基于真实骨料模型数据库和虚拟扫描成像技术的多相材料三维细观模型构建方法

Although the three-dimensional (3D) numerical simulation for multi-phase materials (such as asphalt concrete and cement concrete) has been well applied, the development of 3D mesostructural modeling for multi-phase materials has been noticeably constrained. The traditional CT-imaging approach has a high accuracy but also high in cost due to the equipment requirement and image post-processing. It is sort of similar to the block printing. On the other hand, the recently developed computer generated models is cost saving, but the model accuracy is low due to the difference between the real aggregate shape and the model shape. In addition, the computer generated 3D finite element modeling using user-defined aggregates has not been well solved yet due to arithmetic problem. This study aims to utilize the advantages of the both the two approaches via using the model of real aggregates to construct the 3D mesostructure model of multi-phase materials, which can achieve high accuracy while low cost, sort of similar to the movable-type printing. In detail, the 3D model with the real shape of aggregates are constructed first and then a model database is established. The 3D basic model for the multi-phase material can be constructed first based on the aggregate model database. Then the 3D mesostructure model using the virtual scanning and imaging. This study provides a highly efficient and reliable approach for the reconstruction of 3D mesostructure model for multi-phase model and will stimulate the development of the 3D numerical simulation for such materials.

虽然针对多相材料（如沥青混凝土和水泥混凝土）细观模型的数值模拟已经得到广泛应用，多相材料三维细观建模的发展依然受到很大的制约。传统的CT扫描法虽然精度较好，但是所需设备成本和后期处理成本高，类似于印刷术中的“雕版印刷”。近年来的电脑生成模型虽然成本低，但是生成的骨料模型和真实骨料有差异，从而导致模型精度不高。而且由于算法困难，基于自定义不规则骨料形状的电脑生成三维有限元模型的构建一直未能有效解决。本研究旨在结合这两种方法的优势，使用真实骨料的三维模型构建多相材料三维细观模型，既保证了精度又节省了成本，类似于印刷术中的“活字印刷”。具体而言，首先构建和真实骨料外形一致的三维模型，并建设骨料三维模型数据库。基于三维数据库构建多相材料的三维基础模型，然后使用虚拟扫描成像技术构建三维细观模型。本研究给多相材料的三维细观建模提供了一种高效而可靠的方法，对多相材料的三维数值模拟的发展有积极的促进作用。

数值模拟是研究土木多相材料的有效手段和对实验方法的补充。建模是数值模拟的基础，但现有的多相材料建模依赖于CT扫描，成本过高。本研究提出了与真实多相材料具有高拟合度的模型构建方法。本项目构建了集料三维形态特征检测与评价体系，集成了集料三维数字模型重构系统、集料三维形态定量评价体系和集料三维评价精度验证体系，比传统的二维方法更加全面和精确，也为骨料的分类和建模确定了基础标准；构建了和真实集料形态一致的集料三维模型数据库，并提出了集料三维数字模型编码、解码方法，实现了有序存储和调用；基于此，构建了基于真实集料形状和内部结构的沥青混合料三维数字模型，集料模型从已建立的数字模型库中调用，通过计算机随机抽样方法生成沥青混合料模型，和真实沥青混合料模型具有很高的拟合度。通过三维重构的方法构建了基于真实形状的沥青混合料三维数值模型，提出了基于体积阈值法的沥青混合料三维内部结构分析方法和骨架接触特性定量评价指标；仿造现实中CT扫描获取试样断面图像原理，提出虚拟扫描和成像技术，用于重构三维沥青混合料有限元模型，解决了当前沥青混合料三维有限元模型需要通过CT扫描真实试样的局限性。