X-ray CT visualization of particle array structure in sandy soil using ring shear experiment

抄録

The phenomena that occur inside the ground must be clearly understood and modeled to evaluate ground stability. However, it has been difficult to evaluate structural changes with the progression of destruction in the same specimen because it is necessary to physically cut open the specimen to understand the internal materials conditions. This study examined the formation mechanism of shear zones in the ground caused by external forces associated with earthquakes. We conducted a ring shear experiment to reproduce large deformations in a laboratory and used microfocus X-ray computed tomography (CT) to clearly and nondestructively visualize the interior of specimens. The microscopic structure of the shear zone was quantitatively evaluated by analyzing CT images. As shearing progressed, the porosity in the shear zone and its variability increased and the direction of the particles changed. The long axis of the particles shifted to the direction of shear in the horizontal cross section and to the horizontal direction in the vertical cross section. These results can contribute to the improvement of the stress strain models of geomaterials and provide important information for evaluating the stability of geomaterials against earthquakes.