Evaluation of geological conditions ahead of a tunnel face using seismic tomography between a tunnel and ground surface

摘要

Evaluating geological conditions ahead of a tunnel face accurately and quantitatively is essential for a safe and reasonable tunnel excavation. Recently, it has also become important to ensure that geological surveys do not interrupt the daily tunnel excavation cycle. In this research, the authors have developed a new seismic tomography technique between a tunnel and ground surface. In order to conduct an accurate seismic tomography analysis, the source and receiver systems must be synchronized with negligible errors. Furthermore, utilizing the tunnel blasting vibrations as survey sources and the newly developed automatic data acquisition system made it possible to conduct the survey without interrupting the tunnel excavation. The results of applying this new method to the tunnel construction site show that the predicted values were in good agreement with actual geological conditions around the tunnel face.