The bulking factor of blasted muck piles in open-pit mines serves as a crucial metric for assessing blast performance.Precise estimation of muck pile volume is vital for optimizing blast parameters,controlling frag-mentation effects,and planning subsequent excavation and haulage operations once the target excavation volume is established.To overcome limitations such as inefficiency,reliance on traditional volume-measurement approaches,and inadequate precision in small-sample predictions for blasted muck piles,this research develops an intelligent predic-tion model that leverages airborne LiDAR and machine learning algorithms.A lightweight UAV-LiDAR system for ef-ficient,ground-control-independent acquisition of muck pile point cloud data was developed.Feature selection used the DeepSeek API to develop a hybrid model that integrates Pearson correlation analysis,ANOVA F-test,random for-est feature importance assessment,and recursive feature elimination,ultimately extracting six critical factors from eight initial parameters.The GS-KCV-optimized Bayesian Ridge Regression model demonstrates predictive capabili-ty,achieving a test set R2 of 0.76,a marked improvement over traditional approaches.The model reduces MAE to 19 949.67 m3(26％decrease)and RMSE to 23 020.80 m3(28％decrease),while effectively addressing the com-mon limitation of local-optima convergence in small-sample scenarios.Field tests conducted with DJI M350 drones integrated with Zenmuse L2 LiDAR systems verify the method's ability to holistically optimize the operational process,spanning blast parameter collection,volume prediction,and performance assessment,providing a practical technological solution for intelligent mining transformation.
To study the influence of saturation on dynamic mechanical behavior and energy absorption in layered phyllite,phyllite specimens with varying bedding angles(0°,30°,60°,90°)and moisture conditions(dry versus satu-rated)were prepared,and then a dynamic impact test was carried out by using the Split Hopkinson Pressure Bar(SHPB)test system.Finally,the mechanical properties and energy absorption characteristics of the specimens under varying bedding angles and saturation levels were analyzed.The results show that the deformation and failure mode of phyllite are influenced by the combined effects of bedding dip angle and moisture conditions.The mechanical param-eter variation follows the sequence 0°＞90°＞30°＞60° for bedding angles,with saturated specimens exhibiting lower values than dry specimens.Specimens predominantly exhibited crushing failure at 0° inclination,shear failure along bedding planes at 30° and 60°,and compressive bar instability at 90°,while showing higher degrees of fragmentation under saturated conditions.Experimental results demonstrate that saturated phyllite specimens exhibit higher energy dissipation density across all tested bedding angles compared to dry specimens,with maximum energy absorption oc-curring at 0° inclination angle and minimum dissipation observed at 90° inclination angle.
During the mining process,tensile failure represents a predominant mode of ore fragmentation.This re-search systematically examines the dynamic tensile mechanical properties of both high-grade(Fe＞60％)and low-grade(Fe 10～20％)iron ores through the combined application of Split Hopkinson Pressure Bar(SHPB)testing and Ultra-high-speed Digital Image Correlation(DIC)techniques for dynamic splitting tests.The analysis focused on failure mechanisms,strain field evolution,dynamic tensile properties,and energy absorption capacity.Results reveal that high-grade iron ore specimens experience localized crack propagation at their geometric center,predominantly failing through the formation of a dominant central fracture.A strong positive correlation was observed between in-creasing impact pressure and improvements in both dynamic tensile strength and loading rate.In contrast,low-grade i-ron ores exhibit dispersed crack propagation along pre-existing internal joints due to their structural heterogeneity.The dynamic tensile strength and loading rate exhibit less predictable trends in these specimens,which are predominantly governed by joint network characteristics.Energy dissipation analysis indicates superior energy absorption capacity in high-grade ores,where failure mechanisms are primarily determined by mineral grain strength,while low-grade ore fail-ure is dictated by joint plane integrity.Comparative analysis reveals that under identical impact pressure conditions,high-grade iron ores exhibit superior mechanical performance compared to low-grade specimens,with higher loading rates,dynamic tensile strength,peak tensile strain capacity,and energy absorption.This study confirms the substantial influence of both lithological characteristics and ore grade classification on mechanical properties.These findings estab-lish a theoretical framework for optimizing blasting parameters and implementing effective damage mitigation strategies in iron ore mining operations.
