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Seismic monitoring is recognized as an effective tool for investigating rock bursts in coal mines; however, a universally accepted and rational assessment method for the detection capabilities of coal mine seismic monitoring systems has yet to be established. A method based on event energy has been developed to evaluate the monitoring performance of a mine seismic network. Utilizing statistical principles, this methodology quantifies the detection capabilities of individual seismic stations in mine monitoring and provides a comprehensive assessment of the overall network monitoring quality in critical surveillance areas. This is achieved by considering the detection probability of fixed-energy events and the minimum integrity energy across the entire seismic network. Experimental trials were conducted at the Dongtan Coal Mine, where a seismic network was established. A comparison of detection probability maps for different stations revealed performance variations under various energy and distance conditions. The overall detection capability of the network for the critical monitoring area, specifically the 6306 longwall, was calculated and validated using blasting test data. The experimental results demonstrate the successful application of this new method in practical mine environments, with potential advancements in the technology of mine seismic source monitoring for both academic and engineering practices. Highlights: Utilizing a novel evaluation criterion based on energy and distance to calculate the detection capability of individual stations. Employ rationalization methods to enhance the credibility of computational results from a single station. Introducing two new indicators, namely the Minimum Integrity Energy and the detection probability for fixed energy, to assess the detection capability of the seismic network. [ABSTRACT FROM AUTHOR]

Nowadays, open-pit mining is the large-scale extraction of valuable ore materials from the surface with the use of modern mining equipment. If not operated properly, various unexpected events, such as equipment breakdown, slope collapse, hazardous gas emission and land pollution, would occur. With the rapid development of computer technology and big-data science, emerging applications of machine learning could significantly improve mining predictability, feasibility, efficiency and sustainability. However, there is still a lack of up-to-date systematic literature reviews on applications of machine learning to open-pit mining. To address this issue, this study reviews over 200 relevant papers mainly published in the last five years. In this review, we initially conduct a descriptive statistical analysis of these papers according to different phases in open-pit mining. Consequently, we classify their research findings into four main categories: exploration, exploitation, production and reclamation. In addition, each main category is further divided into some sub-categories, namely, feasibility evaluation and mine design planning in exploration; mine block sequencing in exploitation; drilling, blasting, haulage and processing in production; waste control and environmental protection in reclamation. Based on such a bi-level classification, we systematically summarise promising machine learning techniques (i.e. reinforcement learning and deep reinforcement learning) and potential research opportunities (e.g. integration of machine learning and simulation for mining equipment scheduling) in real-world implementations for the mining industry. [ABSTRACT FROM AUTHOR]

Copyright of Industrial Minerals & Processing / Huagong Kuangwu yu Jiagong is the property of Industrial Minerals & Processing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To address the challenges faced by coal miners when encountering collapsed pillars in local hard rock formations, we researched ultra-deep hole loosening blasting technology. To overcome issues related to the inapplicability of existing blasting zoning theories and the lack of a solid foundation for borehole design in ultra-deep hole loosening blasting sites, we introduced a blasting zoning model and theoretical calculation formula based on thick-walled cylinder theory. Building on this foundation, we proposed coupled and uncoupled charge calculation methods that take into account strain rate variations and confining pressure effects. Furthermore, numerical simulations using the ANSYS/LS-DYNA software demonstrated that the results obtained from this theory were consistent with the simulation results. Ultimately, based on the blast zone results derived from both theory and simulation, we determined the blasting range of individual blast holes to design effective construction plans for ultra-deep hole blasting sites, achieving satisfactory results. [ABSTRACT FROM AUTHOR]

Accurately control the release of explosive energy is critical, the number of slit charge is the key to control the precise release of explosive energy. By carrying out model experiments and LS-DYNA finite element numerical calculations on glauconite, the experiment results showed that, compared with that of the non-slit charge, the slit charge in the glauconite specimens was able to produce directional penetration through the blast fissure surfaces in the direction of the slit. Triple slit charge can control energy release while further reducing the impact of explosion energy on surrounding rock. [ABSTRACT FROM AUTHOR]

Due to the extensive use of explosives, the failure to identify hazards and assess risks in blasting may lead to catastrophic consequences. However, classical risk assessment approaches are limited in their ability to address ambiguity and uncertainty, as well as in assigning weights to the criteria involved in the risk assessment process. This study employs a multi-criteria decision-making system to address these limitations and assess the risks associated with blasting. The proposed model integrates Grey Relational Analysis (GRA) to prioritize risks and the Fuzzy Best-Worst Method (FBWM) to assign weights to the criteria critical to the risk assessment process. The findings indicated that "not using personal anti-static protection devices during blasting (R12)", "placing the explosive fuse near explosive materials (R15)", and "bringing explosive materials to the explosion site before completing drilling and blasting operations (R23)" were the most significant blasting risks, respectively. These risks stem from operational processes, human factors, and the working environment, thus requiring special attention. The weighting of the study criteria, including Consequence (C), Probability (P), and Exposure (E), revealed that the C criterion, with a final weight of 0.538, was the most influential in the risk assessment process. The P and E criteria, with weights of 0.294 and 0.167, respectively, ranked second and third in importance among the assessment criteria. To ensure the applicability and accuracy of the proposed method, a validation study comprising two distinct parts—sensitivity analysis and comparative analysis—was conducted. The results of these evaluations highlighted the appropriate and reliable performance of the proposed approach. This approach can assist decision-makers, managers, and risk analysts in more accurately identifying and assessing risks by addressing some of the limitations inherent in classical risk assessment methods. [ABSTRACT FROM AUTHOR]

