摘 要
本文针对寒冷地区混凝土结构在反复冻融作用下的耐久性问题，开展系统的试验研究与分析。随着全球气候变化及极端天气频发，冻融循环对混凝土材料性能的劣化效应日益显著，成为影响工程寿命的关键因素。本研究旨在揭示不同冻融环境下混凝土内部损伤演化规律，评估其对力学性能和渗透性的影响，并提出适用于寒区工程的设计优化建议。通过设计多组冻融循环试验，采用快速冻融法模拟实际环境，结合质量损失率、相对动弹性模量、抗压强度及氯离子扩散系数等指标，全面评价混凝土耐久性变化特征。同时引入微观测试手段（如SEM和XRD）从细观层面解析冻融损伤机理。结果表明，随着冻融次数增加，混凝土表现出明显的质量下降与刚度退化趋势，且水灰比和矿物掺合料种类对其耐久性具有显著影响。本研究创新性地将宏观性能退化与微观结构演变相结合，构建了基于冻融损伤累积的耐久性退化模型，为寒区混凝土结构服役寿命预测提供了理论支撑。研究成果可为高寒地区基础设施建设提供科学依据和技术支持，具有重要的工程应用价值。
关键词：冻融循环；混凝土耐久性；损伤演化；微观结构；寒区工程
ABSTRACT
This paper presents a systematic experimental investigation and analysis on the durability of concrete structures in cold regions under repeated freeze-thaw cycles. With global climate change and the increasing frequency of extreme weather events, the deterioration effect of freeze-thaw cycles on concrete material properties has become increasingly significant, emerging as a key factor affecting the service life of engineering structures. This study aims to reveal the internal damage evolution mechanisms of concrete under different freeze-thaw environments, assess their impacts on mechanical properties and permeability, and propose design optimization suggestions applicable to engineering projects in cold regions. By designing multiple freeze-thaw cycle tests and simulating real-world conditions using the rapid freezing and thawing method, this research comprehensively evaluates the variation characteristics of concrete durability through indices such as mass loss rate, relative dynamic elastic modulus, compressive strength, and chloride ion diffusion coefficient. Additionally, microscopic testing techniques (such as SEM and XRD) are introduced to analyze the freeze-thaw damage mechanisms at the meso-scale. Results indicate that with an increase in freeze-thaw cycles, concrete exhibits a clear trend of mass reduction and stiffness degradation, while the water-to-cement ratio and types of mineral admixtures are found to have a significant influence on its durability. Innovatively integrating macroscopic performance degradation with microscopic structural evolution, this study establishes a durability degradation model based on cumulative freeze-thaw damage, providing theoretical support for predicting the service life of concrete structures in cold regions. The findings offer scientific basis and technical support for infrastructure construction in alpine areas, demonstrating important engineering application value.
Keywords: Freeze-Thaw Cycles; Concrete Durability; Damage Evolution; Microstructure; Cold Region Engineering
目 录
摘 要 I
ABSTRACT II
第1章 绪论 2
1.1 研究的背景与意义 2
1.2 冻融环境下混凝土劣化机制概述 2
1.3 研究现状 2
1.4 本文研究方法与技术路线 3
第2章 冻融循环试验设计与材料性能分析 4
2.1 混凝土试件制备与配合比设计 4
2.2 冻融循环试验装置与控制参数 4
2.3 初始物理力学性能测试结果 5
2.4 材料组成对冻融性能的影响 5
2.5 试验数据采集与处理方法 6
第3章 冻融循环作用下混凝土性能退化规律 7
3.1 质量损失率随冻融次数的变化趋势 7
3.2 相对动弹性模量衰减特征分析 7
3.3 抗压强度与抗拉强度退化规律 8
3.4 表面剥落与内部损伤演化观察 8
第4章 冻融损伤模型构建与耐久性评估 10
4.1 冻融损伤变量定义与量化方法 10
4.2 基于试验数据的损伤模型建立 10
4.3 模型参数敏感性与适用性分析 11
4.4 混凝土耐久寿命预测方法探讨 11
结论 13
参考文献 14
致 谢 15
