1 Common structural diseases of roads and bridges

1.1 Cracks in the main arch ring

1.2 In the structural diseases of road bridges, cracks in the main arch ring are a common problem, which has a serious impact on the overall quality of road bridges. Usually found during inspection, the main realizations are: longitudinal cracks, transverse cracks, irregular cracks, etc. Most of the cracks are about 10 meters away from the vault. Severe cracks can directly cause the strength of the main arch ring, and then the performance declines and the stability is unbalanced. The existence of the main arch ring cracks will leave a safety hazard to the road and bridge.

1.2 Cracks in pavement

The cause of cracks in the pavement layer is mainly affected by the changes in the ambient temperature, and the pavement layer is unevenly heated and cold, and the phenomenon of cracks will gradually appear. In addition, roads and bridges are traffic routes provided for heavy vehicles. If there are frequent overloads, speeding, etc., the degree of wear of the pavement layer will become more and more serious. Beyond the stress range of the pavement layer, cracks will occur. At the same time, improper use of concrete can also cause cracks in the pavement layer, such as unreasonable mix ratio and inadequate maintenance.

1.3 Corrosion of steel bars

In road and bridge structures, reinforced concrete structures are very common. Improper construction and improper maintenance will result in revealing situations, and rusting of steel bars cannot be avoided. The corrosion will cause the volume expansion of the reinforced concrete structure to occur, and the expansion speed is also very fast. In severe cases, the volume can reach more than 10 times the original volume, which directly affects the actual performance of the reinforced concrete structure. At the same time of expansion, the surrounding concrete will also be squeezed, and severe squeezing will cause cracks. Once quality problems such as rust and cracks occur, it will threaten the stability of the overall structure of the road and bridge.

1.4 Partial damage to the end

End damage is the main cause of vehicle jumping. Therefore, more attention should be paid to the problem of end damage, and the cause of end damage should be required. After years of research on broken ends, it has been found that there are three reasons. First, in the design process, the bearing capacity design does not meet the actual requirements, and there are errors, and the errors are more serious after construction, and the bearing capacity is obviously insufficient. Second, the construction unit does not pay much attention to the construction quality of the bridge end, and there are problems with the quality of the expansion joints, which can be easily damaged during use. Third, the maintenance is unreasonable, and the maintenance plan does not have scientific and reasonable characteristics. The maintenance is not timely, and the correct treatment method is not selected for the existing cracks, resulting in more and more serious damage to the broken head, and it is easy to affect the jumping of the vehicle during the driving process.

1.5 Concrete carbonization

The carbonization of concrete is mostly caused by natural factors. Calcium hydroxide is one of the components of concrete. When it fuses with carbon dioxide in the air, it will chemically react to form calcium carbonate. Calcium carbonate is the main factor causing the direct drop of concrete pH. If no measures are taken, calcium carbonate will be generated more and more, and the steel structure will corrode, the performance of the concrete structure will decline, and the quality of the road and bridge structure will be threatened.

2 Road and bridge reinforcement technology

2.1 Bridge deck pavement reinforcement technology

The reinforcement technology includes local repair chiseling method, repouring method, and reinforcing layer reinforcement method. The local repair chiseling method is suitable for the diseases such as falling off and chipping of the pavement of the bridge deck, and the local disease of the paving is the construction scope. The paving layer is chipped and the waste is cleaned up until the aggregate is exposed, and then the repair material and the corresponding bonding material are used for painting to promote the bonding of the new material with the original solid material. The pouring reinforcement method is suitable for severely damaged bridge decks. The deck is removed and new concrete is poured to form a new deck. The reinforcing layer reinforcement method not only satisfies the repair of cracks and peeling layers, but also increases the performance of the bridge slab.

2.2 Pouring Sealant Pouring Reinforcement Technology

The potting glue pouring reinforcement technology is more suitable for the main body deformation and serious cracks. Before the application of this technology, it is necessary to check the performance of the bridge structure, grasp all the information of the disease, and implement the potting glue infusion reinforcement method. For example, if the main body of the bridge suffers from a decrease in bearing capacity and a decrease in rigidity, it is necessary to use potting glue to infuse the cracks, and after the cracks are treated. With the help of prestressed reinforcement technology and bonded steel reinforcement technology, the exterior of the structure can be reinforced and the overall performance of the structure can be improved.

2.3 Reinforcement technology of outer wrap profile

The outer wrapping profile reinforcement technology uses a combination of wrapping and bonding methods to reinforce concrete components. The main application materials are steel plates, profiles, etc., and the reinforcement range is outside the concrete members. Reinforcement of concrete components is usually carried out in a wet-outsourcing reinforcement method. The selection of materials requires selection of section steel materials that meet the reinforcement requirements based on the damage of the concrete components. Use special adhesive glue to spread even the external parts of the component that need to be reinforced, and then bond the section steel to the periphery of the component to effectively exert the reinforcement effect, and the overall performance of the road and bridge structure will also be improved. This reinforcement technology has relatively simple construction, good reinforcement effect and low cost, and has been widely used at present.

2.4 Concrete replacement and reinforcement technology

The concrete replacement reinforcement method is mainly to reinforce beams or columns with low strength or quality defects in the pressure-bearing area of the bridge. The advantage of this method is that after the reinforcement construction is completed, it will not affect the building clearance. However, its defects are also more obvious, that is, after the defective beams and columns are reinforced, there may still be a problem of long wet working time.

2.5 Prestressed reinforcement technology

The prestressed reinforcement method is mainly a technical method for strengthening concrete flexural members. Under the combined action of the prestress and the newly added external load, the axial force will be generated inside the tie rod, and at the same time, the tie rod end will be anchored and eccentrically transmitted to the component, forming a corresponding eccentric pressure on the component. Under the influence of the above-mentioned forces, the influence of external loads on the bridge structural members will be significantly reduced, so that the overall flexural load-bearing capacity and the diagonal-section shear load-bearing capacity of the members are effectively improved. Not only that, through the effective transmission of this pressure, the overall performance of structural members can be strengthened, and the development of concrete cracks can be controlled and relieved. For reinforced concrete components, after the pre-stressed bracing rods are reinforced, they will be closely connected with the reinforced components to form a statically indeterminate structural system. Under the dual action of external load and prestress, the axial force generated by the tie rod will be transmitted to the reinforced member through the component node, thereby changing the internal force characteristics of the section.