In April 2016, the tunnel face of a section of Huaishaoheng railway tunnel collapsed during the tunneling process. In order to ensure the construction safety, the Fourth Survey and Design Institute of China Railway used TeTSP-1 to carry out the tunnel advance detection.

Figure 1. Site construction

Figure 2. Detection result

The detection results show that the seismic wave velocity in the range of DK21+881 ~ DK21+927 is significantly reduced, there are multiple sets of reflection interfaces, and the Poisson ratio varies greatly. It is inferred that the rock mass is fragmented, the joint fracture is developed, and there is a weak interlayer. The seismic wave velocity in the inner part of DK21+950 ~ DK21+970 is slightly reduced, which indicates that the rock mass fracture is slightly developed in this range. The actual excavation situation is roughly consistent with the detection results.