Road and bridge engineering inspection technology?

The detection technology of road and bridge engineering is very important. The realization of technology is to better handle every detail, achieve the expected construction effect and ensure the engineering quality. Zhong Da Consulting will introduce the detection technology of road and bridge engineering to you.

1 Common problems in the use of roads and bridges at present

There will be various problems in the use of highway bridges, which will lead to the destruction of the safety of highway bridges. At present, the causes of road and bridge diseases are as follows:

Firstly, the lack of scientific and reasonable design scheme leads to unclear project construction planning; Secondly, during or after the trial operation of the highway bridge, there are serious diseases on the highway bridge, which greatly affect the bearing capacity of the highway bridge; Third, the road and bridge construction was not carried out according to the specifications during the construction process, which led to poor project quality and failed to meet the pre-design requirements of the project when the project was completed; Fourth, the construction quality of some bridges is relatively good, which has reached the requirements of good condition during trial operation, but the bearing capacity of the bridges can not meet the requirements after a period of operation.

Analysis method of appearance disease of 2-way bridge

2. 1 Inspect the parts one by one.

The structure of roads and bridges can be divided into upper and lower parts, and the rest are subsidiary structures. In view of the different stress characteristics of different structural parts, some unconventional diseases will occur in different parts. For unconventional diseases, inspectors should carefully study the causes of the diseases, and at the same time make corresponding quality evaluation according to the degree of diseases in different parts, and then replace the damaged parts to maintain normal operation.

2.2 according to the stress characteristics to determine the detection focus.

Generally speaking, the focus of inspection can be determined according to the type of bridge, mainly focusing on cracks, shear joints, deflection, the safety of bridge girder connection parts and the appearance quality of highway bridges.

2.3 Test and investigate material characteristics.

With the continuous development of new technologies and new products and the increasing diversification of bridge structures, more and more materials and designs are applied to the structural construction of bridges, among which steel bars and concrete structures are still the most widely used. Among them, the strength of steel bars is often based on the relevant data in design and construction. If the inspectors find that there is a problem with the quality of steel bars or the data is unclear, they should take certain measures to conduct material inspection on related problems before construction.

2.4 Internal defect detection

Cracking, honeycomb, delamination, environmental erosion, steel corrosion and other defects often occur in road and bridge concrete frames. If these defects can't be found in time only by visual inspection, it is necessary to use other detection technologies to carry out related detection. At present, the commonly used bridge detection methods include radar detection technology, acoustic wave detection method and ultrasonic flaw detection method.

2.5 Structural performance test

After the overall evaluation of roads and bridges is completed, the corresponding checking work should be carried out according to the relevant technical specifications, and the relevant technical parameters in the checking process should be based on the actual bridge. After the checking calculation is completed, bridges that do not meet the requirements of the code can be rebuilt, and those that are relatively available can be further identified and tested.

2.6 Bridge reinforcement corrosion assessment

If steel bars are corroded due to insufficient density, carbonation depth, water content and thickness of protective layer of concrete or cracking damage, the corrosion degree of steel bars can be detected by simple operations such as appearance inspection and tapping inspection.

2.7 Static test or dynamic test

The calculation results are not reliable until the detailed information is fully obtained. At this time, the inspectors should further carry out relevant static tests or dynamic tests to further determine the stress situation of the evaluation structure.

3 road and bridge detection technology

3. 1 ultrasonic testing technology

The basic principle of ultrasonic detection of road and bridge defects is to use ultrasonic detector and acoustic transducer to measure and analyze the propagation speed, amplitude and main frequency of ultrasonic pulse in road and bridge, and then judge the defects of road and bridge according to these parameters and corresponding changes.

