Most work from the literature dedicated to soil classification systems from cone penetration test (CPT) data are based on simple two-dimensional charts. One alternative approach is using machine learning (ML) to produce new soil classification systems or to reproduce existing ones. The available studies within this research field can be considered limited, once most of them do not include more than two inputs within their analysis and are applicable only to specific regions. In this context, the aim of this work is to use distance-based ML techniques to replicate two chart-based methods from the literature. Up to five input feature combinations are tested, with the objective of discussing geotechnical aspects of soil classification systems. Results are compared using the statistical test of Friedman with the post-hoc statistics of Nemenyi and the signed-rank statistical test of Wilcoxon. The used dataset can be considered diversified because it contains 111 CPT soundings from several countries. Results show that the used ML techniques maintain reasonable accuracy when inputs are substituted and when incomplete data is used, which can lead to cost reduction in real engineering projects. It is important to notice that these observations would not be possible by using the replicated soil classification systems alone.

The most popular methods for soil classification from cone penetration test (CPT) data are based on examining two-dimensional charts. In the last years, several authors have dedicated efforts on replicating and discussing these methods using machine learning techniques. Nonetheless, most of them apply few techniques, include only one dataset and do not explore more than three input features. This work circumvents these issues by: (i) comparing five different machine learning techniques, which are also combined in an ensemble; (ii) using three distinct CPT datasets, one composed of 111 soundings from different countries, one composed of 38 soundings with information of soil age and the third composed of 64 soundings taken from the city of São Paulo, Brazil; and (iii) testing combinations of five input features. Results show that, in most cases, the ensemble of multiple models achieves better predictive performance than any technique isolated. Accuracies close to the maximum were obtained in some cases without the need of pore pressure information, which is costly to measure in geotechnical practice.