This study investigates the superposition law of blasting damage between double cylindrical charges in PMMA through laboratory experiments and numerical simulation. The results showed that the evolution of blasting damage is consistent with fractal law. For a single cylindrical charge, the crushing area is distributed throughout the charge section, whereas the stemming section consists primarily of sparse cracks and contains no crushing area. The blasting damage peak between double cylindrical charges is concentrated between 5 and 12.5 times the borehole's diameter from the initiation point. The distance between the boreholes does not affect the damage pattern between double cylindrical charges. [ABSTRACT FROM AUTHOR]

This study investigates the control mechanism of blasting damage to surrounding rock and conducts a quantitative evaluation of the damage using laboratory experimentation and field test. A comprehensive evaluation system of blasting damage for roadway contour quality and internal damage of surrounding rock is established using digital image processing, multifractal spectrum calculation, CT scanning, borehole televiewer, and acoustic testing. The results show that the evolution of blasting damage conforms with fractal law, and the relationship between blasting damage area and fractal dimension follows a power function. Slit charge blasting causes the initiation and propagation of two straight main cracks along the slit. The peak velocity measured at the center of the slit charge is found to be 1.74 times that of the ordinary charge. The slit charge can effectively reduce the blasting damage. [ABSTRACT FROM AUTHOR]

AbstractSubsea tunnels are different from mountain tunnels in many aspects. During the construction process using drilling and blasting methods, there are complex environments such as unlimited seawater replenishment and complex geological structures that pose serious challenges to construction safety. In order to more accurately assess the safety of subsea tunnels so as to reduce the probability of disasters, this article proposes the characteristic indicators of “overburden thickness/depth of overlying seawater” (RSR) for subsea tunnels, and combines cloud model theory with Bayesian networks to establish a risk assessment method for subsea tunnel collapse. Taking the Jiaozhou Bay Second subsea tunnel as an example, prior risk reasoning and ex-post risk diagnosis are carried out. The maximum disaster risk section of the tunnel has been determined, and the key influencing factors of the collapse risk of the subsea tunnel have been identified, providing assurance for construction safety. The main contributions of the research results are as follows: (a) analyzed the factors affecting the risk of subsea tunnel; (b) the characteristic indicator for subsea tunnel collapse risk assessment was proposed; and (c) combined the Bayesian network and cloud model, and established the risk assessment method of subsea tunnel by drilling and blasting method. [ABSTRACT FROM AUTHOR]

Stemming of blast holes is an essential operation for controlled explosions, serving the purpose of filling the voids left after loading with explosives. This process prevents the escape of gases produced during the explosion, which have a pressure of around 10,000 daN/cm², and enhances the breaking effect while reducing dust and noise. Efficient use of stemming can significantly reduce the consumption of explosives and, consequently, the costs of rock fragmentation through drilling and blasting operations, allowing a reduction in explosive consumption by 20-25%. Furthermore, improper stemming of blast holes results in low breaking efficiency, large material granulation, misfires, and, in other words, increased costs for drilling, blasting, and crushing operations, as well as potential accident hazards due to misfires. In this article, we will explore the materials used for stemming, the technologies employed, and improvement proposals to maximize the efficiency and safety of mining operations, leading to more efficient and safer use of explosives in rock fragmentation operations, enhancing breaking efficiency while reducing associated costs and risks. [ABSTRACT FROM AUTHOR]

The basic principles for the design of the parameters of the shooting techniques are: the exact definition of the technical and economic objectives and especially those related to the granulometry of the demolished material, knowledge of the characteristics of the rock massif (degree of cracking and local fracturing, compressive and tensile strength of the rocks, the degree of homogeneity and their compactness), knowing in detail the possibility of executing the firing holes for loading and crushing the demolished material, knowing the explosive used and its behavior in the concrete conditions of the quarry, specifying the restrictions imposed by the protection of the environment (distances from the surrounding objectives, the maximum accepted levels of vibrations, noises, dust). In order for all these principles to be fulfilled, there are methods of designing and executing the drilling and shooting works so that the results of the shooting works are those expected in conjunction with a rational exploitation in safe conditions. The paper presents a case study where the design and execution of drilling and blasting parameters was successfully applied using modern equipment. [ABSTRACT FROM AUTHOR]

The application of blasting in modern engineering construction is prized for its speed, efficiency, and cost-effectiveness. However, the resultant vibrations can have significant adverse effects on surrounding buildings and residents. The challenge of optimizing blasting procedures to satisfy excavation needs while minimizing vibration impacts is a critical concern in blasting excavation. This research addresses this challenge through the development of a 3D simulation and analysis model for an underground pumped storage power plant in East China, utilizing the LS-DYNA finite element analysis software. To explore the influence of charging structures on rock fragmentation and vibration propagation, three distinct blasting programs were formulated, each featuring varied configurations within the machinery room. The analysis revealed that the adoption of an optimized charging structure can significantly decrease damage to the protective layer by approximately 40%, while also reducing the impact on the upstream and downstream side walls by 27.25% and 12.03%, respectively, without compromising the efficacy of the main blast zone. Moreover, the vibration velocities at the remote measurement point were found to be reduced across multiple directions, indicating effective control of the vibration effects. The post-implementation of the optimized blasting strategy at the site, the assessment of the retained surrounding rock integrity, and the impact on protected structures demonstrated that the proposed solution met satisfactory outcomes. This study underscores the potential of simulation-based optimization in managing vibration risks during blasting operations, offering a valuable tool for engineers and practitioners in the field of underground construction. [ABSTRACT FROM AUTHOR]