To address blasting safety risks caused by language barriers between Chinese and foreign personnel in international blasting projects,this research utilizes an integrated methodology incorporating retrospective case stud-ies,questionnaire surveys,and controlled field experiments to develop a specialized Chinese training system for blas-ting safety and validate its practical implementation effectiveness.Initially,retrospective analysis was conducted on two near-miss incidents in international blasting projects to identify key risk-inducing factors.Subsequently,a struc-tured questionnaire survey involving 142 practitioners from seven countries was administered to assess risk percep-tions and training requirements.Building upon the Chinese for Specific Purposes theory and Situated Learning princi-ples,a Terminology-context-pragmatics' three-tier specialized Chinese training system was developed,followed by the implementation of an instructional pilot program.The findings demonstrate that language-barrier-induced safety risks in international blasting projects are objectively prevalent and widely acknowledged by professionals.Terminology mistranslation and procedural comprehension errors,which together constituted over 70％of the contributing factors,emerged as the dominant causes in near-miss events.Additionally,96.5％of Chinese management personnel and 88.7％of foreign operational personnel identified insufficient specialized Chinese-language competency as a funda-mental project safety concern.The experimental group demonstrated terminology recognition accuracy rates of 92.1％(post-test)and 31.4％(pre-test),and safety procedure situational test pass rates of 86.5％(post-test)compared to 28.3％(pre-test).Significant improvements were observed in the experimental group across terminology recognition,safety procedure execution,and Blasting Safety Management Cognition Scale scores relative to the control group,con-firming the training system's effectiveness in enhancing foreign personnel's specialized Chinese competency,safety knowledge acquisition,and operational compliance.This study provides both a language-based solution and empirical evidence for improving safety management in international blasting projects.
Understanding the coupled effects of impact velocity,rockfall dimensions,and impact angle on the per-formance of flexible barrier nets is crucial for optimizing the design of rockfall protection systems during high-slope blasting operations.Employing energy method principles,this study establishes a mechanical model for analyzing rock-fall impacts on protective barrier nets along high slopes,deriving theoretical correlations between maximum impact force and key parameters,including rockfall mass,velocity,and impact angle,expressed as Fmax=v0 cos α √mk.Additional-ly,a numerical model simulating rockfall impacts on barrier nets was developed,with comprehensive simulations per-formed to analyze both isolated single-parameter effects and coupled interactions among rock mass,velocity,and im-pact angle,elucidating their individual and combined influences on barrier net deformation patterns.Results demon-strate that the peak impact force follows a square-root dependence on rockfall mass while maintaining direct linear proportionality to velocity.Increasing vertical impact angles induces outward displacement of impact points,conse-quently diminishing net deformation.The deformation magnitude is linear,whereas higher impact velocities induce material yielding and subsequent stiffness enhancement,thereby decelerating deformation progression.Parameter sen-sitivity analysis reveals the following significance ranking for multi-factor interactions:impact velocity(33.96％),rockfall radius(32.11％),and vertical impact angle(30.91％).Based on these findings,a dual-layer interceptor net system was designed and implemented.Field applications confirm the system's effectiveness in dissipating kinetic en-ergy through the primary net and in successfully intercepting rockfalls by the secondary net,demonstrating superior terrain adaptability and protective capabilities.
