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.

In order to investigate the dynamic response, damage evolution and failure of concrete tunnel structure by underwater explosion load, laboratory tests and numerical calculations are adopted in this paper. Firstly, a 40∶1 specimen was designed according to the East Lake underwater tunnel. An explosion test of the underwater box concrete tunnel model was then carried out. The dynamic response rule of the concrete specimens under different emulsion explosive equivalent was compared by monitoring the strains. Meanwhile, the failure forms of the scaled model of the box tunnel caused by the underwater blasting load were investigated by measuring the size of the failure range and the length of crack propagation. Furthermore, a 1∶1 modeling simulation analysis of the test was carried out using the S-ALE algorithm in ANSYS/LSDYNA. It is found that the simulation results were basically consistent with the experimental results by comparing the experimental data and failure patterns. At the same time, the complete propagation process of the underwater explosion shock wave and the deformation law of the specimen structure were obtained by further analysis of the simulation results. Finally, the dynamic response mechanism of the box tunnel specimens under explosion load was revealed through statistical analysis of strain and displacement data at the measuring points. The results show that the transverse strain of the box concrete tunnel structure is much larger than the longitudinal strain. The failure location of the tunnel is mainly concentrated in the area near the explosion source and the structural angle position. It is verified that the S-ALE algorithm can simulate the dynamic response and damage evolution of the structure by underwater explosion accurately.

The blockage of a fine ore bin is a common problem during the process of the beneficiation and smelting of non-ferrous metal mine due to its inherent structure, the properties of fine ore and environmental factors. The treatment methods such as air gun and manual knocking are inefficient and labor-intensive, which cannot meet the production requirements. It is a feasible way to dredge the blockage of the fine ore bin by controlled blasting. The key to handling the blockage by blasting is to determine the explosive charge amount under the condition of ensuring safety. According to the blockage position and degree, two kinds of charge calculation formulas were used by analyzing the reason for the fine ore bin blockage, the characteristics of the blockage body and the principle of blasting dredging. One method is refer to the empirical formula of condensate disassembly blasting. The charge amount for viscous plugging is designed and calculated according to the slagging thickness. The calculations indicate that the charge for the upper part with a larger diameter is 0.59 kg, while the charge for the lower conical feeding port with a smaller diameter is 0.07 kg. The other method is according to the calculation principle of volume charge and the characteristics of the clogging body of the fine ore bin. The calculations indicate that the charge for the upper part with a larger diameter is 0.49~0.98 kg, while the charge for the lower part with a smaller diameter is 0.15~0.30 kg. The safety charge amount is determined through calculating the safety pressure by the Faupel correction formula and shock wave calculation. As a result, the charge amount for the upper part and the lower part are determined as 0.6 kg and 0.15 kg, respectively. During the implementation process, 15 blocked fine ore bins were treated by charge amounts not exceeding 0.6 kg and 0.15 kg, all of which were safely dredged as expected. The practice shows that the calculated charge amount is reasonable, and the safety measures are effective.

For the purpose of studyingTo study the influence of hydration rate of static explosives on the mechanical behavior and damage mechanism of coal ore body, numerical simulations of ore body mechanical damage were carried out using a stress-damage coupling model under different hydration rates. The impact of hydration rate on the evolution of stress field and damage zone in the ore body was analyzed, and the mechanism of the effect of drilling arrangement model on hydration rate was revealed. The research results indicate that the development of the damage zone in static blasting can be divided into four stages: compaction stage, micro-damage formation stage, damage zone development stage, and damage zone connection stage. Among them, the stages of damage zone development and connection stages show the most significant stress effects. The stress field and damage zone increaseincreases with the increase in of hydration rate. Specifically, and the influence of hydration rate on the stress field and damage zonesuch kind of influence is relatively small during the initial rapid energy release phase, but becomes significantly different in the later stages. Besides, Tthe borehole arrangement model affects the mechanism of hydration rate. withUnder the single-hole mechanical model, the hydration rate promotes expansion pressure differences, while However, the under the double hole mechanical model, hydration rate promotes stress superimposition forunder the double hole mechanical model. The guided hole arrangement model has the most significant effect, where the initial hydration rate accelerates stress transfer and the later hydration rate promotes stress superimposition, leading to the expansion and connection of the damage zone under the combined effects of time and stress dimensions. In the numerical simulation and field tests scheme of this study, the hydration rate of the static blasting agent was 1.8 MPa/min, the blast orehole diameter was 113 mm, the borehole spacing was 1000 mm, and the reasonable ratio of borehole spacing to diameter (η) was 9. The guided hole arrangement model can effectively fractures the ore body and generatees a large number ofmany damage zones. This research provides a reference basis for improving the fracturing effect and construction arrangement of static blasting technology.

