In channel dredging engineering, the underwater drilling and blasting technology is often used for underwater reefs higher than the designed bottom elevation. However, after drilling and blasting, there are still some rocks that cannot be completely removed and irregular and unstable underwater shallow points remaining. In actual construction, emulsified explosive is often used to remove such isolated stones. Compared with drilling and blasting, adobe blasting has small contact surface between explosive and rock face, large amount of explosive, low energy utilization rate, high explosive consumption, large noise and water shock wave, affecting ecological environment and so on. In order to analyze the influencing factors of shallow blasting, field monitoring research was carried out to compare the adobe blasting underwater and the drilling & blasting method. Under the same effect, the water hammer wave and seismic wave data of CO₂ adobe blasting, drilling CO₂ gas blasting and drilling emulsion explosive blasting were obtained. In this paper, taking the foundation groove, berthing excavation, reef blasting and reef clearing project of 18#~22#berth wharf in Fangchenggang as examples, the arrangement and amount of charge are formulated according to the property of rock strata, rock formation, water depth and shallow point thickness of the blasted rock top. The results show that the overpressure of CO₂ adobe explosion is 1.87~41.9 times that of CO₂ drilling gas explosion under the same cylinder condition. The overpressure of underwater drilling emulsion explosive blasting is 7.9~18.7 times of the water shock wave of CO₂ drilling gas explosion, and the vibration value is 3~10 times of the latter. Based on the research on the propagation law of underwater blast wave, this paper comprehensively analyzes the harmful effect of underwater shock wave.

In order to solve the existing problems in the explosive welding technology of clad metal plate, such as low utilization rate of explosive energy, environment harm and potential safety hazard, a simple closed explosive charging process, namely a production method of energy-saving explosive welding of clad metal plate, was designed. More precisely, an isolation plate with a thickness about 2 mm was placed on the surface of ordinary explosive, and a 10~12 mm height emery sands layer was laid on the isolation plate. Then, experimental research was conducted to verify the difference of the mechanical properties between the energy-saving explosive welding and the ordinary explosive welding. Non-destructive testing and mechanical properties tests showed that the interface binding strength, binding rate and mechanical properties of clad metal plates produced by the energy-saving explosive welding technology could meet or exceed the technical requirements of the national standard GB/T 8165 and industry standard NB/T 47002. The new method of covering something on the explosive surface can achieve the purpose of saving 1/3 energy compared with the ordinary explosive welding process. And even under the condition of reducing the explosive consumption by 30%, the mechanical performance index of the clad metal is still higher than the national and industrial standards. The experimental results show that the mechanical properties of the clad metal produced by the energy-saving explosive welding process and ordinary explosive welding process are almost the same, which can meet the needs of large-scale chemical equipment manufacturing field. Therefore, the production process of clad metal plate by the method of energy-saving explosive welding is simple, efficient, safe and reliable, and the purpose of saving energy as well as reducing consumption is realized.

Due to the influence of complex environment of tunnel blasting and the electromagnetic interference of instruments, the measured blasting vibration signals mostly contain high-frequency noise, which makes it ineffective to analyze related laws by the raw blasting vibration data. In order to obtain the real blasting vibration characteristics, a signal smoothing and noise reduction model based on the optimal variational mode decomposition (OVMD) and the multi-scale permutation entropy (MPE) is adopted, which is verified by the simulated superposition signals and measured signals. Firstly, the signal is decomposed by OVMD to obtain the band-limited intrinsic mode functions (BIMF). Then, the high-frequency BIMFs larger than the threshold set by MPE are removed as noise. Finally, the remaining BIMFs components are reconstructed to obtain the noise-reduced signal. The results show that the OVMD-MPE model can accurately identify the signal frequency information, and the first two order components can effectively reflect the effective contents of the superimposed signal, which is suitable for high-precision data analysis and feature extraction. Compared with EEMD-MPE and CEEMDAN-MPE models, the OVMD-MPE model has better noise reduction performance. The noise reduction error ratio, root mean square error and smoothness are increased by 22.05%, 48% and 33.34%, respectively. The denoised curve is closer to the original signal and is more suitable for blasting signal analysis with different source distances. The blasting vibration signals measured during the construction of the right line of Shuangzishan Tunnel are concentrated in the middle and the low frequency bands below 200 Hz. The natural frequency of the lining structure is similar to the main frequency of the blasting signal, which means shock absorption measures need to be taken to ensure the construction safety of the tunnel project.

