Taking fan-shaped medium-deep hole blasting of underground iron ore as the research object, a full band frequency analysis was conducted on the actual collected blasting vibration waves. Based on Matlab fitting and superposition analysis, a method was proposed with the half-cycle corresponding to the high-frequency sub-cycle as the optimal delay time. It was verified by numerical simulation and field test. Results show that, by subtracting the half-cycle corresponding to the main frequency of blasting vibration waves in a staggered manner, the vibration reduction is not significant, and vibration enhancement is observed. The optimal delay time between holes is mainly related to the high-frequency sub-cycle contained within the effective band of the blasting vibration wave. Determining the delay time with the high-frequency sub-cycle is more accurate. The strength of multiple stacking is still related to the high-frequency sub-cycle. Under the condition of low stacking times, the sensitivity between the two is not high, and the sub-period of sub high frequencies can also have a certain vibration reduction effect. However, as the number of stacking increases, the correlation between the two continues to strengthen, so only high-frequency sub-cycles have good continuous superposition vibration reduction effects.

In order to study the perforation process of perforating charge into rock strata and the distribution of energy after the explosion, a fluid structure coupling algorithm based on symmetric penalty function and the RHT (Riedel-Hyermaier-Thoma) constitutive model of rock layers were used. With the explicit nonlinear dynamic analysis program LS-DYNA, a 1/2 2D symmetrical numerical simulation model of perforating charge-air-rock strata was established. The perforation depth into rock strata and energy conversion of jet were systematically analyzed under different charge types, wall thicknesses of liner, and cone angles. The research results indicate that the detonation velocity and brisance of the main explosive of the perforating charge have a significant impact on the penetration depth into rock layers of jet. The higher the detonation velocity and brisance of the explosive, the higher the peak velocity of the jet head, and the greater the penetration depth into rock strata. When the main explosive of the perforating charge is RDX, the effective energy conversion rate of the jet is the highest, followed by HNS and HMX, respectively. Within the range of 0.6-1.5 mm, appropriately reducing the wall thickness of the liner can improve the jet velocity at its front and the penetration depth into rock strata. But at the same time, the proportion of effective energy of the jet will decrease, and the detonation energy will increase. Within the range of 55°-70°, appropriately reducing the cone angle of the liner will increase the effective energy conversion rate of the jet and the penetration depth into rock strata, while the conversion rate of detonation energy will decrease.

A new type of linear shaped charge structure was adopted to study the influence of stand-off on the damage of linear shaped charge jet on concrete walls. In numerical simulations, it has found that when the cone angles of the shaped charge are 80° and 50°, it can effectively avoid the phenomenon of pulling and breaking. The variation law of jet head velocity and penetration depth with stand-off for linear shaped charge structure was obtained. The optimal penetration depth reaches 130.6 mm when the stand-off is 60 mm. Experimental study was conducted on linear shaped charge with stand-off of 60 mm and 100 mm. The results show that when the stand-off is 100 mm, the penetration depth reaches 125.0 mm, which is in good agreement with the simulation results. The linear shaped charge structure has been verified to have a good destructive effect on concrete walls. It can provide reference for the design and experimental research of linear shaped charge structures.

The reliability of digital electronic detonators in high-altitude environments is poor. The effects of low pressure, high and low temperature cycling conditions on five types of electronic control modules, A (tantalum capacitor), B (electrolytic capacitor), C (electrolytic capacitor), D (tantalum capacitor), and E (tantalum capacitor), were studied at 52 kPa from -40 to 15 ℃. The voltage changes of five types of ignition capacitors in each stage of the ignition process were tested. The ignition powers of the five kinds of electronic detonators were tested by the lead plate method after the cycle test of low pressure and high temperature difference. The results show that the conditions of 52 kPa from -40 to 15 ℃ have no effect on Modules A, B, D, and E, while Module C experiences insufficient capacitor charging. It has no effect on the power of the detonator.

