Dominant frequency response and dynamic mechanism of rock slopes under blasting loads: A machine learning-driven time-frequency analysis

Understanding how rock slopes respond to blasting loads is crucial for maintaining excavation safety and slope stability. Nevertheless, the spatiotemporal evolution, nonlinear dependence on blasting parameters, and predictive behavior of dominant frequency responses in slope vibrations remain insufficiently understood and quantified. This study combines time-frequency analysis with machine learning to explore how the dominant frequency ( f_d ) evolves in slopes under blasting. Continuous Wavelet Transform (CWT) was employed to characterize the temporal–frequency evolution of vibration signals, revealing that the dominant frequency exhibits strong spatial dependence and nonlinear variability influenced by blasting parameters and rock mass structures. Three machine learning models, namely Back Propagation Neural Network (BP), Support Vector Machine (SVM), and Random Forest (RF), were developed to predict f_d based on 1,000 monitoring samples obtained from numerical and field simulations. Among them, the RF model achieved the highest prediction accuracy, with mean absolute percentage errors (MAPE) below 15%, demonstrating strong robustness and generalization capability. Our analysis shows that external excitation factors, especially the loading frequency ( f_p ), mainly control the frequency response, while internal controlling factors, such as spatial position, lithological variation, and mechanical heterogeneity, modulate localized frequency amplification and energy redistribution. The results reveal that f_d tends to decrease with elevation and distance from the blasting source, whereas structural planes and weathered zones induce high-frequency amplification due to scattering and modal coupling effects. This study offers a new framework combining time-frequency analysis and machine learning to measure the nonlinear interaction between blasting and rock mass response, offering new insights for dynamic stability evaluation and hazard mitigation in complex rock slope systems.