In order to improve the analysis accuracy of loosening blasting vibration signals, a hybrid denoising method based on local mean decomposition (LMD), multiscale fuzzy entropy (MFE), and singular value filtering (SVD) was established. Firstly, the vibration signal was decomposed by LMD method to obtain a series of product components (PF). Then, the blasting vibration signal was preliminarily denoised by calculating MFE and correlation coefficients. Finally, the real signal components were denoised and extracted by SVD filtering on the residual noise of the main PF components. The results show that the proposed LMD-MFE-SVD denoising method can effectively deal with the noisy PF components. For the simulated signal with multiple components with noise, the LMD algorithm is more efficient than the EMD algorithm. Furthermore, the signal-to-noise ratio (SNR), root mean square error (RMSE) and percentage of distortion (PRD) of the proposed LMD-MFE-SVD method are significantly improved by 11.73%, 22.07% and 9.25%, respectively, compared with the LMD algorithm, which indicates that the noise reduction efficiency is considerable. According to the waveform and spectrum comparison of the measured loosening blasting vibration signal after denoising by the proposed LMD-MFE-SVD method, the denoised signal waveform is more concentrated with most of the signal information retained. The frequency spectrum is clearer, and the signal frequency peaks are effectively displayed.

Distortion phenomenon would occur in time-frequency analysis when Hilbert-Huang Transform (HHT) is used to process the blasting seismic signal mixed with noise. In order to improve the analysis performance for noisy blasting seismic signals, the factors affecting the accuracy of time-frequency analysis of HHT were improved through an improved algorithm. Firstly, the empirical mode decomposition (EMD) was improved by the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) to suppress the low-frequency trend terms. Furthermore, the multiscale permutation entropy (MPE) code was added to control the high-frequency noise. Finally, the normalized Hilbert transform (NHT) was performed on the IMFs obtained by CEEMDAN·MPE. Through the above three steps, the problem of insufficient precision in the time-frequency analysis of noisy blasting seismic signals by the traditional HHT can be improved. In order to verify the accuracy of the CEEMDAN·MPE-NHT algorithm, a comparative study on the HHT and CEEMDAN·MPE-NHT algorithm was carried out, and the CEEMDAN·MPE-NHT algorithm was used for underwater drilling blasting seismic signals. The results show that the time-frequency spectrum of the IMF decomposed by CEEMDAN·MPE and processed by NHT has a greatly improved high resolution compared with HHT in both time and frequency domain. The research results can be used for identifying and controlling the hazards of blasting seismic waves.

The slope stability is bound to be affected in the blasting process of open-pit mine, especially when the slope is in the karst area. In order to study the influence of karst on slope stability under blasting and based on Tangya limestone mine slope project, this paper takes the exposed karst at the 1014 m platform of the mine as the research object, and uses ANSYS/LS-DYNA finite element analysis software to conduct numerical simulation. Considering the effect of blasting vibration, the stress distribution of the surrounding rock is obtained, and the effects of blasting on slope stress, vibration velocity, rock damage and effective stress of slope with or without karst cave are compared. The results show that the force of the bench changes and stress concentration occurs for several times due to the existence of karst caves, but the stress value generated by the bench loads is only 7.6 MPa, which still cannot reach the degree of rock mass destruction. For monitoring points at different spatial locations, the difference of vibration velocity becomes larger due to the existence of karst caves, and the vibration velocity in the vertical direction changes more than that in the horizontal direction. In particular, the spatial locations of the monitoring points near the slope edge are more sensitive to this situation. The vibration velocity difference of the monitoring points on the slope edge is about 1 cm/s at most, which does not exceed the allowable vibration velocity. In the process of increasing blasting times, the damage inside the rock mass is also gradually increasing, and the damage is more obvious under the influence of karst caves. The larger the radius of karst area, the more blasting times, the more serious the damage. Compared with previous uniaxial compressive strength experiments, it is found that although the existence of karst caves will cause the change of stress value and stress concentration phenomenon, the peak effective stress generated is far lower than the uniaxial compressive strength of rock mass. In view of the influence of blasting process on slope stability, the support treatment measures of slope in karst area are put forward.

