To explore the influence of ignition position change on overpressure characteristics of methane/air premixed explosion under different equivalence ratios, several tests with varying length-to-diameter and equivalence ratios on the rise rate of peak overpressure and positive pressure duration were carried out through a self-built explosion test system. The main influencing factors affecting the pressurization characteristics of methane/air premixed explosion were analyzed by the dimensional analysis method, and the calculation formulas of rise rate of overpressure peak and positive pressure during methane/air premixed explosion were proposed. The results show that the rise rate of the overpressure peak increases with the increase of the equivalence ratio, and the increase in length-to-diameter ratio makes the rise rate decrease gradually, which is different from the attenuation rate. The positive pressure duration is gradually prolonged with the rise of the length-to-diameter ratio. However, the maximum positive pressure duration corresponds to different equivalence ratios with the length-to-diameter ratio changes. Furthermore, the calculation formulas of the rise rate of overpressure peak and positive pressure duration of methane/air premixed explosion are obtained by the dimensional analysis method, and the feasibility of the formulas is verified by comparing the experimental values with the theoretical values. It was found that methane/air premixed explosion is significantly affected by the ignition position and equivalence ratio, which can provide a reference for the power evaluation and safety control of methane explosions.

Since the concept of intelligent blasting was proposed, the on-site mixed explosive vehicles (MEVs) have struggled to meet the evolving demands of the field. Reviewing the development of MEVs abroad reveals that while developed countries have a higher proportion of on-site mixed explosives usage, their levels of automation and intelligence have progressed slowly, with only a handful of civil explosive giants proposing related concepts. In China, to meet the national requirements for intelligent mine construction, some civil explosive enterprises and MEV manufacturers have begun exploring intelligent upgrades and applications for MEVs, achieving notable technological breakthroughs. China Gezhouba Group Explosive Co., Ltd. has developed an intelligent on-site mixed ANFO vehicle featuring precise borehole positioning, automatic blasting design acquisition, one-button charging, and automatic information collection. This article introduces this intelligent ANFO vehicle, detailing its key technologies: high-precision charging metering control systems, intelligent high-precision positioning, and smart loading systems. These advancements offer references for the intelligent development of similar explosive vehicles. The future direction for on-site MEVs is to achieve full intelligence and crewless operation, encompassing capabilities such as unmanned driving, automatic hole targeting, and smart charging. Ultimately, these vehicles aim to integrate seamlessly into the framework of safe and collaborative operations within the mining sector.

A large-area concrete site was prepared to eliminate the boundary effects to investigate the propagation law of detonation-induced cracks in differential blasting under varying hole spacing. Multiple sets of linear three-hole and cross-five-hole model tests were conducted using electronic detonators and detonating cords as the blasting sources. The propagation length, direction, and crack arrest position of detonation cracks were recorded under different blasting parameters. The key factors affecting crack propagation were identified by combining the experimental results with the theory of sequential controlled blasting. The results indicate that in the three-hole model, a through-crack forms between the blast holes when the middle hole detonates first, followed by the two side holes. However, as the hole distance increases, the crack becomes increasingly irregular. When the distance reaches 25 times the hole diameter, the crack fails to penetrate and no longer propagates along the direction of the blast holes. In the cross five-hole model, a through-crack can only form when the spacing is within 20 times the hole diameter. The crack generated by the first blast tends to propagate towards the nearest subsequent hole. Still, it does not follow a straight path, exhibiting deflection due to the influence of the additional holes. Therefore, to achieve straight cracks along the contour surface in practical engineering, it is crucial to adjust the timing and control blasting parameters based on specific hydrogeological conditions to fully utilize the void effect and the detonation timing difference.

