Effects of Soil Compaction to its Shear Property

The survey shows that the bulk density of lunar soil increases with the depth. The compaction of lunar soil also differs in the depth. The lunar soil mechanical condition plays an important and non-negligible roll on the mobility of the rover. It is important to make research on the change of the mechanical parameters at different lunar soil conditions, and it is also important to research the trafficability of rover on different lunar surface condition. The presented paper simulates the lunar soil with different depth by means of three kinds of lunar soil simulant on different compact condition. Based on the direct shear apparatus, it was researched that the cohesion, internal friction angle, bull density of lunar soil simulant on different compaction conditions, including loose, normal, and compressed. The measurement results show that the bulk density and cohesion of the lunar soil simulant increase with the compact conditions in general. The bulk density changes within a narrow range from1.1 g/cm3 to 1.4 g/cm3. The cohesion increases, and changes significantly, which varies from 0 kPa to 0.5 kPa. The internal friction angle changes without regularity within a range from 30 deg to 40 deg. The measurement results can be used to explain the different trafficability of wheels after repeatedly passing the same lunar surface. Also it will be of significant to the evaluation of the rover mobility at different lunar soil condition.