This study focuses on the impact of charge structure on the distribution of blast pile morphology in a limestone mine. A combination of theoretical analysis, GDEM-BlockDyna numerical simulation, and on-site optimization tests were conducted to investigate the morphological distribution of step blasting and blast reactors. The change in blast pile morphology with different charge structures was analyzed. The results indicate that the looseness and throwing distance of the blast pile initially increase and then decrease with an increase in the upper charge proportion of the interval section. The height of the explosion pile generally decreases but shows an initial decrease followed by an increase when there is a large air interval proportion. Additionally, the slope angle of the blast pile increases with an increase in charge proportion in the upper section of the interval section but decreases when this proportion becomes too large. These findings demonstrate that explosive pile patterns vary according to charge structure. Furthermore, through numerical simulation methods, effective optimization can be achieved for charge structure, leading to improved on-site explosion patterns and economic benefits for mining operations.

Due to the limitations in construction scope, blasting a medium-section tunnel is challenging as it often results in short circular footage and significant over and under excavation. To reduce costs and increase efficiency, it is essential to focus on long footage excavation and fine control of over and under excavation. In this study, a straight hole cutting blasting scheme was designed for a medium section tunnel project and 40 cycles of blasting excavation field tests were conducted. The results revealed that when designing the long footage blasting parameters for a medium section tunnel based on the blasting design manual, issues such as high block rate and uneven face frequently arise. However, by appropriately increasing the charge of the cut part (the proportion of charge of the cut part increased from 12.8% to 18.1% in our field test), better blasting effects were achieved. Additionally, by reducing the charge amount of peripheral holes and adjusting their distance from each other, smooth blasting effect was effectively ensured. During the field test, adjustments were made to the charge amount of peripheral holes based on preliminary design for blasting parameters. This resulted in good contour forming effects with a half-hole rate exceeding 90%. However, an average overcutting value of 18.6 cm was observed across all 40 excavation sections during the blasting cycle. The main cause for this overcutting was identified as platform irregularities along the contour line. To address this issue, it is necessary not only to reduce external drilling angles but also control platform width alongside reasonable parameter designs for surrounding holes. The straight hole cutting scheme proved compatible with three-arm rock drilling truck construction methods while enabling mechanized long-shot blasting excavations. Nevertheless, precise control over overcutting and undercutting remains challenging along with cost management during blast construction. It is necessary to optimize and improve the operation technology of drilling personnel and the management mode of site construction.

In urban centers, there are numerous old masonry buildings that possess poor seismic performance and may suffer damage under the effects of blasting. To investigate the dynamic characteristics of these structures when subjected to blasting, a strong motion instrument was installed near a blasting site on an old masonry building. This allowed for observation of both instantaneous and cumulative damage effects on the structure. By analyzing records of blasting acceleration and velocity in both time and frequency domains, it is concluded that the dynamic characteristics of the masonry structure can be better identified using blasting velocity rather than acceleration. Additionally, it is found that the transverse resonance of the masonry structure is most influenced by the blasting seismic velocity. Furthermore, both blasting seismic velocity and acceleration can approximately identify low order translational and torsional frequencies of the masonry structure. However, when calculating natural vibration frequency, it is observed that using blasting velocity yields a lower value (1.8%~3.4% lower) compared to calculations based on ground pulsation methods. This discrepancy arises because blast vibrations provide a more accurate reflection of structural response under larger vibrations. Moreover, frequent blasts may induce nonlinear responses in old masonry structures. By monitoring changes in natural vibration frequency over time due to long-term exposure to blasts, it is determined that with increasing blast frequency, first-order torsional frequency decreases by 4%, second-order transverse frequency decreases by 3.6%, and second-order longitudinal frequency decreases by 5.2%. These reductions occur even though individual blasts meet safety regulations, thus highlighting the importance of considering cumulative damage effects from long-term exposure to blasts for old masonry structures with poor seismic capacity during safety monitoring.

