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.

The inlet cofferdam of the expansion engineering of Wuqiangxi hydropower station consists of the reserved rock barrier, concrete, soil and stones. The rock barrier is a bedding slope with relatively developed soft interlayers, which results in a complicated geological condition and blasting demolition environment for the cofferdam. In the process of demolishing the bedding rock barrier, it is impossible to break the rock once in a large area according to the economic section of a conventional cofferdam due to the large engineering quantity of the underwater blasting excavation, high requirement of fragmentation, long construction time and high risk. Under the condition of ensuring the stability of the cofferdam, the method of vertical stratification, horizontal zoning and loosening bench blasting was adopted to implement land excavation as much as possible. For the underwater blasting, according to the geological conditions of rock barrier, the mechanical characteristics of rock mass, the water depth (20~37 m) and the fragmentation requirement, the powder factor of 0.9~1.1 kg/m³ and maximum charge per delay of 60 kg was adopted. Electronic detonators were used for blast hole initiation and a series of safety measures such as bubble curtains and flexible protective nets were set. The field monitoring results show that the effect of blasting vibration and water percussive wave on structures such as inlet gate has been effectively controlled, and the efficiency of underwater slag removal and transfer has been improved.

The conclusions including: the Kuznetsov and kansake models are still applicable to the prediction of unit explosive consumption in bench blasting tunnel engineering, and the Kuznetsov model considers the influence of rock mass characteristics, which is more practical than the kansake model. In addition, the Kuznetsov model can predict the average blasting fragment as the basis of the distribution model of blasting fragment. Compared with the lower bench, the upper bench has higher single blasting consumption, higher content of fine particles and smaller fragments. The Kuz-Ram model has a good prediction effect for the small blasting fragments that below the average value. For the large blasting fragments that above the average value, the KCO model has a better prediction effect, and it has more accurate for the prediction of the largest blasting fragment. This paper analyzes the applicable conditions and scope of the prediction model for rock fragment, which provides a basis for the unit explosive consumption and fragment distribution of tunnel blasting. The methods for predicting the specific consumption of explosives and the fragmentation of rock mass during blasting originated from open-pit blasting. However, the stress state of the rock mass in stepped tunnels is different from that in open-pit mines, so it is unknown whether the above prediction methods are applicable to stepped tunnel blasting. Based on statistical data from the bench blasting in the Tianjiangli tunnel, several commonly used calculation methods in open-pit mines were used to predict the specific consumption of explosives and the distribution of fragments, and the predicted results were compared with the actual measurements. The results show that the Kuznetsov model and the Kansake model are still applicable to predicting the specific consumption of explosives in stepped tunnel blasting, and the Kuznetsov model takes into account the influence of rock mass characteristics, making it more practical than the Kansake model. In addition, the Kuznetsov model can predict the average value of the blasting fragmentation and serve as a basis for the fragmentation distribution model. The specific consumption of explosives is higher on the upper bench, resulting in a higher content of fine particles and smaller overall rock mass after blasting, while the specific consumption is lower on the lower step, resulting in a lower content of fine particles and a larger overall rock mass after blasting. The Kuz-Ram model is better in predicting the blasting fragmentation of small rock masses with a block size below the average value, while the KCO model is better for predicting the blasting fragmentation of large rock masses with a block size above the average value, and the KCO model can accurately predict the maximum blasting block. This article analyzes the applicable conditions and scope of the prediction models and provides a basis for the specific consumption and fragmentation distribution in tunnel blasting.

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.

To improve stemming effectiveness for tunnel excavation and blasting, a stemming device was designed utilizing the expansion characteristics of aluminum tubes under explosive action. The expansion-induced circumferential strain of the stemming device colliding with the steel tube was then measured using a dynamic strain gauge. The simulated explosive stemming devices were subjected to uniaxial compression deformation tests using a universal testing machine. The stemming effects were evaluated by recording the blasting process of cement pillars through high-speed photography. Results showed that the peak circumferential strain of the steel tube under the impact of the stemming device reached 0.02, indicating that the expansion impact force of the device on the blast hole wall was substantial which helped the device adhere to the wall. The compressive strength of the stemming device after adhesion to the blast hole wall was between 4.1 MPa and 5.5 MPa and its shear strength ranged from 0.49 MPa to 0.66 MPa, far greater than the conventional stemming material's shear strength of 0.09 MPa. In practical use, the stemming device together with the stemming material could effectively prevent its movement. When the traditional stemming material was used for stemming cement pillars, punching phenomenon appeared while no damage was observed after blasting. However, when the stemming device was used instead, there was no punching, and the stemming device only shattered after creating cracks at the collar of the blast hole, resulting in the cement pillar being split into three parts. Therefore, the stemming device significantly improved the stemming effects, and helped increase rock-breaking efficacy of the explosive gas while also enhancing the throwing effect, which is of great significance in improving blasting effects for cut holes.

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.

In order to solve the problem of blasting demolition of tall reinforced concrete water towers in restricted space, a vertical in-situ blasting demolition technology was developed. The impact failure mechanism, collapse process and touchdown vibration of the water tower were analyzed comprehensively by means of high-speed photography, vibration monitoring and numerical simulation. It was found that the collapse process of the tower by vertical in-situ blasting demolition is similar to free fall motion with an acceleration of 9.4 m/s² calculated by regression analysis, which was slightly smaller than the gravity acceleration. By using the “separated” finite element model, the collapse process of the water tower could be approximately simulated and the impact time of each section cylinder could be accurately captured. In general, cumulative damage by multiple impacts is the main characteristic of the complex failure process of the water tower, which can be simulated by the No.159 concrete material model. The main frequency band of the vibration is mainly concentrated in the range of 5~60 Hz. The high frequency part of the vibration signal attenuates rapidly, and the energy is mainly concentrated in the low frequency part. Moreover, the total energy of the vibration signal decreases significantly with the increase of distance. The test results show that the successive vertical collapse of the tower and the simultaneous blasting on the top water tank can control not only the collapse range of the tower, but also the touchdown vibration and blasting dusts.

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.

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%.

In order to comprehensively evaluate the effect of deep hole bench blasting in Weijiamao Coal Mine, considering the three objectives of blasting quality, safety and economy, eight parameters such as block rate, root rate, back crack distance, loose coefficient, unit consumption, long-meter blasting amount, vibration speed and flying distance were selected as evaluation indexes. Through UAV, high-speed photography, vibration monitoring and other technical means, the field monitoring of four production blasting flat plates in Weijiamao Coal Mine was carried out. In the meantime, the data analysis was carried out by Split-desktop, Motion studio and other software, and the quantitative indexes of the above parameters were obtained. The subjective and objective weights of evaluation indexes are obtained by using analytic hierarchy process and CRITIC method respectively, and then the combined weights of each index are determined based on the principle of maximum sum of squares of deviations. The grey clustering method is optimized by using the center point triangle whitening weight function, and the grey clustering evaluation model of blasting effect is established. The deep hole bench blasting effect of Weijiamao Coal Mine is comprehensively evaluated, and the order of blasting effect of four flat plates is obtained according to the comprehensive clustering coefficient. Finally, the main problems of the flat plate with the worst blasting effect are analyzed by comparing the index data. The results show that the combined weight of explosive unit consumption, bulk rate and base rate is greater than 0.15, which has a great influence on the blasting effect. The order of blasting effect of four flat plates is that 1080 flat plate > 1064 flat plate > 1096 flat plate > 1112 flat plate. The 1112 flat plate needs to be combined with geological conditions to optimize the bench blasting parameters for the problems of large back crack distance, high unit consumption, small blasting amount per meter and large flying distance.