According to continuous blasting vibration monitoring results carried out on three monitoring points (bottom, middle, and top) at different vertical positions at the same horizontal distance from an underwater blasting project in a channel adjacent to high-rise buildings, the three-dimensional spatial patterns of blast vibration velocity, vibration frequency, and vibration energy were analyzed, and the elevation effect mechanism of blasting vibrations on high-rise buildings was explored. The analysis results show that: (1) Blasting vibration velocity is influenced by the combined action of the elliptical motion of Rayleigh wave, energy attenuation, and whiplash effect. It presents a significant three-dimensional spatial effect in the propagation among high-rise buildings, in which the vertical direction is dominated by Rayleigh wave elliptical motion and whiplash effect, showing a significant elevation amplification effect, while the horizontal and tangential directions are dominated by Rayleigh wave elliptical motion and energy attenuation, exhibiting an elevation attenuation effect. (2) The propagation of blasting vibration frequency in high-rise building is mainly affected by the vertical distance from the wall, showing an elevation attenuation effect in all three directions. (3) The distribution of vertical blasting vibration energy presents a significant elevation amplification effect from the bottom, middle to the top of the building. Specifically, the high-frequency energy proportion shows an elevation attenuation effect in the middle and top relative to the bottom, while the low-frequency energy proportion exhibits an elevation amplification effect in the middle and top relative to the bottom.

The charge parameters are crucial factors affecting the damage effect of RC components under close-in explosion. The study of the influence law of different charge parameters on component damage is of guiding significance for improving warhead design and optimizing fire strike scheme. A cylindrical charge with a length to diameter ratio of 5.5 and a charge of 10 kg was used to carry out near explosion damage tests of the supporting column of a reinforced concrete single-storey stacked structure plant at a proportional distance of , and a comparison test of spherical charge was set up. The experimental results show that the damage effect of a cylindrical charge is stronger than that of a spherical charge, and the reliability of the numerical simulation model is verified by the experimental data. The length to diameter ratio, blast height, charge amount and action distance of cylindrical charge are taken as the research factors, and three levels are determined for each factor. The simulation results of blast damage of reinforced concrete under 9 different charging parameters were designed and obtained by orthogonal simulation test method, and the influence law of cylindrical charging parameters on the damage effect of reinforced concrete columns was analyzed. The amount of the cylindrical charge has the greatest effect on the damage degree, the ratio of length to diameter has the second effect, and the blast height has the least effect on the damage degree. When 4.5≤L/D≤6.5, the damage effect on the component is greater. When the blast height is 1/4, 1/2 and 3/4 column height respectively, the explosion at the 1/4 column height has the best damage effect on the support column.

In order to study the deformation and damage of tunnel surrounding rocks under the coupling action of static and dynamic stresses, a tunnel model under the coupling action of ground stresses and blasting loads is established. Firstly, the JH2 constitutive parameters of surrounding rock are deduced based on the on-site monitoring data of Wenbishan tunnel and the wave velocity of the rock mass. According to the surrounding rock grade, combined with the known parameters and wave equation, a simple method to determine the JH2 constitutive parameters is given, and the damage model of the surrounding rock is established by embedding a subprogram into ABAQUS. In order to make the simulation model closer to the reality, this research first balances the ground stress, takes the soil state at this time as the initial stress state of the blasting simulation, then using the equivalent blasting load method to simulate the tunnel blasting, so as to realize the blasting simulation for large-scale geotechnical engineering under the coupling of static and dynamic stresses on a macro level. The simulation model not only considers the blasting effect on the working face, but also focuses on the impact of blasting on the surrounding rock of the tunnel. The results show that the initial ground stress plays a significant role in the damage and deformation of the surrounding rock during tunnel excavation. The existence of the initial ground stress induces damage propagation. The greater the ground stress is, the greater the damage is. The maximum damage depth of the arch bottom in vertical direction is 2.2 m. At the same footage, the smaller the ground stress is, the greater the deformation is. The maximum deformation of 11.7mm is produced at the arch crown near the excavation face. The horizontal convergence deformation of the surrounding rock is different. The upper part is away from the tunnel, and the lower part points to the tunnel. In addition, the surrounding rock at the boundary between the upper and lower benches is subject to shear load. The damage and deformation of the surrounding rock are closely related to the actual project.

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.

