To investigate the effects of decked charge structure on the energy transfer and blasting outcomes, a study was conducted to improve the energy utilization rate of explosives and enhance the blasting impact based on the blasting operations of a limestone mine in Chenzhou. Combining LS-DYNA numerical simulations with on-site optimization experiments, this research examined the rock stress distribution across different charge structures during bench blasting. Simulations were performed on four charge structures: continuous charge, 0.6 m deck, 1.0 m deck, and 1.5 m deck, with effective stress monitored at key points. Field optimization experiments were then conducted using a novel transmissible explosive deck to analyze the overall blasting performance of the blast pile. The research results indicate that the rock damage extent and average maximum effective stress reach peak values at a 1.0 m deck length, resulting in favorable fragmentation. In field tests, the decked charge reduced the powder factor from 0.199 kg/t to 0.179 kg/t, lowered the fine ore rate by 6.54%, reduced the oversize rate by 3.7%, and increased the average block size by 5 cm. This approach minimized energy wastage and resolved uneven fragmentation issues with mixed emulsion explosives, enhancing the mine's economic efficiency.

Ore crushing is a crucial phase in hard rock mining and mineral resource recovery, significantly focusing on optimizing the energy consumption balance between blasting and mechanical crushing. This study analyzed industrial test data from an iron mine to explore the relationship between parent rock size distribution characteristics and mechanical crushing energy sensitivity, providing a theoretical foundation for process optimization and energy efficiency improvement. Initially, the connection between the key parameters of the parent rock size distribution curve and crushing power consumption was investigated. Subsequently, the maximum block size under the screen (D75) was identified as a sensitive indicator for crushing power consumption through correlation analysis. Finally, a theoretical model based on shared blasting control was developed, utilizing an optimal parent rock size distribution curve, R=1-\exp \left[-{\left(\frac{X}{282.1}\right)}^{1.69}\right] to control the block size. Field application of this model demonstrates a cost reduction of 17.63%, affirming its potential for enhancing energy management and cost efficiency in mining operations.

To further investigate the influence of surrounding rock mass damage on the rock burst mechanism, material selection for simulating the damage zone was carried out, and a test piece containing the damage zone (1000 mm×600 mm×400 mm) was fabricated. Using the self-developed rock burst model test system's drilling device, caverns were excavated in the specimens (with a hole diameter of 110 mm). Rock burst model tests were then conducted on specimens with varying damage zone thickness through step loading, considering the damage effects on the surrounding rock. During the tests, cameras monitored the damage process of the tunnel wall. Image expansion was performed based on the rubber paper model principle, and the box dimension of the expanded image was calculated and analyzed. The results show that the macro-failure process of a rock burst consists of crack initiation, particle ejection, crack propagation, and debris avalanche stages. As the thickness of the damage zone increases, the failure depth of the specimen chamber's side wall gradually increases. In the stage of slow increase and sharp increase in the box dimension of the left and right tunnel walls, the growth rate of the box dimension decreases linearly with the increasing thickness of the damage zone. With the increase in damaged zone thickness, cracks in the tunnel wall primarily concentrate within the damaged zone during loading, and the damage depth of the tunnel wall increases when the cavity is damaged. The findings further elucidate the breeding and failure mechanism of rock bursts in deep-buried caverns under the condition of surrounding rock damage.

On-site double-hole slitting blasting experiments were conducted to study the effect of controlling fracture damage by double-hole slitting blasting. A test double hole slitting blasting model was constructed using ANSYS/LS-DYNA software, and its crack propagation and changes in gas unit pressure on the hole wall were compared and analyzed. The on-site results indicate that an intersecting fracture surface is formed between the two blast holes in the direction of the cutting seam after the explosion, and the half-hole residue is more obvious. Besides, the cracks will still develop towards the cutting direction by changing the cutting angle to 157°, and the guiding effect of the cutting seam is not affected by the change in angle. Meanwhile, the fracturing effect of adding empty holes between blast holes is better than that of non-empty hole slot blasting, which indicates that the existence of empty holes can effectively improve the directional fracture effect of slot blasting. The model results of the crack propagation and damage are consistent with the on-site results. By comparing and analyzing the double hole slit blasting and ordinary smooth blasting models, the superposition effect of stress waves causes the development of cracks between the holes to deflect, which forms a crack void between the two holes. Though analyzing the peak pressure of gas units around the hole wall at 0°~90°, it is found that the time when the pressure peak reaches the slit direction is earlier than that in the non-slit direction. More importantly, the pressure peak decreased significantly, and then the curve gradually tended to flatten during the slit blasting range of 0°~15°. The larger the angle, the smaller the peak change. The slit tube effectively controls the distribution of explosion energy during the explosion process, which forms stress concentration at the slit, with the maximum stress peak being about four times higher than that in the vertical direction.