As the electronic detonators can control the detonation error within 1 ms, short-delay blasting was nowadays proposed to replace multi-hole simultaneous blasting to reduce the vibration hazards. In this study, the Heelan model was used to study blast-induced vibration of short-delay cylindrical charges. The influence of delay time on the vector peak particle velocity (VPPV) of superimposed vibration waveforms was analyzed and the calculating formula of the shortest delay time between adjacent holes based on vibration reduction was established. It is found that as the delay time increases, the overlapping area of VPPV becomes further away from the explosion source. The main influencing factors for the shortest delay time between holes include the distance between the monitoring point and the explosion source, the difference between P wave and S wave velocities, and the duration of S wave in the first and second explosion holes. As the distance from the explosion source increases, the shortest inter hole delay time based on vibration reduction also increases. The research results have guiding significance for the control of blasting vibration in underground mines. [ABSTRACT FROM AUTHOR]

In the context of heightened safety concerns and the intricate nature of geological structures in coal mining, accurately localizing microseismic events is a critical challenge. This paper introduces the LGF SeismoLocator, a novel deep learning model tailored to enhance the precision of seismic source detection within coal mines. By innovatively combining long short-term memory networks (LSTM), graph convolutional networks (GCN), and fully convolutional networks (FCN), and utilizing 3D Gaussian distributions as labels, this model demonstrates remarkable capabilities in processing complex seismic data. When tested with microseismic events from the Dongtan Coal Mine, the LGF SeismoLocator exhibited superior accuracy in event localization and computational efficiency. Its effectiveness was further validated through controlled blasting experiments. This study not only highlights the potential of deep learning to improve microseismic monitoring but also provides a practical solution for mitigating risks associated with rockbursts and other mining-related hazards. Highlights: Introduction of the LGF SeismoLocator, a novel deep learning model designed for microseismic event localization in coal mines with enhanced accuracy. Integration of LSTM, GCN, and FCN to enhance the accuracy and efficiency of microseismic localization, demonstrating superior performance in processing complex seismic data. Validation of the LGF SeismoLocator's effectiveness through testing against microseismic events from the Dongtan Coal Mine and controlled blasting experiments. [ABSTRACT FROM AUTHOR]

The prediction of rock fragmentation (Fr) is highly beneficial to the optimization of blasting operations in the mining industry. The characteristics of the rock mass, the blast geometry, and the explosive qualities are the primary elements influencing Fr. The methodical explosion of explosives within a rock mass results in the production of smaller rock pieces. This work is a step toward the prediction of the degree of Fr in opencast mining using advanced soft computing (SC) methods like: back propagation neural network (BPNN), k-nearest neighbor (KNN), multilayer perceptron (MLP), radial basis function (RBF), multi-variable regression (MVR), gene expression programming (GEP), Takagi-Sugeno fuzzy model (TSF), least-square-support vector machine (LS-SVM), and support vector machine (SVM). A dataset consisting of 219 blasting events with 10 influencing parameters: hole diameter (HDM), spacing (S), burden (B), maximum charge per delay (MCPD), stemming (ST), compressive strength (CS), powder factor (PF), specific drilling (SPD), number of holes (NH), and bench height (BH), were used in the present study. All models were assessed with the help of following performance parameters: RRSE, RSE, NRMSE, RRMSE, MAD, MAPE, MSE, RMSE, and R2. Based on loss function for Fr, scattered diagram, importance ranking, sensitivity analysis, rank analysis, and violin plot the top models were chosen. From the obtained results, it is seen that SVM produce better result compare to other models when predicting the Fr of rock. Under sensitivity analysis, spider diagrams and Tomado diagrams were plotted to determine the variation of input and output factors. The sensitivity analysis of the developed model shows that HDM has the least impact, whereas the parameters B and PF have the maximum impact on the Fr of rock. [ABSTRACT FROM AUTHOR]

Optimizing blasting parameters is of paramount importance in minimizing overbreak during tunneling. Hence, this paper proposed an intelligent approach, which integrates separate parameter optimization based on varying rock mass qualities, with the objective of reducing overbreak. This novel intelligent method constructs a comprehensive model with three distinct functions, which can provide precise overbreak prediction, analyze the mechanisms by which input parameters influence overbreak, and integrate feature importance into the blasting parameters optimization process. First, the hyperparameters of seven tree-based algorithms were optimized using the Sparrow Search Algorithm (SSA), and the best predictive model was selected by comparing various performance metrics. Then, the importance and influencing mechanisms of input features on overbreak were revealed through the utilization of the Shapley Additive Explanation. Subsequently, interactions among crucial parameters were investigated, and their design values were recommended. Finally, a novel parameter optimization method was employed to reduce overbreak, which combines the conclusions drawn from the importance analysis of input features with SSA through three key steps: modification of the initial position, expanding the search scope, and neighborhood perturbation. Compared to the unimproved methods, the proposed approach can significantly reduce post-blast overbreak areas in different sections of the tunnel by 12.8 % and 16.4 %, respectively. • Predicted blast overbreak based on deep learning algorithms. • Stabilized importance analysis results of input parameters. • Revealed influencing mechanisms of overbreak via SHAP. • Incorporated feature importance with parameter optimization. [ABSTRACT FROM AUTHOR]

