# An Advanced Soil Classification Method Employing the Random Forest Technique in Machine Learning
## 2 Dataset  
The USCS, introduced by [PERSON], is a widely utilized system for classifying soils based on their properties and behavior, particularly in engineering applications. The primary parameters used in the USCS include grain size distribution, Atterberg limits, soil classification symbols, plasticity chart, Cu, and Cc. These parameters are specified within defined ranges to construct a synthetic database for training the RF model. The parameters compiled in this study are listed in Table 1 below. Table 1 presents the descriptions of the datasets used in this study, where Factor 1 to Factor 7 represent the relevant soil property parameters used in USCS evaluation, including Cc, Cu, PI, organic or inorganic soil, LL, percentage passing No. 4 sieve, and percentage passing No. 200 sieve. Factor 8 represents the soil classification. This study establishes a synthetic database to determine the reasonable upper and lower limits for Factor 1 to Factor 7 and then evaluates the soil properties using the USCS. Factor 8 includes 25 types of soil properties. These parameters are defined within specific ranges to build a synthetic database. By establishing the maximum and minimum values of these parameters that are physically meaningful and setting appropriate intervals, as shown in the synthetic database in Table 1, this study has developed a total of 521,316 datasets. For encoding categorical variables, Factor 4 (organic soil or inorganic soil) differentiates between organic soil and inorganic soil, with 1 indicating organic soil and 0 indicating inorganic soil. Factor 8 relates to soil classification and is encoded from 1 to 25, representing 25 different soil types. The corresponding soil types for each code are summarized in Table 2.  
Generally, in soil classification, gravel (G) represents particles larger than 4.75 mm, which are typically coarse and provide good drainage characteristics. Sand (S) represents particles between 0.075 mm and 4.75 mm, offering a range of grain sizes from fine to coarse sand, which influences soil texture and compaction properties. Salt (M) represents particles between 0.002 mm and 0.075 mm, known for their smooth texture and moderate water retention capacity. Clay (C) represents particles smaller than 0.002 mm, characterized by \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**No** & **Soil Type** & **No** & **Soil Type** & **No** & **Soil Type** & **No** & **Soil Type** \\ \hline
1 & CL & 6 & CH & 11 & GW-GC & 16 & GC-GM & 21 & SP-SM \\ \hline
2 & ML & 7 & MH & 12 & GP-GM & 17 & SW & 22 & SP-SC \\ \hline
3 & CL-ML & 8 & GW & 13 & GP-GC & 18 & SP & 23 & SC \\ \hline
4 & OL & 9 & GP & 14 & GC & 19 & SW-SM & 24 & SM \\ \hline
5 & OH & 10 & GW-GM & 15 & GM & 20 & SW-SC & 25 & SC-SM \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Definition of soil classification symbol. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Data Description** & **Unit** & **Maximum** & **Median** & **Minimum** & **Standard** & **Interval** \\ \hline
1 & Coefficient of curvature (Cc) & NA & 10 & 4 & 0 & 3.42 & 1 \\ \hline
2 & Coefficient of uniformity (Cu) & NA & 10 & 5 & 1 & 3.18 & 1 \\ \hline
3 & Plasticity index (PI) & \% & 70 & 35 & 0 & 24.15 & 10 \\ \hline
4 & Organic soil or inorganic soil & NA & 1 & 0 & 0 & 0.50 & NA \\ \hline
5 & Liquid limit (LL) & \% & 100 & 55 & 0 & 33.23 & 10 \\ \hline
6 & Percentage passing No. 4 sieve & \% & 100 & 75 & 0 & 27.10 & 10 \\ \hline
7 & Percentage passing No. 200 sieve & \% & 100 & 35 & 0 & 27.94 & 10 \\ \hline
8 & Soil classification & NA & 25 & 15 & 1 & 8.20 & 1 \\ \hline \hline \end{tabular}  
* Notation: NA is not applicable.  
\end{table} 
Table 1: The synthetic database constructed in this study. their fine texture, high plasticity, and significant water retention ability. These classifications help in understanding the soil's mechanical behavior and suitability for various engineering applications. According to the soil classification symbols, soils are broadly divided into three categories.