In blasting demolition projects of housing buildings, reinforced concrete columns serve as the primary load-bearing structural elements and consequently represent the most frequently targeted components for controlled demolition. The effectiveness of reinforced concrete column demolition through blasting operations plays a pivotal role in ensuring structural instability and controlling the overall collapse mechanism. The evolution of modern reinforced concrete columns, characterized by increased cross-sectional dimensions, higher reinforcement densities, and enhanced material strengths, has significantly elevated the technical complexity of the design of blasting parameters and the protection of flying rocks. The Particle Blasting Method coupled with the Finite Element Method (PBM-FEM) was employed to simulate the dynamic process of explosion impact loading and explosion gas escaping from the borehole through the high-speed motion collision of particles. Full-scale 1∶1 physical model tests were conducted using industrial electronic detonators to accurately replicate the blasting demolition process of high-rise building structural members. The research reveals critical insights into the failure mechanisms and damage propagation characteristics of reinforced concrete columns under controlled demolition conditions. The results show that the explosion gas escapes from the orifice and reduces the utilization rate of explosive energy due to the limited constraint effect of the blocking material on the side of the blast hole. The severity of concrete spalling on the surface of the column is left and right sides > front side > back side. The direction of the minimum resistance line is the main direction to induce concrete damage and throwing.

Pre-splitting blasting has been widely employed in river channel slope excavation to effectively mitigate damage to the retained rock mass, reduce blast-induced vibrations, and optimize blasting parameters for water-saturated slopes. Investigation of reasonable parameters for pre-splitting blasting in such conditions is important for river channel excavation projects. Based on geometric, physical, and dynamic similarity principles, an experimental model for pre-splitting blasting water-saturated slopes was designed, utilizing concrete as a substitute for red sandstone and detonators instead of emulsified explosives. The quality of pre-split crack formation, slope face shaping, and retained rock mass damage were evaluated under various conditions. The results showed that the pre-split crack formation quality and slope shaping quality significantly improved. The damage to the retained rock mass was reduced by 24.86% when the hole diameter increased from 0.8 cm to 1.2 cm. Field test results indicated that the optimal blasting effect can be achieved with a pre-split hole diameter of 115 mm and a hole spacing of 80 cm in a practical application of pre-splitting blasting for water-saturated slopes when the geological conditions involve medium-hard rocks.

Given the current lack of comprehensive research on the mechanism of rock fracturing by high-pressure gas, this study draws upon the research method used to determine peak pressure at the borehole wall in the drilling and blasting method. By analyzing the complete rock fracturing process through the liquid oxygen expansion method, a calculation model for the peak pressure at the borehole wall was derived from the shock tube theory, considering the changes in the rock medium and uncoupling coefficient. Using a dynamic strain tester, a concrete model experiment was conducted to measure the peak pressure at the borehole. Under fixed conditions of a 60 mm expansion tube diameter and four different apertures (75~120 mm), the peak pressure was measured. The test results show that, with the same liquid oxygen equivalent and rock medium conditions, the time to peak pressure increases linearly with the uncoupling coefficient, following the relationship t=230.6k-127.85. As the uncoupling coefficient increases, the peak pressure at the borehole wall decreases gradually, with the attenuation rate gradually slowing. A comparison between the experimental results with the theoretical calculations shows a similar trend in peak pressure attenuation with the uncoupling coefficient, confirming the reliability of the theoretical model.

Blasting excavation generates transient P-waves that significantly impact tunnel stability. For water-filled diversion tunnels, the dynamic response of the surrounding rock differs from conventional dry tunnels. Most existing analytical studies focus on the steady-state solution and single-lined tunnels, rarely accounting for composite linings or the presence of water. This paper investigates the transient stability response of deep-buried circular composite lining diversion tunnels under transient P-wave disturbances. The fluid within the tunnel is treated as a distinct medium, and the tunnel-lining interface is considered a non-ideal contact surface. By applying Fourier synthesis, wave function expansion, and trapezoidal quadrature formula, an analytical solution is derived. Validation through comparison with existing literature demonstrates the method's effectiveness. The study analyzes the effects of Poisson's ratio of surrounding rock, the non-ideal interface's elastic coefficient, and the disturbance's loading duration on the dynamic stress concentration coefficient. Results indicate that the compressive stress concentrations occur at the roof and floor, while tensile counterpart concentrations appear at the two sidewalls during dynamic disturbance. As Poisson's ratio increases, there is a transition from tensile to compressive stress concentration, with a gradual degree in compressive stress intensity. Poor contact between the rock mass and liner induces oscillations in the stress time-history curve. The dynamic response converges accordingly as the elastic coefficients of an imperfect interface approach those of a perfect interface. With increasing blasting load duration, peak dynamic stress around the roof and floor initially rises, then stabilizes, while stress at the sidewalls initially decreases before leveling off.

