Three Dimensional Visualization of the Excavation Mechanism for Dry Sandy Ground by a CT-scan Technique

摘要

This study aims to clarify three dimensional (3-D) excavation mechanisms in sand. When dealing with a 3-D problem using a narrow cutting bit, considerable uncertainty exists in the theoretical evaluation. The main cause of such uncertainty is the lack of information on the 3-D failure mechanisms around a cutting bit. In this study, model excavation tests using a flat simple cutting bit were performed on Toyoura standard sand. The failure mechanisms in these tests were visualized using an X-ray computed tomography scanner (CT-scanner). This technique has been widely used as a medical diagnostic method, but recently this machine has also been adopted as a nondestructive testing apparatus for engineering purposes. As a result, the three dimensional structure of the failure mechanism could be clarified. This will facilitate a reasonable modeling of the excavation resistance under 3-D conditions.