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.

In the blasting demolition of large-volume reinforced concrete bridges in China, the traditional method of manual drilling of 40 mm small-diameter holes for blasting of bridge pier columns is time-consuming, labor-intensive, difficult to ensure drilling accuracy, and has high construction costs. Based on the experience of previous studies, a new method of large-diameter drilling for bridge demolition has been proposed, which includes technical measures for blast hole diameter, hole layout, powder factor, initiation network, and safety protection. To verify the effectiveness of this new method, the blasting demolition project of Ronghui 2 bridge of Chongqing Lijiatuo compound line bridge south diversion project was selected. According to the structural loading of the bridge and the environmental conditions, delayed initiation technology was used, and explosives were detonated at a certain height above the bridge pier, which led to the bridge sequentially collapsing in place from the center to both ends, achieving the goal of one-time completion of the demolition. In this method, water-mill drilling was used to dig holes into the bridge piers, with a hole diameter of 70 mm and crosswise drilling layout, and nonel millisecond delay detonators were used inside the holes, while electronic detonators were used outside for ignition. Multiple layers of protection were provided by bamboo boards, rubber mats and flexible wire mesh. After ignition, the blasting sound was muffled, and the bridge completely collapsed and disintegrated according to the design requirements, while the impact of flying rocks, blasting vibrations, collapse ground vibrations, and explosion shock waves were all controlled within the allowable range.

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.

Explosive welding is an efficient, economical and practical technique that uses explosives as energy to achieve solid-state connection of the same or dissimilar materials. Because it can achieve large-area welding and combination of dissimilar materials, it is widely used in the preparation of layered metal composites. In order to explain the research development of explosive welding of dissimilar metal materials, the related concepts and basic principles of explosive welding are reviewed. Through the introduction of welding window theory, it is pointed out that choosing explosion welding parameters in the welding window surrounded by four boundaries can obtain relatively high-quality corrugation. Based on the research status at home and abroad, explosive welding interface is discussed in detail from three aspects: the structure and mechanical properties of the explosive welding interface, the influence of heat treatment on the interface structure, and the influencing factors of the bonding interface. Studies have found that defects such as cracks, adiabatic shear bands, and intermetallic compounds often appear at the interface junctions, which can be improved by heat treatment, use of intermediate layers, and gas shielded explosive welding. However, the formation mechanism and control methods still need further in-depth research. In addition, the current numerical simulation is mainly based on the SPH method. After comparative analysis, this method can effectively simulate the bonding interface and jet flow, but it also has the disadvantage of a single simulation process, and the formation mechanism of the interface wave is still unclear. Therefore, it is necessary to establish a scientific and perfect interface wave formation mechanism and a systematic and comprehensive numerical simulation process. With the continuous emergence of new materials, explosive welding technique will continue to play an important role in more fields.

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.

In order to develop a kind of packaged emulsion explosive with full appearance and long storage period, the formulation of the packaged emulsion explosive with the best natural storage performance was selected as the reference object. The corresponding emulsion matrix was prepared by testing different kinds and proportions of emulsifiers, and the corresponding packaged emulsion explosive was prepared by physical sensitization and chemical sensitization. The storage stability of each emulsion explosive was evaluated by means of high-low temperature cycle tests and water solubility tests. The results show that the stability of the emulsion explosive prepared by polymer emulsifier LZ2832 is better than that prepared by polymer emulsifier EPE-3002. Among the composite emulsifiers, the stability is best when the ratio of emulsifier Span80 to emulsifier LZ2832 is 1∶9, which can be subjected to at least 40 high-low temperature cyclic tests. It is expected that this packaged emulsion explosive product can be stored naturally for more than 24 months. In explosive sensitization, hollow glass microspheres with a matrix mass of 1.2% are first physically sensitized. In addition, accelerant #2 with 0.2% matrix mass and a sensitizer with 0.3% matrix mass are used for chemical sensitization when the temperature dropped to 50~55 ℃. The aftereffect of explosive sensitization is obvious, and the final density is controlled at 1.05 to 1.10 g/cm³. The results of batch production tests on the production line are consistent with the experimental results, and the full and elastic packaged emulsion explosive product with a long storage period has been successfully developed. The explosive has remained stable in natural storage for 12 months with the detonation velocity more than 4500 m/s, the brisance more than 16 mm, and the detonation distance more than 6 cm.