In order to investigate the influence of additives with different properties on the fire suppression performance of water mist on single base propellant, a comparative experiment of single base propellant combustion and suppression was conducted on a self-built platform. It compared the performance of pure water mist and water mist containing Na₂SO₃, FeCl₂, K₂CO₃ and KHCO₃ additives in suppressing the combustion of single base propellants. Changes in temperature, radiant heat flux, and flame morphology during the fire suppression process were studied. The results show that the fire suppression performances of water mist containing reducing additives (Na₂SO₃, FeCl₂) or non-reducing additives (K₂CO₃, KHCO₃) are significantly better than that of pure water mist, with shorter extinguishing time. The performances of water mist containing non-reducing additives in suppressing single base propellant fires is poor at low concentrations. When the mass fraction of nonreducing additives rises above 3%, the fire extinguishing ability is significantly improved. The fire suppression performances of water mist containing reducing additive are superior to that of water mist containing nonreducing additive at all concentrations. In addition, as the increase of the concentration of reducing additive, the fire suppression performance is saturated.

Aluminum containing explosives (dull black aluminum, DHL) have issues with safety and energy output. An insensitive single-compound explosive FOX-7 (1,1-diamino-2,2-dinitroethylene) was used as the main explosive, high-purity ultrafine amorphous boron powder (B) was used as the high-energy fuel, ammonium perchlorate (AP) was used as the oxidant and gas generator, ethylene vinyl acetate copolymer (EVA) was used as the binder, and microcrystalline wax was used as the desensitizer. Based on relevant theories, the optimization design of the explosive formula was carried out. Finally, a formula based on impact sensitivity was adopted, and a mixed explosive was prepared by wet ballmilling-assisted solvent evaporation method. The packing density of this explosive is 1.469 g/cm³, with an impact sensitivity of 10%, a friction sensitivity of 12%, a detonation heat of 8 092.9 kJ/kg, and a five-second delay period of 303 ℃. Vacuum stability of the explosive is qualified, and the thermal stability is good. Therefore, this explosive is an insensitive high-energy explosive that can replace DHL explosives.

In order to investigate the thermal decomposition characteristics and thermal safety of polymer bonded explosives (PBX), the accuracy of two small weight experiments in predicting the self accelerated decomposition temperature (SADT) of PBX was investigated. The thermal decomposition behaviors of a typical RDX based PBX were studied simultaneously using differential scanning calorimetry (DSC) and adiabatic accelerated calorimetry (ARC), and thermodynamic parameters and thermal safety parameters of PBX were calculated. Based on Semenov theory, SADT of PBX under the two thermal analysis methods was further calculated, and the accuracy of the results was verified by isothermal storage experiments. DSC analysis results show that activation energy of PBX is 125.70 kJ/mol, critical temperature for thermal explosion is 460.08 K, non return temperature T_NR at the 10 g level is 417.22 K, and SADT is 405.72 K. ARC analysis results show that T_NR of PBX at the 10 g level is 427.97 K, and SADT is 421.57 K. Through a 7-day constant temperature thermal explosion test, the minimum SADT of PBX was determined to be 418.15 K, proving that predicting the thermal safety of large weight samples based on ARC small weight test is more in line with the actual situation. It can be used to solve the safety issues of explosives during storage, production, transportation, and use.

In order to study the influence of shear parameters on stability and explosive performance of mixed emulsion explosives, mixed emulsion explosives produced in a ground station in an open-pit coal mine in Xinjiang was studied. Emulsification process and shear parameters of mixed emulsion explosives were optimized by the methods such as natural storage, transportation vibration, and explosive performance testing. The results indicate that, within a certain range, the anti-vibration and natural storage stability of emulsion matrix are positively correlated with shear strength. The emulsion matrix prepared with turbine blades has the best stability, followed by the emulsion matrix prepared with propulsion blades and propeller blades. As the length of the stirring blade or the number of blade layers increases, crystallization rate of the emulsion matrix shows a decreasing trend, and the stability is higher. The on-site blasting test results show that, using optimized emulsification technology and shear parameters, the mixed emulsion explosive has a detonation speed of about 4 200 m/s. After a long-distance transportation of 1 000 km, it can still detonate stably. And the rock fragmentation and block rate significantly decrease after explosion, resulting in a significant improvement in the blasting outcomes.

