Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at ...Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.展开更多
Reinforced concrete(RC)beams face potential near-field blast threats as key structural components in building structures.To investigate the failure modes and dynamic responses of RC beams subjected to near-field blast...Reinforced concrete(RC)beams face potential near-field blast threats as key structural components in building structures.To investigate the failure modes and dynamic responses of RC beams subjected to near-field blast loading,this paper presents both blast tests and numerical simulation studies on RC beams.First,near-field blast tests were conducted on five RC beam specimens under strong and weak-axis bending loading.Then,a refined finite element model of RC beams was established to verify the applicability of the adopted finite element analysis method.Finally,based on the calibrated finite element model,the failure mechanisms of RC beams were explored,and the influence of blast incidence angle on the failure modes and dynamic responses of RC beams was investigated.The results indicate:(i)Near-field blast loading demonstrates pronounced non-uniform distribution patterns.Under strong-axis incidence,clearing effects beyond the mid-span region are more significant than weak-axis incidence,leading to accelerated impulse attenuation.(ii)Three consecutive developmental stages primarily control the damage mechanism of RC beams:stress wave-induced local damage,local deformation causing plastic hinge propagation,and free vibration of the beam;(iii)As the scaled distance decreases,the failure mode of RC beams under weak-axis blast loading evolves from flexural failure to local failure.The resistance mechanism of RC beams under weak-axis blast loading is more prone to transition from compressive membrane action to tensile membrane action,reducing their blast resistance capacity;(iv)As the explosion incident angleθincreases from 0°to 90°,the blast wave-structure interaction transitions from regular reflection to Mach reflection and back to normal reflection,causing the dynamic response of RC beams to first decrease then increase,with corner concrete spalling damage being the primary failure mode.展开更多
Predicting rock blasting outcomes in mining has been crucial since its inception.Blasting remains the most energy-and cost-efficient method for rock breaking and is often the only practical option.However,the mechanis...Predicting rock blasting outcomes in mining has been crucial since its inception.Blasting remains the most energy-and cost-efficient method for rock breaking and is often the only practical option.However,the mechanism is complex,influenced by various rock properties,explosives,and blast design parameters,making their effects difficult to quantify.Traditional stress-based models struggle with many parameters,such as stress and Poisson's ratio,which are challenging to measure in the field.Empirical models,though simpler,often oversimplify blast conditions.Both types of models are limited to simulating a few blastholes and cannot handle full-scale blasts involving hundreds of blastholes.However,modeling full-scale blasts with all blast design parameters is most required for modern mining applications.This paper presents a novel strain-based modeling approach for blasting and geomechanical applications,utilizing measurable variables such as particle velocity,strain,and displacement.By bypassing complex constitutive relations,strain-based models capture critical blasting trends and simulate full-scale blasts with full-blast design parameters with minimal calibration.The framework encompasses field strain measurements,model construction based on measurable variables,and laboratoryderived strain-failure criteria,each offering potential for future enhancement.Additionally,a standardized field test for site characterization is recommended.The approach is demonstrated through the Multiple Blasthole Fragmentation model,which simulates rock fragmentation and fragment strain during blasting,highlighting the practicality and effectiveness of strain-based modeling for multiple blasthole blasts.Moreover,this approach extends beyond blasting,with potential applications in highwall stability monitoring and other geomechanical applications.Strain-based modeling provides a simplified yet effective solution,avoiding the complexities of rock constitutive relations and field stress measurements while enabling full-blast design simulations for large-scale field blasts.展开更多
Deep mining of natural resources,like coal,is increasingly utilizing directional blasting technology with slit charge for rock blasting at greater depths.This study,based on numerical simulation methods,analyzes the d...Deep mining of natural resources,like coal,is increasingly utilizing directional blasting technology with slit charge for rock blasting at greater depths.This study,based on numerical simulation methods,analyzes the dynamic behavior of slit charge blasting in three aspects:slit tube dynamic response,hoop stress evolution,and crack propagation.According to research findings,the failure mode of the slit tube mainly manifests as a tensile fracture of the inner wall and a shear fracture at the end connection,where the end connection of the slit tube is the weak point of the overall structure.The dynamic response of the slit tube mainly exhibits radial response in the vertical direction of the slit and hoop response in the slit direction.The hoop tensile stress plays a crucial role in determining the spread of cracks caused by explosions.As the in situ stress increases,the peak hoop tensile stress reduces,and the peak hoop compressive stress increases.This hinders the propagation of cracks.In addition,the directional impact is most pronounced in the middle of the borehole,with the longest primary directional crack observed.Conversely,the directional impact is least favorable near the bottom of the borehole.When the in situ stress reaches 60MPa,the purpose of directional fracture has not been achieved,suggesting combining presplit blasting for in situ stress relief to improve rock breaking efficiency.展开更多
This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality...This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality classification were determined based on wave theory of Kelvin medium.Then,a calculation model was obtained for the millisecond-delay cut blast vibration in Kelvin media using the Starfield charge superposition principle.Further,the influence of the delay time on the cut blast vibration was quantitatively analyzed and a method for calculating the reasonable cut blasting millisecond delay time is proposed according to the principle of dimensional analysis.Finally,field tests were used to verify the applicability of the method.The results show that 5 ms to 20 ms is a better detonator delay time range and cut blasting vibration can be effectively controlled using the delay time calculated by the calculation model described in this paper.展开更多
Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angl...Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angle,and the mechanism governing these processes in the rock.In this study,a single-hole bench blasting model is developed using LS-DYNA software to comprehensively investigate the relationship between burden and rock breakage.The simulation results show that the breakage angle decreases with the increase in burden,and the blasted volume reaches a peak value with a burden of 4 m.Meanwhile,backbreak distance increases with increasing burden.The optimum burden in this simulation is found to be 4.0 m,as the ratio of burden to blasthole diameter is equal to 20.62 and the ratio of burden to bench height is 0.44,based on a comprehensive analysis of the blasted volume,average damage,and total damage.Under the optimum burden condition,tensile stress wave regions are simultaneously generated at the free surfaces of both the bench top and bench slope,allowing more effective utilization of the two free surfaces and resulting in a more uniform damage distribution within the burden region.展开更多
Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate ...Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.展开更多
北京时间11月30日晚间,BLAST Slam V成都站入围赛正式开赛。尽管在此前的小组赛阶段,四支中国队的表现并不能令观众满意,名次最高的是小组排名第六,但胜率却不到50%的Tidebound战队,而另外的三支战队XG、YB和Tearlaments则全部落入小组...北京时间11月30日晚间,BLAST Slam V成都站入围赛正式开赛。尽管在此前的小组赛阶段,四支中国队的表现并不能令观众满意,名次最高的是小组排名第六,但胜率却不到50%的Tidebound战队,而另外的三支战队XG、YB和Tearlaments则全部落入小组后四名。好在小组赛并设置淘汰机制,只是排名靠后的三支中国队必须从入围赛首轮开打。最终XG有惊无险地以2∶1的比分战胜Tearlaments,而YB则轻松战胜Execration进入下一轮。展开更多
Understanding how rock slopes respond to blasting loads is crucial for maintaining excavation safety and slope stability.Nevertheless,the spatiotemporal evolution,nonlinear dependence on blasting parameters,and predic...Understanding how rock slopes respond to blasting loads is crucial for maintaining excavation safety and slope stability.Nevertheless,the spatiotemporal evolution,nonlinear dependence on blasting parameters,and predictive behavior of dominant frequency responses in slope vibrations remain insufficiently understood and quantified.This study combines time-frequency analysis with machine learning to explore how the dominant frequency(f_(d))evolves in slopes under blasting.Continuous Wavelet Transform(CWT)was employed to characterize the temporal-frequency evolution of vibration signals,revealing that the dominant frequency exhibits strong spatial dependence and nonlinear variability influenced by blasting parameters and rock mass structures.Three machine learning models,namely Back Propagation Neural Network(BP),Support Vector Machine(SVM),and Random Forest(RF),were developed to predict f_(d) based on 1,000 monitoring samples obtained from numerical and field simulations.Among them,the RF model achieved the highest prediction accuracy,with mean absolute percentage errors(MAPE)below 15%,demonstrating strong robustness and generalization capability.Our analysis shows that external excitation factors,especially the loading frequency(f_(d)),mainly control the frequency response,while internal controlling factors,such as spatial position,lithological variation,and mechanical heterogeneity,modulate localized frequency amplification and energy redistribution.The results reveal that f_(d) tends to decrease with elevation and distance from the blasting source,whereas structural planes and weathered zones induce high-frequency amplification due to scattering and modal coupling effects.This study offers a new framework combining time-frequency analysis and machine learning to measure the nonlinear interaction between blasting and rock mass response,offering new insights for dynamic stability evaluation and hazard mitigation in complex rock slope systems.展开更多
Drilling and blasting in layered rock masses faces significant challenges,as pre-existing joints cause unbalanced energy distribution,leading to poor forming effects and severe over-excavation.However,a comprehensive ...Drilling and blasting in layered rock masses faces significant challenges,as pre-existing joints cause unbalanced energy distribution,leading to poor forming effects and severe over-excavation.However,a comprehensive understanding of the complex coupling mechanisms between key joint parameters and the in-situ stress field on the final blasting outcome is still lacking.The model tests are used to quantitatively analyze the macroscopic crushing characteristics and crack propagation velocity.The numerical simulation then reveals the underlying mechanisms of stress wave propagation and energy partitioning,which are validated against the experimental results.The results indicate that the joints and the in-situ stress field play distinct,competitive roles in the blasting outcome.First,the joints control the anisotropy of the damage:crack propagation is primarily guided along the joint direction(the channel effect),and the apparent crack velocity exhibits a V-shaped trend with the joint inclination angle(0°-90°).Second,the in-situ stress state controls the overall extent of the damage:Increased confining pressure(both equal and unequal)inhibits crack propagation by increasing the failure threshold of the rock mass.Mechanistically,while this locking effect enhances stress wave transmission(i.e.,reduces the locking effect),this is secondary to the dominant inhibitory effect of the increased overall rock mass strength.The primary contribution of this study is the identification of this dual control mechanism,revealing that the final blasting effect is a non-linear competition between the joint's structural guidance and the dominant strengthening effect from the in-situ stress field,which clarifies the complex energy partitioning mechanisms at the blast source.展开更多
Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigate...Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigates the effects of sheath(duct)implementation and confinement assumptions through nonlinear finite element analysis.Four modeling cases were defined,consisting of an explicit sheath without tendon-concrete confinement(S)and three no-sheath variants with different confinement levels(X,N,A).One-way beams and two-way panels were analyzed,and panel blast responses were validated against experimental results.In both beams and panels,average initial stress levels were similar across models,through local stress concentrations appeared when the sheath was modeled.Under blast loading,these local effects became critical,and the sheath-implemented model reproduced experimental behavior most accurately,whereas non-implemented models deviated.Reduced blast intensity diminished the differences among models,thereby reaffirming that sheath-induced localization and damage propagation are critical factors.These findings highlight the importance of explicit sheath implementation for realistic numerical assessment of unbonded PT structures under extreme loads.展开更多
