To mitigate blasting vibration during the excavation of a drainage tunnel located 2.30~3.10 m beneath an existing tunnel, an optimized blasting scheme using millisecond blasting by electronic detonators and a subsection in blasting holes was implemented. The field blasting scheme was initially adjusted based on the conventional blasting situation near the existing tunnel. This involved optimizing hole position parameters and reducing the number of holes. Before the formal blasting in the underpass section, a single-hole blasting test was then conducted near the excavation face to capture the vibration waveform and geological information. Using the linear superposition method, the vibration waveform of various delay intervals was analyzed to select the optimal delay interval. To further improve blasting performance and reduce the vibration of the cut blasting, the first blasting in the cut area was performed by using the subsection blasting in the hole. Field tests and calculations determined that the optimal delay times were 5 ms for the same row of cut holes or spreader holes, 40 ms between rows, and 3 ms for contour holes. The new blasting scheme was implemented and optimized in the field. When the drainage tunnel was excavated at a footage of 1.5 m through the existing tunnel, the maximum vibration of the road surface monitoring point at a distance of 3.10 m directly above was maintained below 4.0 cm/s, ensuring structure safety. Using electronic detonators for precise initiation and sectional blasting successfully controlled site vibration, protected adjacent structures, and provided valuable insights for similar future projects.

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.

Reinforced concrete structures are usually subjected to explosion impact load, resulting in severe damage. Different protective materials are typically laid on reinforced concrete slabs to improve the explosion resistance. The experimental study on the explosion resistance of reinforced concrete slabs with different protective materials was conducted using the drop hammer test, and an accelerometer tested the impact of reinforced concrete. An embedded piezoelectric intelligent aggregate is used to monitor the internal damage signal of a reinforced concrete slab under the drop hammer impact load. The test results show that both carbon fiber reinforced matrix composites (CFRP) and polyurea can effectively protect the specimens in the single-layer reinforced structure, with an average decrease of 78.20% and 79.05% relative to reinforced concrete acceleration and 40.98% and 65.79% peak impact stress, respectively. Additionally, the average acceleration reduction of polyurea-concrete-CFRP (IPC), polyurea-CFRP-concrete (ICP), and CFRP-concrete-polyurea (CIP) compared with reinforced concrete slabs are 70.29%, 77.46% and 79.85% in the composite protective structure, respectively. The average peak impact stress reduction is 32.73%, 56.32%, and 51.07%, respectively, which can effectively protect the specimens and improve the impact resistance of concrete slabs. It can provide a reference for related engineering applications.

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.

Blasting Engineering is a core course in urban underground engineering and mining engineering in universities, and teaching blasting experiments is an indispensable link in practical teaching. As explosive engineering has a characteristic of great danger, the traditional explosive engineering experiment construction is rugged enough to be carried out indoors, which inconveniences teaching. Therefore, more and more schools rely on virtual simulation platforms. According to the teaching idea and demand of explosive engineering virtual simulation, this paper builds a virtual simulation teaching platform for blasting experiment teaching. Unity3D, a development tool for virtual simulation systems, was utilized to ensure high compatibility when running on different platforms. Meanwhile, the 3DS Max and Maya were applied to build and improve a realistic model. Furthermore, problems like slow loading speed and non-realistic animation through the cloud rendering technology were solved. The software ANSYS was used to simulate the propagation mechanism of blasting vibration waves in different rock layers better to reflect the blasting vibration waves in practical engineering. Finally, the wave field cloud map was saved as a snapshot in the virtual simulation system, and virtual simulation experiments of blasting vibration were carried out. The practice and application results show that the virtual simulation experiment platform can enable students to participate in the experiments of explosive engineering independently and deeply and improve students' experimental experience and practical innovation ability.

To investigate the energy evolution and failure patterns of magnetite during blasting and to minimize the impact of blasting disturbances on the stability of pillars and surrounding rocks, a series of multi-stage strength impact tests were conducted on magnetite samples using a Split Hopkinson pressure bar (SHPB) apparatus. The dynamic response characteristics of magnetite were analyzed, focusing on parameters such as dynamic peak compressive strength, failure modes, fragmentation size, and energy dissipation density under varying strain rates. The results show that magnetite's dynamic peak compressive strength and energy dissipation density increase exponentially with the increase in strain rate. At the same time, the crushing size decreases exponentially, demonstrating a strong strain-rate dependency. The failure process of magnetite can be divided into three stages: crack compaction, elastic deformation, and crushing. The dynamic increase factor (DIF) also increases with the increase in strain rate. The failure mode of magnetite transitions from splitting failure at lower strain rates to crushing failure at higher strain rates as crack interactions intensify. Therefore, when blasting rock breaking is applied to magnetite mining, it is crucial to balance impact strength and energy dissipation to enhance crushing efficiency while meeting the required fragmentation standards.

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.

During aero-engine casing containment tests, the explosive separation method used to achieve the constant-speed fly-off of titanium alloy blades often produces a bright titanium fire phenomenon. This titanium fire obstructs high-speed camera recording of the blade fly-off process. To address this issue, this study analyzed the mechanism of titanium fire generation and proposed a barrier layer method to suppress titanium fire during shaped energy cutting of titanium alloys. Numerical simulations using the Euler algorithm in AUTODYN were conducted to evaluate the blocking effect of the barrier layer and its feasibility for titanium fire suppression. Experimental investigations were then performed to quantitatively assess the brightness reduction of titanium fire, comparing the effectiveness of four barrier materials. The results indicate that 0.1mm thick aluminum and titanium tin foil achieve titanium fire suppression rates of 29.5% and 24%, respectively, demonstrating moderate effectiveness. A 0.1 mm thick copper sheet shows poor performance with a suppression rate of only 4.3%, while a 0.1 mm thick aluminum silicate coating exhibits the best performance, achieving a suppression rate of 70.9%. This study has summarized the mechanism of titanium fire suppression suing barrier layers during shaped energy cutting of titanium alloy plates and validated the feasibility of the barrier layer method. The findings can provide a practical approach for titanium fire elimination in explosion separation processes involving shaped energy cutting of titanium alloys.

To enhance excavation speed in small-section tunnels and address the limitations of oblique and burn cut blasting techniques, a new burn cut blasting method combining long and short straight holes is proposed based on rock blasting theory, stress wave rock breaking theory, and sacrificial blasting theory. This method improves the burn cut blasting approach with equal resistance lines, eliminating the need for empty holes. The blasting parameters and cavity formation process are discussed in detail. Through field tests and the use of different detonators and cutting layouts, the performance of various cutting methods was evaluated in terms of blasting advance, powder factor, and over-excavation and under-excavation. The results show that the proposed burn cut blasting method is not constrained by tunnel cross-sectional area, allowing for independent hole depth design and optimal delay intervals to achieve staged and layered blasting. This technique enhances the role of free surfaces in the cutting process, reducing the minimal resistance line in deep holes. The resulted cavity is a regular rectangular shape, increasing blast hole utilization from 78.5% to 89.3%. Field tests show that, in small-section tunnel blasting, this method increases the advance from 1.6~2.2 m to 2.2~2.5 m compared to traditional inclined-hole cut blasting. Over-excavation was further reduced by 20%~30% when the displacement of surrounding holes remained within 10cm. The proposed cutting method effectively controls costs, improves operational efficiency, and offers both technical and economic advantages with improved blasting outcomes.

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.