In recent years, the technology of controlled fracture blasting with sequential timing has been extensively utilized in the construction of mining engineering projects and hydraulic infrastructures. To investigate its influence on crack propagation mechanisms in rock masses, C50-grade concrete specimens with 3, 5, and 9 boreholes were cast. Detonators were used instead of explosives to conduct multi-hole blasting tests on rock-like models, examining the propagation paths of cracks and the effects of fracture formation. The LS-DYNA software was used to simulate blasting processes under various working conditions, utilizing the RHT constitutive model to characterize the dynamic failure behavior of rock. A fluid-solid coupling algorithm was employed to simulate the interaction between explosive stress waves and rock masses. By regulating variables such as borehole spacing and detonation timing, several numerical models were developed. Post-processing software was used to extract the simulation results, which were subsequently compared with experimental data to investigate crack propagation patterns within rock masses. The results indicated that time-sequenced controlled blasting technology effectively guides cracks to propagate along predetermined paths. Both the detonation timing sequence and borehole spacing significantly influence crack formation, with more pronounced effects observed in configurations containing a greater number of boreholes. Rational design of initiation timing and borehole spacing can substantially enhance the efficiency of explosive energy utilization while reducing damage to the surrounding rock. This study provides theoretical foundations and technical support for precision blasting operations in complex geological conditions.

Prestressed continuous rigid-frame bridges, a prevalent structural system in large-span bridge construction, present unique demolition challenges due to spatial constraints and adjacent infrastructure constraints during demolition. This study examined the controlled demolition of a river-crossing, prestressed, continuous, rigid-frame bridge using a blasting demolition practice. The demolition strategy incorporated mechanical crushing of mid-span deck and wing plates, complemented by strategically positioned blasting cuts at critical structural elements, including piers, mid-span box girder webs, top slabs, external prestressed steel cable anchor piers, and bridge-end box girder connections. The implementation of a sequential detonation order (mid-span box girders followed by external prestressed cable anchor piers, concluding with bridge-end connections and piers) resulted in controlled segmental collapse. Numerical simulation using LS-DYNA's dynamic finite element analysis validated the demolition scheme, revealing key process parameters: a total collapse duration of 4.5 seconds and a deck impact velocity of 13.6 m/s. The analysis identified impact stress as the primary mechanism for structural disintegration. A significant finding emerged regarding external prestressing technology. While originally implemented to enhance service performance and load-bearing capacity, the release of prestressing forces through controlled blasting was found to improve structural fragmentation efficiency significantly. Field implementation demonstrated the technical feasibility and safety of this approach, providing an effective solution for dismantling long-span, prestressed, continuous, rigid-frame bridges in complex environments. The study establishes a comprehensive framework for similar demolition projects, highlighting the importance of integrated mechanical and explosive techniques in modern bridge demolition engineering.

This study introduces a straightforward two-dimensional vortex model to examine the release and absorption of vortex energy. The energy transfer resulting from vortex collapse during explosive detonation and the microscopic mechanisms underlying detonation growth are analyzed. The relationship between the macroscopic phenomena of detonation growth and extinction and microscopic factors, such as pore size distribution, is established through experimental validation. Findings suggest that the stability of the detonation process is microscopically governed by thermal flux and the effective number of vortices per unit volume within the field. The effects of particle size and density of the explosives on the macroscopic detonation behavior can be elucidated by considering the effective vortex volume concentration and distribution. Control of the ignition vortex pore size is essential, and stabilization of detonation can be achieved by adjusting pore sizes within defined minimum and maximum limits. An optimal and effective pore volume concentration is necessary to maximize the energy utilization efficiency of the explosives. Based on this research, successful tests on the regulation of detonation velocity of emulsion explosives through the use of mixture sensitizers with varied size distributions and constant densities were conducted.

The design of the tunnel blasting course is an important comprehensive practical teaching link of the "Blasting Engineering" course of related majors in colleges and universities. To explore new ideas for reforming teaching practice, given the challenges of complex calculations, difficult parameter selection, and cumbersome diagram drawing in traditional curriculum design, a tunnel blasting intelligent design software platform was proposed for course design. By integrating digital and intelligent design technologies, the authors develop an intelligent design platform that converts abstract blasting parameter design into a clear visual model. The platform includes four modules: blasting design, resource library, data management, and global settings. It innovatively realizes real-time modification of blasting parameters and implementability judgment, has a guided operation process, and forms an interactive teaching mode. The practical results demonstrate that the intelligent design platform effectively reduces the computational burden and the subjectivity of parameter selection for students in traditional teaching practices through the guided operation process, enhances drawing efficiency and accuracy, and ensures that the blasting design scheme is scientifically and reasonably formulated. The interactive teaching mode enhances students' ability to combine theory and practice, stimulates their interest in active learning, thereby improving their understanding of professional knowledge, cultivating intelligent design ideas, and providing support for becoming high-quality talents serving the new era.