2025年11月14日,随着中国香港亚洲国际博览馆这个1.2万人的场馆屏幕上映现出李小龙的画面和声音,2025 BLAST Premier Rivals中国香港(以下简称BLAST中国香港)第一天线下比赛在两块红色屏幕的倒计时中开始。作为中国香港首个S级电竞赛事...2025年11月14日,随着中国香港亚洲国际博览馆这个1.2万人的场馆屏幕上映现出李小龙的画面和声音,2025 BLAST Premier Rivals中国香港(以下简称BLAST中国香港)第一天线下比赛在两块红色屏幕的倒计时中开始。作为中国香港首个S级电竞赛事的落地,BLAST中国香港在本次举办过程中获得了诸多第一。展开更多
The global mining industry,particularly deep high-stress hard-rock mining,confronts prominent challenges of massive energy consumption and low crushing/grinding efficiency.Optimized blasting,as an alternative to grind...The global mining industry,particularly deep high-stress hard-rock mining,confronts prominent challenges of massive energy consumption and low crushing/grinding efficiency.Optimized blasting,as an alternative to grinding,effectively reduces energy usage and improves transportation efficiency.Despite extensive research on the effects of confining stress to cut blasting,studies focusing on fragmentation characteristics of deep confined blasting remain scarce.This study integrates theoretical analysis,similarity model tests,and SPH-FEM simulations to investigate fragmentation size distribution and energy dissipation under varying confining stresses.Results show that the Swebrec(SWE)function achieves superior fitting to fragmentation data(goodness-offit>0.95).With increasing confining stress,the fractal dimension of specimens increases(ranging from 2.16 to 2.42 in model tests),while fragmentation energy decreases—55.23% lower under high confining stress than no confining stress in tests,and 50.61%lower at 40 MPa than 0 MPa in simulations.The ratio of fragmentation energy to blasting energy is 2%-10%.Distinct from previous studies emphasizing confining stress macroeffects on cut blasting,this work explores fragmentation distribution functions and energy under biaxial confining stress,providing valuable insights for blasting efficiency evaluation and promoting energy conservation and emission reduction in post-mineral processing.展开更多
The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium...The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium,without considering the wave attenuation caused by viscoelasticity and wave separation induced by rock discontinuities,as well as plane waves while neglecting geometric attenuation of near-field nonplane blast waves.This paper establishes a theoretical model of cylindrical P-wave propagation across a fault to an adjacent existing tunnel.Based on the time-domain recursive method,vibration equations and peak particle velocity on the adjacent existing tunnel wall caused by a cylindrical wave passing through a fault are derived.The rock mass and fault are assumed to satisfy Kelvin viscoelastic bodies,and contact interfaces between fault and rock mass follow a nonlinear hyperbolic deformation model in the normal direction and a linear model in the tangential direction.The results show that tunnel vibration caused by the blast cylindrical P-wave is primarily induced by transmitted P-waves.With the increase of the fault dip angle,vibration on the upper side of the adjacent existing tunnel gradually decreases,while vibration on the lower side increases.The closer the vibration to the upper and lower sides,the stronger the shear effect on the tunnel wall,and the closer the vibration to the middle,the stronger the pressure effect on the tunnel wall.Larger fault thickness and higher initial blast wave frequency result in weaker vibration of the adjacent tunnel.The deeper the burial depth,the stronger the vibration of the adjacent tunnel wall.Findings of this study provide insight into the dynamic response of rock construction and safety evaluation in engineering service.展开更多
During the development blasting of circular tunnels, the detonation of multiple blastholes arranged onconcentric circles induces a complex dynamic response in the surrounding rocks. This process involvesmultiple blast...During the development blasting of circular tunnels, the detonation of multiple blastholes arranged onconcentric circles induces a complex dynamic response in the surrounding rocks. This process involvesmultiple blast loadings, static stress unloadings, and stress redistributions. In this study, the dynamicstresses of the surrounding rocks during development blasting, considering multiple blasting-unloadingstages with exponential paths and triangular paths (linear simplified paths of exponential paths), aresolved based on the dynamic theory and the Fourier transform method. Then, a corresponding discreteelement model is established using particle flow code (PFC). The multiple-stage dynamic stress andfracture distribution under different in situ stress levels and lateral coefficients are investigated. Theoreticalresults indicate that the peak compressive stresses in the surrounding rocks induced by bothtriangular and exponential paths are equal, while the triangular path generates greater additional dynamictensile stresses, particularly in the circumferential direction, compared to the exponential path.Numerical results show that the exponential path causes less dynamic circumferential tensile damageand forms fewer radial fractures than the triangular path in the first few blast stages;conversely, itexacerbates the damage and instability in the final blasting-unloading stage and forms more circumferentialfractures. Furthermore, the in situ stress determines which of the two opposite effects isdominant. Therefore, when using overly simplified triangular paths to evaluate the stability of surroundingrocks, potential overestimation or underestimation caused by different failure mechanismsshould be considered. Specifically, under high horizontal and vertical stresses, the static stress redistributionwith layer-by-layer blasting suppresses dynamic circumferential tensile and radial compressivedamage. The damage evolution of surrounding rocks in multi-stage blasting under different in situstresses is summarized and classified according to the damage mechanism and characteristics, which canguide blasting and support design.展开更多