The dynamic compression mechanical characteristics of the surrounding rock mass of the shale formation tunnel in western Hubei province need detailed exploration. A Split Hopkinson Pressure Bar (SHPB) and a highspeed camera were employed to conduct impact tests on shale samples at five different bedding angles (the angle between the direction of impact loading and the normal of the bedding planes of the specimen, including 0°, 30°, 45°, 60°, and 90°). Meanwhile, the research team also studied the influence mechanism of bedding angles, impact pressure, and strain rate on the dynamic compression mechanical characteristics and failure mode of shale with different dynamic loading strain rates under different impact pressures. The research results indicate that the dynamic compressive strength of shale has an approximately U-shaped pattern with increasing bedding angles under different impact pressures and strain rates. Among them, the shale with bedding angles of 0° and 90° has relatively higher compressive strength, while the shale with a bedding angle of 60° has the most minor compressive strength. Furthermore, the dynamic compressive strength of shale with different bedding angles increases as the impact pressure and strain rate increase. The macroscopic failure modes of shale are mainly divided into tensile failure, shear failure, and mixed failure. Significantly, the macroscopic failure modes of samples with bedding angles of 0° and 90° under different strain rates are mainly tensile failure. The primary macroscopic failure mode of the sample shows a transition process of shear failure mixed failure tensile failure' as the strain rate increases when the bedding angle is 30°. The primary macroscopic failure mode of the specimen evolves from shear failure to mixed failure as the strain rate increases when the bedding angle is 45° and 60°. The energy absorption ratio of shale samples first increases and then decreases as the bedding angle increases under the same impact pressure. Additionally, the energy absorption ratio and the degree of sample damage are simultaneously maximum as the bedding angle is 60°. The degree of fragmentation of shale samples with different bedding angles increases, and the energy absorption ratio gradually tends to be consistent as the impact pressure and strain rate increase.

The intrinsic mode confusion of empirical mode decomposition (EMD) and the ensemble empirical mode decomposition (EEMD) can only suppress mode confusion to a limited extent, as the white noise added by EEMD cannot be fully neutralized, which compromises the completeness of the original signal. Additionally, both methods fail to avoid interference from endpoint effects. Modal confusion and endpoint effects lead to distortions in the time-frequency analysis results obtained from the Hilbert transforms of EMD and EEMD. A complete ensemble empirical mode decomposition with adaptive noise and endpoint processing (EP-CEEMDAN) is proposed to address these issues. Simulation experiments were conducted to compare EMD, EEMD, and EP-CEEMDAN decomposition results on simulated vibration signals. Through multiscale permutation entropy detection and marginal spectral analysis, it was verified that EP-CEEMDAN has better control over endpoint effects and mode confusion, proving that EP-CEEMDAN is a more effective adaptive algorithm than EMD and EEMD. Finally, EP-CEEMDAN was applied to the processing of measured non-stationary vibration signals, where adaptive white noise was added at the endpoints of the vibration signals during each stage of decomposition. The method successfully generated various intrinsic mode functions (IMF) by calculating a unique residual signal. The EP-CEEMDAN algorithm effectively suppresses IMF endpoint divergence and modal confusion, while the time-frequency spectrum obtained through the Hilbert transform offers high resolution in both time and frequency domains. This result can be used for vibration feature recognition in non-stationary vibration signals.