This study investigates the blasting demolition of a 180 m-high reinforced concrete chimney under site-specific conditions, systematically addressing critical challenges in collapse control through targeted engineering solutions. By designing symmetrically arranged directional and positioning windows, combined with empirical formula calculations, optimal blasting parameters were determined to be a 216 central angle and a 3.5 m cut height, effectively guiding the chimney's collapse along the predetermined trajectory without significant backward displacement. A 1:1 scale numerical model employing the Interface Stress Element Method was developed to simulate the collapse process, showing complete structural failure within 14.0 seconds with controlled lateral deviation (<0.5%) and minimal settlement/forward surge. A comparative analysis with the Decoupled Co-node Model revealed the superior performance of the Interface Stress Element Method in simulating rebar-concrete decoupling at cut closures, reducing backward displacement by approximately 1.0 m through differentiated load-bearing mechanisms at material component nodes. The model successfully replicated restrained rebar scattering during top section ground impact, due to the bonding forces of the spring elements, confirming enhanced simulation accuracy in collapse kinematics. Field implementation validated the numerical predictions, achieving precise directional collapse, complete structural disintegration, and compliance with safety thresholds, thereby establishing a replicable framework for ultra-high chimney demolition engineering.

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.

To address the challenges of low efficiency, insufficient accuracy, and interference from complex environments in mining blast fragmentation recognition, this paper proposes a novel blast fragmentation recognition method based on binocular vision. By constructing a YOLOv8 instance segmentation model, the post-blast rock contours are accurately extracted under complex lighting conditions. By combining binocular measurement technology with the principles of three-dimensional coordinate transformation and disparity calculation, the maximum size of the fragments is determined. An indoor experimental platform was established to verify the accuracy of fragmentation recognition and size calculation under different parameters. Furthermore, an intelligent recognition architecture for open-pit mine blast fragmentation was proposed, and an automatic fragmentation recognition and analysis system was developed. The results of indoor simulation tests indicate that a lower camera height helps improve the model's recognition accuracy. Although fragment contact slightly affects the recognition of individual targets, the overall accuracy remains unaffected, with the recognition accuracy of all fragments exceeding 85%. The recognition accuracy slightly decreases in dynamic environments. However, the size calculation accuracy for 80% of the fragments remains above 90%, and the overall error remains within an acceptable range, meeting the requirements for real-time monitoring and subsequent analysis in blast fragmentation. This method has been successfully applied at the Husab Mine in Namibia, utilizing Radio Frequency Identification (RFID) technology to obtain material source information. It enables dynamic monitoring, precise analysis, and comprehensive evaluation of the fragment size distribution (FSD) throughout the entire block, providing a novel technological approach for assessing the effectiveness of open-pit bench blasting.

Accurate and efficient explosive detection technologies facilitate real-time monitoring of blasting materials throughout their storage, transportation, and usage, enabling the prompt identification of expired or unstable explosives. Furthermore, trace detection methods can detect residues of illegal explosives, offering technical support for safety supervision and public security, while striking a balance between engineering efficiency and environmental safety. This study introduces an optical fiber Raman sensor utilizing silver nanoclusters (AgNCs) for the explosive detection of explosives. By integrating Raman spectroscopy with fiber-optic sensing technology, it achieves highly sensitive spectral detection and efficient signal transmission specifically for TNT detection. The AgNCs substrate, modified with silver-sulfur bonds and functionalized with 4-ATP, acts as a capture probe for TNT. The formation of the TNT-4-ATP complex significantly amplifies the SERS signal of TNT, resulting in a detection limit (LOD) as low as 10^-10 M.

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.

In order to study the dynamic mechanical response characteristics of crystalline graphite ore under the coupling effect of grade and dynamic load, the dynamic compression tests of crystalline graphite ore samples with four grade levels (5.19%, 10.79%, 12.65%, and 15.50%) under different impact pressures were carried out by using a 50 mm diameter split Hopkinson pressure bar test device. The effects of grade and strain rate on the dynamic mechanical properties and energy consumption characteristics of crystalline graphite ore were comparatively analyzed. Furthermore, a dynamic constitutive model for crystalline graphite ore incorporating both grade and strain rate effects was established based on the viscoelastic ZWT model. The test results show that the dynamic compressive strength and peak strain of crystalline graphite ore increase progressively with rising strain rate, while the elastic modulus remains strain-rate-independent. As the ore grade increases, the initial compaction deformation and peak strain of the samples increase, whereas the dynamic elastic modulus, dynamic compressive strength, and their strain-rate sensitivity gradually decrease. Additionally, within a specific strain rate range, the degree of fragmentation of medium- and low-grade ores intensifies with increasing energy consumption density. In contrast, high-grade ores exhibit minimal variation in fragmentation degree. This indicates that ore grade significantly influences the dynamic fragmentation behavior of crystalline graphite ore. A dynamic constitutive model that considers both grade and strain rate was established, and its accuracy and applicability were verified by comparing the model-predicted results with experimentally obtained dynamic stress-strain curves. The model offers theoretical support for investigating the mechanical behavior of crystalline graphite ore under dynamic loading.