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.

In the process of blasting excavation of rear tunnel with mall clear distance and large section, it is very important to ensure the safety of front tunnel exposed to blasting vibrations. Based on the six-lane Xiaoyu Tunnel of Beijing-Qinhuangdao Expressway, a blasting vibration velocity distribution law of the longitudinal and transverse sections of the front tunnel was monitored and analyzed during the excavation of the rear tunnel. The blasting parameters of the rear tunnel were dynamically adjusted and optimized, and the safety control measures of blasting vibration were put forward according the monitoring results. The results showed that the vibration velocity on the radial direction of the side wall of the front tunnel was the largest when the rear tunnel was excavated, and it is mainly caused by cut hole blasting. The vertical vibration velocity is slightly lower than the transverse vibration velocity. However, there is little difference between them, and the blasting vibration energy is mainly concentrated in the frequency band of 30~100 Hz. For the vibration distribution on the longitudinal section of the front tunnel, the peak vibration velocity decays with distance, but the vibration velocity on the unexcavated direction is relatively higher, which is 1.2~1.6 times of the vibration velocity on the same excavated distance. For the vibration velocity distribution on the cross-section of the front tunnel, the vibration velocity on the front side is 5~10 times higher than that on the back side. Multi-stage cutting was adopted to optimize the distribution of the holes.12 different delays were adopted to reduce the charge per delay, and the delay interval was increased to 60 ms to control the blasting vibration. The field practice shows that the optimized blasting design can reduce the vibration velocity of the side wall of the front tunnel by about 50%.

The study of damage expansion process of the surrounding rock mass under blasting is of great significance to the blast resistance design of a chamber. In order to explore the damage propagation law of the surrounding rock mass around a chamber under the action of different blasting sources, a numerical calculation model including top explosion, vault side explosion, side wall explosion, bottom side explosion and bottom explosion was established by using the finite element simulation software ANSYS/LS-DYNA. The RHT model was used to analyze the damage propagation process of the chamber surrounding rock mass at different positions. On this basis, 10 vibration velocity monitoring points were set equidistantly from the blast source to the chamber boundary in the model, and the vibration velocity attenuation law from the blast source center to the chamber boundary was studied. The results show the damage point first appears at the shortest distance from the blast source, and is then formed subsequently. The damage zone expands gradually along the boundary of the chamber and finally forms the damage zone. Compared with the decay law of the blasting vibration velocity, the blasting vibration wave is fully reflected in the surrounding rock mass, which makes the blasting vibration velocity appear an amplification effect. At the same time, the damage evolution from the blast source to the surrounding rock mass corresponds to the change law of the peak vibration velocity, which can be used to determine if damage happens.

The peak vibration velocities and distributions of main frequencies induced by the tunnel blasting operations of Wuhan Metro Line 5 when it was passing through the air defense chamber, Beijing-Guangzhou railway, Yellow Crane Tower and Sacred Stupa were analyzed based on the field monitoring data. Furthermore, FLAC3D software was used to analyze the vibration velocity attenuation law, displacement, and stress response law of the air defense chamber structure under the influence of upper bench blasting. The field monitoring results were in good agreement with the numerical simulation results. The results showed that the air defense chamber and Sacred Stupa were affected the most by blasting with the vibration velocity close to the limit value. While the impact of blasting on the reinforced concrete structure of Yellow Crane Tower was small. The blasting vibration of the existing railway was less than 0.9 cm/s, lower than the control value of 2 cm/s. With the advance of tunnel working face, the impact of blasting vibration on the railway will get smaller. The maximum peak vibration velocity of each measuring point appears in the vertical direction, and the corresponding main frequency is mainly located in the low and medium frequency region. In addition, the vibration energy mainly concentrated in the frequency range of 20~65 Hz. The attenuation of peak vibration velocity (PPV) at each part of the civil air defense chamber is different with the maximum value appears near y=4 m, and the PPV attenuates faster in the excavated area. The displacement of the air defense structure is within the control range, and the maximum displacement and principal stress are concentrated at the arch foot B which is closer to the blasting source. Finally, the safety control value of the peak vibration velocity of the civil air defense structure is obtained by regression of peak vibration velocity and maximum principal stress.