In order to successfully demolish a high pier reinforced concrete aqueduct by blasting between the 75^#~84^# piers of Dongfeng Canal in Yichang City and reduce the impact on the surrounding complex environment, a bidirectional collapse design was adopted. In the design scheme, the aqueducts between the 75^#~76^# piers collapse in a northerly direction perpendicular to the aqueduct trend, and the aqueducts 77^#~84^# piers collapse westward along the aqueduct trend. More precisely, an initiation network of electronic and non-electric detonators with delays of 50 ms and 150 ms was adopted using the 75^# pier as the initiation point. Moreover, the harmful effects of blasting on the environment were controlled by using lifting holes as blast holes, excavating vibration reduction ditches, hanging nets and covering protection layer, storing water in the trench body, and covering soil protection. The results show that the aqueduct collapsed with a 4-minute delay after initiation, and the collapsed pier body was basically decomposed into blocks with intact aqueduct body, with most fragments scattered along the trend within 10 m of the central axis of the aqueduct, and only a few small pieces flying farther than 10 m. The adopted protective measures can effectively control the blasting flying rocks and vibration, and no damage has been found to the inverted siphon of temporary water delivery pipeline and the road pavement. The project was carried out successfully despite the delay in collapse. The possible reasons for the delayed collapse include no incision on outside of the structural column, the delay time interval between pier columns is small, and the blasting incision is small.

The experimental signals collected in explosion experiments are always mixed with different degrees of noise interference. In order to accurately analyze the variation laws conveyed by these signals, four sets of explosion experiments were designed with different charge amounts and vacuum environments in the vacuum explosion vessel. Then, the collected impact load data were analyzed by applying both Fourier filtering algorithm and median-averaged filtering algorithm. By comparing the P-t curves processed by the two filtering algorithms with the original ones, it is found that the Fourier filtering algorithm is a global analysis of the signal, which can extract the frequency information of the function in the whole frequency domain, while the characteristics of the signal cannot be revealed in a local time range. Although the processing speed is faster, the error for the characteristic parameters is larger, and the effect of the filtering process directly applied to test signals of the blast impact is less satisfactory. The fit degree between the signals of explosion impact processed by the median-averaged filtering algorithm and the original ones is higher, and the varying details of the impact load with time in the blast container can be clearly reflected with a smaller error and a higher reliability.

The impact vibration caused by blasting demolition of tall buildings (structures) may affect the service status of adjacent subway tunnels. In order to demolish a 24 story frame structure building only 6.5 meters away from the subway tunnel, on-site tests and analysis of blasting vibrations and dynamic strains were first conducted. And then, a three-dimensional finite element calculation model was established for analyzing the dynamic response of the subway tunnel structure by ANSYS/LS-DYNA, which can reasonably describe the impact of the collapsed part on the ground during the blasting demolition of the building. Finally, the vibration response characteristics and dynamic stress changes of the tunnel structure under the impact of building collapse were simulated and compared with the field measured data. The research results show that the peak particle vibration velocity (8.61 mm/s) in the subway tunnel caused by the drilling and blasting of the load-bearing columns is greater than the peak particle vibration velocity (4.95 mm/s) caused by the impact of the building on the ground. The main frequency of the blasting vibration and the collapse impact vibration are about 100 Hz and 2 Hz, respectively. The vibration velocity of the subway tunnel under the action of the collapse impact load is equivalent to the structural vibration caused by an earthquake with an intensity of Level Ⅲ (3.82~8.19 mm/s). The low-frequency collapse impact vibration can cause relatively obvious additional dynamic stress to the subway tunnel. The dynamic compressive stress generated in the circumferential direction of the tunnel is about 4 MPa, and the dynamic tensile stress generated in the axial and tangential directions is about 0.4 MPa. The existing cracks may expand, or delamination may occur when the internal damages or construction defects are generated in the tunnel structure under the impact of dynamic tension and compression cycles. The safety allowable particle vibration velocity value of 10~12 cm/s when f<10 Hz required in the current blasting safety regulation (GB6722—2014) is dangerously high, and it should be adjusted in combination with the frequency and dynamic strain characteristics.