High energy explosives are the source of energy for the destruction of various weapons and ammunition. Study on the damage and ignition characteristics of high-energy explosives (condensed phase explosives) is of great significance for the safety of weapons and ammunition. The research progress on the damage and ignition characteristics of condensed phase explosives was introduced from four aspects: molding process, experimental simulation of damage, observation and characterization of damage, and damage-ignition correlation. Firstly, the influence of molding processes such as press-fitting, pouring, and melting and casting on the initial damage of the charge was explored. Secondly, the generation of damage, experimental simulation, observation and characterization methods of damage during the use of condensed phase explosives were summarized. Furthermore, the damage-hot spot-ignition process of explosives was analyzed in terms of the typical types of damage. Finally, based on the analysis of the current research status, the future development trends and challenges of damage-ignition characteristics of condensed phase explosives were proposed.

Aiming at the problem of inaccurate prediction of block size after rock blasting in mines, a CatBoost block size prediction model based on improved grey wolf algorithm (IGWO) optimization was proposed. A new nonlinear convergence factor and a dynamic weight strategy were introduced to improve the existing grey wolf algorithm (GWO). The optimization ability of IGWO was verified by four test functions and five optimization algorithms. Thirty-two sets of data collected from the public database and the field were predicted and analyzed. Firstly, the random forest algorithm was used to screen the feature importance, and IGWO was used to optimize the parameters of CatBoost to establish the IGWO-CatBoost prediction model for blasting fragmentation. Then, the prediction results were compared and analyzed with the CatBoost, XGBoost and LightGBM models established under the same conditions. The prediction accuracy of the CatBoost model is effectively improved by IGWO, and the prediction accuracy of IGWO-CatBoost model is better than the other three prediction models. The comparison results show that IGWO-CatBoost model has good prediction ability and adaptability.

In order to avoid and reduce the impact of tunnel blasting vibration and noise on complex and sensitive urban areas, taking the newly built Banzhangshan Tunnel in Zhuhai as an example, numerical simulation and field blasting tests were used to monitor the blasting vibration on the blasting side of the existing tunnel under different delay times of cut holes. When the delay time between the cut holes is 4 ms, the blasting vibration velocity on the blasting side of the existing tunnel is the smallest. At the same time, aiming at the problems of numerous buildings around the entrance section of the tunnel, high blasting noise, and flying stones splashing, experiments of gun hole plugging and anti-flying stone was carried out. A new type of gun hole plugging device was designed. When the charge increases, the blasting noise can be controlled within the allowable range. The use of joint protective door curtains at the entrance reduces the risk of flying stones splashing. It provides a reference for the control of blasting vibration and noise in urban tunnels in complex and sensitive environments.

In order to study the impact of blasting vibration on the tailings dam nearby, five sets of different parameters were taken for on-site blasting tests in the mountain beam blasting near a tailings dam. The main frequency of blasting vibration of the tailings dam body is 0~50 Hz. The monitoring results were fitted with the Sodovsky empirical formula to simulate the vibration load of the tailings dam under actual blasting conditions. The vibration response and dam stability of the tailings dam under actual blasting schemes and amplified blasting loads were calculated. Based on the relationship between the blasting velocity threshold and the stability safety factor of the dam, it is determined that the allowable particle velocity for the safety of this tailings dam is 3 cm/s. In the designed blasting plan, the most dangerous area affected by blasting vibration is located at the elevation of 713.0 meters in the accumulation dam. The maximum vibration speed of the initial dam is 0.220 cm/s, and the maximum vibration speed of the accumulation dam is 0.157 cm/s. It meets the requirements of safety allowable particle velocity for tailings dams. It meets the allowable particle velocity requirement for the safety of the tailings dam.

