.2 云南高海拔地区沥青混合料三轴剪切试验模拟及分析 69-87 4.2.1 数值模拟参数取值 71-72 4.2.2 数值模拟步骤 72-73 4.2.3 试样颗粒的生成 73-74 4.2.4 设定恒定围压 74-75 4.2.5 沥青混合料的仿真模型的生成 75-80 4.2.6 仿真结果分析 80-84 4.2.7 仿真结果与试验结果的分析验证 84-86 4.2.8 PFC2D 程序解决本模型的可行性 86-87 4.3 本章小结 87-88 第五章 结论及展望 88-90 5.1 主要结论 88-89 5.2 存在的问题及展望 89-90 致谢 90-91 参考文献 91-95 在学期间发表的论著及取得的科研成果 95
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