Overview of road and bridge detection technology?

Quite a few experts believe that when the bridge is used for more than 25 years, it will enter what we call aging period. According to authoritative statistics in related fields, about 40% of bridges in China belong to the category of "older" bridges. Therefore, the daily maintenance cost of bridge structure in China is very huge every year, such as reinforcement, maintenance and replacement. There is no doubt that all the powerful countries in the world are not transportation powers. The simplest example is the United States, because a country's traffic construction is directly related to a country's economic development and military security.

1. Present situation of bridge detection in China

Due to the slow start of infrastructure construction in China, we refer to the experience of developed countries to see how the level of bridge maintenance will directly affect whether the bridge can be put into use safely. For this reason, the Ministry of Communications specially set up a project to carry out the research work of bridge management system, and finally formed the highway bridge management system in China. The main principle of the system is to determine the score according to the regular inspection of the bridge maintenance engineer. Of course, the basis of grading will mainly depend on the structure and construction of the project. Finally, the grade of each bridge and road is evaluated by data analysis, and it is used as the basis for formulating maintenance strategies. Therefore, we can see that how to accurately and reliably determine, a large number of data is the key. However, the existing bridge regular inspection methods can not meet our needs, which may lead to major accidents and cause a lot of personnel and property losses.

1. 1 Problems existing in the use of highway bridges

The main problem of A is the lack of scientific construction design and unclear project planning.

B The main problem is that the construction quality of many bridges can't meet the requirements, and some even don't follow the engineering design.

C Many roads, bridges and roads are seriously damaged after a period of actual operation, which greatly limits the bearing capacity of bridges.

1.2 road and bridge inspection preparation

Therefore, it is necessary for us to make a comprehensive and detailed preparation before testing, such as the testing equipment we will use in our work and the corresponding plan. Besides, we need to collect appropriate information. What kind of engineering design data, and the corresponding maintenance, reinforcement and engineering construction data, etc.

2. Several methods commonly used in road and bridge detection at present.

2. 1 Internal defect detection of the project

The so-called engineering internal defect detection refers to the detection of common defects such as cavities, spalling, cracks, honeycomb, steel corrosion and environmental erosion in concrete members. Some of these defects are difficult to find by naked eye external observation. In this case, we need to use other means to identify them. Usually, we will use nondestructive identification. At present, the commonly used nondestructive testing methods mainly include radar detection technology and acoustic wave detection method. Ultrasonic pulse fast method can detect cracks, slag inclusions, cavities, fires and other problems in welds, steel and concrete, which cannot be detected by external detection.

2.2 Performance test and evaluation of engineering structures

With the development of nondestructive testing technology, there are many ideas. Our traditional detection technologies mainly include ultrasonic detection, acoustic emission, spontaneous potential detection, acoustic emission, infrared detection and so on. Of course, these traditional testing and analysis methods have been further developed and improved. Although they can also get more reasonable analysis and judgment, they still cannot make a comprehensive performance evaluation of the project. At this time, for higher data requirements, we will adopt more advanced local detail testing and comprehensive damage location testing methods.

When we can't get detailed information about bridges or roads, at this time, we can use dynamic or static tests to carry out corresponding tests, which can correctly reflect the structural stress of the project. The commonly used structural performance test method is dynamic test plus static test.

2.3 Appearance inspection

First of all, appearance inspection is not simply looking at things. We want to analyze the causes of bridge diseases by visual inspection of roads and bridges. So the first thing we have to do is to determine the corresponding detection points according to the bridge type. The key points of general bridge inspection are: inclined cracks at the span end, cracks and deflection in construction quality, appearance and the status of the connection parts of the main girder.

Almost all bridge structures can be generally divided into three parts: superstructure, substructure and accessory structure. In the beam bridge, the auxiliary structure of the bridge includes expansion joints, railings and deck pavement. The superstructure of the bridge mainly refers to the main beam; The substructure of this edition includes foundation, bearing platform, abutment, pile and pier, etc. Although each part of them has its own unique stress characteristics, these diseases usually have some * * * characteristics. If it is found to be a conventional disease, it should be carefully studied to find out the cause, and it must not be judged blindly.

2.4 Inspection of material characteristics of the project

With the continuous technical innovation in the field of architecture and the diversified development of bridge design. More and more materials are used in bridge construction. Of course, the most basic and widely used materials are still steel bars and concrete. However, these materials also have aging and damage. We also have relevant detection methods. For large bridges, we often use test blocks to determine their strength, but for those bridges without test blocks, we often use coring test, ultrasonic method, fracture method, rebound method and penetration method to determine their strength. Among them, comprehensive interface method, rebound method and ultrasonic method are nondestructive testing methods, so they are widely used.

3. Summary of road nondestructive testing technology

The application of nondestructive testing technology in road and bridge engineering, like other technologies, needs research, development and utilization. Therefore, the research, development and application of nondestructive testing technology for road and bridge engineering is a relatively new field, which requires us to make a breakthrough in its application field and solve many urgent problems. These problems are mainly manifested in the following aspects: due to its unique advantages, it is necessary to conduct special research on the application of nondestructive testing technology in road and bridge engineering and other fields. Because this field is relatively new, it is necessary to make small steps in its application field and study the methods to solve the problems. These problems mainly focus on the following aspects:

A. the research of far infrared imaging technology to detect the damage of road and bridge structures;

B, detecting and quantitatively analyzing fatigue cracks in engineering by using microwave technology;

C, determining the compactness and smoothness of the foundation of the project by using ultrasonic detection technology.

D research and development of earthwork proportion detection technology in the design of retaining wall burial depth and route crossing;

Research and development of detecting the depth of retaining wall by ground penetrating radar in route survey and design;

F use GPS positioning technology to measure bridge deformation, and measure and monitor the TRIP steel sensor used for bridge overload detection.

Non-destructive testing technology is a multi-disciplinary comprehensive application technology, which is based on the cross-application of basic disciplines. Only by constantly learning the basic theory can we gradually improve and develop. It can be said that it is the crystallization of advanced technology. It indirectly promotes the development of industry and the whole national economy. In a sense, nondestructive testing technology can be used as an index to measure a country's industrial and economic development level.

4. Future development trend of road and bridge detection technology

At present, the latest technical research in this field is to develop the application of NDE technology. There are several main aspects:

1) Advanced bridge detection and health monitoring system, mainly including wireless transmission of monitoring data of the whole bridge and application of precise differential global positioning system (GPS). The main field is measuring bridge deformation.

2) Research on advanced corrosion detection and evaluation technology, including research and application of embedded corrosion sensor, research and application of magnetic flux leakage detection technology and development of infrastructure measurement system based on magnetism.

3) Advanced fatigue crack detection and evaluation system, mainly including new ultrasonic bridge crack detection and magnetic analyzer system, recently popular wireless strain measurement system, thermal imaging system using microwave technology for detection and quantitative analysis, and portable acoustic emission system. In terms of design and sensor, this is a passive fatigue load measuring device and an electromagnetic acoustic emission sensor.

5. Conclusion

He not only needs the relevant staff to have rich practical work experience, but also needs our staff to have a solid theoretical foundation and constantly enrich their own on-site technology, so as to constantly learn the latest detection methods at home and abroad. Only in this way can we ensure the engineering quality of our roads and bridges.

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