Underwater blasting vibration poses significant challenges in mining engineering applications, particularly channel dredging, seaport, and bridge construction. This study investigates the vibration attenuation mechanism and propagation characteristics through damping borehole configurations. The attenuation law of underwater blasting damping holes was studied, and a comprehensive experimental program to analyze the blasting vibration signals and piezoelectric signals was conducted by comparing three scenarios: conventional blasting without damping measures, water-coupled damping holes, and air-coupled damping holes. The optimized borehole parameters included a 2 cm diameter, 5 cm spacing, 4 cm row spacing, and 17 cm depth, positioned 20 cm from the explosive source. Experimental results demonstrated that using underwater blasting damping holes can effectively reduce the peak vibration velocity of blasting. The average damping rate of water-coupled damping holes and air-coupled damping holes is 17.5% and 27.2%, respectively. Time domain analysis revealed a consistent correlation between piezoelectric signals and the peak vibration velocity. The damping mechanism primarily affected vertical vibration components, with effectiveness positively correlated with charge weight. Field validation tests confirmed an 18.1% vibration reduction, establishing the practical efficacy of the proposed damping borehole array.

The original stope benches of Dahuangshan Open-pit Mine were in disarray, with pumice between benchs and steep slope conditions. Following blasting operations, a crushing system was introduced to improve rock fragmentation efficiency, significantly increasing potential safety risks near high and steep slopes. This study researched safe blasting techniques and protective measures for slopes in open-pit mines to ensure slope safety during blasting construction. Active protection methods were proposed, including limiting instantaneous charge to 200 kg, aligning the blasting direction parallel to the slope, and preserving approximately 5 m of rock wall along the slope edge. Protective infrastructure was enhanced by installing two protective nets on a cleaning platform mid-slope, excavating a 7 m-deep and 20 m-wide stone protection ditch at the foot of the slope, building a 2 m-high stone protection wall using crushed stones outside of the ditch, and erecting a 2 m-high isolation net outside the protection wall. These safety measures were complemented by auxiliary monitoring methods to enhance the safety of blasting operations and protect the crushing system. Field inspections confirmed that the construction methods effectively ensured the stability of the high-steep slopes and minimized risks during blasting.

The occurrence of oversized fragments during blasting operations significantly increases the cost of blasting, crushing, and hauling expenses. This study addressed the slab' phenomenon observed in the blasting of intact hard rock at the Pingtanyuan Pumped Storage Power Station, where the oversized fragments of the surface blasting area was up to 6 m×5 m×2.5 m. Through comprehensive mechanism analysis, the investigation indicated that the quality of the stemming was the key reason for forming large fragments at the upper part. Meanwhile, the mechanism of its influence lies in the over-long stemming length of the original blasting scheme, which resulted in a low charge center, leading to insufficient energy distribution at the top of the blast hole. Furthermore, an oversized blasting fragments control measurement based on stemming quality optimization was proposed. The stemming length was optimized from 3~4 m to 2.1~2.4 m using a time-sharing piecewise calculation method and the optimization principle, which allowed the part of the stemming structure to rush out of the blast hole. Besides, the decontaminated rock chips were used as stemming material. The results show that the optimized scheme prevented the occurrence of the slab phenomenon, significantly reduced boulder rates, and saved rock breakage costs.