By integrating an established rock damage model into the LS-DYNA computer code and using a widely used method for equivalently simulating multiple blastholes detonation, the damage processes of surrounding rock with different properties under the bench blasting of a large cross-section tunnel are comparatively studied. The damage distribution across the excavation cross-section is characterized by greater damage at the upper and lower ends, with lesser damage in the middle (junction between adjacent benches). For grade III surrounding rock excavated with two-bench blasting, the maximum damage depth of 3.6 m occurs in the middle floor. For grades IV and V surrounding rock excavated with three-bench blasting, the maximum damage depths both occur at the vault, with 3.6 m and 2.5 m, respectively. In bench blasting, the blasting of breaking holes closest to the excavation boundary significantly impacts surrounding rock, whereas the damage caused by smooth holes blasting is minor. The surrounding rock with poorer mechanical properties tends to exhibit greater damage under the same blasting operations. According to the proposed method, the critical Peak Particle Velocity (PPV) for cumulative damage in grades III, IV, and V surrounding rock of the Longnan tunnel is 16.8 cm/s, 13.7 cm/s, and 11.5 cm/s, respectively. [ABSTRACT FROM AUTHOR]

Copyright of Revista Foco (Interdisciplinary Studies Journal) is the property of Revista Foco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Chinese Journal of High Pressure Physics is the property of Chinese Journal of High Pressure Physics Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Slopes are formed as a result of mining operations. These slopes are classified as artificial slopes. Improper planning of slopes can lead to instability and potentially trigger landslides. PT. Allied Indo Coal Jaya employs the open-pit mining method in its coal mining operations. Slopes are naturally formed in open-pit mines. Additionally, PT. Allied Indo Coal Jaya utilizes blasting for rock demolition. Therefore, it is crucial to assess the impact of blasting activities on slope stability. This study investigates the influence of blasting on slope stability in coal mines using the limit equilibrium method (LEM). The study evaluates the effects of factors such as ground vibration, blast distance, and blast hole count on the factor of safety (FoS) of slopes. The limit equilibrium method (Fellenius, Bishop, Janbu, Spencer, and Morgenstern-Price) is employed to determine the factor of safety. The factor of safety is modeled using RocScience SLIDE version 6.0 in this study. The factor of safety (FoS) is defined as the ratio of the stabilizing force to the destabilizing force acting on the slope. This study also models the influence of ground vibration, distance, and total number of blast holes on the factor-of-safety (FoS) value. The results indicate that the slope remains stable both pre- and post-blasting, with an overall FoS value greater than 1 for the five slopes examined using various limit equilibrium method (LEM) techniques. However, the FoS value decreased prior to blasting due to the impact of ground vibration and blast distance. It is evident that the ground vibration (PPA) increases with the number of blast holes. The amount of ground vibration decreases as the number of blast holes increases. An increased number of blast holes leads to a decrease in the FoS value. The observed decline in slope FoS values and the increase in PPAs is attributable to the growing number of blast holes. The type of explosive, along with its power and rate of detonation, influences the amount of energy produced, which in turn affects the degree of ground vibration. The findings indicate that the slopes remain stable (FoS > 1) both before and after blasting, although blasting slightly reduces the FoS. The study reveals that as the number of blast holes increases, both ground vibration (PPA) and the reduction in FoS increase, underscoring the effects of explosive power and detonation rate on slope stability. [ABSTRACT FROM AUTHOR]

In the blast phenomenon, the explosives release a lot of energy, which causes damage and fractures the rock mass. One of the influencing parameters in the blasting results is the way the blast hole is charged. Power Deck blasting has been introduced as a blasting method to reduce or eliminate sub-drilling, optimize crushing, and reduce undesirable results. The purpose of this research is to investigate the impact of the Power Deck blasting method on the borehole pressure and damage to the rock mass compared to the conventional method. In this regard, the numerical simulation of a single blast hole was carried out using conventional and Power Deck methods by using LS-DYNA software. The results showed that in the Power Deck method, in the area of the air deck, the initial pressure of the hole is reduced compared to conventional blasting, and secondary pressures are produced, which leads to a reduction in the expansion of the hole along the air deck by 45% and increases the destruction in multi-stage. On the other hand, the generation of secondary pressures in the Power Deck method causes a 30% and 48% increase in rock mass destruction in the area of the bottom of the hole compared to the conventional method. As a result, the Power Deck blasting method improves the amount of expansion and destruction by using less explosive, which indicates the optimal use of the explosive energy. [ABSTRACT FROM AUTHOR]

Placing empty holes between charging holes is widely used in blasting engineering to achieve directional fracture blasting. Studies have shown that the presence of a notch along the empty hole wall enhances stress concentration and supports improved control over crack propagation. The notch angle and length are the two main parameters influencing the impact of notch holes. Therefore, in this study, we used numerical simulations to investigate how varying notch angles and lengths influence the directional fracture blasting effect. The findings suggest that, among the different types of holes used in directional fracture rock blasting, notched empty holes have the most significant guiding effect, followed by empty holes, while the absence of empty holes yields the least effective results. In the directional fracture blasting of a notched empty hole, stress concentration occurs at the notch tip following the explosion. This alters the stress field distribution around the empty hole, which shifts from a compressive to a tangential tensile state. Additionally, this concentration of stress causes the explosion energy to be focused on that location, resulting in a directional fracture blasting effect. In blasting construction, selecting the appropriate notch hole parameters is necessary to achieve optimal effects and reduce damage to surrounding rocks. Based on the notch parameters assessed in this study, the optimal effect of directional fracture blasting is achieved when the notch angle is 30°. [ABSTRACT FROM AUTHOR]

