During drilling and blasting of open-pit mining in high and cold regions, water inrush or freezing often occurs on the borehole inside. This phenomenon creates a decoupled charge structure with water and ice, affecting the blasting effect and the rock-breaking mechanism under decoupled conditions. To determine the geometric parameters of the blasting crater and analyze the blasting effect under three types of decoupling medium in the high-cold area, a series of tests were conducted on the blasting effects of different decoupling charges in the Karma open-pit mining in Tibet. Based on the Livingston curve fitting results, the blasting parameters were optimized and applied to on-site engineering blasting. The results indicated significant differences between the visible volumes of the blasting crater and the crushed funnel at burial depths of 1.09~1.49 m. However, these volumes resembled burial depths of 1.49~1.69 m. Compared to the air-deck decoupling, the peak particle velocities under water and ice decoupling were reduced by 25.33% and 11.24%, respectively. The critical charge depths varied among the three decoupling materials, with water decoupling having the most significant critical depth, ice decoupling charge, and air-deck decoupling having the shallowest. The charge weights required for water and ice decoupling and ice decoupling were 18.9% less than those for air-deck decoupling. In multi-hole bench blasting, the explosive factor for water and ice decoupling was reduced by 18.2% compared to air-deck decoupling, and the rate of large fragments decreased from 8.9% to 4.3%. This indicated that water and ice decoupling charges made the energy distribution of explosives more uniform.

With the rapid advancement of modern industry, the demand for high-performance materials has grown significantly. Titanium/duplex stainless steel composite plates, known for their exceptional corrosion resistance, demonstrate vast potential for diverse applications. In this study, a bimetallic composite plate comprising TP270C titanium alloy and SUS821L1 high-strength duplex stainless steel was fabricated using explosive welding. The microstructural characteristics of the composite plate interface were thoroughly investigated through metallographic microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and electron backscatter diffraction (EBSD). Additionally, the welding quality was systematically evaluated. The results showed that the welded interface exhibited an intermediate structure between flat and wavy when the interface deposition energy was low. In contrast, the welded interface displayed a wavy structure at higher interface deposition energy. Element diffusion and grain refinement were observed in the regions adjacent to both interfaces. Complete recrystallization predominated in the welded interface, molten zone, and adiabatic shear band. Near the welded interface, titanium underwent partial recrystallization, while duplex stainless steel exhibited a combination of partial recrystallization and deformed grains. Localized thermal accumulation facilitated grain growth in the molten layer, whereas titanium particles encapsulated within the molten layer exhibited refined grain structures. Mechanical performance tests indicated that the sample with higher interface deposition energy achieved a 40.33% increase in shear strength and a 4.52% improvement in bending strength compared to the sample with lower interface deposition energy.

This study explored the influence of high-pressure gas blasting on coal's crack propagation and vibration characteristics. Using independently developed high-pressure air blasting devices, the high-pressure air blasting experiments were carried out on the simulated coal specimens. The surface crack propagation speed and particle vibration of the specimen were measured using a blasting speed acquisition instrument and a blasting vibration acquisition instrument, respectively. Furthermore, the crack propagation and fracture induced by high-pressure air blasting and the variation characteristics of particle vibration energy were analyzed. Scanning electron microscopy (SEM) was used to examine the evolution of pore cracks in specimens before and after blasting. The experimental results indicate that the surface cracks on the specimen are induced to develop and propagate along the direction of confining pressure loading at a design pressure of 15 MPa, and the crack development and propagation speed is v_{Bi-directional unequal pressure} > v_{no confining pressure} > v_{Bi-directional equal pressure}. Besides, The crack development and propagation speed vary under different confining pressure conditions, exhibiting two stages: rapid development and steady-state development as the distance from the crack initiation hole increases. The induced particle vibration signal is distributed in the range of 0~250 Hz, with the energy in the main frequency band of the vibration signal significantly different from that in other sub-bands and the vibration main frequency band significantly differing from other sub-bands. The primary vibration signal is concentrated in the low-frequency band of 0~31.25 Hz. These findings provide a theoretical basis and guidance for optimizing the distribution of fractures induced by high-pressure gas blasting and improving the effectiveness of gas extraction.

Accurate acquisition of blasting vibration signals is essential for analyzing the harmful effects of blasting operations. However, geological conditions, electromagnetic interference, and instrument errors can introduce significant high-frequency noise into the collected signals, leading to distortion and inaccurate data interpretation. To address this issue, a signal decomposition algorithm based on Ospley Optimization Algorithm (OOA) is proposed to optimize Variational Mode Decomposition (VMD). Multiscale Permutation Entropy (MPE) is also employed to construct a noise reduction model for tunnel blasting vibration signals. OOA is iteratively applied to determine the optimal VMD parameters (K & α) and obtain the intrinsic mode formula (IMF) using the maximum information coefficient as the fitness function. The MPE values of each decomposed signal are then used to identify the noise components, which are removed to reconstruct the denoised signal. This coupled algorithm was applied to analyze the blasting effects in Dashan Tunnel, Yunnan Province. The results demonstrate that the proposed optimization algorithm effectively decomposes the signal and eliminates noise without significantly affecting the low-frequency energy. The OOA-VMD denoising method's performance is superior to the complete ensemble empirical mode decomposition (CEEMD) and conventional VMD algorithm, thereby verifying its reliability.

