Knowledge-guided Sequential Learning for CPT-based Soil Stratification in Site Investigation
摘要
This study proposed a knowledge-guided sequential learning framework for soil stratification based on cone penetration test (CPT) data. Empirical knowledge of CPT interpretation was distilled into curve-morphology indicators that quantified single-curve fluctuations and peak prominence, as well as inter-curve relative strength and crossing frequency. These indicators were encoded into a differentiable knowledge-based rule layer, where learnable gating functions transformed heuristic curve–soil relationships into knowledge-augmented soft labels. A multi-scale feature extraction scheme and a bidirectional long short-term memory network were used to learn depth-dependent CPT representations from local transition-sensitive features and mid-scale morphological features, which enabled joint prediction of soil-layer boundaries and soil types. The framework was optimized using a composite loss function that combined supervised learning with soft-label regularization to guide predictions toward stratigraphically consistent results. The method was validated using a cross-project dataset with 265 CPT soundings and 102016 records. It achieved F1-scores of 0.762 for boundary identification and 0.829 for soil-type classification and outperformed the variant without the knowledge-based rule layer, the random forest baseline, and the deep neural network baseline. The results demonstrated that incorporating differentiable geotechnical knowledge into sequential CPT learning improved stratification accuracy, profile-level stability, and cross-project robustness.