In order to carry out the controlled blasting of two 200 m reinforced concrete bridges (an old continuous beam bridge and a new arched bridge) under complex environment, the piers of the two bridges, the webs of the continuous beam and the double-curved arch foot of the arch bridge were selected as the blasting locations, and the main bearing parts of the bridges were destroyed. Furthermore, deep hole blasting method and shallow hole blasting method were adopted for the pier and main beam respectively to improve the construction safety and efficiency. Specifically, large-diameter vertical holes facing the pier from the bridge were adopted for the blasting of the pier to overcome the influence of pier arc face on the calculation of minimum resistance line and reduce the drilling workload. Additionally, the two bridges were detonated span by span in the same direction from south to north, with an equal delay interval between two adjacent spans. At the same time, the detonation time of the new bridge is 50 ms later than that of the old bridge. To reduce the damage of blasting vibrations and ground touch vibrations, millisecond delay controlled blasting was adopted, and the direction of the minimum resistance line was deviated from the near shore protection object. Meanwhile, in order to control the flying stone, sandbags were piled on the abutment, and the blasting objects were bounded with wire meshes and covered with multilayer bamboo basketries. After detonation, the bridge collapsed span by span as expected, the vibrations and flying rocks were controlled well.

The explosion of premixed gas in a closed vessel is very complicated. In order to study the effect of ignition position on the explosion characteristics of methane/air premixed gas, the central ignition explosion experiment with 10 vol. % methane concentration in a 1 m³ closed spherical explosive vessel was carried out under an initial pressure of 101 kPa and an initial temperature of 300 K. Besides, the effect of different ignition positions (center ignition, 0.5R ignition, R ignition) on the explosion characteristics of methane/air premix in the vessel was studied by LES turbulence model and Zimont combustion model of the Fluent numerical simulation software. It includes flame structure evolution, explosion temperature, explosion pressure and explosion pressure rise rate. The results show that the flame expands around until the wall and profile of the vessel gradually change from the initial “left thin and right thick” to the “left raised sharp angle” and gradually stretch from the “circular arc” to the “sharp shape” to the left when the flame is ignited at the center, 0.5R and R. And then, there is a temperature gradient in the temperature field at different ignition positions. The heating law is continuously released from the energy of the ignition center, and the temperature continuously accumulates and rises. Furthermore, the variation trend of explosion pressure under different ignition positions is basically the same. The final maximum explosion pressure is stable at about 766 kPa due to the wall insulation. Finally, the rise rate of the maximum explosion pressure in the center ignition is the highest, which is 94.5% and 141.8% higher than that in 0.5R ignition and R ignition, respectively.

In open-pit bench blasting, blasting TBlasting toe rocks is an important indicator to measure the blasting effect in open-pit bench blasting, and it is most directly influenced by the blasting parameters have the most direct influence on the formation of blasting toes. In order to find outresearch the influence of ultra-deepsubdrilling on the smoothness flatness of bench in deep-hole bench blasting, statistical analysis of the relationship between damage variables and wave velocity in rock mass was conducted based on the basic theories of rock damage mechanics. based on the basic theories of rock damage mechanics and through statistical analysis of the relationship between damage variables in engineering and wave velocity in rocks, Tthe threshold values of damage variable, D_d for critical damage variable damage state of of rock mass is determined as Dd that is was 0.2, and the damage threshold D_t of for rock breaking mass in critical broken state is was were defined as 0.2 and 0.8, respectively. based on the basic theories of rock damage mechanics and through statistical analysis of the relationship between damage variables in engineering and wave velocity in rocks. Furthermore, Based on the dynamic damage model of rock with comprehensive consideration of the damage effect of tension and compression, the damage range of bench blasting under different conditions of with different subdrilling conditionsultra-deep was simulated by using the dynamic finite element analysis program LS-DYNA based on the dynamic damage model of rock mass with a comprehensive consideration of tension and compression effect. Meanwhile; based on the threshold of critical damage variable, the fluctuations distribution image of the bench surface after blasting was drawn to determine the optimal ultra-deep of subdrilling hole based on D_t the threshold of critical damage variable, and the image is was used for the quantitative analysis, so as to ensure that the rock mass of upper bench was fully damaged without affecting the construction of the lower bench surface. Finally, combined with the actual situation of deep-hole bench blasting in Ezhou Airport, the influence mechanism of ultra-deepsubdrilling on blasting toes is was verified in the deep-hole bench blasting of Ezhou Airport, and an optimal method for determining the optimal ultra-deepsubdrilling value for deep-hole bench blasting is was concluded.