The presence of joint fractures significantly influences the dynamic performance of the rock mass. To investigate the effects of joint angles and filling materials on the dynamic response of filling joint samples under impact loading, a series of impact tests were conducted using a split Hopkinson pressure bar (SHPB). Samples with seven different joint angles and three types of filling materials were tested. The relationships between dynamic characteristics, energy dissipation, joint angles, and properties of the filling material were systematically analyzed. The results indicate that: (1) The stress-strain curves of the joint samples of different filling media are significantly different. The stress-strain curves of sediment and lime filling samples show plastic failure characteristics at joint angle α≤45° and brittle failure at joint angle α>45°, while gypsum filled samples primarily display brittle failure, except at joint angle α=45°, where plastic failure occurs due to stress wave propagation effects. (2) The dynamic compressive strength of joint samples with the same filling material initially decreases and then increases with the increasing joint angle α, reaching a minimum value at α=45°. Among the three filling materials, gypsum-filled joints exhibit the highest compressive strengths. (3) Energy dissipation characteristics vary with joint angle. The reflected energy ratio increases initially and then decreases, peaking at α=45°, while the transmitted and absorbed energy ratios decrease initially and then increase, reaching their lowest values at α=45°. These findings provide critical insights into the dynamic behavior of jointed rock masses and have practical implications for engineering applications involving impact or blast loading.

To investigate the inhibitory effect of calcium carbonate on methane explosion in the presence of coal dust, experiments and numerical simulations were applied in this study. The inhibitory performance of calcium carbonate under various particle sizes and concentrations was analyzed, providing a theoretical basis for safety protection in high-risk environments, such as coal mines. By using a self-developed 9.6-meter-square straight pipe, the experiments were conducted with Calcium carbonate, whose particle sizes ranged from 6.5 to 74 micrometers, and the concentration levels were maintained within the optimal range of 100 to 200 g/m³. Based on this, the optimal particle size and concentration of calcium carbonate were determined by analyzing the pressure changes during the explosion process. The experimental findings reveal that the explosion process can be divided into four stages: initial methane combustion, subsequent methane combustion involving coal dust, calcium carbonate decomposition, and a final inhibition stage. Meanwhile, the calcium carbonate reduces oxygen concentration. It absorbs heat through thermal decomposition reactions, which slows down the combustion reaction rate and establishes local thermal equilibrium, thereby suppressing the propagation of the explosion. The calcium carbonate achieves optimal explosion suppression performance with a maximum pressure reduction rate of 46.7% at specific parameters: a calcium carbonate of 150 g/m³ combined with a particle size of 23 micrometers. Additionally, numerical simulations were employed to verify the experimental results, which demonstrate that the pressure change trends are consistent with the experimental results, with a relative error of less than 15%. As an effective explosion inhibitor, calcium carbonate demonstrates significant inhibitory effects on methane explosions in the presence of coal dust under specific particle size and concentration conditions. This study provides experimental and theoretical support for the application of calcium carbonate in industrial explosion protection.

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.

With the increasing complexity of the urban environment and environmental awareness of the public, directional toppling blasting demolition of frame structure buildings often encounters the problems of large collapse recoil distance and strong ground impact vibration, which limits the development and application of blasting demolition technology. To control the collapse recoil and touchdown vibration of the directional blasting demolition of the frame structure building, the design method of the hinge point forward high blasting cutting was put forward, and the theoretical calculation model of blasting cutting height was established based on traditional bottom cutting blasting demolition technology. Meanwhile, a blasting demolition technology of high-cutting blasting with a reserved buffer layer was developed combined with engineering practice. Three kinds of blasting cutting forms were designed to meet the control requirements of different degrees of collapse recoil and touchdown vibration according to the treatment method of the reserved buffer layer. Furthermore, the collapse and disintegration effects of frame structure blasting demolition in different blasting schemes are compared and analyzed by theoretical analysis, numerical simulation, and field test. The results show that the hinge point forward high blasting cutting can increase the inclination angle, prolong closure time, and control the structure's collapse recoil and touchdown vibration, greatly improving the reliability of structural instability and collapse. Compared with the traditional bottom-cutting blasting scheme, the reserved buffer layer hinge point forward high-cutting blasting scheme can effectively shorten the length of the blasting pile, reduce the speed of structural collapse to the ground, and effectively control the height of the blasting pile. The selection of a reserve buffer layer should be considered comprehensively with the structural characteristics of the building and the surrounding environment.

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.

Researching blasting similar simulation materials for ultra-deep shaft surrounding rock and conducting physical model tests are the basis for studying the dynamic response law of ultra-deep shaft surrounding rock under blasting. This paper used the monzonitic granite in Xiling subsidiary shaft of Sanshandao gold mine as the simulation object to prepare similar granite materials. The iron ore powder and barite powder were selected as fine aggregates, the quartz sand was selected as coarse aggregate, the rosin alcohol solution was selected as binding material, and the gypsum was selected as adjusting material. The orthogonal design method was used to prepare the simulation materials. The mechanical parameters of similar materials with different proportions were determined, and the sensitivity analysis of each influencing factor and the blasting test of the simulated materials were carried out. The results show that the selected proportion can meet the requirements of indoor blasting model tests based on the specimen's density, unaxial compressive strength and elastic modulus. The proportion of fine aggregate in the total aggregate significantly affects the density of the simulated materials. The binder concentration significantly affects the compressive strength, tensile strength, elastic modulus and cohesion of the simulated materials. The proportion of gypsum significantly affects the internal friction angle of the simulated materials. The peak strain value in the model test block under high confining pressure is more significant as a whole, and the attenuation rate of the peak strain gradually decreases with the distance increase.