The influence of charge shape on the dynamic response of underground structures was investigated. A dynamic finite element analysis program was used to establish a model consisting of air, soil, reinforced concrete pipe corridors, and explosives. The response of the underground pipe corridor under explosion load in soil was studied using a fluid-structure coupling algorithm. In tests, TNT is often arranged as a square group charge to detonate underground structures, while in practice, precision-guided bombs are cylindrical in shape. Comparing the response of cylindrical charges and block charges with equivalent sizes and detonation positions, it was found that when the proportional distance is less than 0.5 m/kg^1/3, the axial overpressure of cylindrical charges at the same proportional distance exceeds the radial overpressure by approximately 1.12~4.79 times its peak value. Additionally, when the proportional distance is less than 0.4 m/kg^1/3, the axial overpressure of cylindrical charges surpasses their radial counterparts. The radial overpressure generated by cylindrical charges is greater than that produced by group charges at equivalent proportional distances. Furthermore, blast shock waves propagate faster along the axial direction compared to radial propagation. Under top initiation conditions for both types of charges, one notable difference lies in vertical responses at the top part of structures. The vertical disturbance duration of the roof of the structure is longer, and the peak vertical acceleration of the roof is 15.6% higher in the top part of the large cabin and 12.2% higher in the top part of the small cabin, which has no great influence on the acceleration and displacement of the side wall. These findings demonstrate that charge shape indeed influences dynamic responses within structures.

To explore the destructive forms of bridge damage caused by explosions of hazardous materials in vehicles and the distribution of explosion load pressures on the bridge deck, a refined numerical model was established using AUTODYN software. The study analyzed the regional distribution characteristics of the bridge load pressure field under various explosion conditions with different shapes and sizes of steel plates, and determined the critical dimensions at which the steel plates play a blocking role against shock waves. In response to the challenges of conducting bridge explosion experiments, which involve high risks and large expenses, the research referred to a detailed inspection report of a real bridge after an explosion accident and inferred its explosion damage process. Based on the least squares method, a polynomial curve fitting was applied to numerous of numerical calculation results, and the traditional calculation formula for explosion shock wave pressure in the free air domain was modified. A prediction formula for the peak overpressure on the bridge deck under the explosive effects from the vehicle-borne cargo, taking into account the blocking of carriage steel plates, was proposed. The load pressure distribution calculated by this formula corresponded well to the damaged areas on the bridge deck as reported in the real bridge inspection report.

Experiments of vented explosion were conducted in a 1 m³ vessel under the conditions of top ignition for premixed methane-air gas with a concentration from 7% to 13% to investigate the influence law of methane concentration on flame evolution and internal overpressure during the vented explosion process. The explosion venting mechanism was analyzed by analyzing the pressure-time curve and the flame evolution image. The results prove that concentration has a significant impact on the explosion venting characteristics of the methane-air premixed gas. The overpressure inside the container presents a double-peak phenomenon with a specific methane concentration. The first pressure peak P₁ can appear at each concentration, while the second pressure peak P₂ only occurs when the concentration is 9%. P₁ increases first and then decreases with the increase of concentration, while the trend of the timing of the peak is the opposite. However, both reach the extreme value at the methane concentration of 10%. This is mainly formed by the combined effects of initial flame propagation, external explosion, Helmholtz oscillation and Taylor instability, etc. The phenomenon that P₂ is much higher than P₁ is mainly formed by the mutual promotion of flame and sound pressure and the thermoacoustic coupling effect triggered by disturbance. The flame downward propagation velocity increases first and then decreases with the concentration, and reaches the maximum value when the methane concentration is 10%, and the combustion velocity is generally faster in the slightly rich combustion state.

In order to study the protective performance of minesweeper protective equipment on the chest and abdomen under the action of explosion shock wave, it is necessary to explore efficient test methods to improve the experimental research index system and overall performance of individual soldier protective equipment. In this paper, two sets of minesweeper protective equipment were taken as experimental research objects, and the real explosion test of minesweeper EOD operators for typical kneeling posture was designed based on Hybird III dummy model under different sealing conditions. The shock wave was generated by the explosion of 50 g TNT charge column. Two wall overpressure sensors were installed in the chest and abdomen of the dummy model to measure the shock wave overpressure generated by four real explosion tests, and a free field pressure sensor was set at the same distance relative to the explosion source to compare the test data. Using the dummy data acquisition system, the whole process data of overpressure on the chest and abdomen after the shock wave penetration of the minesweeper protective equipment were obtained. Through data processing, the pressure-time curve of chest and abdomen subjected to explosion impact and the peak attenuation rate of overpressure were obtained and compared. The test results preliminarily verify that the better the sealing performance of the joint, the higher the protection performance, which indicates that the protective equipment with high sealing performance has a certain blocking attenuation effect on the diffraction of explosion shock wave, and can reduce the damage caused by superimposed overpressure to the chest and abdomen to a certain extent. The experimental design and data analysis in this paper can be used for further equipment performance improvement.