This research focuses on addressing fragmentation heterogeneity in the Dengjiashan limestone mining area,which is exacerbated by complex joint development conditions and affects downstream processing productivity and economic performance.Through systematic quantification of the effects of critical blasting parameters on fragmen-tation consistency,this research establishes a foundation for optimizing precision blasting using orthogonal experimen-tal methodology.The cumulative rates of 8 cm,3 cm,and 0.5 cm sieving were used as the evaluation indices for frag-mentation distribution to examine four key variables,including hole network parameters,delay time,subdrilling,and charge interval,in on-site blasting tests.Test results indicate that establishing an air buffer layer between explosive columns effectively modulates stress-wave propagation and energy-transmission efficiency,substantially reducing the 8 cm sieve undersize accumulation while predominantly regulating boulder yield,with drilling-pattern parameters ex-erting direct control over explosive energy concentration patterns.Meanwhile,reduced blasthole spacing configurations produce finer fragmentation patterns,whereas expanded spacing configurations result in coarser fragmentation.The delay time affects the stress-wave superposition effect by precisely controlling the blasting timing,effectively lowering the percentage of 8 cm oversize fragments in adjacent rows while primarily determining the medium and fine particle-size distribution characteristics.Optimizing subdrilling depth between 2.5 m and 2.8 m can help reduce the founda-tion,but the effect weakens when blasthole spacing exceeds the optimal range.Furthermore,range and variance analy-ses quantitatively assessed parameter influences,revealing charge spacing and blasthole patterns as dominant controls on coarse fragments,while delay timing critically governed the distribution of medium and fine particles.The opti-mized parameter combination comprised 6.0 m ×3.5 m hole spacing,20 ms interhole delays,33 ms interrow delays,2.8 m subdrilling depth,and 2.0 m charge intervals.This study systematically evaluated the effects of critical blas-ting parameters on fragmentation characteristics in Dengjiashan limestone,successfully addressing fragmentation non-uniformity while enhancing downstream processing efficiency and reducing operational expenses.
Given the pressing demand for eco-friendly and low-carbon development in mining operations,decar-bonizing the blasting techniques has emerged as a pivotal challenge.The effectiveness of rock fragmentation critically determines the ore size distribution,thereby exerting a decisive influence on the energy requirements of subsequent processing stages.Using Chengchao Iron Mine as a case study,this study developed a stope production carbon emis-sions model that quantitatively correlates D50 particle size with critical operational parameters,including drilling pow-er consumption,blasting explosive usage,and haulage equipment energy demand.By integrating carbon emission co-efficients for associated energy and materials,the research systematically quantified process-wide carbon emissions influenced by fragmentation performance,ultimately determining 32.55 cm as the optimal D50 particle size for mini-mizing carbon emissions.Subsequently,sixteen groups of orthogonal experiments were designed by varying blasthole length,stemming length,and toe spacing.A fluid-solid coupling algorithm was implemented to characterize the dy-namic constitutive behavior of formations.Building on this foundation,ANSYS/LS-DYNA simulations were conducted to analyze the distribution of blast-induced fractures across various design schemes.Grayscale processing and binari-zation were applied to simulated fracture patterns to enhance rock block boundary contrast,followed by an adaptive multi-scale Canny algorithm for precise extraction of fragment-fracture interfaces.Finally,the boulder yield,fines fraction,and D50 particle-size distribution for each experimental configuration were statistically analyzed to enable precise calculation of associated carbon emission intensities.Simulation data analysis reveals that carbon emissions across the 16 schemes range from 1.4391 kg CO2/t to 1.6296 kg CO2/t,with a pronounced inverse relationship be-tween the oversize fragment proportion and fine ore generation efficiency.Subsequently,a fragmentation prediction model was developed using a PSO-ELM algorithm based on the experimental datasets.The NSGA-Ⅱ optimization method was employed to refine blasting parameters,yielding an optimal configuration that simultaneously minimizes carbon emissions and enhances fragmentation performance:a 166 m blasthole length,a 21.6 m stemming length,and a 2.0 m toe spacing.This configuration achieves a carbon emission intensity of 1.43617 kg CO2/t,with an oversize fragment ratio of 18.83926％and a fine ore production rate of 17.28788％.The results confirm that the developed collaborative optimization approach substantially reduces whole-process carbon emission intensity during stope pro-duction while maintaining consistent operational efficiency.This research provides both a measurable technical frame-work that combines sustainable transformation with intelligent control to achieve the"dual carbon"target and action-able implementation guidelines for industrial practice.
