Detection of grouting effect in defective areas of metro concealed tunnels in loess areas

The occurrence of grouting defect areas in metro concealed excavation tunnels will lead to water seepage or deformation of the tunnels, which in turn will affect the metro operation and the safety of the buildings around the metro. In order to detect the effect of grouting in defective areas of concealed tunnel, this paper introduces the principle and characteristics of seismic scattering technology, and illustrates the application of this technology in detecting the effect of grouting in defective areas of concealed tunnel in Xi'an metro line 6 from Textile City to Textile Road with the application example of seismic scattering technology. The results show that: the grouting area shows high speed anomalies in the wave velocity image, and the defect area shows low speed anomalies, and the location and morphology of the grouting area and the defect area can be determined according to the distribution of high and low wave velocity anomalies in the wave velocity image. The technology also has the features of simple operation, large detection depth and high resolution, which is an effective tool for future urban metro construction and environmental impact detection and evaluation.