To investigate the reduction effect of water on explosion shock waves in open spaces, an experimental platform was constructed based on a horizontal shock tube for the interaction between shock waves and suspended rectangular water walls. Eight sets of experiments were conducted at the near-field position of the water wall. The process of interaction between shock waves and water walls was recorded using a high-speed schlieren testing system, and the influence of water wall thickness on wall fragmentation and velocity was investigated. A pressure testing system was used to record the pressure changes behind the water wall, and the results were analyzed in conjunction with the highspeed schlieren imaging data. The results show that the pressure changes behind the water wall are not related to the reflection, transmission, and diffraction phenomena of shock waves, but mainly depend on the impact effect generated by the water wall. Momentum extraction is the main explosion reduction mechanism for suspended rectangular water walls. The water wall has a significant reduction effect on the peak pressure of the shock wave, and as the thickness of the water wall decreases, the reduction effect on the peak pressure gradually increases. However, the reduction effect on the peak impulse is not significant.

In converter transformer stations, transformers may experience explosion accidents under uncontrolled conditions. By simulating transformer explosion accidents through experiments, the reliability and anti-explosion performance of the fire cannon were verified. It was found that, within the range of high-temperature and high-pressure gas cloud explosion fireballs, the anti-explosion performance of fire cannon cannot meet practical needs. There is a loss of function after the explosion of the transformer. Weak links in the explosion resistance of the fire cannon were identified, and suggestions for the explosion resistance design and installation improvement of the fire cannon were proposed. It could provide conferences for the design of anti-explosion fire cannon in converter transformer stations.

In order to study the combustion heat performance of nitrous oxide based composite monopropellants, several typical propellant formulations were taken as research objects, and theoretical calculations of combustion heat were carried out using Hess law. An automatic adiabatic calorimeter (oxygen bomb) and a constant temperature explosive heat calorimeter (detonation bomb) were used to investigate the influence of different additives and container geometry on the combustion heat of some formulations. The results show that, under the same conditions, the combustion heat of N₂O/C₂H₄, N₂O/C₃H₈ and N₂O/NH₃ decreases sequentially. With the increase of CO₂ content, the combustion hea of N₂O/C₂H₄?decreases gradually. With the increase of C₃H₈ content, the combustion heat of N₂O/NH₃ increases first and then decreases, and it reaches the maximum when the mass fraction of C₃H₈ is 3.8%. The combustion heat increases with the increase of the container geometry size.

In order to study the influence of damage and cushion materials on the initiation of Composition B, numerical simulation was conducted using LS-DYNA software. The impact velocity of explosive was changed to change the damage degree. The calculation results show that when the second impact velocity is fixed, the relationship between the initiation time t and the first impact velocity v₁ is t=－0.02v₁+C₁, and the distance of impact detonation also decreases accordingly. The increase of the first impact velocity leads to the slight deformation of the explosive, and the damage degree inside the explosive increases. Therefore, the explosive is easier to be triggered during the second impact. Among the three different cushions, the material with higher resistance to impact is stronger. The internal damage of the explosive containing this material is not easy to produce, and the time and distance of impact initiation of this explosive are longer. The critical initiation pressure of the explosive varies little, ranging from 31.48 GPa to 32.98 GPa. It indicates that different cushion materials will affect the time and distance of impact initiation of the damaged explosive, but will not affect the critical initiation pressure.

In order to study the influence of boron-based fuel on the energy output characteristics of composite charges composed of Al/PTFE active materials and thermobaric explosives under air explosion conditions, three kinds of composite charge samples with the same mass but different components were designed and prepared. The free-field static explosion test was carried out, and the shock wave overpressure at different explosion center distance was obtained. The evolution process of explosion fireball was recorded by high-speed photography. The experimental results show that Al/PTFE active materials can improve the shock wave overpressure of composite charge and cause severe post-combustion reaction. The decomposition process of boron-based fuel has a delay of about 2.0 ms. The energy contribution at the initial stage of the reaction is low, which reduces the peak overpressure of the shock wave of composite charge. But the subsequent combustion reaction promotes the further expansion of fireball volume, reduces the rate of shock wave overpressure decline, and increases the shock wave impulse. Al/PTFE and boron-based fuel with proper proportion can enhance the peak overpressure and impulse of shock waves of the composite charge. When boron-based fuel is added to Al/PTFE, the reaction above deflagration occurs, and the overpressure of shock wave appears obvious secondary peak, which is about 0.478 MPa.