Subdrilled cut blasting technology is extensively employed for deep shaft sinking through hard rock formations.In contrast to equal-depth cutting methods,where the cutting depth matches the auxiliary hole depth,this advanced technique significantly improves advance per round and enhances blast hole utilization rate.Optimizing subdrilled-cut parameters is of substantial engineering significance in hard-rock shaft-sinking projects.Based on the actual blasting design and geological conditions at the auxiliary shaft of the Ansteel Group Iron Mine in Xi'anshan,this study uses the numerical simulation software ANSYS/AUTODYN to establish 7 types of subdrilled cut-blasting calculation models,including cutting holes and auxiliary holes.Through comprehensive simulations of excavation blasting processes under varying subdrilling configurations,the research systematically analyzes variations in rock particle velocity and overpressure dynamics during detonation.These investigations aim to elucidate the mechanisms of damage evolution in rock masses under different subdrilling conditions and to determine the optimal depth range for maximum blasting efficiency.Results demonstrate that subdrilled cut blasting substantially enhances advance per-formance compared to traditional methods.Both peak rock pressure and particle ejection velocity between the cutting and auxiliary holes increase progressively with greater subdrilling,thereby promoting rock fragmentation and excava-tion efficiency.However,this growth trend gradually stabilizes as subdrilling increases.Field validation confirms sig-nificant tunnelling improvement after parameter optimization,achieving an average advance per round of 4120 mm(with a 4500 mm perimeter hole depth and a 500 mm subdrilling)and a monthly progress exceeding 115 m.These findings provide valuable references for optimizing subdrilling parameters in similar engineering projects.
Glass and basalt fibers have been extensively utilized in civil engineering applications,and their inclu-sion can enhance the mechanical properties of concrete materials.Empirical studies indicate that integrating fibers in-to reinforced concrete(RC)components augments their blast resistance.Specifically,at a volume incorporation rate of 0.2％,the efficacy of these fibers in enhancing the anti-explosion performance of concrete is notably pronounced.This investigation involves the design of standard concrete test blocks with a strength grade of C40,alongside glass fi-ber reinforced concrete(GFRC)and basalt fiber reinforced concrete(BFRC)test blocks,each with a volume incor-poration rate of 0.2％.These specimens undergo compressive and split tensile strength tests to evaluate the influence of the respective fibers on concrete's mechanical properties.The results demonstrate an improvement in the mechani-cal characteristics of both fiber-reinforced concretes.To assess the blast resistance of GFRC and BFRC beams,three types of beams-ordinary reinforced concrete(RC),GFRC,and BFRC-were constructed.Each beam was subjected to four explosive loads to observe the dynamic response and surface damage.The findings reveal that fiber reinforcement enhances concrete toughness and significantly mitigates the dynamic response of the beams under explosive loading conditions.Specifically,GFRC beams with a 0.2％volume fiber content exhibited lower peak accelerations and strains compared to BFRC beams,and the GFRC beams' surfaces showed reduced spalling and crack formation rela-tive to BFRC beams.
In a limestone aggregate quarry,excessive fines generation following blasting was primarily caused by extensively developed joint fractures and prolonged implementation of continuous coupled charging configurations.To minimize the generation of blasting fines and improve rock fragmentation,a small-diameter charge technology was de-veloped based on the principles of decoupled charge blasting.Firstly,a fragmentation-damage correlation model for blast-induced fractured rock mass was developed in ANSYS/LS-DYNA based on field-collected measurement data.Secondly,numerical simulations were conducted to evaluate the blasting performance of the small-diameter charge structure relative to traditional decoupled charge methods,thereby confirming the technical viability of the proposed small-diameter charging approach.Thirdly,numerical simulations were conducted to determine the correlation be-tween segmented small-diameter charge lengths and fines generation rates,thereby enabling technical optimization.Finally,field verification tests were conducted in accordance with simulation findings to assess the performance of the refined small-diameter charging method.Numerical simulations demonstrate that the small-diameter charging tech-nique provides superior control over rock fragmentation,with the optimal dust reduction achieved using a dual-seg-ment 2.0 m small-diameter charge configuration.Field tests demonstrate that employing a dual-segment 2.0 m small-diameter charge configuration reduces blasting fines generation by 6.53 percentage points compared to conventional continuous coupled charging,while maintaining comparable boulder yield,offering practical guidance for similar ag-gregate quarry operations.