Burst morphology is a crucial indicator for evaluating the effectiveness of blasting, as it directly reflects the actual state of the blasting results. The results of rock displacement following blasting partially reflect the effectiveness of throw blasting, while the rock ejection process serves as the macroscopic manifestation of the blasting method. To accurately assess the impact of different delay times on burst formation, this study addressed the issues of rock movement and ejection in underground blasting. Using three-dimensional modeling, we constructed a FEM–SPH model and utilized LS-DYNA numerical simulation software to investigate the movement patterns of rock in precise delayed blasting scenarios underground. This study explored the spatiotemporal evolution characteristics of rock movement post-blasting. Digital electronic detonators were used to set precise inter-row delay times of 25 ms, 50 ms, and 75 ms. The results revealed that the ejection distance of blasted rock in underground mining increased with longer inter-row delay times, while the slope angle of the blasted muck pile decreased as the delay time increased. Furthermore, at a micro level, the study found that a 75 ms delay created new free surfaces, providing effective compensation space for subsequent blasts, thereby improving blasting outcomes. Analysis of the 25 ms and 50 ms delay periods indicated a clamping effect on rock movement. Field comparisons of blasting results were conducted to validate the influence of precise delay times on the movement patterns and spatiotemporal evolution characteristics of blasted rock. [ABSTRACT FROM AUTHOR]

When excavating tunnels and underground openings with the drill-and-blast method, minimizing excavation overbreak is vital, as it reduces the costs associated with excavation stability, mucking, and rock support. Overbreak in excavations not only causes safety concerns but also increases the cost of construction and completion time. This paper proposes a contour blasting design in which the parameters are optimized based on the rock's structural properties. Numerical modeling was used to identify the possible damage zones of rock with a change of the seismic load due to blasting. The results were used as input for the design of the proposed contour blasting with a low-brisance explosive. Experimental blasting tests were conducted at the Akbakai mine, located in Kazakhstan, and the performance of the design was examined. The proposed contour blasting was compared with the standard blasting method. The results indicated that the cross-section of excavation with the conventional blasting method varied between 10.5 and 12.1 m2, indicating an overbreak between 17 and 34%. However, with the suggested contour blasting, the overbreak was less than 13%. It was concluded that charging contour boreholes with low-brisance explosives is an effective method of reducing overbreak due to excessive explosive loads on the contour massif, which can improve the safety and profitability of mining operations. [ABSTRACT FROM AUTHOR]

During the mining process of open-pit mines, multiple operations are prone to generating dust, especially during the blasting, where a significant amount of dust is raised and subsequently deposited on the surface of the blast pile. The impact of the blasting force further saturates the interior of the pile with dust. Subject to the combined effects of natural wind and shoveling operations, this dust is re-suspended and disseminated throughout the mine pit, posing a significant threat to the safe operation of the mine and the health of workers. This study comprehensively utilizes field testing and numerical simulations to delve into the migration characteristics of blast pile dust under the combined influence of wind and shoveling operations. Attention is paid to the effects of different wind speeds, wind directions, and shoveling operations on the distribution and migration trajectory of blast pile dust. The research results indicate that the movement of dust is primarily controlled by wind flow, determining its ultimate migration path and diffusion range. This study not only provides a significant theoretical foundation for precise prevention and control of dust pollution in open-pit mines but also has vital practical significance for enhancing the safety of mine operating environments and safeguarding the physical and mental health of workers. [ABSTRACT FROM AUTHOR]

Overbreak induced by tunnel blasting is a harmful phenomenon. Accurate assessment of overbreak can effectively reduce investment and ensure operational safety. In this study, a hybrid intelligent model for assessing blasting-induced overbreak is proposed which can accurately predict overbreak and effectively evaluate the importance of feature parameters. To ensure accurate prediction of overbreak, hyperparameters of four machine learning algorithms are optimized using a whale optimization algorithm. Their performance is compared based on three regression metrics: R2, RMSE, and VAF. Given the limitations of traditional feature importance analysis methods, the Shapley Additive Explanation method is used in conjunction with the random forest algorithm. After accurately predicting overbreak caused by different sections of the tunnel, the impact of each input parameter on overbreak is analyzed, and recommendations for design values of certain significant parameters are provided. The research indicates that the proposed method can accurately predict overbreak caused by actual engineering blasts and provide insights into the selection of design parameter values. [ABSTRACT FROM AUTHOR]

To investigate the propagation mechanisms of stress waves and the characteristics of crack distribution in tunnel structures subjected to explosive effects, an experimental model simulating rock mass using cement mortar was employed. Blasting experiments were conducted at various vertical locations relative to the tunnel. Utilizing ultra-dynamic strain monitoring alongside high-speed digital image recognition, we captured in real time the dynamic evolution of stress waves as well as the precise initiation and expansion paths of cracks. A comprehensive analysis was performed on both stress wave propagation and damage patterns within the refuge structure. Furthermore, the reliability of our numerical simulation algorithm was validated through an examination of fluid-structure coupling algorithms. The results indicated that peak strains at monitoring points within the tunnel increased as detonation points approached it, leading to heightened structural damage. Numerical simulations demonstrated a strong correlation between observed peak strains at critical locations and corresponding damage data from our experimental model. Additionally, it was found that decreasing height between detonation points and the tunnel resulted in increased dynamic response parameters—such as overpressure, velocity, and acceleration—at monitoring sites within the tunnel, thereby exacerbating damage to key areas including vaults and footwall structures. To mitigate potential structural instability within refuges, a full-section molded concrete lining support system was implemented along with supplementary anchor (mesh) spraying in critical regions to ensure long-term operational safety. [ABSTRACT FROM AUTHOR]

