A detection method of elastic wave tomography based on the arrangement of small crossing lines

Abstract

The invention discloses an elastic wave tomography scanning detection method based on the arrangement of small crossing lines. When performing elastic wave tomography scanning detection on concrete structures, since the included angle of P wave propagation is mainly concentrated within 45°, it is necessary to According to the length of the side where the measuring point is located a The length of the survey line perpendicular to the side where the survey point is located b The relationship between the size of the survey line is selected, when a less than b , you can choose the layout of full crossing survey line, partial cross survey line or small cross survey line, which can ensure that the survey line perpendicular to the edge of the measurement point and the excitation point and its receiver The angle between the survey lines formed by the point tail points is less than 45°, and the survey line layout options are diversified, which has strong applicability; when a greater than or equal to b When using the arrangement of small intersecting lines to meet the above angle requirements, it can greatly reduce on-site work, improve detection efficiency, and complete the detection of the required detection area at one time.

Description

technical field [0001] The invention belongs to the technical field of concrete structure detection, and in particular relates to the design of an elastic wave tomography scanning detection method based on the arrangement of small crossing measuring lines. Background technique [0002] At present, the shock elastic wave CT (tomography) method is usually used for internal defect detection of large concrete structures. The principle is that when there is a weak area or defect in the detection area, the wave velocity of the elastic wave propagating in this area will decrease. Therefore, the internal defects of the structure can be detected by back-calculating the wave velocity in the test field by using computer tomography technology. Since the P-wave velocity in the shock elastic wave is the fastest, it mainly uses the change of the P-wave velocity for scanning. [0003] For the shock elastic wave CT method, the factors affecting the detection accuracy include: (1) The includ...

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Problems solved by technology

(2) Since the sensor of the shock elastic wave CT method usually uses a single-axis sensor, if the angle of the sensor measurement line is too large, the energy perpendicular to the main axis is small

The above two reasons will cause the starting point of the P wave waveform at the receiving end to be unclear, which will easily lead to wrong point selection, resulting in the illusion of "lower wave speed" and lower detection accuracy.

[0004] The survey line layout methods of shock elastic wave CT method include full cross survey line layout and partial cross survey line layout. Among them, some survey lines in the full cross survey line layout cannot meet the above angle requirements, making the P wave energy at the receiving point relatively low. Weak, low signal-to-noise ratio, which makes it difficult to control the change of P-wave velocity; the arrangement of some crossing survey lines can ensure that the angle between all survey lines in each survey area is less than 45°, but it will increase the work of site survey area division , in the later data processing, it is necessary to stitch the survey area, and the overall method is relatively cumbersome

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