To address critical technical challenges in the-450 m level middle roadway blasting of an iron mine,including excessive blasthole quantities,difficulties in enhancing advance per blast cycle,and low blasthole uti-lization efficiency,this study proposes and develops an optimized multi-blasthole burn cut blasting design.The pro-posed scheme aims to improve roadway excavation footage by simultaneously reducing the number of required blast-holes and enhancing cut-blasting performance.Firstly,theoretical calculations were performed utilizing rock fragmen-tation range theory,rock breakage expansion space effects,and relief hole concentration effects,establishing a prelim-inary center-to-center distance of 24.4 cm between the central cutting hole and relief hole.Subsequently,a numerical model for multi-hole cut blasting was developed using ANSYS/LS-DYNA.Through comparative analysis of stress contours,damage distribution patterns,and fragmentation characteristics under various hole-spacing and relief-hole configurations,the optimal parameters for the relief-hole cutting scheme were determined as follows:25 cm spacing between central cutting holes and relief holes,with 5 relief holes.Field trials conducted with these theoretically and numerically optimized parameters demonstrated significant improvements,achieving an average advance of 2.3 m per blast cycle and increasing blasthole utilization to 92％.Compared to the original blasting design,the optimized scheme demonstrates measurable improvements:a 0.2 m advance per blast cycle,a 10％reduction in required blast-holes,and an 8％improvement in hole utilization efficiency,collectively resulting in significant tunneling productivity gains.These findings validate the scientific rationale and practical viability of the multi-hole burn-cut blasting optimi-zation approach,establishing both a theoretical framework and operational guidelines for refining blasting parameters in comparable iron mine roadway development projects.
Current initiation delay settings in high-gas tunnels typically follow fixed intervals(0 ms,25 ms,50 ms,75 ms,and 100 ms),yet the limited number of delay segments(fewer than the blast hole rows)forces auxilia-ry holes to share delays.This configuration,combined with inadequate cut-hole delay durations,significantly compro-mises optimal blasting outcomes.To address this issue,a field-programmable digital electronic detonator was imple-mented.Theoretical analysis determined the complete rock mass fracturing duration in the cutting area to be 40 ms,which was further validated through numerical simulation of rock mass displacement dynamics,establishing this as the optimal delay interval.The study reveals that rock mass displacement in the cutting area progresses through three distinct phases:fracture propagation,volumetric expansion,and rock material ejection.Based on the optimal cutting area delay time,the ideal initiation sequence for blast hole rows was established as 0 ms,40 ms,60 ms,80 ms,100 ms,and 120 ms,with subsequent field validation conducted in a high-altitude gas tunnel.Statistical analysis of blasting performance demonstrates that implementing the optimized delay sequence(0 ms,40 ms,60 ms,80 ms,100 ms,and 120 ms)achieves over 90％half-hole preservation and controls linear overbreak within 20 cm,satisfying construction specifications while validating the delay configuration's efficacy,with direct applicability to analogous tunnel blasting operations.
