# Research on the Compactness of Lunar Soil Simulant Based on Static Cone Penetration Test
## 2 Experimental Design
### Test Scheme  
The compacted lunar soil simulant in each barrel was measured layer by layer. The compaction and measurement methods were as follows: First, the layered compaction barrel was fixed with screws. Then, the mass of lunar soil simulant required for the experiment was weighed, and then it was slowly poured it into the barrel. The simulant was vibrated and compacted using vibration table until it filled the barrel completely. The vibration time and frequency were adjusted to obtain different levels of compactness for the simulant. The same vibration time and frequency were used to produce samples of the same compactness. Next, the screws were removed and the compactness of the lunar soil simulant in the barrel was measured layer by layer. Finally, lunar soil samples for the static cone penetration test were prepared again using the same method. The experiment was repeated many times, with the error of each two groups of experiments controlled to under  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Sample** & **Feldspar/\%** & **Olivine/\%** & **Pyroxene/\%** & **Opaque Mineral/\%** \\ \hline Apollo11 & 26.7 & 3.2 & 53.7 & 16.3 \\ Apollo12 & 23.0 & 8.7 & 63.4 & 4.9 \\ Apollo14 & 49.7 & 1.8 & 47.0 & 1.5 \\ Apollo15 & 37.9 & 8.4 & 52.2 & 1.5 \\ Apollo17 & 35.5 & 5.5 & 56.3 & 2.7 \\ CUG-1A & 35.0 & 5.0 & 48.0 & 12.0 \\ \hline \end{tabular}
\end{table}
Table 1: Mineral composition of some real lunar soils and CUG-1A lunar soil simulant [16].  
5%. The average value of the test results of the three groups was taken as the compactness of lunar soil simulant in the single-layered compaction barrel.  
The minimum dry density of the CUG-1A lunar soil simulant was experimentally measured to be 1.1 g/cm\({}^{3}\), and the maximum dry density was 2.0 g/cm\({}^{3}\). The lower-density lunar soil simulant was relatively loose, and the static cone probe encountered lower resistance, which is not of practical significance. However, it is difficult to prepare lunar soil simulant samples with relatively high density. Therefore, four groups of lunar soil simulants with densities of 1.5 g/cm\({}^{3}\), 1.6 g/cm\({}^{3}\), 1.7 g/cm\({}^{3}\), and 1.8 g/cm\({}^{3}\) were selected for the experiment. The overall compactness levels of the corresponding lunar soil simulants were 58%, 68%, 78%, and 86%. The total volume of the layered compaction barrel was approximately 0.075 m\({}^{3}\). Through calculation, the masses of lunar soil simulants required for the four groups of compacted barrels were determined to be approximately 113 kg, 121 kg, 128 kg, and 136 kg, respectively. The overall porosities corresponding to the four groups of compacted lunar soil simulant are shown in Table 2.  
The prepared static cone penetration test barrels were moved directly beneath the probe to commence the experiment. The experimental procedure was as follows: First, the probe, rod, and computer were connected. Then, the probe was lowered until the cone tip just touched the lunar soil simulant, at which point the experiment began. During the experiment, data was collected once every 1 cm penetration of the probe. The experiment stopped when the total penetration depth reached 60 cm, and the experimental data was  
\begin{table}
\begin{tabular}{c c c} \hline
**Overall Compactness/\%** & **Overall Density/(g/cm\({}^{3}\))** & **Overall Porosity/\%** \\ \hline
58 & 1.5 & 44 \\
68 & 1.6 & 40 \\
78 & 1.7 & 36 \\
86 & 1.8 & 33 \\ \hline \end{tabular}
\end{table}
Table 2: Average porosity of lunar soil simulant with different levels of compactness.  
Figure 2: Schematic diagram of static cone penetration equipment: (**a**) equipment (1—probe; 2—rod; 3—layered compaction barrel; 4—data acquisition instrument; 5-equipment frame); (**b**) static cone penetration sample.  
then saved. The test was repeated at least three times. The error of each two groups of tests was controlled to under 5%. The average value of the test results of the three groups was taken as the cone tip resistance value of the static cone penetration test.