No matter violent & terrorist incidents or explosion accidents, parameters related to the explosion source, such as explosive equivalent, are always important for the post-explosion accident investigation. The characteristic trace of the medium under explosion load is an important basis for tracing the cause of an explosion accident and obtaining the corresponding explosion source parameters. After reviewing the typical research progress of explosive characteristic traces, including explosion crater, damage of surrounding buildings, and personnel damage degree, it is found that there are significant differences in the shape and size among the explosion craters created by near surface explosions, exposed surface explosions and explosions with certain depth. This research is based on an underground explosion accident in a gold mine in 2021, which was caused by that the dropped welding slag from the shaft ignited the underground combustible materials and explosive equipment. According to the sizes of three explosion craters formed at the accident site, the TNT equivalents are calculated as 654.17 kg, 232.49 kg and 193.83 kg, respectively. Then, the particle vibration velocity and the shock wave overpressure of the shaft wall are calculated as 40 cm/s and 2129 Pa, according to the TNT equivalents. The calculation results are consistent with the damage degree of the cage and shaft wall.

Aiming at the problem that the blasting effect is not good due to poor or even no stemming of blast holes in underground coal mine, numerical simulation was used to analyze the mechanism of rock breaking and stemming mechanism. A 3 m×3 m two-dimensional concrete model with blast hole diameter of 0.04 m and hole depth of 1m was established using the finite element analysis software. In addition, the continuous emulsion explosive charge was set as 0.3 kg, and the stemming material was set as sand. For the explosive simulation, concrete and sand were modeled by Lagrange grid, and the air was modeled by Euler grid. ALE algorithm was used to simulate the explosion stress nephogram and damage cloud maps with a single hole stemming length of 0 mm, 200 mm and 400 mm respectively under the blast load. The results show that the maximum stress around the hole with stemming is significantly higher than that without stemming. Meanwhile, the damage degree around the hole with stemming is more severe with smaller fragments than that without stemming. On the basis of analyzing the advantages and disadvantages of clay and water stemming structures commonly used in underground mines, a stemming structure by expansion-pipe water injection was designed, which can replace the clay and water stemming structure in underground coal mine blasting as a good field application.

Underwater blasting tests are dangerous and costly. The requirements for the related test equipment and site in laboratory are very strict. Each test must be approved in accordance with relevant procedures. In view of the current situation of cumbersome blasting test procedures and long waiting periods, a wave barrier curtain which can achieve satisfactory results with as few underwater blasting tests was designed by using collision and vibration simulation technology. In order to achieve this purpose, the protection of wave barriers made of different materials were simulated by the ANSYS LS-DYNA module. Data were collected at a position 5 m away from the explosion point with a pressure of 7.5 MPa, and the detonation wave reduction coefficients of the canvas wave blocking curtain and other five different materials were compared and analyzed. The simulation results showed that the wave resistance performance in order from high to low is: air bubble, porous aluminum plate, automobile tire, foamed plastic, asbestos cloth. Among them, under the equivalent working condition of 1 kg TNT, and at the location 5 m away from the explosion point with a pressure of 0.22 MPa, the air bubble's pressure reduction rate reached 97%, and the protection effect was the best.

Using a closed explosion experimental system, the combustion performance of a new type of rock-splitting equipment's loading agent was studied, providing guidance for the drug components and proportions in subsequent products. Different gradient components with a ratio of 9∶1 to 4∶6 were designed to mix the loading agents for the closed explosion experimental, and the p-t curve and dp/dt-t curve of all agents were analyzed. The drug ratio used in the explosive strength experiment was determined to be 7∶3 and 5.5∶4.5. The mixed drugs were subjected to the explosive strength experiment using two types of loading densities, 0.12 g/cm³ and 0.2 g/cm³. The mixed drug was assumed as a single entity with a density of 1.5 g/cm³, referring to the method of treating the gunpowder burning speed. On this assumption basis, the Γ-ψ curve of the drug combustion and the corresponding parameters such as explosive strength and burning rate coefficient were obtained, among which the explosive power of the single + additive (7∶3) formula was the highest, reaching 564.87 kJ/kg. The explosive power of the dual + additive (7∶3) formula was slightly lower but still higher than that of the 5.5∶4.5 formula. The reason for the apparent incomplete combustion phenomenon observed in the experiment of the dual + additive (5.5∶4.5) formula was explained by analyzing the Γ-ψ curve of the drug. The analysis of the corresponding explosive strength and burning rate coefficient of the mixed drugs showed that the explosive force of the gunpowder on the overall drug is the dominant factor, and the increase in the ratio of the gunpowder will significantly improve the efficiency of the drug's combustion. However, the effect of the change in loading density on the burning of the two types of gunpowder is inconsistent. The increase in loading density will cause a decrease in the burning efficiency of the monobasic formula, while the dual-base formula will exhibit an increase in burning efficiency.

