土石混合体细观结构力学及尺度效应研究

发布时间：2018-03-01 14:30

本文关键词： 土石混合体细观结构力学尺度效应三轴试验精细结构重建　出处：《清华大学》2016年博士论文　论文类型：学位论文

【摘要】：土石混合体(S-RM)常见于多种浅表生地质灾害以及水利水电工程、道路工程、房屋建筑、矿山开采等领域。其中“土”和“块石”在粒径及强度方面均存在很大差异,使得土石混合体的细观结构特征对其宏观物理力学性质有显著影响,且与研究尺度密切相关,并具有明显的非均质特性。论文通过物理试验和数值模拟开展了土石混合体细观结构力学及尺度效应的系统研究。结合实时无损的CT扫描技术,开展了土石混合体室内三轴试验。研究了含石量、粒度组成、试样尺度对其宏观强度及变形特性的影响,并实现了对试样细观结构及其演化过程信息的实时获取。应用数字图像处理、数据库管理和3D可视化技术,研发了土石混合体三维细观结构重建及分析系统(MSRAS3D),实现了土石混合体试样三维细观结构模型重建及细观结构定量统计分析,为揭示三轴试验全过程的细观结构演化规律提供了有力手段。在此基础上,揭示了土石混合体试样在外荷载作用下内部块石的空间运动规律、典型破碎形式和变形局部化现象。基于土石混合体重建模型开展了三轴试验的离散元数值模拟,根据室内试验结果反演获得了“土”与“块石”的颗粒细观力学参数。应用反演计算参数,采用随机生成技术获得土石混合体随机模型,系统研究了块石形状、破碎性能和试样尺度等因素对土石混合体宏细观力学行为的影响。基于数值试验结果,对土石混合体剪切破坏过程中内部颗粒的空间运动、颗粒间接触数、法向与切向接触力、细观体变等细观结构特征的演化规律进行了定量分析,从细观层次揭示了粒度组成、块石形状及破碎性、试样尺度等因素对土石混合体宏观强度及变形特性的影响机制。通过论文研究表明:基于室内试验中的重建模型和数值模拟中的随机模型量化分析细观结构演化规律,是揭示土石混合体宏细观力学特性的有效手段。土石混合体的细观结构特征和“土”、“块石”的自身性质,共同影响其力学行为。变形破坏过程中,内部块石运动、破碎等引起内部细观结构的不同调整,从而影响宏观强度和变形特性。研究尺度和粒度组成直接决定了块石在土石混合体力学响应中所发挥的作用类型;棱角性块石未破碎时,能通过咬合有效提高强度;由应力水平和块石自身强度决定的破碎性质,对土石混合体强度参数及变形特性均有重要影响。
[Abstract]:RSA (S-RM) is common in a variety of epigenetic geological disasters and water conservancy and Hydropower Engineering, road engineering, building, mining and other fields. The "soil" and "stone" in terms of size and strength are different, the soil rock mixture microstructure has a significant effect on the the physical and mechanical properties, which is closely related with the research scale, and has the obvious characteristics of the heterogeneous system. This paper research meso structure mechanics and scale effect of soil rock mixture through physical experiments and numerical simulation were carried out. Based on the real-time lossless CT scanning technology, carry out the soil rock mixture of the three axis of particle size test. Stone content, composition, effect of specimen size on the macroscopic strength and deformation characteristics, and realizes the real-time acquisition of the sample microstructure and the evolution of information. The application of digital image processing, database management 3D and visualization technology, research and development of earth-rockaggregate three-dimensional structure reconstruction and analysis system (MSRAS3D), the SRM three-dimension meso structure model of meso structure reconstruction and quantitative statistical analysis, provides a powerful means to reveal the whole process of three axis test of meso structure evolution law based. That reveals the spatial movement of SRM under load inside the stone, crushing and deformation localization phenomenon typical form. The reconstruction model of earth rock mixture discrete element numerical simulation based on three axis test, according to the test results of inversion obtained "soil" and "stone" fine particles the concept of mechanical parameters. Calculation parameters are used for inversion of soil rock mixture stochastic model using random generation technology, studied the shape of block stones, crushing performance and specimen size and other factors on the soil rock mixture Influence of macro and meso mechanical behavior. The results of numerical experiments based on the space motion of particles inside the process of destruction of soil rock mixture shear, particle contact number, normal and tangential contact force, meso evolution body change of meso structure were quantitatively analyzed, revealing the fine granularity level from view, the shape of block stones and broken, the influence mechanism of factors on the sample scale and deformation characteristics of soil rock mixture macroscopic strength. Through the study showed that the model of quantitative analysis of stochastic reconstruction model and numerical simulation of indoor test in meso structure evolution based on earth is to reveal the effective means of combination of macro and meso mechanics the characteristics of soil rock mixture. The meso structure characteristics and the "soil", "stone" of their own nature, influence its mechanical behavior. In the process of deformation and fracture, the internal rock movement caused by breaking internal meso node Different adjustment structure, thus affecting the macroscopic strength and deformation characteristics. Research on the scale and size directly determines the type of stone in the role play in the mechanical response of soil rock mixture; angularity stone is not broken, can effectively improve the strength of the occlusion; by nature should be broken stress level and rock strength that of soil rock mixture strength parameters and deformation characteristics have a significant impact.

【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU411

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