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.

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.

Based on the blasting demolition of a 7-storey frame-shear wall structure in Wuhan, this study investigates the impact of different incision patterns on the collapse process. A refined finite element numerical model was established using ABAQUS, with steel and concrete supporting columns modeled separately and the upper collapse body modeled as a whole. This approach enables accurate simulation of the mechanical behavior of supporting columns while improving computational efficiency. A triangular incision form model was also developed and compared against the trapezoidal incision form used in the project. The stress distribution, recoil distance, and collapse motion characteristics of supporting columns under the two different incision forms were analyzed to explore their effects on the collapse process. Results indicate a high consistency between the numerical simulation and the actual collapse regarding timing, motion characteristics, and overall process, validating the modeling approach. Compared to the trapezoidal incision form, the triangular incision form features a lower center of gravity, causing the structure to tilt quickly around the incision vertex post-detonation. This leads to rapid failure of the rear-row support columns under large eccentric pressure. Consequently, the collapsed body makes ground contact faster, at a higher velocity and disintegrates more thoroughly. Additionally, the triangular incision generates greater horizontal kinetic energy, resulting in a larger recoil distance. This analysis highlights the significance of incision form selection in optimizing blasting demolition outcomes.

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.

The blasting demolition of partial spans in continuous beam bridges frequently entails substantial risks of damage to the adjoining spans. To ensure the effective collapse and fragmentation of the bridge while safeguarding the integrity of adjacent spans, a case study was undertaken focusing on the blasting demolition of a damaged section of a continuous beam bridge in Ankang City. Using ANSYS/LS-DYNA software, numerical simulations were conducted to investigate the impact of water pressure blasting on the upper box girder and evaluate various collapse scenarios for the lower piers. These scenarios included row-by-row inclined collapse, span-by-span collapse, and center-to-both-sides collapse patterns. The optimal blasting scheme was identified by comprehensively evaluating three key parameters: structural fragmentation efficiency, collapse configuration, and induced vibration velocity during demolition. Based on these simulation findings, an optimized blasting design was developed, with subsequent safety verification conducted on the vibration velocities to ensure structural integrity and operational safety. The results demonstrate that implementing water pressure blasting in the upper box girder successfully achieved substantial structural fragmentation while effectively controlling debris dispersion and minimizing potential impacts on neighboring spans. Through a strategic approach involving the conversion of the continuous beam into a supported configuration prior to demolition, coupled with a sequential detonation protocol initiating at the main beams of adjacent spans followed by row-by-row inclined collapse of the lower piers, the proposed scheme successfully achieved controlled bridge demolition. This methodology ensured optimal structural fragmentation while reducing vibration velocities within safe thresholds, effectively protecting adjacent spans. The field implementation results aligned well with the numerical simulations, as evidenced by the controlled collapse process and satisfactory fragmentation patterns observed during the on-site blasting operation. No significant damage was observed in the proximate piers. The peak maximum vibration velocity recorded at the monitoring points in the numerical simulation was 3.58 cm/s, closely aligning with the field-measured value of 3.96 cm/s, demonstrating the simulation results' reliability.

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.

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.

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.

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.

To enhance the accuracy of blasting vibration predictions in an open-pit mine stripping project, a new peak particle velocity (PPV) prediction formula is proposed, incorporating geological elevation differences and slope effects. Based on the principles of dimensional analysis, the traditional Sadovsky formula was modified by introducing the elevation difference (H) and slope coefficient (γ), resulting in a new prediction model (Formula 11). Notably, when H=0, the new formula reverts to the traditional Sadovsky formula, ensuring its reliability. A field vibration monitoring test was conducted in the mine, with 5 monitoring points at elevation differences of 0.222 m, 0.176 m, 0.865 m, 1.617 m, and 2.465 m. Using the TC-4850 blasting vibration meter, vibration data were recorded, and multiple predictions, including the Sadovsky and the newly proposed formula, were fitted using multivariate nonlinear regression. Results show that the proposed formula achieves the highest correlation coefficient (R²=0.905), surpassing other models. Furthermore, the new formula exhibits improved prediction accuracy, with a maximum relative error of 20.85% and an average error of 8.11%, compared to 24.89% and 10.31% for the original Sadovsky formula. By considering the factors of elevation and slope, the proposed prediction formula significantly improves the precision of PPV predictions under complex terrain conditions, providing a scientific basis for blasting vibration control and safety management. Applying the specific scheme and data proves the effectiveness and practicality of the formula.