In order to investigate the influence of crystal surface passivation on the safety and detonation performance of CL-20, fluorine rubber (F2311) was used as a binder, and the changes in mechanical sensitivity and detonation performance of CL-20 before and after coating were compared using water suspension method. The experimental results indicate that coating CL-20 with F2311 can significantly improve the surface defects of CL-20 materials. At －20, 0, 20, 40 ℃ and 80 ℃, the critical impact energy and critical friction load of CL-20 coated with F2311 increase significantly. At －40℃, the coating has no effect on the critical impact energy and critical friction load of CL-20, which may be related to the glass transition temperature of the coating material. The measured detonation heat and detonation velocity of the coated samples can reach 5 612.03 kJ/kg and 8 975.81 m/s, respectively, which reduce by 8.70% and 2.39% compared to CL-20. It has certain guidance for the secure storage, use, and efficient energy output of CL-20.

In order to successfully demolish a 85.8 m-high granulation tower with reinforced concrete structure in a complex environment through blasting, combined with the structural characteristics of the tower and the surrounding environment, a trapezoidal blasting cut was selected, and highly symmetrical directional windows and positioning windows were opened. Based on data analysis, the center angle of the cut was determined to be 216° and the height of the cut was 4.0 m. The directional dumping method was used for blasting demolition. LS-DYNA simulation software was used to establish a three-dimensional finite element model of the separated common node of the granulation tower for simulation calculation to verify the feasibility of the blasting design scheme. The results show that the selected blasting technical parameters are accurate, and the granulation tower is offset to the right by about 4.9°. It collapsed basically along the original design direction, and the cylinder slightly sit down without any forward movement. The demolition blasting outcomes has achieved the expected goal. It can provide reference for similar projects.

In order to investigate the combustion and explosion characteristics of butane-air premixed gases with various concentrations in enclosed pipelines, a squareshaped sealed experimental pipeline was utilized to conduct explosion tests on butaneair premixed gas with different volume fractions of butane. The results indicate that it goes through three stages including initial pressure rise, secondary pressure rise, and pressure decrease in gas explosion. As the concentration of butane gas increases, the increase rate of explosion pressure, maximum flame velocity, and flame acceleration all show a trend of first increasing and then decreasing. When the volume fraction of butane is 5%, the above parameters all reach their peak. In pipelines containing water, the change trends of explosion pressure in the gas phase and liquid phase are basically the same, but compared to pipelines without water, the pressure changes are smoother, and the maximum explosion pressure and pressure increase rate are lower. It provides a theoretical basis for the study on combustible gas explosion.

Potassium bicarbonate (KHCO₃), commonly used as the methane explosion suppression, was mixed with ammonium dihydrogen phosphate (NH₄H₂PO₄) in different proportions in a self-built pipeline experimental system. Five different powder ratios were selected to compare the explosion characteristic parameters such as peak explosion pressure, peak flame velocity, and peak flame temperature at each monitoring point under a single powder and various explosion suppression conditions. The optimal conditions for suppressing methane explosion in the pipeline network were obtained, and the explosion suppression mechanism was explained. The results show that the suppression performance of mixed powder on methane explosion in pipeline networks is better than that of the single powder. Both KHCO₃ and NH₄H₂PO₄ are prone to decomposition during heating, among which KHCO₃ can quickly complete the pyrolysis process at a relatively low temperature, thereby absorbing more heat of reaction, and its explosion suppression performance is better than that of NH₄H₂PO₄ powder. The explosion suppression effect significantly improves with the increase of concentration of KHCO₃ . Among the five mixing ratios, when the mass ratio of KHCO₃ to NH₄H₂PO₄ is 2.0∶1.0, the explosion suppression effect is the best. KHCO₃ and NH₄H₂PO₄ exhibit excellent explosion suppression effects. The conclusions obtained in the study can provide theoretical support for the study on methane explosion suppression.