In order to study the vibration response of the interlaid rock in the small clear distance tunnel under the blasting load, a field blasting vibration test was carried out based on the blasting project of the Xiaolongmen tunnel. The improved variational mode decomposition (VMD) and multi-scale permutation entropy (MPE) algorithm were employed to denoise the blasting vibration signal. Subsequently, the differences in vibration characteristics between the left arch waist (non-interlaid rock area) and right arch waist (interlaid rock area) of the tunnel were analyzed, along with a comparison and analysis of seismic wave attenuation characteristics generated by cut hole blasting and surrounding hole blasting. The results demonstrate that the improved adaptive VMD-MPE algorithm enables automatic determination of modal number K and penalty factor α while effectively eliminating noise from the vibration signal, reducing subjective decision-making influence. During posterior excavation tunnel face blasting, interlaid rock exhibits significant amplification effects on blast vibrations. Peak particle velocity (PPV) values are higher in interlaid rock compared to non-interlaid areas. However, vibrations attenuate faster within interlaid rock regions. Additionally, analysis reveals that low-frequency vibrations below 40 Hz account for a substantial proportion of energy within interlaid rock areas when comparing frequency characteristics at measuring points between non-interlaid and interlaid regions. Attention should be given to these low-frequency vibrations as they are more likely to induce resonance in supporting structures, posing higher risks of damage or destruction within interlaid rock zones. By analyzing the blasting vibration characteristics of the cut hole and the surrounding hole, it can be found that the vibration velocity generated by the surrounding hole blasting in the surrounding rock behind the tunnel face is greater than that of the cut hole blasting within the range of the scale distance (SD) which is less than or equal to 11.57 m kg^1/3 due to the effect of 'corner weakening' and the influence of the seismic wave propagation path. After exceeding the critical value of SD, the vibration velocity generated by the cut hole blasting is greater.

In response to the poor excavation effect of traditional blasting in complex lithology tunnels, a method called advanced cutting control blasting is proposed based on the research of traditional smooth blasting and pre-splitting blasting. This method involves conducting the blasting around weak surrounding rock areas after tunnel contouring hole blasting. A quasi-three-dimensional model was established, and numerical simulations were conducted using the fluid-structure interaction (ALE) algorithm and ANSYS/LS-DYNA finite element analysis software to compare the advanced cutting control blasting method with traditional pre-splitting and smooth blasting methods. The results show that compared to smooth blasting and pre-splitting, advanced cutting control blasting reduced the depth of damage around the tunnel contour by 6.85% and 10.08%, respectively. Based on simulation results, field blast test plans were designed, and comparative tests between smooth surface blasting and advanced cutting control blasting methods were carried out. The blast results demonstrated that after adopting the advanced cutting control method, the tunnel contour had good shaping effects without block falling or collapse in weak surrounding rock areas, while over-excavation was effectively controlled. Three-dimensional cross-sectional scanning data and statistical results of post-blast sections indicated that compared to well-performing smooth surface blasting, maximum over-excavation decreased by 35.98%, average over-excavation decreased by 25.60%, concrete consumption decreased by 26.3%, and flatness standard deviation increased by 24.29%. This method has been verified through field practice as it reduces over-excavation while mitigating blast damage in complex lithology areas, thereby improving tunnel retaining rock flatness.

This study aims to investigate the stability evolution of the safety roof pillar during the transition from open-pit to underground mining in Longshou mine under the influence of blasting vibration. A numerical calculation model was established based on the current mining area conditions. The most critical position of the safety roof pillar was determined through calculations, and a two-dimensional numerical model for this position was developed using top-level mining as an example. By calculating blasting parameters and equivalent elastic boundaries, we obtained the peak blasting load transmitted from cutting holes, auxiliary holes, and peripheral holes to the excavation surface. Subsequently, numerical calculations were conducted to assess the stability of the safety roof pillar after applying an equivalent blasting load to the excavation face. The results indicate that each delayed blast caused displacement and vibration velocity peaks, with maximum displacement observed at monitoring points inside the safety roof pillar closest to the blast site. Vibration velocity spreads spherically around the blasting operation position into surrounding rock mass. Based on criteria related to blasting vibration velocity and rock damage assessment, it can be concluded that overall there is no or only slight damage present in the safety roof pillar. Additionally, analysis reveals that maximum principal stress remains lower than tensile strength of rock mass without any significant formation of a tensile fracture plastic zone on the safety roof pillar. In general, the designed thickness of the safety roof pillar meets requirements for open-pit to underground mining. However, due to actual geological complexities beyond what is captured by the numerical model, it is essential to continuously observe and monitor changes in the safety roof pillar to ensure its stability during ongoing mining operations.

In order to address the problem of predicting blasting vibration in complex geological conditions at open-pit mines, an improved BP neural network prediction model based on Mahalanobis distance discrimination (MD) and principal component analysis (PCA), namely MD-PCA-BP model, is proposed. By combining the monitoring data of blasting vibration at Changtan open-pit mine in Inner Mongolia, outliers in the monitoring data are eliminated using the Mahalanobis distance discrimination method. Then, the principal component analysis method is employed to reduce the dimensionality of factors affecting blasting vibration and obtain three principal component factors. The scores of each principal component factor are calculated, and finally a nonlinear relationship between blasting vibration and principal component scores is constructed through BP neural network to establish the prediction model based on MD-PCA-BP. The results show that the fitting degree between predicted values and measured values of blasting vibration velocity prediction model established based on MD-PCA-BP reaches 0.94, indicating high prediction accuracy of this model. When compared with Sadovsky empirical formula, two improved elevation empirical formulas, MD-BP model, PCA-BP model, and BP model, most of the prediction errors of MD-PCA-BP model are within 10%, demonstrating higher reliability and accuracy compared to empirical formulas and unimproved BP prediction models. The blast vibration prediction model based on MD-PCA-BP exhibits good predictive performance for blast vibration velocity in complex terrains.

