In this study, we aimed to reveal the liquefaction process by visualizing force state from particle-scale. We developed a force-visualization technique for granular material utilizing the mechanoluminescence (ML) phenomena.

ML is force-induced light emitting phenomena, which light intensity is proportional to force-rate. The ML material was defect-controlled strontium aluminate doped with europium as the luminescent center (SrAl2O4:Eu). The surface of the glass beads was coated with an ML paint produced by mixing the ML material with epoxy resin.

In the experiment, first we conducted loading test for single columns of coated particle to calibrate between the luminance and applied force. As the practical application, we conducted loading test of deep foundation in a centrifuge to visualize the load transmission through the granular material. Following figure shows test condition and luminance appearance - the concentrating luminance has observed under the loading plate. It shows qualitative agreement through the comparison between applied load and luminance variation. Moreover, we conducted shaking table test in dry condition as feasibility study for dynamic phenomenon.

Hereafter, we continues these experiments to improve its accuracy in quantitative level, and applying to visualize liquefaction phenomena.