Serhiienko V.M. Defectoscope for control of concrete timbering underground constructions

Details

Parent Category: Geo-Technical Mechanics, 2019

Category: Geo-Technical Mechanics, 2019, Issue 145

Geoteh. meh. 2019, 145, 85-96

https://doi.org/10.1051/e3sconf/201910900084

DEFECTOSCOPE FOR CONTROL OF CONCRETE TIMBERING UNDERGROUND CONSTRUCTIONS

¹Serhiienko V.M.

¹Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine

UDC 622.281.4

Language: English

Abstract.

 

Annotation. The subject of study is concrete support. The object of study is its interaction with the rock mass. During operation of the support there is formation of spaces in adjacent rock mass. Uneven load on the support gradually leads to its destruction. The purpose of work is development of a defectoscope for nondestructive identification of spaces in rock mass on border with a concrete support. The vibroacoustic method is used. The essence of the method is to analyze the vibration parameters of the shell after striking it. The difference from the known developments consists in contactless reception of an acoustic signal with use of the microphone. The vibration support parameters are determined under various conditions of its contact with the rock mass. The spectral composition of the signal is preliminarily determined. In the presence of spaces, low-frequency components prevail in it. The study of the spectral range allows you to select the bandwidth of the input amplifier. Oscillograms of free vibrations of the concrete support also characterize the quality of its contact with the rock mass. As an informative parameter, the characteristic of the oscillation decay time is selected. In the presence of spaces, it increases significantly. A mechanical shock device serves to excite vibrations of the support. A piezosensor is mounted on the striker of the device. It is connected to the electronic unit. Upon impact, a synchronization pulse occurs, after which the process of analyzing the sound signal from the microphone begins. To reduce the influence of interference, frequency filtering of the signal and analysis time limitation are used. Additional noise suppression is carried out by selection of amplitude of signal. The value of the informative parameter is presented in digital form. Testing the defectoscope at hydraulic structures indicates the possibility of identifying cavities behind the shell with a thickness of up to 1 m. The optimal range of distances from the microphone to the shell is from 1 to 3 m. The defectoscope is serviced by one operator. The development is recommended to be used to control the support of underground structures with a low level of acoustic noise.

Keywords: defectoscope, concrete support, underground structure, vibroacoustic control.

 

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About the author

Serhiienko Viktor Mykolaiovych, Candidate of Technical Sciences, Senior Researcher, Senior Researcher of the Department of Rock Mechanics, Institute of Geotechnical Mechanics named by N. Poljakov of National Academy of Sciences of Ukraine (IGTM NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it. .

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