界面区是水泥混凝土结构中的薄弱区域，为揭示华北地区路面混凝土界面区结 构在实际工作环境中的损伤机理，通过室内试验模拟路面混凝土在荷载、冻融和干湿三场 耦合下的工作状态，采用数字图像处理技术对不同工作阶段的路面混凝土界面区结构进 行图像提取与分析，揭示路面水泥混凝土在三场耦合下界面区结构的动态变化过程，进而 研究三场耦合作用下路面水泥混凝土细观损伤机制． 结果表明:标准养护3 个月后混凝土 的界面区宽度在30 ～40μm 之间;随着荷载、冻融和干湿循环三场耦合作用时间的增长， 混凝土疲劳寿命明显缩短，达到疲劳破坏时，界面区宽度接近60 ～ 70 μm; 三场耦合作用 下界面区的扩展速度明显增加，混凝土的结构密实度逐渐降低，最大裂缝长度先延伸然后 减小，而裂缝最大宽度则逐渐增加;最终确定了混凝土疲劳破坏时界面区宽度范围以及界 面区结构破坏特征参数临界值． 

The interfacial transition zone ( ITZ) is a weak area in the cement concrete structure． In order to obtain the deterioration behavior of the ITZ suffering the working environment in North China，coupled loading condition of fatigue load， freezethaw cycles and dry-wet was conducted to simulate the working condition of pavement concrete． Digital image processing technology was used to extract and analyze the structure of pavement concrete interface area in different working stages， the dynamic process of the interface structure of the pavement cement concrete under the three fields was revealed，and then microcosmic damage mechanism of pavement cement concrete was studied． Ｒesults show that after three months of standard curing， the width of ITZ of concrete is between 30 ～40 μm; with the increase of the coupling time of load， freezingthawing and dry-wet circulation， the fatigue life of concrete is obviously shortened，and when the fatigue damage is reached， the width of ITZ is close to 60 ～70μm; the expansion rate of ITZ increases obviously，the structural density of the concrete decreases gradually，the maximum crack length extends first and then decreases，and the maximum width of the crack increases gradually; finally， the width of ITZ and the critical value of the structural parameters of ITZ are determined．