Due to space constraints in mountainous areas,twin tunnels are sometimes constructed very close to each other or even overlap.This proximity challenges the structural stability of tunnels built with the drill-and-blas...Due to space constraints in mountainous areas,twin tunnels are sometimes constructed very close to each other or even overlap.This proximity challenges the structural stability of tunnels built with the drill-and-blast method,as the short propagation distance amplifies blasting vibrations.A case of blasting damage is reported in this paper,where concrete cracks crossed construction joints in the twin-arch lining.To identify the causes of these cracks and develop effective vibration mitigation measures,field monitoring and numerical analysis were conducted.Specifically,a restart method was used to simulate the second peak particle velocity(PPV)of MS3 delays occurring 50 ms after the MS1 delays.The study found that the dynamic tensile stress in the tunnel induced by the blast wave has a linear relationship with the of the product of the concrete wave impedance and the PPV.A blast vibration velocity exceeding 23.3 cm/s resulted in tensile stress in the lining surpassing the ultimate tensile strength of C30 concrete,leading to tensile cracking on the blast-facing arch of the constructed tunnel.To control excessive vi-bration velocity,a mitigation trench was implemented to reduce blast wave impact.The trench,approximately 15 m in length,50 cm in width,and 450 cm in height,effectively lowered vibration ve-locities,achieving an average reduction rate of 52%according to numerical analysis.A key innovation of this study is the on-site implementation and validation of the trench's effectiveness in mitigating vi-brations.A feasible trench construction configuration was proposed to overcome the limitations of a single trench in fully controlling vibrations.To further enhance protection,zoned blasting and an auxiliary rock pillar,80 cm in width,were incorporated to reinforce the mid-wall.This study introduces novel strategies for vibration protection in tunnel blasting,offering innovative solutions to address blasting-induced vibrations and effectively minimize their impact,thereby enhancing safety and struc-tural stability.展开更多
The Rock-soil interface is a common geological interface.Due to mechanical differences between soil and rock,the stress waves generated by underground blasting undergo intense polarization when crossing the rock-soil ...The Rock-soil interface is a common geological interface.Due to mechanical differences between soil and rock,the stress waves generated by underground blasting undergo intense polarization when crossing the rock-soil interface,making propagation laws difficult to predict.Currently,the characteristics of the impact of the rock-soil interface on blasting stress waves remain unclear.Therefore,the vibration field caused by cylindrical charge blasting in elastic rock and partial-saturation poro-viscoelastic soil was solved.A forward algorithm for the underground blasting vibration field in rock-soil sites was proposed,considering medium damping and geometric diffusion effects of stress waves.Further investigation into the influence of rock and soil parameters and blasting source parameters revealed the following conclusions:stress waves in soil exhibit dispersion,causing peak particle velocity(PPV)to display a discrete distribution.Soil parameters affect PPV attenuation only within the soil,while blasting source parameters affect PPV attenuation throughout the entire site.Multi-wave coupling effects induced by the rocksoil interface result in zones of enhanced and attenuated PPV within the site.The size of the enhancement zone is inversely correlated with the distance from the blasting source and positively correlated with the blasting source attenuation rate and burial depth,providing guidance for selecting explosives and blasting positions.Additionally,PPV attenuation rate increases with distance from the rock-soil interface,but an amplification effect occurs near the interface,most noticeable at 0.1 m.Thus,a sufficient safety distance from the rock-soil interface is necessary during underground blasting.展开更多
Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.Thi...Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.This study investigates the blasting effects and underlying mechanisms of concrete frustums subjected to contact explosions,employing both numerical simulations and field tests.It focuses on the effects of top and side blasting,with particular emphasis on fracture modes,damage patterns,and fragment sizes,as well as the causes of different failure modes and the propagation of stress waves.The study also explores the blasting effects of detonating explosives at varying positions along the side and with different charge amounts.The results show that side-blasting leads to complete fragmentation,with tensile waves playing a significant role in creating extensive damage zones that propagate parallel to the frustum's outer surface,concentrating damage near the surface.During top-blasting,the upper half of the frustum undergoes fragmentation,while the lower half experiences cracking.Tensile waves propagate from the top to the bottom surface,forming larger blocks in regions with lower wave intensity.Three distinct damage zones within the frustum were identified,and a series of mathematical formulas were derived to describe the relationship between the maximum fragment size and charge mass.As the charge mass increased from 1.0 kg to 4.0 kg,the maximum fragment size decreased.Detonation at the center of the frustum's side resulted in the most severe fragmentation,with a 51.8%reduction in fragment size compared to other detonation positions.Finally,four broken modes were classified,each influenced by charge mass and explosive location.This study provides valuable insights for optimizing civil blasting operations and designing protective engineering structures.展开更多
基金supported by the Shenzhen Stability Support Plan(Grant No.20231122095154003)National Natural Science Foundation of China(Grant Nos.51978671 and 52422807).
文摘Residents living near drill-and-blast tunnels often experience disturbances from blasting operations.This motivates us to investigate the characteristics of airblasts and resulting noise through on-site monitoring at three tunnels.The research focuses on both the temporal evolution and spatial propagation of airblasts.Temporal analysis,including peak overpressure(POp),positive duration(PD),and Fourier main frequency(MF),emphasizes the relationship between airblast characteristics,blasting delays,and rock grade.It shows that airblast bandwidths are typically in the range of 3e200 Hz,with noise levels exceeding 130 dB,which is comparable to jet engines and rocket launch.Spatial propagation analysis reveals the impact of tunnel space on airblast propagation.Although POp and PD typically decrease with distance inside the tunnel,wave superposition can cause increased overpressure and prolonged durations at far-field distances(above 60 m kg^(-1/3)).Outside the tunnel,sound radiation was influenced by azimuth and was basically determined by sound power d an often-overlooked factor.To address the anisotropic propagation of airblasts,a predictive model was proposed for external noise levels,considering variables like distance,azimuth angle,initial sound power,and wave expansion.Validated by tests,this model successfully unifies data from three studies,helping to explain and predict airblast disturbances near tunnels.
基金supported by the National Natural Science Foundation of China(Grant Nos.52178445,52578544)Open Research Fund of State Key Laboratory of Target Vulnerability Assessment,Defense Engineering Institute,AMS(Grant No.YSX2024KFYS002).
