To address the issue of noise interference in mining blasting vibration signals, a joint denoising algorithm combining the Crested Porcupine Optimizer (CPO), Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN), and an enhanced wavelet thresholding method is proposed. First, the CPO algorithm was employed to globally optimize the key parameters of ICEEMDAN, adaptively decomposing the measured blasting vibration signals from an open-pit mine into a series of intrinsic mode functions (IMFs). A noise identification threshold was then constructed using multiscale permutation entropy (MPE) to screen out high-frequency noisy IMF components. These components were processed with the improved wavelet thresholding method and subsequently recombined with IMFs below the threshold to achieve denoising. Comparative experiments with CEEMDAN-MPE and ICEEMDAN-traditional wavelet thresholding methods demonstrate that the proposed method improves the average signal-to-noise ratio (SNR) by 39.33% and 19.93%, respectively, and reduces the root mean square error (RMSE) by 2~3 times across three sets of vibration signals. Furthermore, three-dimensional time-frequency energy analysis reveals that the main frequency energy distribution remains unchanged before and after denoising. These results indicate that the proposed method not only effectively eliminates noise interference but also fully preserves the main frequency energy characteristics of the original signal, demonstrating superior performance and engineering applicability.

This study investigates the failure and energy dissipation patterns of tuff under impact loads with varying occurrence conditions in Dahongshan Copper Mine through Split Hopkinson pressure bar (SHPB) tests, digital image correlation (DIC), fractal dimension analysis, scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). Results show that: ① At identical strain rate, the dynamic compressive strength of the 300-level tuff was only 71 % ~77 % of that from the 420-level tuff. ② Both types of specimens underwent a transition from uniform strain, local concentration to crack fragmentation. The 300-level tuff exhibited denser cracks, faster propagation, higher peak strain and higher degree of fragmentation under equivalent impact load. ③ While the crushing energy dissipation density of both types of specimens increased linearly with impact load, the 300-level tuff exhibited significantly higher average energy absorption efficiency (35.86 %) than the 420-level tuff (19.29 %). This study reveals how varying rock microstructures and composition affect the dynamic mechanical properties of ore and rock under impact load, providing theoretical implications for their stability analysis under dynamic load and safe mining.

In order to control the lining damage of underground roadways induced by the vibration effect of bench blasting in an open-pit quarry, the dynamic response of the existing adjacent roadway at the transition mining stage from open pit to underground in Lara Copper Mine were studied by means of field vibration monitoring, theoretical calculation and numerical simulation. Through regression analysis of the monitoring data, the vibration attenuation law was obtained, and the dominant frequency and instantaneous energy of the vibration were analyzed. Six models with different relative spatial positions between the open-pit bench and underground roadway were established using the LS-DYNA software. Subsequently, double-hole delayed blasting models were developed to investigate the dynamic response of adjacent existing roadways under blasting loads. The results show that for the existing roadway located below the explosion source of the open pit bench, its maximum vibration velocity mainly appears in the arch and the side wall on the explosion-facing side. The direction and position of the peak vibration velocity change with the different relative spatial position of the roadway and the explosion source. When the vertical distance between the roadway vault and the bottom of the blast hole is fixed at 10 m, and the horizontal distance between the roadway sidewall and the blast hole is less than 15 m, the vibration velocity in the vertical direction of the tunnel structure is greater after explosion. Beyond this 15 m horizontal distance, the vibration velocity in the horizontal and radial directions of the tunnel structure is larger. By fitting the relationship between peak effective stress and peak particle velocity and utilizing the ultimate dynamic tensile strength of the roadway, a vibration velocity threshold of 19 cm/s was derived. After adjusting blasting parameters according to the safety threshold, the safety of adjacent existing roadway can be ensured.

To investigate the damage and failure characteristics of the double-hole blasting medium, theoretical analysis and model experiments are conducted in this study. Based on the analytical solution of the elastic plane strain problem in the double-hole blasting model, a theoretical model is established to study the evolution of the dynamic stress field during double-hole blasting. The damage of double-hole blasting with different blast hole spacing is studied by the model experiment; the damage in different regions around the blast holes is analyzed by partitioned research and fractal dimension quantification. The study shows that as the blast hole spacing increases, the super position effect of stress waves decreases, the radius of the crushing zone and the average length of the main crack gradually increase, the number of cracks decreases first and then increases. Additioanlly, the increase of blast hole spacing lead to gradual decrease of the damage along the direction of the blast hole connection, while the damage perpendicular to the direction of the blast hole connection gradually increases. Small hole spacing is conducive to the penetration of cracks between holes and promotes cracks expansion along the direction of the blast hole connection. With increasing blast hole spacing, the damage variable in the left and right regions of the specimen gradually increases, and reaches a minimum value in the central region when the blast hole spacing is 50 mm. The damage variables in area Ⅰ and area Ⅱ first decrease and then increase, while the damage variable in area Ⅲ gradually decreases. The damage variable distribution in the polar coordinate system shows that area Ⅰ exhibits a uniform damage pattern, and area Ⅱ gradually transitions from an elliptical to a circular distribution. Based on the relationship between the fractal dimension of the damage area and the damage variable, a fractal damage model for double-hole blasting of poly(methyl methacrylate) (PMMA) material is constructed.