On the basis of research on the resource utilization of waste engine oil, the cost of emulsion explosives in a super large mine aboard was optimized, and a waste engine oil-based emulsion explosive was prepared with a small amount of sodium chloride instead of sodium nitrate as an aqueous additive. A basic experimental study was conducted to obtain its water phase crystallization point, storage period, pumping frequency, resistance to turbulence, detonation speed, and rock fragmentation after detonation. The results show that the addition of sodium chloride can reduce the crystallization point of the aqueous phase by about 10 ℃, and the prepared emulsion explosive has good storage stability, which can meet the needs of multiple pumping and long-distance transportation. The detonation speed can reach over 4 600 m/s, with a martyrdom distance of 14 cm. Although the blasting performance is slightly reduced, it does not affect the use in mining blasting. The rock fragmentation after blasting meets the requirements of mining excavation. Compared with the cost of the original formula, the cost of emulsion explosive can be saved by 49.59 dollars/t, which has certain practical value and economic benefits.

In order to improve the anti-static and anti-RF capability of semiconductor bridge (SCB), transient voltage suppression (TVS) diodes (electrostatic reinforcement device) and negative temperature coefficient (NTC) thermistors (RF reinforced device) were integrated into the SCB initiator. The influence of these combined devices on the ignition performance and electromagnetic resistance of the integrated SCB was studied. The results show that, after integrating protective devices, the safety current of SCB increases from 1.2 A to 1.5 A, and the anti-static performance meets the requirement of no ignition under 500 pF/500 Ω/25 kV conditions. Under the condition of 22 μF/16 V, the average explosion time of integrated SCB increases by 1.77 μs compared to that of SCB. Therefore, this combined protective device can effectively improve the antistatic and antiRF capabilities of SCB without changing its ignition performance.

In order to explore the possibility of replacing primary explosives with mixed materials of nano aluminothermal agents and high explosives, Al/Bi₂O₃-PETN and Al/Bi₂O₃-RDX were prepared by physical mixing using nano aluminum powder, nano Bi₂O₃, industrial grade PETN, and RDX as raw materials. The properties of the two prepared samples were characterized and tested by methods such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), thermal analysis, and open environment combustion experiments. The results indicate that the morphology of the two samples prepared by physical mixing method is regular. Al/Bi₂O₃ has a good coating effect on two types of explosive materials, PETN and RDX, and a large amount of gaseous products are generated during the reaction process. The thermal stability of Al/Bi₂O₃-PETN is lower than that of Al/Bi₂O₃-RDX, and the electrostatic sensitivity is lower than that of lead azide and lead stephenate. Two types of mixed materials, 81 mg, were respectively loaded into 8^# detonators for lead plate perforation experiments. It was found that both types of samples can cause perforation of 5 mm-thick lead plates. Based on the perforation diameter of the 5 mm-thick lead plate, the detonation ability of Al/Bi₂O₃-RDX is superior to that of Al/Bi₂O₃-PETN.

In response to the insensitivity requirements of the double-bridge electric detonator, the structural design and performance testing verification were carried out using the bridge belt heating mathematical model and 3D modeling programming method. The results show that the electric detonator with a structure of anti-static board and terminal blocks has stable anti-static performance and can withstand the impact of 16 A direct current without failure. When the thickness of the bridge belt is 0.02 mm and the width of the bridge belt is 0.32 mm, it can meet the requirement of bridge circuit melting time not exceeding 60 ms. The combination of zirconium potassium perchlorate and D8 boron/potassium nitrate ignition can meet the safety current requirement of 1 A, 1 W, 5 min, and the ignition is reliable.

The bubble load near the wall is one of the important loads for underwater warheads to damage obstacles.Focusing on the characteristics of bubble pulsation and jet load in deep-water explosions near the rigid wall, explosion experiments were conducted to simulate a water depth environment of 300 meters. Using the high speed camera, the evolution of bubble jet was obtained. The evolution process of bubble jet was calculated using the Autodyn axisymmetric model, and the influence of scaled distance on bubble pulsation period, jet evolution formation time, and jet intensity characteristics was analyzed. The pressure characteristics within the near-field range of the wall were explored, and the evolution law of jet load was summarized. It can provide theoretical reference for study on the damage effect of warheads on obstacles in deep water environments.

