# CT Scanning of Structural Characteristics of Glacial Till in Moxi River Basin, Sichuan Province
## 4 Results
### Micro-Structure Characteristics of Intact Glacial Till  
The micro-structure of the soil not only reflects the material source of the soil, but also determines its physical and mechanical properties and engineering characteristics [31].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Section** & **Index** & **Maximum** & **Minimum** & **Average Value** \\ \hline \multirow{2}{*}{X} & Circularity & 0.946 & 0.531 & 0.826 \\  & Aspect ratio & 8.086 & 1.813 & 2.470 \\ \hline \multirow{2}{*}{Y} & Circularity & 0.989 & 0.298 & 0.845 \\  & Aspect ratio & 6.699 & 1.362 & 2.617 \\ \hline \multirow{2}{*}{Z} & Circularity & 0.921 & 0.606 & 0.802 \\  & Aspect ratio & 6.676 & 1.057 & 3.700 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Particle shape statistics of glacial till samples.  
Figure 17: The histogram of the grained rose in the CT scan of glacial till. (**a**) X-section particles long axis direction. (**b**) Y-section particles long axis direction. (**c**) Z-section particles long axis direction.  
Therefore, through SEM experiments on the cementitious intact glacial till in the study area, SEM images of the glacial till with different resolutions were obtained (Figure 18).  
The rocks enclosed in the glacial till are mainly mica, quartz, shist and a small amount of marble (Figure 18). As a mineral with relatively weak strength, mica is prone to brittle fracture during transportation. The relatively broken mica in the sample indicate that it was transported over a long distance, crushed and abraded. Quartz particles display obvious erosional features and show various shapes, such as round and angular. The boundary of the particles is clear, indicating that the abrasion of the quartz particles during the transportation process leads to different degrees of crushing and rounding. The surface of round quartz particles has V-shaped percussion cracks, obvious linear grooves and dissolution characteristics (Figure 18c), indicating that quartz particles have the characteristics of surface pre-weathering, and have undergone long-distance glacier melt-water transportation and rounding before deposition. It can be seen from Figure 18a,b that the fine particle components are mainly silty clay adhered to the surface of coarse particles in the form of flakes, or filled in the pores in the form of dispersion. The cement between coarse particles is mainly calcareous cementation at the base, which is mainly due to the collision of marble during transportation; this causes the development of marble cracks and increasing contact with carbon dioxide, carbide and water in the atmosphere, leading to weathering and dissolution and the formation of calcareous cements. The coarse particles have different shapes, and are interlocking and densely cemented. They show mainly line-surface concave-convex contact, and the skeleton structure formed by the inclusion or filling of fine particles is stable. It has high shear strength, and is not dissolvable. This characteristic of glacial till indicates its potential resistance to damage caused by the action of cyclic freezing and thawing in the alpine mountainous area [32].  
Figure 18: Enlarged scanned images at different magnifications. (**a**) Enlarged the scanned image by 100 times. (**b**) Enlarged the scanned image by 200 times. (**c**) Enlarged the scanned image by 400 times. (**d**) Enlarged the scanned image by 1000 times.