Investigative drilling (ID) is an innovative measurement while drilling (MWD) technique that has been implemented in various site investigation projects across Australia. While the automated drilling feature of ID substantially reduces noise within drilling data streams, data cleaning remains essential for removing anomalies to enable accurate strata classification and prediction of soil and rock properties. This study employed three machine learning algorithms--IsoForest, one-class SVM, and DBSCAN--to automate the data cleaning process for ID data in rock drilling scenarios. Two data cleaning contexts were examined: (1) removing anomalies in rock drilling data, and (2) removing both anomalies and soil drilling data in mixed rock drilling data. The analysis revealed that all three machine learning algorithms outperformed traditional statistical methods (the 3-sigma rule and IQR method) in both data cleaning tasks, achieving a good balance between true positive rate and false positive rate, though hyperparameter tuning was required for one-class SVM and DBSCAN. Among them, IsoForest was proven to be the best-performing algorithm, capable of removing anomalies effectively without the need for hyperparameter adjustment. Furthermore, IsoForest, combined with two-cluster K-means, successfully eliminated both soil drilling data and anomalies while preserving almost all the normal data. The automatic data cleaning strategy proposed in this paper has the potential to reduce laborious manual data cleaning efforts and thereby facilitate the development of large-scale, high-quality datasets for machine learning studies capable of revealing complex relationships between drilling data and rock properties.

20 pages, 17 figures, 4 tables