Since uneven stress on the cutter head can easily lead to surface collapse accidents when a shield machine passes through the silt-rock strata, the rock stratum can be blasted and broken by drilling blast holes on the ground surface before the shield machine arrives. However, the seismic waves generated by the blasting would threaten the safe operation of adjacent gas pipelines. In order to study the vibration characteristic of adjacent gas pipelines during blasting in silt-rock strata, the rock breaking project of silt-rock strata in the shield section of Hengqin Station and Hengqin North Station of Zhuhai Metro was selected as the research background. Firstly, the on-site blasting vibration was tested. Then, the ANSYS/LS-DYNA software was used to simulate the blasting process and invert the physical and mechanical parameters of the materials at the blasting site. Finally, the vibration characteristic of the gas pipeline was analyzed. The research results show that the PPV (peak particle velocity) on the pipeline decreases with the increase of the horizontal distance from the explosion source in the axial direction of the gas pipeline. Meanwhile, the maximum PPV position is perpendicular to the center line of the blast holes. Furthermore, the surface PPV above the gas pipeline decreases along the pipeline axis as the horizontal distance from the explosion source increases, and the maximum PPV position is also perpendicular to the center line of the blast holes. Besides, there is a functional relationship between the surface soil PPV₂ along the axial direction of the gas pipeline and the PPV₁on the outer wall of the gas pipeline, which is V₂=0.60V₁+1.29. More importantly, the PPV of the gas pipeline's inner and outer of the gas pipeline are basically the same.

A parameterized hole placement design method for medium-depth holes was proposed to solve the problems of large subjectivity of manual interaction, cumbersome and complex adjustment of hole placement and difficulty in ensuring the uniformity of hole bottom distance. Firstly, a mathematical model in underground mines was constructed using the parameterized hole layout idea combined with the blasting boundary space constraints and blasting parameter requirements. Furthermore, the mathematical model was solved using the operation research method to get the optimal hole design on a digital mining software platform. Finally, the model was used in an underground mine. The result shows that the standard deviations of the bottom distance for the manually laid holes are 0.08 m, 0.10 m, 0.07 m and 0.07 m, respectively, while those for the automatically laid holes with the parameterized method are 0.02 m, 0.03 m, 0.02 m and 0.02 m, respectively. The hole laying time is shortened from 4 hours to 5 min. The proposed method significantly reduces the workload of the designing technicians and maximizes the guarantee of inter-hole laying between holes. It maximizes the uniformity of the bottom distance and avoids the randomness and errorprone nature.

With the continuous development of precision step blasting technology in open pit mines, the disadvantages of traditional layout methods in layout precision and construction efficiency are becoming more and more prominent. In order to improve the precision and efficiency of hole layout, the theory of hole layout is combined with RTK line lofting technology. According to the designed values of the chassis resistance line, hole spacing and row spacing, the RTK line lofting method is used to measure the size of the chassis resistance line and determine the line coordinates and layout direction of the first row of holes. Then, each row of holes can be laid out for construction by setting parameters such as mileage, mileage increment, deviation and deviation direction in the RTK manual book. Finally, a single person can achieve high-precision and high-efficiency hole laying while recording the hole position and measuring the design hole depth. This paper introduces a construction method of RTK line lofting and hole layout in detail, applies it to the actual construction, and gets a good effect. Applying this method provides a new idea for the precision, standardization and high efficiency of the open-pit bench blasting construction, improves the construction efficiency and precision while saving workforce, and reduces the cost of open-pit blasting.

Taking the explosion of a shipyard as an example, the investigative techniques had been comprehensively utilized (such as on-site investigation, interview, numerical simulation, theoretical calculation, trace analysis, etc.) to conduct in-depth research on the development of the accident, consequences and mechanism of the explosion. An on-site survey of the involved hull revealed fresh welding slag remaining on the starboard main deck in the area of the No. 7 empty cabin utility hole. In addition, the empty compartment No. 7 on the starboard side was identified as the explosion's origin based on the ignition source traces, the extent of the hull damage, and the cracking direction. The root of the explosion accident was restored according to results from a comprehensive on-site investigation. The paint and thinner would volatilize and produce massive organic combustibles during painting operations, forming explosive mixtures when mixed with air and accumulating in the empty compartment's limited space. The explosive gas mixture contacted spattered weld slag at the utility hole, causing an explosion in the empty compartment No. 7 on the starboard side, which triggered explosions in the remaining compartments. As a result of the breeding-development-dissipation of the shock wave, the explosion first intensified and then gradually reduced damage to the surrounding of the NO. 7 empty cabin as the center. The simulation with the CFD analysis software FLUENT revealed that the explosion mixture diffused 10% outward through the utility hole in 12 h. According to the diffusivity analysis results, the gas mixture's volumetric concentration was calculated to be 7.3%, which is sufficient for a combustion explosion. The equivalent amount of TNT for the explosion was 188 kg, which was inverted to 203 kg depending on the extent of damage to the buildings at the accident site after the explosion. It is in good agreement with the TNT equivalent of the explosion obtained from calculations based on the physical parameters of the gas mixture, which proves the practicability of the calculation.