文摘Reinforced concrete(RC)beams face potential near-field blast threats as key structural components in building structures.To investigate the failure modes and dynamic responses of RC beams subjected to near-field blast loading,this paper presents both blast tests and numerical simulation studies on RC beams.First,near-field blast tests were conducted on five RC beam specimens under strong and weak-axis bending loading.Then,a refined finite element model of RC beams was established to verify the applicability of the adopted finite element analysis method.Finally,based on the calibrated finite element model,the failure mechanisms of RC beams were explored,and the influence of blast incidence angle on the failure modes and dynamic responses of RC beams was investigated.The results indicate:(i)Near-field blast loading demonstrates pronounced non-uniform distribution patterns.Under strong-axis incidence,clearing effects beyond the mid-span region are more significant than weak-axis incidence,leading to accelerated impulse attenuation.(ii)Three consecutive developmental stages primarily control the damage mechanism of RC beams:stress wave-induced local damage,local deformation causing plastic hinge propagation,and free vibration of the beam;(iii)As the scaled distance decreases,the failure mode of RC beams under weak-axis blast loading evolves from flexural failure to local failure.The resistance mechanism of RC beams under weak-axis blast loading is more prone to transition from compressive membrane action to tensile membrane action,reducing their blast resistance capacity;(iv)As the explosion incident angleθincreases from 0°to 90°,the blast wave-structure interaction transitions from regular reflection to Mach reflection and back to normal reflection,causing the dynamic response of RC beams to first decrease then increase,with corner concrete spalling damage being the primary failure mode.
文摘Predicting rock blasting outcomes in mining has been crucial since its inception.Blasting remains the most energy-and cost-efficient method for rock breaking and is often the only practical option.However,the mechanism is complex,influenced by various rock properties,explosives,and blast design parameters,making their effects difficult to quantify.Traditional stress-based models struggle with many parameters,such as stress and Poisson's ratio,which are challenging to measure in the field.Empirical models,though simpler,often oversimplify blast conditions.Both types of models are limited to simulating a few blastholes and cannot handle full-scale blasts involving hundreds of blastholes.However,modeling full-scale blasts with all blast design parameters is most required for modern mining applications.This paper presents a novel strain-based modeling approach for blasting and geomechanical applications,utilizing measurable variables such as particle velocity,strain,and displacement.By bypassing complex constitutive relations,strain-based models capture critical blasting trends and simulate full-scale blasts with full-blast design parameters with minimal calibration.The framework encompasses field strain measurements,model construction based on measurable variables,and laboratoryderived strain-failure criteria,each offering potential for future enhancement.Additionally,a standardized field test for site characterization is recommended.The approach is demonstrated through the Multiple Blasthole Fragmentation model,which simulates rock fragmentation and fragment strain during blasting,highlighting the practicality and effectiveness of strain-based modeling for multiple blasthole blasts.Moreover,this approach extends beyond blasting,with potential applications in highwall stability monitoring and other geomechanical applications.Strain-based modeling provides a simplified yet effective solution,avoiding the complexities of rock constitutive relations and field stress measurements while enabling full-blast design simulations for large-scale field blasts.
基金National Natural Science Foundation of China,Grant/Award Numbers:52204085,52227805。
文摘Deep mining of natural resources,like coal,is increasingly utilizing directional blasting technology with slit charge for rock blasting at greater depths.This study,based on numerical simulation methods,analyzes the dynamic behavior of slit charge blasting in three aspects:slit tube dynamic response,hoop stress evolution,and crack propagation.According to research findings,the failure mode of the slit tube mainly manifests as a tensile fracture of the inner wall and a shear fracture at the end connection,where the end connection of the slit tube is the weak point of the overall structure.The dynamic response of the slit tube mainly exhibits radial response in the vertical direction of the slit and hoop response in the slit direction.The hoop tensile stress plays a crucial role in determining the spread of cracks caused by explosions.As the in situ stress increases,the peak hoop tensile stress reduces,and the peak hoop compressive stress increases.This hinders the propagation of cracks.In addition,the directional impact is most pronounced in the middle of the borehole,with the longest primary directional crack observed.Conversely,the directional impact is least favorable near the bottom of the borehole.When the in situ stress reaches 60MPa,the purpose of directional fracture has not been achieved,suggesting combining presplit blasting for in situ stress relief to improve rock breaking efficiency.
基金National Natural Science Foundation of China under Grant Nos.51979205 and 51939008。
文摘This research is focused on the calculation of a reasonable detonator delay time for realizing cut blast vibration control.First,the viscoelastic rock mass parameters corresponding to the engineering rock mass quality classification were determined based on wave theory of Kelvin medium.Then,a calculation model was obtained for the millisecond-delay cut blast vibration in Kelvin media using the Starfield charge superposition principle.Further,the influence of the delay time on the cut blast vibration was quantitatively analyzed and a method for calculating the reasonable cut blasting millisecond delay time is proposed according to the principle of dimensional analysis.Finally,field tests were used to verify the applicability of the method.The results show that 5 ms to 20 ms is a better detonator delay time range and cut blasting vibration can be effectively controlled using the delay time calculated by the calculation model described in this paper.
基金supported by the European Union in the frame of Horizon Europe AVANTIS project,Grant Agreement No.101137552.
文摘Burden is one of the main parameters in blast design.However,field tests,either single-or multi-hole blasts,used to determine an appropriate burden,are difficult to capture crack propagation,evolution of breakage angle,and the mechanism governing these processes in the rock.In this study,a single-hole bench blasting model is developed using LS-DYNA software to comprehensively investigate the relationship between burden and rock breakage.The simulation results show that the breakage angle decreases with the increase in burden,and the blasted volume reaches a peak value with a burden of 4 m.Meanwhile,backbreak distance increases with increasing burden.The optimum burden in this simulation is found to be 4.0 m,as the ratio of burden to blasthole diameter is equal to 20.62 and the ratio of burden to bench height is 0.44,based on a comprehensive analysis of the blasted volume,average damage,and total damage.Under the optimum burden condition,tensile stress wave regions are simultaneously generated at the free surfaces of both the bench top and bench slope,allowing more effective utilization of the two free surfaces and resulting in a more uniform damage distribution within the burden region.
