First, the scientific significance of road and bridge detection
In the process of road and bridge construction, natural defects in engineering materials and mistakes in engineering structure design, construction and construction are inevitable. After the completion of the road and bridge, how to identify the actual quality of the road and bridge is the owner's most concerned issue. Mass-produced machinery and equipment, such as ships and automobiles, can be tested to meet the design objectives through destructive prototype tests. Roads, bridges and other building structures are produced in one piece, so it is impossible to carry out destructive prototype tests. Therefore, nondestructive testing technology has received special attention. Patrol visual inspection is simple and convenient, but its defects are also obvious. Not only the visual results vary from person to person, but also the overall quality of roads and bridges cannot be quantitatively judged. Due to the lack of strict and systematic quantitative detection methods for road and bridge quality, some inferior projects cannot be found and treated in time. Lightly, it will increase the cost of road and bridge maintenance in the future and increase the financial burden of national and local governments; What's more, the tragedy of destroying the bridge to death is about to happen. Therefore, it is not only of great theoretical value, but also of broad application prospects to study the detection methods and technologies of road and bridge structures.
Second, the problems existing in the use of highway bridges
(1) The design is unscientific and the project planning is unclear. (2) The bridge construction quality is poor, which does not meet the engineering design requirements. (3) After the actual operation of highway bridges for a period of time, serious diseases appeared, which greatly affected the bearing capacity of the bridges. (4) The bridge construction quality is good, and the actual operation is good, but it can't meet the bearing demand after a period of time. (5) The detection of some super-large bridges is not in place, and such bridges also need high detection technology.
Third, the analysis of highway bridge detection technology
(A) the current problems in road and bridge testing at home and abroad
At present, scholars at home and abroad have made some progress in road and bridge test research. For example, through forced vibration test, the influence of modal parameters of road and bridge structure on local changes of structure can be analyzed; The research results of the influence of vehicle weight, vehicle speed, road surface and bearing on the modal parameters of road and bridge show the feasibility of automatic detection of road and bridge by environmental vibration method. It has accumulated theoretical understanding and experimental proof experience for structural state sensitive parameters suitable for road and bridge detection. The test data can be used to modify the calculation model: various damage detection methods and location technologies based on the changes of frequency, vibration mode, modal curvature and strain vibration mode have been developed.
(B) highway bridge appearance disease analysis method
1. Determine the investigation focus according to the specific characteristics of pressure. Generally speaking, we can determine the focus of the investigation according to the type of bridge. The inspection points mainly include cracks, deflection and shear joints in the mid-span area, the safety status of the connection part of the main girder of the bridge, and the appearance quality of the bridge.
2. Check the parts one by one. As a whole, the bridge can be divided into upper part, lower part and subsidiary structure. Each part of the bridge has its own mechanical characteristics, and the diseases of these parts also have some characteristics. If there are unconventional diseases, the inspectors should study them carefully, find out the causes, and evaluate the quality according to the degree of damage, and then replace the parts to maintain normal operation.
3. Internal defect inspection. In bridge concrete components, the common defects mainly include fragmentation, delamination, honeycomb, environmental erosion and steel corrosion. If these defects are not easy to find only by visual inspection, other methods need to be used for related detection. At present, the commonly used nondestructive testing methods for bridges include acoustic wave detection, ultrasonic flaw detection and radar detection technology.
4. Investigate the characteristics of materials. With the diversification of bridge structures and the continuous development of new technologies, more and more materials and designs have been applied to bridge structures, but at present, the most widely used and basic ones are steel bars and concrete. Among them, the strength of steel is usually checked according to the relevant data of design and construction. If there is a problem with the quality of steel or the data is unclear, the inspectors can take necessary measures to carry out the necessary material inspection.
5. Bridge reinforcement corrosion assessment technology. If steel bars are corroded due to defects such as compactness, water content, carbonation depth, insufficient thickness of protective layer or cracking of concrete, the degree of corrosion can be detected by simple appearance inspection and tapping inspection.
(3) Advanced bridge detection technology abroad.
The first is the bridge deck detection system, including dual-band remote thermal imaging system and ground penetrating radar system. Secondly, the bridge detection and health monitoring system, including the wireless transmission of the whole bridge detection, uses fractional global positioning system to measure the bridge deformation, and uses steel sensors to detect the bridge overload coefficient. Thirdly, the fatigue crack detection and evaluation system includes magnetic analyzer system, portable acoustic emission system, thermal imager system and electromagnetic acoustic emission sensor. Fourthly, corrosion detection and evaluation technology, including magnetic flux leakage detection technology, embedded corrosion microsensor and magnetic-based measurement system.
Four. conclusion
The detection of highway bridges is a very complicated and important work, which not only requires strict on-site experience of relevant staff, but also needs scientific detection methods and systematic theoretical basis as guidance. Only by fully combining theory with practice can we really do a good job in the inspection of highway bridges and make a scientific evaluation.
For more information about project/service/procurement bidding, and to improve the winning rate, please click on the bottom of official website Customer Service for free consultation:/#/? source=bdzd