Aluminum powder is the most used metal fuel in explosives industry. The nano aluminum powder has a much higher specific surface area, reaction reactivity and completeness compared with the micron aluminum powder. Therefore, the application of nano aluminum powder in explosives will undoubtedly improve the explosive power and the ammunition damage efficiency. This article has systematically reviewed the effects of nano aluminum powder on the detonation performance, safety performance, process performance and other explosive properties. As for the detonation performance, the nano aluminum powder can improve almost all detonation parameters of the mixed explosive, including the detonation velocity and heat, the peak value of shock wave overpressure of air explosion, the total energy of underwater explosion, the peak value of explosion pressure and the rise rate of explosion pressure of the fuel-air explosives, the metal acceleration ability, arson ability, work ability, and brisance, et al. However, some incorrect conclusions are often drawn by some researchers due to the low effective aluminum contents of the nano aluminum powder. In terms of safety performance, the introduction of nano aluminum powder increases the impact sensitivity, friction sensitivity, shock wave sensitivity and thermal sensitivity of mixed explosives, which significantly reduces the ignition energy of explosives and promotes the thermal decomposition of common explosives (such as TNT, RDX, HMX, CL-20, NG, etc.). Therefore, the introduction of nano explosives has a negative influence on the safety performance of mixed explosives. In terms of process performance, the nano aluminum powder increases the viscosity of the cast explosive system. However, it reduces the density of the explosive column in the pressed explosive system. Therefore, the introduction of nano-aluminum explosive deteriorates the process performance of the mixed explosive. It is pointed out that it is easy to oxidize in various stages from preparation to storage due to the large specific surface area and high reaction activity of nano aluminum powder, which results in a sharp decrease in the effective aluminum content of nano aluminum powder. This is an important reason why some researchers get wrong conclusions. Therefore, it is necessary to study the preparation methods and storage conditions to make full use of nano aluminum powder in explosives.

Aiming at the problems of high boulder yield, high explosive consumption and poor blasting effect in an open-pit mine with complex lithology in Xinjiang, 59 blasting tests for the optimal inter-hole and inter-row delays in rock masses with different blastabilities were carried out on four levels (between 445 m and 595 m) at the east side of the mine. The optimal delays between holes and rows were determined by the shape of blasting pile, ore rock fragmentation and powder factor. The test results show that the blasting pile is flat and the fragmentation is uniform for benches of mudstone with some fine sands when the delays between holes and rows are 5.9 ms/m and 14 ms/m, respectively. For sandstone with part of mudstone lithologic, when the delays between holes and rows are taken as 2.7 ms/m and 14.2 ms/m respectively, the blasting pile shape and fragmentation are reasonable and the boulder yield is low. The test results are applied to the field production of the mine, and the average powder factor and boulder yield are 4.03% and 1.8%, respectively, which are lower than those of previous years. The research shows that reasonable selecting of delay time between holes and rows for complex geological conditions can obtain flat blasting pile and the uniform block size, which can effectively reduce the powder factor, and save costs. The delay time determined in this test can provide important field data for selecting the delay time of mudstone and sandstone mixed bench blasting under the same geological conditions in Zhundong area.

A monitoring method based on the characteristics of weak grating sensors is proposed for long-term monitoring of the uneven settlement and horizontal displacement of segments in shield subway tunnels during the operation period. The cable type weak grating sensor is fixed on the wall of the shield tunnel in a diamond patten after prestretching. By monitoring the deformation of the weak grating sensor, the tunnel deformations corresponding to different tunnel structure modes can be distinguished and calculated to meet the real-time and precision requirements for engineering. According to the similarity ratio principle, a 1∶5 tunnel displacement model is designed and manufactured to simulate the local expansion, settlement and horizontal displacement of the tunnel segments. The grating sensors are also fixed on the wall surface of the tunnel model. Sensitivity tests of the weak grating sensors are first conducted before displacement monitoring. Then, the weak grating monitoring results with different diamond layout angles are compared. The following step is to monitor the vertical settlement and horizontal displacement of the tunnel model, which are compared with the actual displacement values. The results show that the strain of weak grating with the diamond layout is larger than that with a linear layout under the same settlement condition, which means the sensitivity of the diamond layout method to settlement change is better than that of traditional linear layout. Furthermore, 10°~20° is the optimal angle interval of the diamond layout for weak grating, for the monitoring result error is low. Additionally, the inversion equation of weak grating wavelength change and segment displacement is established based on the test data of diamond layout with an angle of 15°.

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.

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.

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.