Shaped charge blasting technology plays an important role in goaf retaining roadway engineering, and the charge structure is always a hot and difficult issue in current discussions. At present, there is no clear indicator of the pre-splitting charge length of goaf-retaining roof. Taking the track groove of No. 2-11031 working face of the Mengjin Coal Mine as the research background, an isometric charge pre-splitting technology is proposed. Firstly, a three-dimensional directional shaped charge blasting model is established by LS-DYNA numerical simulation software to determine the optimal charge structure. By changing the axial cylinder length and taking the crack propagation length and stress decay rate as the analysis indexes, the numerical simulation shows that the radial slit distance is about 40 cm, and the axial slit distance is about 80 cm per meter when the axial uncoupling coefficient is between 1.25 and 1.7. Additionally, the slit distance is respectively increased by 25% and 12.5% compared with the axial uncoupling coefficient between 2 and 3. Furthermore, the energy utilization is the most reasonable as the stress attenuation rates are all less than 1 when the axial uncoupling coefficients are between 1.25 and 3. Finally, a roof directional blasting experiment with an axial uncoupling coefficient α=1.25~2 was carried out on the track groove of No. 2-11031 working face of the Mengjin Coal Mine. After the pre-split blasting, the middle line of the two holes was drilled and peeping. It is found that the cracks along the cutting seam direction between the two holes have been completely connected, the cracks are smooth, and the field application effect is good. Considering economy and safety, the uncoupling coefficient α=1.7 is the best. The results show that the isometric charging structure can replace the traditional three-stage charging structure.

Smooth blasting in tunnel construction needs decked charge in the peripheral holes. However, this charging method has certain limitations and risk of misfire due to the usage of detonating cord together with detonator. So, it is an urgent problem to improve the effect of smooth blasting and ensure tunnel excavation efficiency at the same time. Related research was conducted by field tests, and a new initiation technology of “Shaped device + digital electronic detonator” has been proposed, which was applied to a plateau tunnel. The experimental results show that, compared with the original technology, the powder factor by using the new technology has been reduced by 0.2 kg/m³, the half-hole rate is increased by 5%, and the average charge time is reduced from the original 1.3 h to 1.0 h. The tunnel excavation cycle footage is stabilized, and the cost of consumables is greatly reduced, and it is expected to be widely used in tunnel smooth blasting.

An equal proportion separated common node model was established by ANSYS/LS-DYNA finite element software to simulate the collapse process of a frame structure with a small height-width ratio demolished by blasting, and the stress characteristics of reinforced concrete columns of the structure were analyzed. It is found that the actual engineering and simulation results are highly consistent in terms of collapse time, collapse process and blast muck pile range, which shows that the numerical simulation is reliable. Additionally, during the collapse process, the plastic hinge was generated at the beam-column joints after each row of columns reached the section resistance moment, and the upper structure rotated with the plastic hinge as the fixed axis. There was a backward reaction force on the rear column, which resulted in an obvious recoiling in the forward leaning process. In the early stage of collapse, the stress of the reinforcing bar and the concrete element is stressed together. The stress of the reinforcing bar element with its co-node suddenly changed after the failure of the concrete element, and then it continuously changed in the state of tension and compression until the collapse ended. The reinforced bar at the blasting cut has certain hindrances to the free fall of the upper structure.

In order to analyze the general rules and causes of civil explosive accidents in China, statistical analysis was carried on the occurrence time, regional distribution, accident grade and other dimensions of nationwide civil explosive accidents from 2006 to 2023. Using analytic hierarchy process (AHP), a hierarchical structure model is constructed. It includes four first-level indicators (human, machine, environment and system) and 11 second-level indicators (safety awareness, technical training, supervision intensity, safety education, standardized operation, production equipment, production process, weather and climate, storage conditions, safety management system and emergency management system). Through analysis, the weight of each index is obtained, and then the importance of the influencing factors on explosion accidents is sorted. The results show that the number of explosion accidents has decreased year by year, and the safety situation is improved. The explosion accident time is concentrated in the second and third quarters of each year, and the space distribution is across all provinces with a staggered characteristic of “North-South and high-low”. Generally, the ordinary accidents and large accidents are the main accident levels. Based on the analytic hierarchy process (AHP), it is learned that human is the most important factor to cause the accidents in the first-level indexes. Meanwhile, the standardized operation, production process, supervision intensity and safety management system are the more important factors in the second-level indexes. Finally, according to the importance of the factors affecting the accidents, preventive measures such as strict standardization of operation, increasing safety input, strengthening supervision and improving safety management system are proposed.

