A 3D numerical model was presented to investigate the blast-induced damage characteristics of highly stressed rock mass. The RHT (Riedel, Hiermaier, and Thoma) model in LS-DYNA was used to simulate the blast-induced damage and its parameters were calibrated by a physical model test. Based on the calibrated numerical model, the influences of confining pressure and free surface span on the blast-induced damage characteristics were investigated. The results show that under uniaxial loading, the crater volume increases with confining pressure increases. The uniaxial static load can change the optimal burden and the critical embedding depth of charge. In stressed rock, the variation law of the crater shape affected by radial tensile fractures is opposite to that affected by reflected tensile fractures. Under the biaxial static load, the crater volume of the borehole placed on the side of the max static load is greater than the other side. The explosion crater can be improved by increasing the free surface span on the same side. Finally, it is suggested that the blasting efficiency can be improved by preferentially detonating the charge on the side of the max static load, and then the charge on the other side can be detonated with a wider free surface span.

Fibres can markedly enhance the uniaxial compressive strength (UCS) of cemented paste backfill (CPB). However, previous studies have mainly verified the effectiveness of polypropylene and straw fibres in improving the UCS of CPB experimentally, while systematic multi-factor evaluation remains limited. In this study, laboratory experiments were conducted on polypropylene- and straw fibre-reinforced CPB to construct a reliable dataset. The factors influencing the intensity of uniaxial compressive strength were divided into four aspects (mixture proportions, physical properties of the cement–tailings mixture, chemical characteristics of tailings, and fibre properties), and four intelligent models were developed for effectiveness analysis and UCS prediction. SHapley Additive exPlanations (SHAP) were employed to quantify the contributions of individual features, and the findings were experimentally validated. The GWO–LGBM model outperformed the SVR, ANN, and LGBM models, achieving R² = 0.907, RMSE = 0.78, MAE = 0.515, and MAPE = 0.157 for the training set, and R² = 0.949, RMSE = 0.627, MAE = 0.38, and MAPE = 0.115 for the testing set, respectively. Feature analysis reveals that mixture proportions contribute the most to UCS, followed by the tailings’ physical properties, the fibre properties, and the tailings’ chemical characteristics. This study found that cement content and tailings gradation control CPB structural compactness and fibres enhance bonding between hydration products and tailings aggregates, while the chemical composition of the tailings plays an inert role, functioning mainly as an aggregate.

Cylindrical charges are widely used in engineering blasting, yet the three-dimensional propagation mechanism of the associated stress waves remains inadequately understood. This study aims to investigate the effects of key wave source parameters on stress wave propagation and rock damage in cylindrical charge blasting. A semi-analytical solution for spherical stress wave propagation in a full elastic space is developed to theoretically describe the stress field, and a computational model for cylindrical charges is established based on the superposition principle of equivalent spherical charges. Numerical simulations using the RHT constitutive model are then performed to verify the theoretical predictions and further investigate stress wave propagation and rock damage. The results show that the attenuation index of radial stress decreases from 1.5 to 1 as the loading rate increases. Higher loading rates produce more but shorter cracks, whereas lower rates result in fewer but longer cracks. The blast-induced damage region shifts from the detonation direction toward the horizontal plane with increasing detonation velocity, and the resulting rock damage exhibits a conical distribution controlled by the initiation point. These findings provide practical guidance for optimizing cylindrical charge blasting and controlling crack patterns in engineering applications.