联合X-RayCT成像技术和格子Boltzmann方法研究沥青路面的渗水性能

Hydraulic permeability of an asphalt pavement is one of the most important parameters that have a direct influence on its design life. The traditional approach to evaluate the hydraulic permeability of pavement is based on laboratory tests or measures on the field. However, such an approach only provides the static Darcy's permeability in one direction. Therefore, a dynamic permeability in any direction is more realistic representation of the response of a pavement pore structure due to the repeated tire loading in the field. In order to estimate the permeability of realistic asphalt mixtures, a novel method will be proposed in this project. The method consists of two key components-reconstruction of 3D porous media (asphalt mix specimens) from 2D slices and 3D flow simulation using the Lattice Boltzmann Method. The 3D real internal microstructures of asphalt mix specimens will be constructed using an X-Ray computed tomography system along with image analysis techniques and used as an input in the Lattice Boltzmann models. The Lattice Boltzmann fluid flow models with multiple-relaxation-time collision operators will be developed. The model will be validated using the well-known closed form solution of Poiseuille flow. Simulations will be carried out to calculate the hydraulic permeabilities of different asphalt specimens exposed to dynamic pressures. The research results could provide scientific basis and theoretical support for mix design, construction controlling and operation management.

沥青路面的渗水性能是直接影响其设计寿命的重要参数之一。传统的评估沥青路面渗水性能的实验一般是实验室测试或现场测试。然而这类方法往往把沥青混合料看成各向同性,且只能提供单方向的"静态"达西渗透系数，并不能真实反映轮载下各方向"动态"的渗水性能。本课题提出一种评估渗水性能的新方法。该方法包括两个重要组成部分- - 从二维切片中重构试样的三维几何微结构和使用格子Boltzmann方法模拟多孔介质内的微观流动。使用X-Ray CT成像技术及图像分析以获得试样的真实内部微观结构并作为格子Boltzmann模型的输入。使用多松弛时间碰撞算子的格子Boltzmann模型模拟不同条件下多组试样的动态渗水性能，并以经典的算例加以验证。本项目研究成果可为沥青路面配合比设计、施工控制和营运管理提供科学依据和理论支撑，具有重要的理论意义和工程应用价值。

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