Correlation between seismic damages of Tawarayama tunnel and ground deformation under the 2016 Kumamoto earthquake

Abstract

This article is the summary for the paper (Zhang et al. 2019) receiving the best research paper award from the Japanese Society for Rock Mechanics (JSRM) in the fiscal year of 2020. An integrated system including data acquisition using airborne LiDAR (light detection and ranging) system, ground deformation detection, and investigation of the seismic damages of mountain tunnel was proposed in this study. A pair of Digital Elevation Model (DEM) datasets were captured from the high-density airborne light detection and ranging (LiDAR) data before and after the 2016 Kumamoto earthquake. A new variant of Iteratively Closest Point (ICP) algorithm named Combination and Classification ICP (CCICP) was introduced to detect the three-dimensional (3-D) ground deformation field. The seismic damages of Tawarayama tunnel caused by the earthquake were studied via site investigation. The results indicated that the strong ground deformation can reflect the seismic performance of the tunnel to some extent. Furthermore, the results of the ground deformation direction validated the assumption of seismic wave propagation along the tunnel. It gives a clear explanation for the mechanism of the seismic damages under the earthquake force, especially lining cracks, pavement damage, and construction joint damage.