This study investigates limitations of conventional shaped-charge blasting in tunnel smooth blasting applications,including excessive charge concentration,operational challenges in charge placement,and induced over-break and surrounding rock damage from concentrated bottom charges.To address these problems,an innovative PVC semi-tubular clasp-shaped charge tube was developed.Following initial effectiveness validation,a reusable steel slit-type charge tube was subsequently designed specifically for weak and fractured surrounding rock mass.Numerical simulations comparing shaped-charge effects between PVC and steel slit-type charge tubes revealed that the steel va-riant exhibited a substantially greater peak stress concentration at the slit and generated longer fracture propagation lengths than its PVC counterpart.The steel slit-shaped charge tube achieved a peak pressure ratio of 5.51 between the slit and non-slit directions,significantly surpassing the PVC tube's ratio of 1.65,thereby demonstrating superior directional energy concentration and protection of the surrounding rock mass.In double-hole blasting tests,the steel slit-shaped charge tube achieved results equivalent to those of the PVC tube at a significantly lower linear charge density(113 g/m vs.314 g/m),demonstrating enhanced directional fracturing efficiency and superior protection for the weak and fractured surrounding rock mass.Field tests in jointed tunnel rock confirmed that the PVC-shaped charge tube enabled uniform explosive distribution and controlled directional energy release,effectively increasing half-cast hole rate while minimizing damage to the retained surrounding rock mass.Comparative blasting tests with/without the steel slit-shaped charge tube confirmed its effective directional energy concentration and reusability.Re-sults demonstrate this steel tube's superior suitability for blasting projects in weak and fractured surrounding rock masses,achieving effective disturbance control with reduced explosive quantities while showing significant potential for practical engineering applications and widespread implementation.
This study systematically investigated the synergistic relationship between matrix temperature and so-dium nitrite concentration to resolve density unevenness and explosive power instability in site-mixed emulsion explo-sives caused by the mismatch between matrix temperature and sensitizer(sodium nitrite)concentration during pro-duction.Using an orthogonal experimental design,matrix temperature gradients ranging from 40℃ to 70℃ and sodi-um nitrite concentration gradients ranging from 1.2％to 2.8％were systematically established.Multiple sets of com-parative tests were conducted to comprehensively examine the impact of these two factors on the density of emulsion explosives.The experimental results demonstrate that matrix temperature plays a critical role in determining the foa-ming reaction rate,with elevated temperatures markedly accelerating the reaction and,consequently,the foaming process.However,this acceleration often leads to excessive foaming,consequently reducing the explosive density.In contrast,lower temperatures slow the reaction,often resulting in insufficient foaming,which increases explosive densi-ty and adversely affects blasting stability.Additionally,the concentration of sodium nitrite,acting as the sensitizer,di-rectly influences both the foaming efficiency and the structural stability of the bubbles.For different matrix tempera-tures,there is an optimal concentration range to achieve ideal explosive density and detonation performance.Based on comprehensive experimental data,this study developed practical guidelines for sodium nitrite proportions across vari-ous matrix temperature ranges.These guidelines explicitly recommended specific sensitizer concentrations for low-to high-temperature conditions,providing quantitative references for field applications.Field validation confirmed that implementing this matching table and associated control techniques substantially enhanced the accuracy of emulsified explosive density regulation.This improvement not only boosted the effective release of explosive energy but also miti-gated safety risks,including density-related misfires,resulting in overall optimization of both blasting performance and operational safety.This study's findings offer valuable theoretical insights and practical applications for enhancing quality control in field-mixed explosives and systematically improving blasting performance.
Three structurally robust,high-seismic-resistance buildings in the urban core of an extremely cold,seismically active region in northwest China required demolition due to serious safety concerns.To ensure successful controlled demolition operations,comprehensive field testing of electronic detonator initiation networks at subzero temperatures was conducted,validating the firing reliability of 10 000 industrial detonators and 11 initiation devices.Based on experimental findings,structural analysis,and environmental considerations,an integrated demolition plan was formulated.Building No.3 was mechanically demolished,while Buildings No.1 and No.2 were concurrently de-molished through controlled blasting,with Building No.1 using a progressive span collapse blasting technique and Building No.2 employing a unidirectional folding collapse methodology.The successful demolition resulted in the complete structural disintegration of both buildings,with outcomes exceeding performance expectations.Field imple-mentation confirmed that for seismically reinforced core tube structures requiring controlled collapse,conducting sub-zero detonator network reliability tests,ensuring accurate delay timing,and optimizing cut design ensure precise dem-olition aligned with engineering specifications.The proposed method ensures optimal protection for surrounding struc-tures,roads,and municipal pipelines while establishing an efficient and secure framework for demolishing seismically reinforced core tube buildings in frigid environments,with potential applications for comparable demolition blasting projects.