This article presents a comparative assessment of energy consumption and fume emissions such as NOx, CO2, and CO associated with the excavation of a specified gypsum volume using two mining methods (blasting and mechanical extraction). The analysis was carried out based on a case study gypsum open-pit mine in Poland where both extraction methods are applied. The findings indicate that, for the same output volume, blasting operations require significantly less energy (ranging from 1298.12 MJ to 1462.22 MJ) compared to mechanical excavation (86,654.15 MJ). Furthermore, a substantial portion of the energy in blasting operations is attributed to explosive loading and drilling (970.95 MJ). Conversely, mechanical mining results in higher fume emissions compared to blasting. However, during mechanical extraction, the fumes are dispersed over a prolonged period of 275 h, whereas blasting achieves the same gypsum volume extraction in approximately 7.5 h. The prediction model suggests that, based on the obtained data, overall gypsum extraction will decline unless new operational levels are developed or the mine is expanded. This reduction in gypsum extraction will be accompanied by a corresponding decrease in energy consumption and emission of fumes. [ABSTRACT FROM AUTHOR]

A scientific and reasonable microseismic monitoring sensor network is crucial for the prevention and control of rockmass instability disasters. In this study, three feasible sensor network layout schemes for the microseismic monitoring of Sanshandao Gold Mine were proposed, comprehensively considering factors such as orebody orientation, tunnel and stope distributions, blasting excavation areas, construction difficulty, and maintenance costs. To evaluate and validate the monitoring effectiveness of the sensor networks, three layers of seismic sources were randomly generated within the network. Four levels of random errors were added to the calculated arrival time data, and the classical Geiger localization algorithm was used for locating validation. The distribution of localization errors within the monitoring area was analyzed. The results indicate that when the arrival time data are accurate or the error is between 0% and 2%, scheme 3 is considered the most suitable layout; when the error of the arrival time data is between 2% and 10%, scheme 2 is considered the optimal layout. These research results can provide important theoretical and technical guidance for the reasonable design of microseismic monitoring systems in similar mines or projects. [ABSTRACT FROM AUTHOR]

The natural caving method, as a new technique in underground mining, has been promoted and applied in several countries worldwide. The destruction of the bottom rock mass structure directly impacts the structural stability of underground engineering, resulting in damage and collapse of underground tunnels. Therefore, based on the principles of explosion theory and field monitoring data, a scaled three-dimensional numerical simulation model of underground blasting was constructed using LS-DYNA19.0 software to investigate the attenuation patterns of underground blasting vibrations and their impact on nearby tunnels. The results show that the relative error range between the simulated blasting vibration velocities based on the FEM-SPH (Finite Element Method–Smoothed Particle Hydrodynamics) algorithm and the measured values is between 7.75% and 9.85%, validating the feasibility of this method. Significant fluctuations in blasting vibration velocities occur when the blast center increases to within a range of 10–20 m. As the blast center distance exceeds 25 m, the vibration velocities are increasingly influenced by the surrounding stress. Additionally, greater stress results in higher blasting vibration velocities and stress wave intensities. Fitting the blasting vibration velocities of various measurement points using the Sadovsky formula yields fitting correlation coefficients ranging between 0.92 and 0.97, enabling the prediction of on-site blasting vibration velocities based on research findings. Changes in propagation paths lead to localized fluctuations in the numerical values of stress waves. These research findings are crucial for a deeper understanding of underground blasting vibration patterns and for enhancing blasting safety. [ABSTRACT FROM AUTHOR]

1, 1′‐azobis‐1, 2, 3‐triazole (C4H4N8, N8) is a novel nitrogen‐rich energetic material with excellent detonation performance, which has received widespread interest. Inspired by recent theories and experiments, the dependence of structural, vibrational, and electronic properties on high pressure up to 10 GPa was systematically investigated using periodic DFT calculations. It was found that the optimized structure belonged to the cis‐N8 structure through comparing the theoretical IR with experimental IR spectra. The third‐order Birch–Murnaghan equation of state for N8 was obtained up to 10 GPa, where the bulk modulus and its pressure derivative were 10.91 GPa and 7.689, respectively. More importantly, the pressure dependence of Laplacian bond order indicated that the five‐membered ring opening was the first step in the decomposition process, and that high pressure could inhibit the decomposition process of N8 due to the reinforcement of non‐covalent interactions. The present work could deepen the understanding of the energetic materials N8 under high pressure, and is of great significance to the blasting and detonation applications of N8. [ABSTRACT FROM AUTHOR]

The Mine-to-Mill (M2M) approach aims to enhance efficiency and reduce costs in the mineral processing industry by optimizing the mining and processing stages. M2M integrates orebody characterization, blasting, and downstream processes, such as grinding and flotation, demonstrating that material fragmentation directly impacts downstream efficiency. This review studies the development and applications of fragmentation models in M2M integration and optimization, finding that their study is divided into three phases. In the first, the potential of M2M is investigated through simulation models that improve fragmentation in blasting to optimize grinding. The second focuses on the practical application of these models in mines, while the third phase integrates geometallurgical data into mine block models, enhancing production planning and selective ore extraction. The M2M integration has demonstrated significant improvements in plant performance, particularly in increasing grinding efficiency through optimized blast fragmentation. The literature also emphasizes the role of optimizing crushing and grinding conditions through models and circuit adjustments to enhance performance and reducing energy consumption. Geometallurgy plays a crucial role in plant optimization by identifying areas with better processing characteristics and adjusting operating parameters to maximize efficiency. Recent studies have shown how the implementation of integrated models can increase the profitability and sustainability of mining operations. [ABSTRACT FROM AUTHOR]