In order to achieve in-situ online detection of important parameters in the crystallization process of energetic materials, a microfluidic crystallization process monitoring system (MCPMS) with multiple detection functions was designed and constructed. This system integrates various online detection devices such as online spectrometers, lasers, CCD cameras, and laser particle size analyzers. It can detect and analyze multiple important factors and properties such as the mixing effect of microreactors, key process parameters of explosive crystallization (crystal solubility, metastable zone width, etc.), and crystal morphology of energetic materials. The mixing process of the chaotic micromixer was analyzed using this system, and the mixing strength of the coaxial micromixer was also characterized. Taking HNS as an example, the crystallization thermodynamic and kinetic parameters of HNS were measured based on a vortex micromixer. The crystal growth kinetics of HNS-based polymer bonded explosives were investigated based on measured particle size distribution data. The relationship between the thickness and optical properties of barium chromate crystals, a commonly used oxidant in delay agents, was analyzed based on a microporous mixer. The system has good functionalities and practicalities.

In order to analyze the influence of different air column positions in the middle of the charge on the stress on borehole wall, based on the Starfield superposition method, the calculation formula for the impact pressure on the entire borehole wall during the middle air interval charging blasting was obtained. Multiple calculation models for different central air column positions were established using ANSYS-DYNA, and the stress and damage degree of the borehole wall and surrounding rock mass were analyzed. Finally, on-site blasting experiments were conducted, and the distribution and variation of the fragmentation were analyzed using WipFrag software. The results show that, during the middle air interval charging blasting, the overall pressure on borehole wall shows a large distribution at both ends and a small distribution in the middle. The impact pressure on the borehole wall in the charging section reaches its maximum, and the shock wave propagates around the hole in an 8-shaped pattern. When the air column position is at the midpoint of the charging section, the stress on the rock mass around the upper and lower sections of the charging column is roughly equal, and the block size is relatively uniform. Therefore, when the open-pit blasting mining is conducted on vertical benches, in order to reduce the production rate of large blocks and powder, the upper and lower sections of the air column can be charged in equal proportions, and the air column position can be appropriately adjusted upwards on inclined slopes.

During the excavation process of the tunnel, the safety risks of the entire tunnel construction can be evaluated by identifying and evaluating the risk factors in the blasting engineering of the tunnel face. Taking Wanshoushan Tunnel on the Shizhu-Qianjiang Expressway as the research object, from the perspective of affecting tunnel blasting safety, four first-level indicators and 14 second-level indicators were determined. Then, the model matrix and fuzzy complementarity matrix were established using the coupling theory of fuzzy hierarchy and improved grey correlation degree, and the weights of each factor and matrix eigenvectors were determined. Finally, the fuzzy multi-level method was used to evaluate the risk of tunnel blasting construction, and the classification of each risk was also determined. The results show that the weights of each factor, from highest to lowest, are tunnel face blasting, blasting management, geological conditions, and blasting design. The comprehensive risk level of tunnel blasting is high risk. Among the first level indicators, geological conditions are at high risk, tunnel face blasting is at extremely high risk, and blasting management and design are at medium risk. Based on risk types and risk assessment results, graded control measures and Beidou integrated monitoring system schemes can be developed to understand tunnel deformation in real-time, implement risk graded control, and provide security for dynamic construction of tunnel excavation.

Based on a blasting project of crossed tunnels of Beijing-Zhangjiakou High-Speed Railway, the dynamic response of the secondary lining of an existing tunnel to the blasting loads from the lower tunnel was studied. Based on Sadowski’s formula, the attenuation laws of the peak velocity and main frequency of blasting vibration corresponding to the intersection points located in front of and behind the tunnel face were studied with the tunnel intersection section as the boundary. In order to compensate for the shortcomings of the method of segmented frequency influence in existing blasting safety regulations, the mathematical relationship between the peak velocity of blasting vibration and the main frequency was obtained through regression analysis, and the impact of blasting vibration frequency on the response characteristics of blasting vibration was quantitatively analyzed. The calculation results indicate that, taking into account the influence of blasting vibration frequency and existing tunnel natural vibration frequency, the optimized v_PPS?is smaller than the measured vibration data v_PP 。 In this blasting project of crossed tunnels, the vibration impact of the lower tunnel blasting construction on the existing tunnel is within a controllable range.