To address the absence of specialized explosives for mine presplitting blasting and excessive detona-tion velocity/power of conventional 32 mm emulsion explosives,this study proposed reducing the explosive diameter to moderate detonation characteristics.By combining critical diameter theory with numerical simulation analysis,a PVC tube charge model was developed in LS-DYNA.The detonation wave propagation was simulated using ignition-growth reaction-rate equations and fluid-solid coupling algorithms,with detonation-curve analysis verifying explosive stability.The BSS-1 intelligent ten-stage detonation velocity meter was employed to measure detonation velocities of emulsion explosives of different diameters,thereby enabling the determination of their critical diameter from experi-mental data.Results demonstrate strong agreement between simulations and experiments:stable detonation occurs at 14 mm diameter,while failure occurs at 12 mm,establishing the critical diameter range as 12～14 mm.Additionally,when the diameter exceeds 14 mm,the detonation velocity exhibits a positive correlation with diameter increase.This study,cross-validation of numerical simulations and field experiments,identifies the critical diameter range for indus-trial emulsion explosives in mining applications,offering empirical support for optimizing presplitting blasting parame-ters and enhancing safety management.
This study investigates the mechanism by which detonation velocity and charge length influence blas-ting performance in muck pile blasting,aiming to optimize blast design parameters while enhancing explosive energy utilization efficiency and operational safety.By establishing a comprehensive evaluation system integrating fuzzy mathematics,the entropy weight method,and the analytic hierarchy process,this study analyzes the optimal ranges of detonation velocity and charge length that meet field construction requirements.Additionally,a mechanical model of muck pile blasting was developed using the discrete element software PFC.The study systematically examined stress wave propagation,fracture propagation,and energy transfer characteristics across various combinations of detonation velocity and stemming length.Field measurements of critical parameters,including blast vibration parameters,rock fragmentation distribution,and muck pile morphology,were conducted and cross-validated with simulation outputs,confirming both the engineering adaptability of optimal parameter ranges and the reliability of numerical modeling predictions.The experimental results demonstrate an optimal detonation velocity range(approximately 4500 m/s)for bull emulsion explosive in muck pile blasting operations,showing optimal compatibility with granite formations.Below this critical velocity threshold,insufficient explosive energy occurs,leading to increased oversize fragment generation in blasted rock masses.Excessive detonation velocities lead to elevated fine ore production rates due to disproportion-ately high peak stress-wave pressures.Furthermore,a critical correlation exists between charge length and bench height.Optimal fragmentation balance between the upper and lower bench sections is achieved when the charge length is 20％to 26％of the total bench height.Through targeted technical interventions,refined blasting implemen-tation,and optimized adjustment of explosive detonation velocity coupled with charge length,significant enhancement of bench blasting performance can be achieved under existing burden and spacing.This research elucidates the cou-pling mechanism between detonation velocity and stemming length,establishing both theoretical foundations and prac-tical guidelines for optimizing blasting parameters in open-pit mine muck pile blasting.
Tonglushan Mine has progressed into deep-level mining operations.This study employs an integrated methodology that combines theoretical models with in situ vibration monitoring to characterize blast-induced vibra-tions in surrounding buildings in the mining region.Vibration monitoring systems with blast seismographs and velocity sensors were deployed in Tongshan Village,adjacent to the open pit's southern perimeter,capturing three sets of me-dium-depth blasting parameters,including dominant frequency,vibration velocity,and other vibration parameters.The acquired data were benchmarked against national safety thresholds to assess the potential for structural impact.Subse-quent application of the Sadovskij empirical formula enabled quantitative modeling of vibration attenuation character-istics and the range of vibration influence.The monitoring results demonstrate:(1)The three medium-deep-hole blasts exhibited dominant frequencies ranging from 9.0 to 50.0 Hz,with peak resultant vibration velocities of 0.036 cm/s,0.048 cm/s,and 0.043 cm/s at respective monitoring stations,all values remaining well within the pre-scribed safety limits.(2)Parameter regression yields Sadovskij coefficients K=93.68 and α=1.76,reflecting site-specific blasting conditions and lithology consistent with medium-hard to hard rock classification.These findings con-firm that current blasting protocols maintain effective vibration control,safeguarding both environmental stability and structural integrity of adjacent buildings during deep mining operations.
