I. Introduction
Since the reform and opening up, with the rapid development of the socialist market economy, China's transportation industry has also flourished. As a transportation hub, the number of bridges is also increasing. According to statistics, by the end of 2009, there were 6210.9 million highway bridges with a total length of * * * 27,260.6 kilometers. Obviously, various damages will inevitably occur in the long-term use of the bridge structure, which will lead to the attenuation of the resistance of the bridge structure and potential safety hazards. How to maintain the existing bridges and prolong their service life is a serious problem faced by traffic management departments at all levels.
Second, the importance of bridge detection
In concrete engineering practice, many bridge builders often ignore the detection of bridges, which is very irresponsible for ensuring the safe and stable operation of traffic. Taking reasonable and effective measures to detect the structural damage of the bridge can find out whether the bridge structure is damaged in time, thus ensuring the normal operation of the transportation hub. At the same time, many other potential benefits can be obtained by detecting bridges.
1. Bridge information can be obtained in time by detecting the bridge. When the bridge quality problem is detected, the bridge can be maintained by closing the bridge. At the same time, technicians can study the changes of the bridge in use through the data of many bridge inspections.
2. Through the regular inspection of the bridge, the possibility of potential safety hazards in the bridge is reduced, the protection of the bridge is more scientific, and the service life of the bridge is obviously improved.
3. Testing the bridge can provide valuable experience for the future bridge structure design, and practice is the only criterion to test the truth. Only by regularly testing the bridge, obtaining all kinds of parameter data and verifying that it is consistent with the theoretical calculation can the design level of the bridge be continuously improved and the functional requirements be met. In the process of bridge detection, engineers and technicians should not only pay attention to the detection of bridge appearance, but also further detect the material and structure of deep bridge through load test. With the continuous progress of science and technology, in the practice of bridge inspection, engineers and technicians should adopt advanced equipment and technology to improve the efficiency and accuracy of bridge inspection.
Third, the present situation of bridge detection technology
In recent years, China has done a lot of research on bridge detection. By accumulating a lot of bridge inspection experience, China has formed some practical inspection methods. In the past decades, China has gradually shifted from semi-destructive testing to non-destructive testing. Non-destructive testing methods mainly include two main contents: local testing of bridges and overall testing of bridges. These two aspects will be briefly discussed below.
1, bridge local detection
Local inspection technology is the main technical means of daily inspection of bridge structures. Local detection technology is to use visual or special detection instruments to detect local damage and defects of structures. Local inspection is mainly to test the material condition and durability of bridge structure. X-ray, penetrant, magnetic particle, eddy current and ultrasonic detection techniques were used to detect concrete strength, carbonation depth, internal damage of concrete, distribution of steel bars and thickness of protective layer, corrosion of steel bars and chloride ion content. In recent years, with the development of science and technology, advanced detection technologies such as far infrared thermal imaging, nuclear magnetic resonance, holography, tomography, microwave and radar have been gradually applied to local detection of bridges.
2, the overall detection of the bridge
2. 1 the role of the whole detection
The overall inspection of the bridge can reflect the bearing capacity and normal service state of the bridge, and overcome the limitations of local inspection of the structure. It mainly collects structural response data such as speed, acceleration, displacement, stress and strain of bridge structure through static and dynamic tests. Then the response data are scientifically processed by mathematical and mechanical methods, and then the overall situation and local damage of the bridge structure are carefully analyzed by technicians. The overall performance of the bridge structure can be truly reflected by the overall detection technology, which can answer the bearing capacity problem of the bridge structure that everyone is most concerned about, thus accurately verifying whether the design process and construction management process of the bridge can meet the standard requirements.
2.2 Comprehensive detection methods
The bridge is tested by applying controllable load, and the response data such as strain, strain distribution and acceleration of the bridge structure are collected through the test, so as to evaluate the overall performance of the bridge structure. The overall detection test of bridge can be divided into static load test and dynamic load test. Static load test refers to the test of applying a static load at a specified position and detecting various indexes of the bridge in order to obtain the overall working performance of the bridge. Bridge dynamic load test refers to the test that causes the bridge structure to vibrate in some way and measures its vibration index to judge its overall stiffness. The dynamic load test of bridge will not hinder the operation of traffic, and it is an indispensable technical means in the comprehensive inspection of bridge structure.
