桥梁混凝土结构耐久性数值模拟的细-宏观转译理论

桥梁混凝土结构耐久性受到材料、环境、构造、受力状态等影响，具有显著时空变异性，现有单一尺度的数值模拟方法难以兼顾精度与效率。本课题拟针对碳化与氯离子侵蚀，探索建立耐久性数值模拟的细-宏观转译理论，解决桥梁混凝土结构耐久性能模拟与设计中的基础科学问题。首先，研究提出细观与宏观数值模拟校验指标与方法，校核与优化现有计算方法。然后基于细观数值模拟，研究骨料随机性对侵蚀结果的影响规律，揭示细观差异与宏观响应的对应关系；分别基于有效扩散系数和非定常环境作用输入提出细-宏观转译模式，并进一步建立宏观尺度上考虑转译的数值模拟方法，解决精度与效率的矛盾。在此基础上，面向桥梁混凝土结构耐久性特点对转译方法进行完善：研究多因素耦合作用的转译方法，准确模拟实际工程状态；研究数值模拟结果的统计与概率特性，及其设计表达形式与应用方法。项目成果将为桥梁混凝土结构耐久性设计的参数、工具、方法提供新的基础数据和理论。

Durability of the bridge concrete structures shows significant time-dependent and spatial variability under the influence of material, environmental effects, component details and stress conditions. It is very difficult to seek both accuracy and efficiency in the current monoscopic numerical simulation methods. In this research, it is intended to explore and establish the mesoscopic to macroscopic translation theory in durability numerical simulation of carbonation and chloride ingression. It is expected that this research will offer viable solutions to some fundamental questions in the durability performance simulation and design for bridge concrete structures. Firstly, verification indices and methods for the mesoscopic and macroscopic numerical simulation are proposed, based on which the current methods can be verified and promoted. Secondly, mesoscopic numerical simulation is adopted to study the scientific laws of aggregates variability influencing the ingression results and the relationship between the mesoscopic variability and macroscopic responses. According to the study, two mesoscopic to macroscopic translation modes are proposed, one of which is based on the effective diffusion coefficient, and the other is based on the non-constant environmental effect input. Then a new macroscopic numerical simulation method with consideration to the aforementioned translation is established, settling the contradiction between simulation accuracy and calculation efficiency. Thirdly, the translation theory is improved with considerations to the characteristics of the durability of the bridge concrete structures, 1) translation theory for the multi-factor coupled effects is studied to precisely simulate the actual engineering state, and 2) the statistic and probabilistic characteristics of the numerical simulation results are discussed and expressed in the durability design for engineering applications. The accomplishments in this research are expected to provide the parameters, instruments and methods of the durability design for bridge concrete structures with novel fundamental data and theory.