As the main index to evaluate the blasting effect, the rock blasting fragmentation directly affects the subsequent construction objectives and construction costs of water conservancy and hydropower projects. In the process of quarry blasting, it is of great significance to improve the blasting efficiency and quality and meet the demand of good grading curve for the dam aggregates in the construction of water conservancy and hydropower projects. The influence of the number of free surfaces and the delay interval between holes on the rock blasting effect is studied by establishing a two-dimensional finite element numerical model. Firstly, the interaction of stress waves between holes and the reflection mechanism of explosion stress waves on free surfaces are explained theoretically. The conditions for the generation of blasting cracks are also analyzed. Then, with the help of ANSYS/LS-DYNA finite element software, RHT model is used to simulate the rock fracture process under different number of free surfaces and different delay times between holes, and WipFrag is used to analyze the rock grading under different blasting conditions. The numerical simulation results show that the influence of different number of free surfaces on blasting grading is obvious. Compared with no free surfaces, the maximum bulk yields of single free surface, two free surfaces and three free surfaces decreases by 25.9%, 46.5% and 61.8%, respectively. It can be seen that the more the number of free surfaces, the more cracks produced in the rock, the better the blasting fragmentation effect. Compared with simultaneous initiation, delayed blasting is beneficial to improve the rock fragmentation effect, but the interaction between stress waves and holes is not obvious in short delayed blasting.

The optimization of delay time is very important for controlling blasting vibrations and guaranteeing the technical-economic effect of blasting projects. The proposed improved linear superposition method can be used to in-depth discover the relationship between the particle peak velocity (PPV) of blasting vibration and delay time. Because blast vibrations actually belong to random process, which means merely using a one-time measured single-hole blasting vibration signal to simulate a multi-hole blast vibration waveform may not be reasonable. Similarly, it is also not enough to simulate a multi-hole blast vibration waveform corresponding to a certain delay time only once. A method involving random variables and statistical treatments is necessary. Firstly, Fourier series is used to represent a measured single-hole blast vibration waveform. This is necessary to formulize a piece of measured time-series data. Secondly, random variables are added to the coefficients and phases of the Fourier series expansion to generate a specified number of single-hole blasting vibration waveforms. Thirdly, Monte Carlo simulation is used to calculate the mean value of PPVs corresponding to each delay time between 0ms and 250 ms with an increment of 1 ms, and the change curve of the average PPV with delay time can be obtained. The results of example analysis show that if the civil house 531 m away from the explosion source is taken as the protection target and 0.45 cm/s is taken as the peak particle velocity control threshold, any delay time more than 7 ms can be selected to meet the safety standard, and when the delay time increases, the PPV decreases in general. To pick a specific delay time from the range determined by the above process, it is necessary to observe the relationship between the rock fragmentation effect and delay times. By investigating the fragmentation results of four blast tests, the total amount of boulder yield decreases first and then increases with the delay time per meter, and the minimum value appears when the delay time is 7 ms/m. That is, if the designed hole spacing is 6 m, and hole-by-hole initiation is adopted, the optimal delay time in terms of rock fragmentation is about 40ms. This delay time just falls into the range larger than 7 ms determined previous by the improved linear superposition method. Therefore, by comprehensively considering both the results of Monte Calo simulation of blasting vibration and the rock fragmentation tests, the optimal delay time of the mine can be finally selected as 40 ms.

The building to be demolished was a framework-tube structure with high structural strength and good stability. It was located in a densely populated area with a complex surrounding environment. To determine a reasonable blasting demolition plan, the “three-dimensional gradual detonation” method was proposed, which was a way of detonation that achieves spatial delay by differentiating the delay time of adjacent blasting column holes in the horizontal and vertical planes of the blasting notch. Then, ANSYS/LSDYNA finite element software was used to simulate and analyze three different blasting schemes: V-shaped detonation, symmetrical detonation, and “three-dimensional gradual detonation” with a delay time of 0.50 s. By comparing the shape and range of blasting muck pile, and energy changes when the structure touches the ground, the blasting scheme “three-dimensional gradual detonation” with a delay time of 0.50 s was finally determined. The results showed that compared with symmetrical detonation, the “three-dimensional gradual detonation” reduced the kinetic energy when the structure touched the ground by 50% and increased the internal energy by 47%. Compared with V-shaped detonation, the kinetic energy when the structure touched the ground was reduced by 36%, and the internal energy was increased by 31%. The use of “three-dimensional gradual detonation” reduces the collapse vibration of the structure and completely disintegrates it, reducing the range of the blasting muck pile. When the delay time is 0.50 s, the width and length of the blasting muck pile and the collapse vibration of the structure are smaller than when the delay time is 0.25 s. The numerical simulation time for the upper part of the structure touching the ground was 3.8 s, while the actual time was 4.0 s. The final formation of the blasting muck pile was at 6.0 s, and the numerical simulation of the building collapse process and the range of the blasting muck pile was in basic agreement with the actual blasting effect.