基金financial support provided by the Natural Science Foundation of Hebei Province,China(No.E2024105036)the Tangshan Talent Funding Project,China(Nos.B202302007 and A2021110015)+1 种基金the National Natural Science Foundation of China(No.52264042)the Australian Research Council(No.IH230100010)。
文摘Automated classification of gas flow states in blast furnaces using top-camera imagery typically demands a large volume of labeled data,whose manual annotation is both labor-intensive and cost-prohibitive.To mitigate this challenge,we present an enhanced semi-supervised learning approach based on the Mean Teacher framework,incorporating a novel feature loss module to maximize classification performance with limited labeled samples.The model studies show that the proposed model surpasses both the baseline Mean Teacher model and fully supervised method in accuracy.Specifically,for datasets with 20%,30%,and 40%label ratios,using a single training iteration,the model yields accuracies of 78.61%,82.21%,and 85.2%,respectively,while multiple-cycle training iterations achieves 82.09%,81.97%,and 81.59%,respectively.Furthermore,scenario-specific training schemes are introduced to support diverse deployment need.These findings highlight the potential of the proposed technique in minimizing labeling requirements and advancing intelligent blast furnace diagnostics.
文摘北京时间11月30日晚间,BLAST Slam V成都站入围赛正式开赛。尽管在此前的小组赛阶段,四支中国队的表现并不能令观众满意,名次最高的是小组排名第六,但胜率却不到50%的Tidebound战队,而另外的三支战队XG、YB和Tearlaments则全部落入小组后四名。好在小组赛并设置淘汰机制,只是排名靠后的三支中国队必须从入围赛首轮开打。最终XG有惊无险地以2∶1的比分战胜Tearlaments,而YB则轻松战胜Execration进入下一轮。
基金supported by the National Natural Science Foundation of China(Grant Nos.52379098,52274075)the Project of Xingliao Talents Program(XLYC2203008)the Science and Technology Program Project of Liaoning Province(2025JH2/101900011).
文摘Understanding how rock slopes respond to blasting loads is crucial for maintaining excavation safety and slope stability.Nevertheless,the spatiotemporal evolution,nonlinear dependence on blasting parameters,and predictive behavior of dominant frequency responses in slope vibrations remain insufficiently understood and quantified.This study combines time-frequency analysis with machine learning to explore how the dominant frequency(f_(d))evolves in slopes under blasting.Continuous Wavelet Transform(CWT)was employed to characterize the temporal-frequency evolution of vibration signals,revealing that the dominant frequency exhibits strong spatial dependence and nonlinear variability influenced by blasting parameters and rock mass structures.Three machine learning models,namely Back Propagation Neural Network(BP),Support Vector Machine(SVM),and Random Forest(RF),were developed to predict f_(d) based on 1,000 monitoring samples obtained from numerical and field simulations.Among them,the RF model achieved the highest prediction accuracy,with mean absolute percentage errors(MAPE)below 15%,demonstrating strong robustness and generalization capability.Our analysis shows that external excitation factors,especially the loading frequency(f_(d)),mainly control the frequency response,while internal controlling factors,such as spatial position,lithological variation,and mechanical heterogeneity,modulate localized frequency amplification and energy redistribution.The results reveal that f_(d) tends to decrease with elevation and distance from the blasting source,whereas structural planes and weathered zones induce high-frequency amplification due to scattering and modal coupling effects.This study offers a new framework combining time-frequency analysis and machine learning to measure the nonlinear interaction between blasting and rock mass response,offering new insights for dynamic stability evaluation and hazard mitigation in complex rock slope systems.
基金supported by funding from the National Natural Science Foundation of China(42372331,52204140)State key Laboratory of Mining Disaster Prevention and Control(Shandong University of Science and Technology)(JMDPC202302)+2 种基金the high-level talent cultivation funding program for the"Double First-Class"initiative in safety discipline at Henan Polytechnic University(AQ20250205)the Taishan Scholar Program of Shandong Province(tsqnz20240825)Open Fund of Shandong Engineering Research Center for Mine Gas Disaster Prevention and Control(No.2022-005)。
文摘Drilling and blasting in layered rock masses faces significant challenges,as pre-existing joints cause unbalanced energy distribution,leading to poor forming effects and severe over-excavation.However,a comprehensive understanding of the complex coupling mechanisms between key joint parameters and the in-situ stress field on the final blasting outcome is still lacking.The model tests are used to quantitatively analyze the macroscopic crushing characteristics and crack propagation velocity.The numerical simulation then reveals the underlying mechanisms of stress wave propagation and energy partitioning,which are validated against the experimental results.The results indicate that the joints and the in-situ stress field play distinct,competitive roles in the blasting outcome.First,the joints control the anisotropy of the damage:crack propagation is primarily guided along the joint direction(the channel effect),and the apparent crack velocity exhibits a V-shaped trend with the joint inclination angle(0°-90°).Second,the in-situ stress state controls the overall extent of the damage:Increased confining pressure(both equal and unequal)inhibits crack propagation by increasing the failure threshold of the rock mass.Mechanistically,while this locking effect enhances stress wave transmission(i.e.,reduces the locking effect),this is secondary to the dominant inhibitory effect of the increased overall rock mass strength.The primary contribution of this study is the identification of this dual control mechanism,revealing that the final blasting effect is a non-linear competition between the joint's structural guidance and the dominant strengthening effect from the in-situ stress field,which clarifies the complex energy partitioning mechanisms at the blast source.
基金supported by the Nuclear Safety Research Program through the Korea Foundation of Nuclear Safety(KoFONS)using the financial resource granted by the Nuclear Safety and Security Commission(NSSC)of the Republic of Korea[RS-2025-02310881]the Korea Institute of Energy Technology Evaluation and Planning[KETEP]grant funded by the Ministry of Trade,Industry and Energy(MOTIE)[RS-2025-25447272].