The quality of tunnel contour surfaces in drilling and blasting construction is fundamentally governed by the propagation efficiency and coalescence behavior of fractures generated between perimeter blast holes.This re-search employed physical modeling and computational analysis to investigate the influence of empty holes around a tunnel perimeter on the propagation law and coalescence effectiveness of cracks.Firstly,comparative model experi-ments were conducted to evaluate crack propagation and coalescence effectiveness between perimeter holes with and without relief-hole guidance,and to systematically analyze how blast-hole spacing(L)and the decoupling coefficient(K)affect these processes.Subsequently,numerical simulations were employed to study the stress wave propagation between holes under both configurations,thereby elucidating the fundamental mechanisms through which empty holes optimize fracture propagation paths and enhance coalescence effectiveness.Results indicate that effective crack coa-lescence between blast holes occurs under two parameter sets without empty hole guidance,K=2.0 with L=11D or K=1.25/1.5 with L=13D,where D denotes blast hole diameter.The empty hole guidance demonstrates optimal performance at K=1.5 and L=13D,producing a smoothly coalesced crack that aligns nearly perfectly with the inter-hole connecting line.The observed guiding phenomenon results from stress concentrations at the empty-hole walls,where superimposed reflected tensile waves and incident waves redirect fracture paths toward the inter-hole center-lines,thereby controlling crack propagation trajectories and coalescence patterns.Both experimental modeling and computational analysis revealed that the radius of the crack zone around the perimeter holes under empty-hole guid-ance was significantly smaller than under conventional blasting,demonstrating their dual functionality in simultane-ously directing inter-hole crack coalescence while restricting undesirable radial fracture propagation.
Precise control of blasting-induced excavation boundaries in deep phosphate stopes presents signifi-cant challenges under complex backfill constraints,with current overbreak/underbreak evaluation methods frequently lacking quantitative rigor.Using the 875-level stope of Shaft No.2 at Guizhou's Xinqiao Phosphate Mine as a case study,this research develops an advanced methodology for blasting boundary characterization and control that levera-ges three-dimensional(3D)laser point cloud data analysis.High-precision post-blast point cloud data were collected using a mobile laser scanning system,followed by the development of a comprehensive analytical framework incorpo-rating point cloud denoising,preprocessing,registration correction,surface reconstruction,and geometric discrepancy analysis.This system allows quantitative evaluation of the spatial distribution of overbreak and underbreak,volumetric deviation,and the degree of contour matching between the excavation boundary and the design profile.Utilizing point cloud diagnostic results from representative stopes,the effects of blasting energy distribution and initiation sequence on boundary formation were analyzed,subsequently developing a control strategy integrating zoned millisecond-delay initiation with optimized blasthole layouts.Field trials at the 875-13#stope confirmed the method's capability to pre-cisely characterize post-blast boundary morphology and deviation characteristics,achieving over 90％contour matc-hing accuracy for both A1 and A2 rows.Volumetric difference analysis of point cloud data provided a reliable quantita-tive basis for assessing overbreak and underbreak and for guiding blasting parameter optimization.The developed boundary control technique demonstrates consistent stability and robustness even under challenging conditions,inclu-ding drilling deviations in the A3 and A4 rows.This methodology offers a quantitative,traceable technical solution for precision blasting design and boundary control in deep mining stopes,delivering practical value by minimizing ore di-lution and enhancing stope extraction efficiency.
