Data processing of backfill grouting detected by GPR in shield tunnel and research on equipment of GPR antenna

Abstract

In recent years, the shield tunneling method has been widely used in the construction of urban underground space. Through using ground penetrating radar (GPR) for nondestructive testing of the distribution of grouting behind segments of shield tunnel, secondary compensatory grouting can be carried out, which is aimed at controlling the final longitudinal settlement of the tunnel. In this paper, the main point is to develop a set of machinery to detect grouting in real time during the construction period. First, a 500MHz bowtie antenna and 500MHz Vivaldi antenna produced good effects by simulation and tests. Second, a set of machinery consisting of arc-tracks was designed. This machinery is connected to the shield tunneling machine. The antenna, which moves along the tracks, can detect the grouting in the assembled segments. The detection data is automatically stored in the upper computer. The secondary compensatory grouting can then be carried out in time if the grouting quality does not conform to the specification.