Statistics on 3D Particle Shapes of Lunar Soil (No. 60501) Obtained by Micro X-Ray CT and Its Image-Based DEM Simulation

A lunar surface soil sample from Descartes highland (No.60501) was investigated by micro X-ray CT. On the basis of obtained 3D information on particle shape, the particles were classified into four groups: (1) monomineralic particles, (2) breccias (fragmentai matrix), (3) breccias (crystalline matrix), and (4) agglutinate particles which have a lot of reentrant surfaces and enclosed voids. The content ratio of these particles obtained in this study was in good agreement with those reported in the previous study by Houck (1982). The detailed 3D shape indices such as the aspect ratio, the flatness ratio, the elongation ratio and the sphericity were computed for all the particles and their statistics were discussed. An image-based DEM in which the particles were directly modeled from the 3D information was employed to quantify the effects of agglutinate content on the mechanical properties of lunar soil under the simple shear condition. The analysis revealed that the minimum void ratio increases with increasing agglutinate content, but that the shear resistance is irrelevant to the agglutinate content. The angle of shear resistance obtained is about 50 degrees, which is in good agreement with those referred in preceding studies.