Taking the “6·13” major gas explosion accident in Shiyan as the research object, this work constructed an accident investigation technique integrating scene investigation, interview and inquiry, numerical calculation and theoretical analysis. During the scene investigation, it was found that a section of DN57 mm medium pressure natural gas pipeline remained in the river below the southeast corner of the market. The pipe was adjacent to the domestic sewage drainage outlet, and it was rusted and partially ruptured due to the long-term wet environment. Meanwhile, yellowish natural gas fume was first found in the river at the southeast corner by video monitoring, visits and inquiries from surrounding residents, which led to the result that the aforementioned pipeline was the leak point. In addition, some merchants were engaged in flame operations before the accident. Some sparks entered the river through the smoke exhaust pipe and ignited the premixed combustible gas accumulated in the river, which resulted in the explosion. A numerical model of the river was established by the ANSYS/FLUENT software, and the volume of the natural gas accumulated in the riverway was 600 m³, which explosive TNT equivalent was 225 kg. The gas volume and explosion equivalent are consistent with the data published in the accident investigation, which proves the feasibility of this analysis method.

When excavating a tunnel in a gently sloping strata, serious overcut and undercut problems occur in various parts of tunnel blasting construction due to the existence of horizontal weak interlayer. Based on the project of Baoanying tunnel of Chengdu-Kunming Railway which passes through horizontal sand-shale interlayers, LS-DYNA software is used to simulate the blasting effect with different layer thicknesses to propose reasonable blasting control parameters. And the reliability of the parameters is verified by field blasting tests. The main research results are as follows: (1) When blasting excavation in a horizontal rock layer, the damage range of rock mass along the horizontal direction is large with long cracks, especially at the junction of sandstone and shale. On the contrary, the damage range along the vertical direction, with a small explosive energy utilization rate. (2) The blasting effect of horizontal sand-shale interlayered surrounding rock is significantly affected by hole spacing and the thickness of soft shale. When the thickness of shale interlayer is thin, smaller hole spacing should be selected. With the increase of the shale interlayer thickness, the controllable cracks can be effectively generated by arranging the hole spacing and empty holes to achieve a better smooth blasting effect. (3) The optimal hole spacing of the surrounding rock blasting with different thickness of sand-shale interlayer is determined. When the shale thickness is 5 cm, 10 cm, 15 cm, 20 cm and 30 cm, the optimal hole spacing is 42 cm, 46 cm, 50 cm and 54cm, respectively. At the same time, the position of the blast hole must be strictly controlled to reduce the blasting vibration as much as possible.

In the field of blasting work, stemming has a significant impact on the effectiveness and safety of blasting operations. To improve the blasting effect and reduce blasting costs, it is essential to determine the optimal length of stemming. This study uses a combination of explosion wave theory, theoretical mechanics, and LS-DYNA numerical simulation to analyze the impact of stemming length on blasting effect, which is then validated through field experiments. The study results indicate that when the blast hole depth is between 0.6 m and 1.4 m, the optimal stemming ratio is between 0.38 and 0.54, and with an increase in blast hole depth, the optimal ratio decreases. When the blast hole depth is between 1.6 m and 2.4 m, the optimal stemming ratio is between 0.36 and 0.38. If the blast hole depth exceeds 1.2 m, and the stemming length equals or exceeds half of the blast hole depth, a detrimental effect may occur. The radial uncoupling coefficient R exerts a significant effect on the optimal stemming length. When R is less than or equal to 1.8, the optimal stemming length decreases with an increase in R. However, when R is greater than 1.8, the optimal stemming length remains unchanged. Additionally, field experiments were conducted at the Wangcun Coal Mine Limited Liability Company 8107 return airway, including tests on 1.2 m and 2.2 m cut holes and a 2.0 m auxiliary hole. The optimal stemming lengths were found to be 50 cm, 90 cm, and 80 cm, respectively, which aligns with the results of theoretical calculation and numerical simulation.