The Yan Zhou power station bridge was built on the proposed structure site of the Yan Zhou hub project, which included construction of a new ship lock, power station, and spillway gate. Due to the progress of the engineering construction, the bridge was dismantled. The Yan Zhou power station bridge is a hyperbolic arch bridge with a total length of 180.0 m and a width of 8 m. It is located in the Pengshan tourist scenic area, surrounded by many famous historical sites and enterprise factories. The environment was complex, and the nearest distance from the bridge to the existing power station dam was 8 m. The reinforced concrete box girder bridge of the power station dam was adjacent and shared a bridge pier with it. Due to the working conditions on-site, blasting demolition was adopted. In order to ensure the reliable collapse and complete disassembly of the entire bridge, as well as the separation of steel bars and concrete, the components such as arch ribs, arch columns, and connecting beams were pulverized through throwing explosive devices, with a powder factor of 1.2~1.5 kg/m. Reinforced loose blasting was used to destroy the bridge piers, and the maximum explosive charge for a single pier was 480 kg. According to the principle of heavy left and light right, the entire bridge was collapsed toward the right bank direction like a domino. An inner-hole delay and out-hole relay initiation network was used. The MS12 detonator was used for the inner-hole delay, and the industrial electronic detonators were used in parallel out of the holes. The blasting order was from left bank to right bank, and then from pier to pier, to ensure that the bridge collapsed orderly and vertically, without causing crushing impact to the left bank bridge pier. A leaky PVC was pre-laid underwater along a 100m line near the left bank power station and water roller dam. An air compressor was used to press the air into the pipe to form an air bubble curtain, which effectively reduced the water shock wave overpressure, thereby reducing the impact of blasting vibration and water shock waves on surrounding buildings and structures.

The dynamic response characteristics such as deformation capacity, acceleration, and load transfer of high-rise frame structure buildings under the condition of single column failure in different parts were studied. Firstly, according to the Code for Design of Concrete Structure (GB50010), a 4×6 span 8-story reinforced concrete frame structure model was established by using PKPM design software. Secondly, based on the component removal method, the finite element software SAP2000 was used to calculate the dynamic response characteristics of the frame structure with the failure of different single columns at the first floor, including the center column, long side middle column, short side middle column and corner column. The results show that the plastic angle is less than 6 for all the four column failure conditions, and the structure will not collapse. When the central column fails, the structural stability is the worst, and the probability of continuous collapse is the highest, followed by that of the short side and long side middle columns, and the corner column has the least probability. Under the condition of center column failure, the dynamic impact of the load on the residual structure is the most significant, with a maximum negative acceleration of about 3 g, which is twice as high as that of the short side middle column and the long side middle column. After the failure of the columns, the loads will be redistributed. The axial force will be borne by the adjacent columns, while the stress form of the upper beam will also change from bending to tension, resulting in a catenary effect. In the scenario of the central column failure, the axial force of the adjacent columns will increase by nearly 20%.

At present, the model of the forming mechanism of the wavy metal interface during explosive welding can only give a quantitative or qualitative description of some aspects of the forming process, rather than fully explaining all the phenomena involved. In the study of explosive welding of the titanium-steel transition layer, the wavy interface was observed by scanning electron microscopy. When the scanning electron microscope was enlarged to 2000 times, the wavy interface turned out to be titanium drops forming island shape bonding interface in the copper. When the relative displacement of the two plates is large, the crest part of the interfacial wave will be pulled off and the "island" will be formed. The theoretical analysis and experimental study of explosive welding show that the Richtmyer-Meshkov instability mechanism can better explain the formation process of the wavy interface in explosive welding. In the process of explosive welding, near the collision point, a thin layer of melting zone will appear at the welding interface, and the material near the interface is in a quasi-fluid state. When the high pressure elastic-plastic stress wave arrives, the interface disturbance will be caused, and the disturbance caused by the previous stress wave will further develop under the action of a series of subsequent stress waves, forming a typical Richtmyer-Meshkov interface instability. Therefore, Richtmyer-Meshkov instability and freezing are responsible for the formation of various types of wavy interfaces observed in explosive welding.