3. Problems existing in bridge detection
3. 1 The detection method is backward and the mobility is low. Engineers and technicians can only test bridges on land by erecting scaffolding under the bridge. For the bridge over the river, the inspection items are complicated, and only scaffolding can be erected on the ship to connect the bridge for inspection. If the bridge is impassable, there is no better way to solve this problem at present.
3.2 The detection cost is expensive and the detection time is long. No matter which detection method is adopted, it takes a lot of manpower and material resources to build scaffolding. Usually, the construction time is long and the cost is high, which undoubtedly increases the cost of testing and prolongs the progress of testing.
3.3 Higher operational risk factor. When engineers and technicians check bridges on scaffolding, the risk factor of operation will increase, and safety accidents are prone to occur during scaffolding.
3.4 The detection range is small. If we only rely on scaffolding to detect bridges, the scope of detection will inevitably be relatively small. If the bridge can't be tested in all directions and in a wide range, the accurate test results can't be obtained, which will affect the test quality.
3.5 Causing traffic inconvenience. If the bridge is to be inspected locally or wholly, it is necessary to control the traffic partially or completely. If the detection time is long, the control time will inevitably increase, which will seriously affect the smooth operation of traffic and bring inconvenience to citizens.
Fourth, the development trend of bridge detection technology
1. Development of bridge nondestructive testing technology
After entering the 1990s, with the rapid development of sensing technology and computer technology, the bridge detection technology has also undergone a revolution, and a large number of new detection methods have emerged. Bridge nondestructive testing technology is also developing rapidly in the direction of rapidity, intelligence and systematization. This solves the limitation that bridge detection in the past had to rely on visual inspection and static and dynamic load tests by inspectors to detect bridge damage. In recent years, researchers who are committed to bridge detection have put forward many successful nondestructive evaluation methods for bridges. It is found that the dynamic response of the structure is a measure of the overall state. When the mass, damping characteristics and stiffness of the structure change, the modal quantity of the bridge structure before and after the damage can be weighted by the structural vibration mode, which can effectively identify and locate the unit damage. It can be predicted that the rapid development of vibration modal analysis technology will surely open up a new way for the safety detection of bridge structures.
2, the development trend of advanced technology
2. 1 The development of bridge deck detection system is mainly the continuous development and improvement of technologies such as ground penetrating radar and dual-band far-infrared thermal imaging system.
2.2 The development of corrosion detection and evaluation technology is mainly the continuous development and improvement of "magnetic" based measurement system marked by embedded corrosion microsensor and magnetic flux leakage detection technology.
2.3 Development of bridge detection and health monitoring system, mainly including measuring bridge overload with steel sensors, accurately measuring bridge deformation with global positioning system, and monitoring data to ensure bridge health.
2.4 The development of fatigue crack detection and evaluation system is mainly the continuous improvement of microwave detection and quantitative analysis system, new ultrasonic and magnetic analyzer system, portable acoustic emission system, thermal imaging system, wireless strain measurement system, electromagnetic acoustic emission sensor, passive fatigue load measurement equipment and other technologies.
Verb (abbreviation of verb) conclusion
Through the inspection of the bridge, we can know the service condition of the bridge, ensure its normal use and reduce the possibility of accidents. However, the traditional detection method has low accuracy and complicated detection process. However, we can foresee that with the rapid development of science and technology, especially computer technology, artificial intelligence will be widely used in the detection and analysis of various bridge structures. At the same time, the cross-utilization of science and technology will become increasingly popular, and the development of emerging technologies will definitely affect the bridge inspection work, making it more efficient and accurate.
Want to know more about "the present situation and development of bridge detection technology" and other construction information, you can search in Zhong Da Consulting Building.
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