Suppression of the influence of surface waves on shear wave imaging for buried pipe location

Abstract

Shear wave imaging has been proposed to detect shallow buried target objects in recent years. However, moderate results have been achieved with limited success since the resultant surface waves hinder the practical applicability of the method. In this paper the influence of surface waves is reduced prior to the image fusion for pipe localization. Field tests were carried out in the Hefei Institute of Public Safety, Tsinghua University. A sensor array was adopted to measure the ground surface vibration in response to the shear wave excitation. The method of connected subgraph traversal is applied to each image to show the suspected depth region of the target pipe. The fused image is subsequently obtained by extracting and fusing the suspected feature regions from the sequence imaging results and attenuating them with equal weighting. The image is finally analyzed to identify the burial depth. Furthermore, the effect of different sensor types and the interference effect of ambient noise on the imaging results are investigated experimentally. Test results show good agreement between the detected and actual depth of the buried pipeline.