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Application of structural inspection of concrete box girder-A1040 MIRA ultrasonic tomography
来源: | 作者:Frank | 发布时间:2020-06-21 | 9 次浏览 | Share:
The A1040 MIRA ultrasonic tomographic imager can detect densely reinforced structures, especially the defect detection of the structure behind the steel mesh. Compared with radar, it has a great advantage, but it can detect the densely reinforced concrete areas and the structure is changed. The detection of cross-sections also has its limitations. The test range of the equipment is 80-120cm for reinforced concrete, and the test range is different according to the density of steel bars. However, for other detection methods, the equipment only needs one test surface and no coupling agent is required. Compared with other detection methods, the influence of steel bars is less, and the overall structure can be displayed in two or three dimensions.
1. Project overview:
This inspection project is the structural inspection of the box girder in a beam factory of a high-speed project. The user mainly confirms the quality of the box girder web, the grouting quality of the drawing rod prestressed pipe, and whether there are obvious defects in the end structure.

2. Testing content and main testing equipment
2.1. Main testing content
It mainly detects whether there are obvious defects inside the concrete structure, such as whether there are voids in the joint surface, internal void defects, cracks and other diseases.
2.2. Main testing equipment
The equipment used this time is the A1040 MIRA ultrasonic tomographic imager developed and produced by the Russian ACS company, which is represented by Beijing IST Technology Development Co., Ltd. and provides technical support and after-sales service. The A1040 MIRA Ultrasonic Tomography Imager is currently the most advanced instrument and equipment used to test the internal defects of concrete structural units and display them in three-dimensional graphics or tomographic pictures. An antenna composed of a series of dry point contact sensors is used to transmit shear waves into the concrete, and then receive the reflected shear waves to form a one-shot and one-collect ultrasonic technology. The host computer creates a three-dimensional image of the detection unit based on the original data. see picture 1

Figure 1
3. Testing data processing analysis
3.1. Detection of the position of the box girder web
In order to detect whether there is a defect in the position of the web, a position of the web is selected, and through grid planning, the actual test area is 110×120cm, and the parameter setting X step length is set to 200mm, and Y step length is set to 100mm.
Get the specific thickness value through the round hole at the upper arrow in Figure 2, set the speed value through the known thickness, adjust to the best test parameters, and test the planned area below (see Figure 2).
Figure 2
Description of actual test results:
Test thickness value verification:
After confirming with the construction party that the actual thickness value of this plane structure is 380mm, the measured thickness value is accurately determined to be very high, as shown in Figure 3.
Defect detection verification: adjust the amplitude and color gain processing through the software and combine the B-Scan, C-Scan, D-Scan and three-dimensional graphics rotation in the software and the actual structure:
1. The distribution of steel bars on the tested surface is clearly visible, the distribution of main bars is clear, and the spacing between main bars conforms to the actual structure.
2. The C-Scan graphics are consistent with the actual steel bar structure, as shown in Figure 2.
3. There is no obvious abnormal performance in the area between the measured surface and the bottom echo reflecting surface. The grouting quality of the pre-stressed tendons included here is in good condition, and the image of the pre-stressed tendons cannot be displayed due to the shielding of the multi-layer steel bars. .
4. After processing by the software, the steel bars of the overall structure are evenly distributed, and there is no obvious abnormality inside the structure, as shown in Figure 4
Figure 3
Figure 4
3.2. Detection of the lower part of the box beam end:
The steel bars are very dense and the diameter of the steel bars is relatively large here, and there are more cases of cavitation diseases due to the lack of compaction. Therefore, the inspection is carried out here.
The thickness of the structure is not equal to the thickness of the structure, it is a variable cross-section structure, the overall thickness is between 95cm-120cm, and the actual measurement area is 120×30cm, as shown in Figure 5.
Figure 5
Description of actual test results:
The dense structure of the structural steel bars here is complex. Multi-point verification has been carried out here. The measured data after adjusting the technical parameters have not improved significantly, but the surface steel bars are clearly visible, and the structure can not get effective data here. The thickness has exceeded the detection range of the equipment, and the bottom echo signal cannot be obtained due to the dense reinforcement. See picture 6
Figure 6
4. Test conclusion
The A1040 MIRA ultrasonic tomographic imager can detect densely reinforced structures, especially the defect detection of the structure behind the steel mesh. Compared with radar, it has a great advantage, but it can detect the densely reinforced concrete areas and the structure is changed. The detection of cross-sections also has its limitations. The test range of the equipment is 80-120cm for reinforced concrete, and the test range is different according to the density of steel bars. However, for other detection methods, the equipment only needs one test surface and no coupling agent is required. Compared with other detection methods, the influence of steel bars is less, and the overall structure can be displayed in two or three dimensions.
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