In order to demolish a 57 m high double-cylinder ammonium nitrate granulation tower in a complex environment, this study analyzes the structural characteristics of the tower, including its large potential energy and uneven mass distribution. A blasting method was designed with intermediate initiation and sequential detonation towards both sides to achieve a controlled collapse effect through “directional blasting + internal convergence”. The blasting design includes trapezoidal cut notches with strictly controlled perimeter and height. The bottom supporting walls are partially retained, and highly symmetric directional windows were created at specific heights. The demolition was carried out using high-precision nonel detonators combined with delayed initiation inside the holes and external relays outside the holes. Through theoretical analysis and calculations, the final blast notch length was determined as 13.5 m with a height of 3.5 m. To validate the design scheme, LS-DYNA simulation software was used to establish a three-dimensional finite element model of the granulation tower for pre-collapse analysis. Simulation results show that the collapse process takes approximately 8.8 seconds without any significant forward movement or toppling during collapse, indicating that the overall blasting parameters selected in this scheme are reasonable and can achieve the desired demolition effect.

The shock wave generated by underwater explosions has a significant destructive impact on the surrounding environment. Therefore, it is crucial to implement bubble curtain protection for blast area safety. This study aims to investigate the influence of the number of bubble curtain layers on attenuating underwater explosion shock waves. An underwater explosion model with free water and varying numbers of bubble curtain layers was established using AUTODYN finite element software. Through experimental validation of the numerical model, a formula for calculating peak overpressure of the shock wave was derived, and the impact of different numbers of bubble curtain layers on shock wave attenuation in water was compared. The results demonstrate that employing a bubble curtain can effectively reduce peak overpressure from an underwater blast shock wave, achieving an attenuation ratio as high as 83%. Furthermore, increasing the number of bubble curtain layers can further enhance this attenuation effect, reaching more than 94% reduction in peak overpressure. Specifically, when comparing two-layered and one-layered bubble curtains at a distance of 12 m from the detonation center behind the bubble curtain, there is a reduction in peak overpressure by 61.94%. Similarly, using a three-layered bubble curtain leads to an additional decrease in peak overpressure at this distance by 11.38% compared to using a two-layered one. However, when utilizing four-layered curtains instead of three-layers ones, there is only a marginal decrease in peak overpressure (6.42%) at this same distance. In conclusion, implementing a bubble curtain significantly weakens shock waves within water bodies during explosive events. Moreover, fewer layers within the bubble curtain result in greater attenuation effects. However, diminishing returns are observed with each subsequent increase in layer count.

Due to the complex terrain and geological conditions in the blasting area, as well as errors in monitoring instruments, reflections of vibration propagation medium, and interference from magnetic fields, a significant amount of noise is often present in the original blasting vibration signals collected. To address this issue, a signal noise reduction smooth model based on complementary ensemble empirical mode decomposition (CEEMD) is proposed. Firstly, the measured blasting vibration signal is decomposed using CEEMD and an algorithm for low-pass filtering is established based on the obtained intrinsic mode function (IMF) component from the decomposition. Additionally, an objective function is constructed to calculate the optimal solution according to similarity and smoothness criteria for filtering algorithms. The resulting filtering algorithm model represents an optimal denoising smooth model for blasting vibration signals. To verify our noise reduction smooth model, a simulation signal is constructed and applied to actual open-pit deep-hole blasting vibration signal research. Finally, the noise reduction effects of empirical mode decomposition (EMD) method, wavelet threshold method, CEEMD-wavelet threshold method, and filter algorithm model BP3 are quantified and compared using two indexes: signal-to-noise ratio and root-mean-square error. It has been confirmed that the proposed noise reduction smooth model effectively reduces noise in open-pit blasting vibration signals. The findings demonstrate that our CEEMD-based noise reduction smooth model for open-pit deep-hole blasting vibrations possesses excellent denoising capabilities while preserving essential characteristic information from the original signals. Furthermore, the denoising effect of the proposed model surpasses that of EMD method, wavelet threshold method, and CEEMD-wavelet threshold method.