Among the shrinkage types of concrete, plastic shrinkage and dry shrinkage are the main causes of volume deformation of concrete. When cement contacts with water, the crack of concrete bridge is a common technical problem, and the crack of concrete bridge is a common technical problem. The sub-micro research is carried out through modern concrete strength theory. Rich engineering practice experience.

　　结果表明，混凝土结构的裂缝是不可避免的，细裂缝的使用是无害的。在混凝土桥梁的设计计算理论中，允许构件开裂，但裂缝宽度不能控制得太宽。还有一种方法可以修复和加强混凝土桥梁的裂缝。找出裂纹的真正原因后，采用正确合理的修复材料和方法。

　　The results show that cracks in concrete structures are inevitable and the use of fine cracks is harmless. In the design and calculation theory of concrete bridges, cracks are allowed, but the width of cracks can not be controlled too wide. There is another way to repair and strengthen cracks in concrete bridges. After finding out the real cause of the crack, the correct and reasonable repair materials and methods are adopted.

　　加强桥梁构件，提高结构性能，提高桥梁承载能力，延长桥梁使用寿命，适应现代交通运输的要求。可以看出，设计裂缝、施工质量差、监理质量差等因素都可能导致混凝土桥梁产生裂缝。因此，严格按照有关标准和技术标准进行设计、施工和监理是保证结构和耐久性的前提和基础。

　　Strengthen the bridge components, improve the structural performance, improve the bearing capacity of the bridge, extend the service life of the bridge, and adapt to the requirements of modern transportation. It can be seen that design cracks, poor construction quality, poor supervision quality and other factors may lead to cracks in concrete bridges. Therefore, design, construction and supervision in strict accordance with the relevant national standards and technical standards are the premise and foundation to ensure the safety and durability of structures.

　　在经营管理过程中，进一步加强检查管理，及时发现和处理问题也是非常重要的环节。钢筋锈蚀引起的裂纹。由于混凝土质量差或保护层厚度不足，混凝土保护层被二氧化碳碳化到钢表面，降低了钢筋周围混凝土的碱度。或者由于氯离子的介入，钢筋周围氯离子的含量较高，导致钢筋表面氧化膜断裂，钢筋内铁离子侵入凝固。土壤中的氧气与水发生反应而生锈。

　　In the process of operation and management, it is also very important to further strengthen inspection and management, and to find and deal with problems in time. Cracks caused by corrosion of steel bars. Due to the poor quality of concrete or insufficient thickness of protective layer, the protective layer of concrete is carbonized by carbon dioxide to the steel surface, which reduces the alkalinity of concrete around steel bars. Or because of the intervention of chloride ion, the chloride ion content around the reinforcing bar is high, which leads to the rupture of the oxide film on the surface of the reinforcing bar and the invasion and solidification of iron ion in the reinforcing bar. Oxygen in the soil reacts with water and rusts.