The efficiency of rock excavation depends on cut blasting. However, medium-deep hole cutting blasting faces the challenges of large clamping action and unsatisfactory blasting efficiency. The study proposes sectional charge cutting blasting technology and analyzes the mechanism of cavity formation by establishing a numerical model. The results demonstrated that sectional charge blasting in the hole can expand the range of stress waves, and the segment interaction is also optimized by introducing a delay time difference. These factors contribute to an increase in the rock-breaking volume and an improvement in the degree of rock breaking. Furthermore, the cutting effects of different segmented proportional models are quantified. When the upper and lower sections are symmetrically charged, the damage range caused by the upper section is greater. The reason is that the clamping force exerted on the rock mass increases with the depth of the hole. In addition, when the upper section ratio is 0.4, the model exhibits the most excellent cavity volume; this results from charging according to the symmetry principle for optimal energy distribution. [ABSTRACT FROM AUTHOR]

Firearm examiners may face challenges with subclass characteristics. Subclass characteristics have the potential to be confused with individual characteristics if a careful analysis for the presence of subclass characteristics is not performed. Several case studies are reported in the literature that discuss the presence of subclass characteristics and advise firearm examiners to disregard these characteristics for identification purposes. As far as can be determined, no fundamental study has been performed that explores the various methods used in firearm manufacturing and assess the potential of subclass characteristics being produced. In this study broaching, plunge milling, and lathe turning were used to produce consecutively manufactured breech faces for a Thompson/Center® (T/C®) Contender® G2 pistol. The breech faces were finished by tumbling or glass bead blasting. The 3D topographical scans of the breech faces were collected using a confocal microscope and then compared using the National Institute of Standards and Technology (NIST) congruent matching cells (CMC) algorithm. The results of this study demonstrated the presence of subclass characteristics after manufacturing by broaching and plunge milling. Lathe turning did not produce any subclass characteristics. ANOVA and Kruskal–Wallis H tests were used to determine significant differences between finishing methods within each manufacturing method. Significant differences were found in glass bead blasting versus tumbling and glass bead blasting versus no finish. No significant differences were found in no finish versus tumbling. [ABSTRACT FROM AUTHOR]

Proper presetting of circular holes is the crux of blasting control. Currently, the influence mechanism of preset circular holes on directional propagation of blast-induced cracks remains unclear due to the instantaneity of blast loading and the complexity of action process. In this study, the evolution of the stress field around preset holes under blast loading was clarified based on experiments and numerical simulations. Besides, the influence mechanisms of single holes with different offset distances and double holes with different hole spacings on propagation patterns of blast-induced cracks were revealed. The results show that circular holes do not just promote or inhibit the propagation of blast-induced cracks under blast loading. Instead, the effect of a preset circular hole is determined by its relative position to the blast hole. Specifically, at the top of the blast-facing side of a preset hole, rock is subjected to tensile stress, which promotes crack propagation; in contrast, on two sides of it, rock is subjected to compressive stress, which inhibits crack propagation. Moreover, when the offset distance is short, the crack propagation trajectory will be deflected under the influence of tensile stress at the top of the circular hole. With the increase of offset distance, the inhibitory effect of compression at two sides of the hole tends to dominate, and the crack propagation will be suppressed. Particularly, the inhibitory effect at the two sides gradually weakens with the increase of offset distance. In the case of double-hole arrangement, the compressive stress fields at hole sides overlap with each other, which further strengthens the inhibitory effect on propagation of blast-induced cracks. Highlights: Experiments and numerical simulations were conducted to explore the interaction mechanism between circular holes and blast-induced cracks. Circular holes do not just promote or inhibit the propagation of blast-induced cracks. Instead, the effect of a circular hole is determined by its relative position to the blast hole. At the top of the blast-facing side of a preset hole, rock is subjected to tensile stress, which promotes crack propagation; in contrast, on two sides of it, rock is subjected to compressive stress, which inhibits crack propagation. [ABSTRACT FROM AUTHOR]

The right bank plant of Baihetan Hydropower Station has exposed C4, C5, and other fault fracture zones (FFZs), thereby increasing rock mass instability. In this paper, the effects of the number and location of FFZ on rock mass deformation were analyzed using field monitoring data. In addition, a validated numerical simulation method was employed to discuss the influence of excavation methods and FFZ properties on rock mass deformation. Results show that as the width of the middle pilot tunnel increases, the top arch deformation initially rises and then falls. Excavating the sidewalls first will significantly aggravate the deformation. As the width or dip-angle of FFZ increases or its height from the top arch decreases, the top arch deformation becomes more significant. The first layer excavation of the plant significantly influences the rock mass deformation. The rock mass located more than twice the width of the tunnel is almost unaffected by FFZ. This study is significant for the stability analysis of deep-buried caverns across FFZ. [ABSTRACT FROM AUTHOR]

In order to explore the distribution law of the peak value of floor vibration velocity under the influence of blasting vibration, the blasting vibration data through on-site vibration monitoring of 7-story masonry structure was collected taking the tunnel blasting project of Gui-Xi section of Qingdao Metro Line 1 as the background. According to the actual working conditions, four numerical models with different blast center distances were established to analyze the vibration response characteristics of buildings. The results show that the combined vibration velocity of the top floor of the masonry structure shows a relative amplification phenomenon with different blast center distances of 2 m, 10 m and 35 m respectively, and the relative amplification coefficients are 2.02, 1.80 and 1.67 respectively. With the decrease of the blast center distance, the relative amplification coefficient of the masonry structure shows an increasing trend. When the blasting center distance is 70 m, the vibration velocity of the masonry structure decreases with the increase of the floor, showing an absolute decrease. The research findings herein have certain guiding significance for judging whether the building exceeds the safe allowable vibration velocity and optimizing the blasting parameters of urban tunnel excavation in practical engineering. [ABSTRACT FROM AUTHOR]