文摘Unbonded post-tensioned(PT)concrete systems are widely used in safety-critical structures,yet model-ing practices for prestress implementation and tendon-concrete interaction remain inconsistent.This study investigates the effects of sheath(duct)implementation and confinement assumptions through nonlinear finite element analysis.Four modeling cases were defined,consisting of an explicit sheath without tendon-concrete confinement(S)and three no-sheath variants with different confinement levels(X,N,A).One-way beams and two-way panels were analyzed,and panel blast responses were validated against experimental results.In both beams and panels,average initial stress levels were similar across models,through local stress concentrations appeared when the sheath was modeled.Under blast loading,these local effects became critical,and the sheath-implemented model reproduced experimental behavior most accurately,whereas non-implemented models deviated.Reduced blast intensity diminished the differences among models,thereby reaffirming that sheath-induced localization and damage propagation are critical factors.These findings highlight the importance of explicit sheath implementation for realistic numerical assessment of unbonded PT structures under extreme loads.
文摘2025年11月14日,随着中国香港亚洲国际博览馆这个1.2万人的场馆屏幕上映现出李小龙的画面和声音,2025 BLAST Premier Rivals中国香港(以下简称BLAST中国香港)第一天线下比赛在两块红色屏幕的倒计时中开始。作为中国香港首个S级电竞赛事的落地,BLAST中国香港在本次举办过程中获得了诸多第一。
基金supported by the Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology(No.2024yjrc71)State Key Laboratory of Precision Blasting,Jianghan University(No.PBSKL25B15)+2 种基金Foundation of Anhui Engineering Research Center of New Explosive Materials and Blasting Technology(No.AHBP2024B11)National Natural Science Foundation of China(No.52208384)Auhui Provincial Key Laboratory of Urban Rail Transit Safety and Emergency Management,Hefei University(No.2024GD003)。
文摘The global mining industry,particularly deep high-stress hard-rock mining,confronts prominent challenges of massive energy consumption and low crushing/grinding efficiency.Optimized blasting,as an alternative to grinding,effectively reduces energy usage and improves transportation efficiency.Despite extensive research on the effects of confining stress to cut blasting,studies focusing on fragmentation characteristics of deep confined blasting remain scarce.This study integrates theoretical analysis,similarity model tests,and SPH-FEM simulations to investigate fragmentation size distribution and energy dissipation under varying confining stresses.Results show that the Swebrec(SWE)function achieves superior fitting to fragmentation data(goodness-offit>0.95).With increasing confining stress,the fractal dimension of specimens increases(ranging from 2.16 to 2.42 in model tests),while fragmentation energy decreases—55.23% lower under high confining stress than no confining stress in tests,and 50.61%lower at 40 MPa than 0 MPa in simulations.The ratio of fragmentation energy to blasting energy is 2%-10%.Distinct from previous studies emphasizing confining stress macroeffects on cut blasting,this work explores fragmentation distribution functions and energy under biaxial confining stress,providing valuable insights for blasting efficiency evaluation and promoting energy conservation and emission reduction in post-mineral processing.
基金Natural Science Basic Research Program of Shaanxi Province,Grant/Award Number:2023-YBGY-085National Natural Science Foundation of China,Grant/Award Numbers:41902277,42172302Fundamental Research Funds for the Central Universities,Grant/Award Number:CHD.300102282201。
文摘The vibration caused by blasting excavation of rock mass frequently poses a threat to the stability of adjacent tunnels.Previous research is limited by the simplification of a rock mass as a homogeneous elastic medium,without considering the wave attenuation caused by viscoelasticity and wave separation induced by rock discontinuities,as well as plane waves while neglecting geometric attenuation of near-field nonplane blast waves.This paper establishes a theoretical model of cylindrical P-wave propagation across a fault to an adjacent existing tunnel.Based on the time-domain recursive method,vibration equations and peak particle velocity on the adjacent existing tunnel wall caused by a cylindrical wave passing through a fault are derived.The rock mass and fault are assumed to satisfy Kelvin viscoelastic bodies,and contact interfaces between fault and rock mass follow a nonlinear hyperbolic deformation model in the normal direction and a linear model in the tangential direction.The results show that tunnel vibration caused by the blast cylindrical P-wave is primarily induced by transmitted P-waves.With the increase of the fault dip angle,vibration on the upper side of the adjacent existing tunnel gradually decreases,while vibration on the lower side increases.The closer the vibration to the upper and lower sides,the stronger the shear effect on the tunnel wall,and the closer the vibration to the middle,the stronger the pressure effect on the tunnel wall.Larger fault thickness and higher initial blast wave frequency result in weaker vibration of the adjacent tunnel.The deeper the burial depth,the stronger the vibration of the adjacent tunnel wall.Findings of this study provide insight into the dynamic response of rock construction and safety evaluation in engineering service.
基金supported by the National Natural Science Foundation of China(Grant Nos.51927808 and 41630642)the Postgraduate Innovation Fund Project of Hunan Province(Grant No.CX20200242).
