Grasp and evaluation of the unsaturated seepage behavior of soil by using MRI

Background: It is essential for residents to understand ground disaster and improve disaster prevention awareness, because natural disasters have occurred frequently in recent years. In this study, nondestructive unsaturated seepage behavior was continuously visualized by using MRI (magnetic resonance imaging) with test equipment constructed of non-metal parts. Additionally, the water content of the soil from the MRI image was evaluated, the results of previous experiments were considered and compared. Results: The study revealed from the imaging with MRI that seepage will flow faster in the lower part of the cylinder than in the upper part. A discontinuous water content ratio change of the seepage line part was confirmed from image with the MRI. There was a tendency for air to be trapped on the border of different soil materials in an acrylic cylinder. It was possible for the water content of the sand in the cylinder to be evaluated from the MRI image. Conclusions: The study suggests that complicated unsaturated seepage behavior can be easily visualized. It was suggested that air may be trapped in the different layer border of soil. And these finding will lead to the elucidation of relevance of slope collapse and the piping phenomenon with the rainfall.