Both weight reduction and increase in safety of a car body are required in the automobile industry. Therefore, studies on a multi-material car body structure have progressed. To achieve this structure, techniques that can join dissimilar materials are necessary. Adhesive bonding is an effective joining method used for this purpose. However, the strength of adhesively bonded joints is low and should be improved. Treatment of the adherend surfaces is an effective method to increase the strength of adhesively bonded joints. In this study, blasting, atmospheric-pressure plasma irradiation, and their combined treatment were applied to steel plate cold commercial (SPCC) surfaces, and adhesively bonded joints were prepared using the treated SPCC sheets. The effects of the treatments on the characteristics of the SPCC surfaces and strength of the adhesively bonded joints were investigated. The characteristics of the SPCC surfaces were analyzed using laser microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The static shear strength and fatigue properties of the adhesively bonded joints were examined. Blasting was found to be effective for increasing the static shear strength and fatigue properties of the adhesively bonded joints formed with the SPCC adherends because of the creation of surface asperities and generation of an anchor effect. Although atmospheric-pressure plasma irradiation decreased the contact angle of the SPCC surfaces owing to the elimination of the organic pollution layer, it did not increase the static shear strength and fatigue properties of adhesively bonded joints with the SPCC adherends. Therefore, the effect of the surface morphology on the static shear strength of the SPCC adhesively bonded joints was investigated in detail. Surface asperities with considerable height, narrow width, and several fine valleys were found to be effective for realizing adhesively bonded joints with higher static shear strength. [ABSTRACT FROM AUTHOR]

Exploiting a sharply-dipping thin vein mine is a challenging task because of the troubles in ore drawing and functioning large-scale mining tools in the limited underground space. Thus, considerations are mandatory to assume an effective mining technique that is able to handle unequal boundaries of this kind of orebody, providing a high recovery rate while lessening preparations before/after stoping and ore dilution. This paper analyses the medium-deep hole blasting of sharply inclined thin vein mines under different blasting factors using LS-DYNA. The links between blasting factors and over-under-excavation percentage of blasting, blasting cracks' density and nearby rock particles' vibration velocity are proven in the current research. Results show that segmental blasting is not much different from one-time blasting in the whole center section in terms of the blasting effect, but its impact on nearby rock is smaller. Two types of holes were designed in W- and X-type, and the distance between the holes were selected to be 0.8, 0.9, 1 m, with total 6 hole types. The effective stresses and displacements at the key monitoring points of the modeled nearby rock were analyzed by W- and X-types of hole placement. Compared with X-type holes, the effective stresses and displacements of W-type holes are smaller, indicating that W-type holes cause less damage to nearby rock. Based on the cumulative damage cloud map, it was concluded that the 0.8 m hole spacing had a larger influence on nearby rock, and that 0.9 m hole spacing was selected considering the factors of blasting effectiveness and resource recovery efficiency. Finally, this mining technique has the potential to be broadly employed to exploit related orebodies. [ABSTRACT FROM AUTHOR]

[Objective] The drilling and blasting method is a widely used technique in tunnel excavation and mining engineering. However, chemical blasting tests pose significant risks and are difficult to control. Owing to strict regulations, the use of explosives in universities is heavily restricted, leaving most universities in China without the ability to use chemical explosives to conduct mining blasting tests or offer related blasting teaching and experimental platforms. To address this issue and facilitate indoor rock blasting experimental teaching, a metal wire pulse electric blasting platform has been designed. [Methods] The platform consists of a high-voltage pulse generation system, a trigger control system, a safety grounding system, and a non-contact ultra-dynamic strain field monitoring system. The high-voltage pulse generation system injects powerful, fast pulse currents into metal wires, causing them to transition from solid to plasma and explode electrically through Joule heating. The resulting plasma channel generates shock waves at GPa levels. By adjusting the charging voltage, the energy for rock breaking can be precisely controlled. Different geometric shapes of metal wires simulate various charge structures. Straight metal wires mimic the structure of columnar drug packaging, while metal coiled wires like mosquito coils resemble the structure of spherical drug packaging. The trigger control system minimizes strong electromagnetic interference and accurately controls the discharge time of the energy storage capacitor. The safety grounding system adopts a dual method using an oil switch and grounding rod to ensure experimental safety. The ultra-dynamic strain field non-contact monitoring system consists of a high-speed camera and a digital speckle analysis component to accurately capture the entire process of rock strain field evolution. [Results] The platform has successfully simulated experiments with both columnar and spherical explosive charges. The results indicate that the blasting damage characteristics of rocks owing to metal wire electric explosion closely resemble those caused by chemical explosive blasting, particularly regarding the shape of the blasting funnel. By employing digital speckle analysis technology, the platform provides insights into the evolution of the free surface strain field by analyzing the cloud map of the ultra-dynamic strain field during rock blasting. The experiment shows that high-power pulse electric explosion technology can effectively simulate the rock blasting process in various blasting environments, allowing for visualization of the dynamic process of rock blasting damage. [Conclusions] Compared with traditional chemical blasting experiments, the rock blasting teaching experimental platform utilizing metal wire electric explosion is more flexible, safe, precise, and controllable. Key factors affecting the blasting effect, such as energy, charge shape, and the depth of the sample's resistance line, can be artificially controlled within the platform. This adaptability meets diverse experimental needs, improving the teaching effect of rock blasting and boosting students' scientific research and innovation skills. The platform is recommended for broader application in scientific research and teaching. [ABSTRACT FROM AUTHOR]