基于非饱和渗流理论的路面排水基层平衡设计理论及方法研究

The water-induced damage is one of the main diseases with respect to the pavement of highway in high-rainfall area, and the appropriate drainage system is a significant measurement to reduce the water-induced damage.Currently,there are shortages in terms of the theory foundation in the drainage layer design of highway. The applicant's previous researches investigated the capillary effect on the flow in drainage layer of highway, and it demonstrated that the unsaturated flow should not be neglected in the drainage layer design. Accordingly, as a continued and extended study, the theory and method of design for the drainage layer in highway pavement is selected as the breakthrough point of this research. Based on the investigation analysis of pavement diseases, water penetration test and percolation theory, the simulation model and method will be established and presented to determine the quantity of inflow which offer the reference to the material selection and structure design of the draiange layer. Futher，the relationship between the unsaturated hydraulic properties and mechanical performance of the drainage materials will be obtained through laboratory tests, which is the foundation for flow model establishment and theoretical analysis. Then, the flow models with respected to steady-state and transient flow in the drainage layer will be developed and the solutions of water table distribution in the drainage layer will be obtained and validated through the numerical as well as laboratory methods. Furthermore, based on the numerical simulation, the test and the theoretical analysis results, the balanced design method in terms of "thickness-strength-permeability" and the evaluation method will be presented through optimizing the combinational relationships of the parameters of the drainage material and structure of the drainage layer. The theory and method with respected to drainage layer design of highway pavement will offer the beneficial reference to extend and improve the efficiency of drainage design and evaluation related to structure drainage system of highway.

水损害是多雨地区路面的主要病害之一，合理的排水系统是降低水损害的重要手段。针对目前我国路面排水基层设计理论基础存在的不足，申请人前期研究探索了非饱和渗流对排水基层排水过程的重要影响。作为前期研究的延续和拓展，本课题拟以路面排水基层的设计理论和方法为切入点，基于路面病害调查分析并结合路面渗水试验，建立路表水渗入率计算的理论和数值仿真模型，获得路表水渗入率估算表达式，为排水基层设计提供依据；通过室内试验获得排水材料非饱和渗流性质与力学性能之间的关系，为建立渗流模型以及理论分析提供基础；基于非饱和渗流理论建立排水基层稳态和瞬态渗流模型，获得排水基层孔隙水的渗流特征，并与室内模型试验和数值模拟进行对比验证；通过优化材料和结构参数的组合关系提出排水基层"厚度-强度-渗透性"平衡设计方法以及排水基层排水效率的评价方法。本项目成果将为拓展和完善国内外路面内部结构排水系统的设计和评价提供有益的理论参考。

本课题采用理论建模、数值分析以及试验验证的手段开展研究工作，结合饱和与非饱和渗流理论、分离变量法、有限元法以及大型动三轴试验开展沥青路面排水基层的渗入率、渗流性质以及力学强度的研究，取得了预期的研究成果，完成了预期考核目标。取得的主要研究成果如下所示：.（1）建立了路面面层和排水层之间水的渗流平衡方程以计算路面水的渗入率大小，获得了沥青路面路表水渗入率的解析表达式。.（2）获得了四种级配碎石渗流过程中水力梯度和渗流速度的关系曲线，揭示了级配碎石中的非达西渗流现象，基于Forchheimer方程并结合试验结果获得了级配碎石的渗透系数。.（3）通过试验研究了公路路面排水基层级配碎石材料在不同含水量和应力水平下的动态模量对含水率的影响，提出了表征级配和含水率的动态模量的变化表达式。.（4）采用两种饱和流模型（BM和LM）和一种非饱和流模型（RM）对公路路面排水基层中的渗流进行了系统地模拟计算，阐明了非饱和渗流的重要性。.（5）采用Gardner土水特征曲线方程结合稳态Boussinesq方程，获得了稳态条件下的水位分布解析解，并用于排水基层最小厚度的确定。.（6）建立了考虑毛细水作用的基于一维瞬态Boussinesq方程模型，将time-to-drain和depth-of-flow两种排水基层设计方法结合起来以评估排水基层的排水效率；推荐了获得良好的排水效率的排水基层材料的水力参数，以供设计时参考。.（7）以最大水位厚度来表征排水基层的厚度，阐述了不同级配条件下的强度控制指标，通过渗透试验结果并结合排水基层排水效率的评价方法，获得排水基层渗透性的控制指标。基于基层厚度设计、强度控制和渗透性评价，提出了排水基层的“厚度-强度-渗透性”平衡设计方法。