When using ultrasonic detection technology to detect roads and bridges, ultrasonic waves can penetrate concrete structures and spread in them, which has the advantages of simple operation and safe use. Penetration test is the most commonly used method when ultrasonic instruments are used for testing, but there is a limitation in using this method, that is, two opposite test surfaces are needed for testing, such as the tunnel concrete structure can not use ultrasonic testing technology. At the same time, because ultrasonic testing is a kind of acoustic wave penetration testing technology, whether it can effectively capture its defect signal has always been a key issue affecting its development. Therefore, when using ultrasonic detection technology to detect roads and bridges, it is often necessary to compare the data of multiple measuring points, process the detection data by using the principle of probability and statistics, and then evaluate the defect state. Therefore, ultrasonic detection technology is not intuitive, and in order to obtain higher detection accuracy, multi-point detection is needed.

3.2 Geological Radar Detection Technology

Geological radar technology, also known as detection radar technology, is a high-precision, nondestructive testing, intuitive, economical and fast high-tech detection technology. This technology mainly uses geological radar to emit high-frequency electromagnetic waves into the object, and then receives the corresponding reflection from the object to judge the internal situation of the object. Ground penetrating radar technology is a high-precision physical detection technology, which is mainly used in engineering geology, basic engineering, cultural relics archaeology, road and bridge detection and concrete structure detection.

3.3 Acoustic Emission Detection Technology

Local stress concentration will lead to unstable stress distribution due to uneven internal structure of materials or defects with different properties. In the process of crack, plastic deformation and fracture, materials will release certain stress and make it spread around in the form of stress wave, which is called acoustic emission. Concrete structures in roads and bridges will deform under load. When the deformation exceeds the design requirements, cracks will appear and energy will be released in the form of waves. When the acoustic emission method is used to detect roads and bridges, the acoustic transmitter is placed in the position to be detected, and the location of defects can be determined by detecting the time difference of receiving acoustic waves at different positions. Acoustic emission method can be used to detect the changes of bridge internal structure in detail, accurately and quickly. By analyzing and studying the position of the defect, the type, size and cracking speed of the crack can be analyzed in detail. Because this detection method is easily influenced by environmental noise, it will lead to the decline of detection accuracy; On the other hand, this method makes use of the internal defects of roads and bridges, so it can carry out continuous dynamic detection.

3.4 Impact echo detection technology

Shock echo detection technology is that the detection instrument sends stress pulse waves to the surface of the detected object through a mechanical impactor. When the compression wave propagates in an object and encounters internal defects, the shock wave cannot penetrate and reflect. When the wave velocity is fixed and the correct impactor is selected, the position of the defect can be accurately measured through the test, and the thickness of the object can be measured even if there is no defect.

Shock echo detection technology is often a single-sided reflection testing technology, and it can be judged whether there is damage here with a little detection, so this method has the advantages of convenience, rapidity and intuitive test results. This method is widely used to determine defects in concrete or concrete structures of roads and bridges, such as cracks. On the other hand, although this method is simple to detect, it belongs to a single point measurement, and the detection results are not comprehensive and the practical application is less.

3.5 Infrared Thermal Image Detection Technology

Infrared thermal imaging detection technology is to use infrared thermal imaging detection instruments to detect the infrared energy emitted by various parts of the object, and then display the discontinuous defects in the material and structure of the object intuitively according to the temperature field distribution on the surface of the object. Infrared thermal imaging detection technology is a non-contact nondestructive testing technology.

Infrared thermal image detection technology has the following advantages:

1) The detection focal length of infrared thermal image detection technology can be from 20cm to infinity, so it is more suitable for non-contact and large-scale nondestructive detection;

2) Infrared thermal image detectors only respond to infrared rays, so as long as the temperature of roads and bridges is higher than zero, infrared thermal image detection technology can be used for detection;

3) Because the infrared thermal image detector can achieve high detection accuracy, its temperature resolution can reach 0.65438 0℃;

4) The detection mode is more flexible, and its camera speed ranges from 1 to 30 frames /s, which is suitable for both static detection and dynamic detection.

4 conclusion

Road and bridge inspection has become an important part of daily management and maintenance of roads and bridges. The establishment of road and bridge test and detection system to realize the systematization and intelligentization of road and bridge safety guarantee requires not only the staff to have rich field practical experience, but also a solid theoretical foundation, combining theory with practice, effectively obtaining various test data, accurately evaluating the bridge and eliminating potential safety hazards in time.

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