文摘During the development blasting of circular tunnels, the detonation of multiple blastholes arranged onconcentric circles induces a complex dynamic response in the surrounding rocks. This process involvesmultiple blast loadings, static stress unloadings, and stress redistributions. In this study, the dynamicstresses of the surrounding rocks during development blasting, considering multiple blasting-unloadingstages with exponential paths and triangular paths (linear simplified paths of exponential paths), aresolved based on the dynamic theory and the Fourier transform method. Then, a corresponding discreteelement model is established using particle flow code (PFC). The multiple-stage dynamic stress andfracture distribution under different in situ stress levels and lateral coefficients are investigated. Theoreticalresults indicate that the peak compressive stresses in the surrounding rocks induced by bothtriangular and exponential paths are equal, while the triangular path generates greater additional dynamictensile stresses, particularly in the circumferential direction, compared to the exponential path.Numerical results show that the exponential path causes less dynamic circumferential tensile damageand forms fewer radial fractures than the triangular path in the first few blast stages;conversely, itexacerbates the damage and instability in the final blasting-unloading stage and forms more circumferentialfractures. Furthermore, the in situ stress determines which of the two opposite effects isdominant. Therefore, when using overly simplified triangular paths to evaluate the stability of surroundingrocks, potential overestimation or underestimation caused by different failure mechanismsshould be considered. Specifically, under high horizontal and vertical stresses, the static stress redistributionwith layer-by-layer blasting suppresses dynamic circumferential tensile and radial compressivedamage. The damage evolution of surrounding rocks in multi-stage blasting under different in situstresses is summarized and classified according to the damage mechanism and characteristics, which canguide blasting and support design.
基金supported by the Shenzhen Stability Support Plan(Grant No.20231122095154003)National Natural Science Foundation of China(Grant Nos.51978671 and 52378425)Guizhou Provincial Department of Transportation Science and Technology Program(Grant No.2023-122-003)。
文摘Due to space constraints in mountainous areas,twin tunnels are sometimes constructed very close to each other or even overlap.This proximity challenges the structural stability of tunnels built with the drill-and-blast method,as the short propagation distance amplifies blasting vibrations.A case of blasting damage is reported in this paper,where concrete cracks crossed construction joints in the twin-arch lining.To identify the causes of these cracks and develop effective vibration mitigation measures,field monitoring and numerical analysis were conducted.Specifically,a restart method was used to simulate the second peak particle velocity(PPV)of MS3 delays occurring 50 ms after the MS1 delays.The study found that the dynamic tensile stress in the tunnel induced by the blast wave has a linear relationship with the of the product of the concrete wave impedance and the PPV.A blast vibration velocity exceeding 23.3 cm/s resulted in tensile stress in the lining surpassing the ultimate tensile strength of C30 concrete,leading to tensile cracking on the blast-facing arch of the constructed tunnel.To control excessive vi-bration velocity,a mitigation trench was implemented to reduce blast wave impact.The trench,approximately 15 m in length,50 cm in width,and 450 cm in height,effectively lowered vibration ve-locities,achieving an average reduction rate of 52%according to numerical analysis.A key innovation of this study is the on-site implementation and validation of the trench's effectiveness in mitigating vi-brations.A feasible trench construction configuration was proposed to overcome the limitations of a single trench in fully controlling vibrations.To further enhance protection,zoned blasting and an auxiliary rock pillar,80 cm in width,were incorporated to reinforce the mid-wall.This study introduces novel strategies for vibration protection in tunnel blasting,offering innovative solutions to address blasting-induced vibrations and effectively minimize their impact,thereby enhancing safety and struc-tural stability.
基金supported by the National Natural Science Foundation of China(Grant Nos.41972286 and 42102329).
文摘The Rock-soil interface is a common geological interface.Due to mechanical differences between soil and rock,the stress waves generated by underground blasting undergo intense polarization when crossing the rock-soil interface,making propagation laws difficult to predict.Currently,the characteristics of the impact of the rock-soil interface on blasting stress waves remain unclear.Therefore,the vibration field caused by cylindrical charge blasting in elastic rock and partial-saturation poro-viscoelastic soil was solved.A forward algorithm for the underground blasting vibration field in rock-soil sites was proposed,considering medium damping and geometric diffusion effects of stress waves.Further investigation into the influence of rock and soil parameters and blasting source parameters revealed the following conclusions:stress waves in soil exhibit dispersion,causing peak particle velocity(PPV)to display a discrete distribution.Soil parameters affect PPV attenuation only within the soil,while blasting source parameters affect PPV attenuation throughout the entire site.Multi-wave coupling effects induced by the rocksoil interface result in zones of enhanced and attenuated PPV within the site.The size of the enhancement zone is inversely correlated with the distance from the blasting source and positively correlated with the blasting source attenuation rate and burial depth,providing guidance for selecting explosives and blasting positions.Additionally,PPV attenuation rate increases with distance from the rock-soil interface,but an amplification effect occurs near the interface,most noticeable at 0.1 m.Thus,a sufficient safety distance from the rock-soil interface is necessary during underground blasting.
基金the support provided by the Technology Innovation Project (Grant No. KYGYZB002201) for the research work
文摘Investigating the blast effects and mechanisms on typical finite-sized obstacles is essential for optimizing defense strategies and designing more robust barriers to deter terrorists and protect critical locations.This study investigates the blasting effects and underlying mechanisms of concrete frustums subjected to contact explosions,employing both numerical simulations and field tests.It focuses on the effects of top and side blasting,with particular emphasis on fracture modes,damage patterns,and fragment sizes,as well as the causes of different failure modes and the propagation of stress waves.The study also explores the blasting effects of detonating explosives at varying positions along the side and with different charge amounts.The results show that side-blasting leads to complete fragmentation,with tensile waves playing a significant role in creating extensive damage zones that propagate parallel to the frustum's outer surface,concentrating damage near the surface.During top-blasting,the upper half of the frustum undergoes fragmentation,while the lower half experiences cracking.Tensile waves propagate from the top to the bottom surface,forming larger blocks in regions with lower wave intensity.Three distinct damage zones within the frustum were identified,and a series of mathematical formulas were derived to describe the relationship between the maximum fragment size and charge mass.As the charge mass increased from 1.0 kg to 4.0 kg,the maximum fragment size decreased.Detonation at the center of the frustum's side resulted in the most severe fragmentation,with a 51.8%reduction in fragment size compared to other detonation positions.Finally,four broken modes were classified,each influenced by charge mass and explosive location.This study provides valuable insights for optimizing civil blasting operations and designing protective engineering structures.