In order to accurately regulate the damage effect of slit pack blasting on the backfill of the quarry in deep mines, this study focuses on the damage control mechanism of the peripheral hole spacing (500, 600, 700, 800 mm). Based on the theory of elastic fluctuation and the dynamic propagation characteristics of shock waves in rocky media, the diffusion mechanism of the stress wave under the action of multi-media in the constrained orientation during slit packet blasting is established. Combined with the strong correlation between brittle concrete materials and the damage evolution of the backfill, the cross-media equivalence calibration framework of the Riedel-Hiermaier-Thoma (RHT) intrinsic model is established. Based on the numerical simulation software ANSYS/LS-DYNA, we constructed a multi-media dynamic coupling numerical model of “filling body-mineral body-cutting slit package”, arranged observation points at the junction of filling body-mineral body, and conducted a combined analysis of the peak stress change, the change of the blast vibration velocity, and the damage evolution of the filling body at the observation points. Then, based on the blasting test of the approach and return stage of the neighboring filling body in Jinchuan Three Mining Area, the blasting test of conventional packs, slit packs and different peripheral hole spacing was conducted. The test shows that: slit pack blasting triggers gas-phase jet and strain-energy convergence effects in the unconfined direction, synchronously suppresses the stress and vibration peaks in the confined direction, and achieves directional attenuation of the blasting load on the neighboring filling body; the field test shows that, compared with the conventional charge, the slit pack significantly reduces the degree of damage of the backfill by more than 36%; the degree of blasting damage and the peripheral hole spacing show a negative correlation, and the damage suppression efficiency is improved with the increase of the spacing. The damage suppression efficiency is improved when the spacing increases.

The crack propagation behavior of brittle materials, such as rock, is often challenging to capture under explosive loading conditions. To address this issue, model experiments were conducted based on the theory of explosive damage, utilizing transparent polymethyl methacrylate as a surrogate material to simulate the fracture response of brittle materials. High-speed photography and computed tomography scanning were employed to investigate the dynamic fracture process and three-dimensional crack evolution under blast loading. In addition, 3D scanning technology was used to reconstruct the morphology of cracks and characterize the fracture surface features. The results indicate that under the sustained action of multi-stage explosive energy, cracks undergo repeated initiation and propagation. Initial cracks induced by shock waves exhibit high density and a “fish scale” pattern, primarily concentrated around the blast hole. In contrast, secondary cracks driven by detonation gases have a lower density and extend outward in “ear-shaped” or “dagger-shaped” forms. As the distance from the explosion center increases, the crack surface morphology transitions from rugged to microwave-like textures, with improved flatness. Specifically, the elevation variance of the fracture surface decreases from 0.796 to 0.586, while the maximum height reduces from 3.2 mm to 2.8 mm, representing a 12.5% reduction. Moreover, the failure mode of the material shifts from compressive-shear to tensile failure with increasing distance from the explosion center. This shift is accompanied by a decline in both the fractal dimension of the crack distribution and the overall damage degree of the model.

In order to investigate the mechanical properties and energy transfer law of jointed deep tuff under one-dimensional dynamic loading, seven kinds of tuff specimens with specified natural joint inclinations were tested by SHPB test device. During the tests, the dynamic process was recorded by high-speed camera in real time. The influence of joint inclination angle on the dynamic response characteristics of deep tuffs was systematically analyzed in terms of dynamic strength, energy dissipation and macroscopic damage. The results show that tuffs has the lowest dynamic strength when the joint inclination is 45°, and the dynamic compressive strength and peak strain show a tendency of decreasing firstly and then increasing in the range of joint inclination angle increasing from 0° to 90°. Besides, the final damage modes of the specimens are controlled by the nodal inclination, and the final damage modes of tuff specimens with different nodal inclinations can be classified into tensile damage, tensile-shear composite damage and shear damage. When the incident energy is roughly the same, the reflection energy ratio and transmission energy ratio of tuff present a decrease-increase trend with the increase of natural joint inclination angle, with the lowest energy ratio at 45°. However, the trend of the dissipation energy ratio is opposite. The energy-time density increased first and then decreased with the increase of joint inclination angle. When the direction of load and joint is within 45°~60°, more energy is absorbed and used for self-crack propagation.