In order to study the development track and hot spot changing trends of blasting technology in openpit mining, 1116 valid journal articles were retrieved as a sample from the China National Knowledge Infrastructure (CNKI) database by selecting “open-pit mining” and “blasting” as the search criteria. According the visual analysis reports from CNKI and utilizing the visual knowledge graph tool CiteSpace, a comprehensive and in-depth study has been conducted on the state of the art, distribution characteristics, research hotspots, and cutting-edge trends in the field of open-pit mining blasting research in China. The research findings indicate that the study of open-pit mining blasting has undergone three distinct stages: the establishment and development of open-pit mining blasting theory (pre—2010), the phase of modern technology application and innovation (2010—2015), and the stage of green, intelligent, and precision development (2015—present). The disciplinary distribution primarily focuses on mining engineering and general industrial technology and equipment. The prominent journals for publication include Blasting, Engineering Blasting, and other journals in the field of mining engineering. The majority of authors and institutions are affiliated with mining-related universities, enterprises and research institutes. The research topics encompass various aspects, including the development and application of blasting design software, optimization of blasting parameters (such as blast hole pattern, powder factor and charge structure), deep-hole blasting, bench blasting, cast blasting, pre-splitting blasting, control and monitoring of blasting vibration, numerical simulation, and application of artificial intelligence algorithms, analysis of factors affecting blasting quality and evaluation of blasting effects. The future of open-pit mining blasting will continue to evolve towards automation, intelligence, precision and environmental friendliness. Through technological innovation and interdisciplinary integration, the industry aims to provide more efficient, safer and sustainable blasting solutions for the mining sector.

In order to solve the problems of large displacement, high boulder yield and low shovel loading efficiency in the front row of Husab mine blasting operations, a series of buffer blasting trials were designed and conducted. The project has successively completed the buffer blasting tests in 5 large blocks, and each section has 360 000 tons to 530 000 tons of ores, 15~21 rows of holes, and 5~40 meters wide buffer materials on the free surface. The muck pile shape, shovel productivity, fragmentation and floor elevation deviation were measured and compared with the non-buffer blasting results in the same period. The test results show that there are forward pounce and uplift phenomenon to the blasting pile under the impact of explosion. Meanwhile, the muck pile surface presents a shape with unequal heights, and the maximum height difference varies from 4.06 m to 5.85 m. The productivity of a hydraulic shovel is 2722 t/h in the buffer blasting blocks, which is 4.69% higher than that in the non-buffer blasting blocks in the same period. Moreover, the results of fragmentation analysis reveal that the buffer blasting is better than non-buffer blasting on the fragmentation performance, and the buffer blasting has the advantage in reducing boulders. Finally, the test results show that the buffer blasting has certain advantages in floor elevation control. It is the first time to promote buffer blasting technology to the blasting of large sections with multiple rows of holes (15 to 21 rows), which is not only in line with the objective needs of large-scale mine production, but also an inevitable trend as large-scale equipment is used.

Boulder yield is an important index to evaluate the blasting quality in the blasting process of an open pit mine. Since a high boulder yield will not only greatly reduce the mining efficiency, but also increase the cost of secondary rock breaking, so fragments size statistics is an important work in open pit mining. Aiming at the problem that the statistics of fragment size is complex and not accurate enough, a statistical model of boulder yield was built by deep learning based on the takes the image data of blasting piles collected in the Unugetushan copper and molybdenum mine. Firstly, the annotated data set was initially segmented into an initial effect diagram of the mine rock contour based on the U-net image segmentation model. And then, the annotated data for training was optimized and the Resu-net model was improved on the basis of the residual learning module, which resulted in the final segmentation effect map of mine rock contour. Finally, the fragment size information of the blasting pile was obtained through the minimum external rectangle method combined with OpenCV image processing technology. The results show that the segmentation accuracy of U-net+Resu-net fragment size optimization model proposed in this study is 97.84% with an accurate image data segmentation. The statistics of fragment size in an inclined blasting pile is realized by OpenCV technology combined with the camera monocular imaging principle. In addition, the developed interactive interface is simple to operate and can quickly calculate the boulder yield.