Contents
2024
Volume: 41 Issue 2
31 Article(s)
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Study on Rock Fragmentation under Condition of Delayed Initiation between Holes in an Openpit Mine
YU Chuan-ze, GUO Lian-jun, DENG Ding, WANG Xue-song, and CHAI Qing-ping
To optimize the initiation delay time of an openpit mine and enhance blasting efficiency,a threedimensional bench blasting model is developed using ANSYS/LSDYNA software.The model consists of 2 blast holes in the front row and 1 blast hole in the back row arranged in a triangular pattern.The bottom initiation was emTo optimize the initiation delay time of an openpit mine and enhance blasting efficiency,a threedimensional bench blasting model is developed using ANSYS/LSDYNA software.The model consists of 2 blast holes in the front row and 1 blast hole in the back row arranged in a triangular pattern.The bottom initiation was employed,and 5 stress monitoring points were placed within the hole placement area.Simulated tests were conducted to evaluate rock fragmentation under different delay times between rows(42 ms) and between holes(11,13,15,17,19,21,and 23 ms),while monitoring their effective stress levels.Additionally,a delayed detonation profile model for the two front row boreholes was established to observe the propagation characteristics of explosion stress waves.The results indicate that when the delay time between rows is set at 42 ms and between holes at 17 ms,it leads to peak values of maximum effective stress at each monitoring point which facilitates overall rock fragmentation.The advantage of timedelay blasting lies in its ability to enhance rock damage by utilizing the preblast hole as a foundation,while the frontrow hole acts on the postblast hole through predetonation effects,creating a new free surface.Through field testing and demonstration,we analyzed the distribution of rock fragmentation in blasting pile photos using splitdesktop software.The findings indicate that with an interrow delay time of 42 ms and an interhole delay time of 17 ms,approximately 77.24% of rocks are below 20 cm in size,while only a negligible proportion(0.31%) exceeds 50 cm.Overall,the crushing effect is satisfactory and meets both production and operational requirements for openpit mining operations..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 1 (2024)
Numerical Simulation Study on Damage Law of Surrounding Rock in Blasting Excavation of Ultradeep Shaft
YANG Xiao-lin, ZHANG Guang-ran, CHU Huai-bao, SUN Bo, XU Jie, WANG Dong-hui, CHEN Lu-yang, GUO Peng, and WANG Shao-hua
This study aims to analyze the damage evolution law of the surrounding rock mass in an ultradeep shaft under blasting load.To achieve this,a numerical simulation method is adopted based on the blasting construction practice of Xiling Auxiliary Shaft in Sanshandao Gold Mine.The simulation utilizes a restart technology This study aims to analyze the damage evolution law of the surrounding rock mass in an ultradeep shaft under blasting load.To achieve this,a numerical simulation method is adopted based on the blasting construction practice of Xiling Auxiliary Shaft in Sanshandao Gold Mine.The simulation utilizes a restart technology based on ANSYS/LSDYNA and adopts the equivalent explosion load method according to the blasting design scheme.The surrounding rock mass damage of the ultradeep shaft is calculated under four different ground stresses(15 MPa,30 MPa,45 MPa,and 60 MPa) and four different side pressure coefficients(1.0,1.25,1.5,and 2.0).Furthermore,this study analyzes the damage effect on the shaft's surrounding rock mass and investigates how ground stress and side pressure coefficient influence the extent of damage to the surrounding rock.The numerical results demonstrate that as ground stress increases from 15 MPa to 60 MPa,there is a significant inhibition in the damage area with a decrease in radius from 5.75 m to 3.4 m.Additionally,it is observed that with an increase in lateral pressure coefficient,there is anisotropy in terms of blasting damage area distribution where greater ground stress leads to concentrated damage areas..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 8 (2024)
Study on Influence of Charge Structure on Contour Forming Effect of Hard Rock Tunnel
ZHANG Guang-hui, ZHANG Jia-tuo, WANG Yang, CHENG Yuan-long, JANG Hong-jie, and CHEN Ming
The contour forming effect of a hard rock tunnel is of significant importance in enhancing the stability of surrounding rock and reducing support costs.This paper aims to optimize the singlehole charge and charge structure for tunnel contour holes.The theoretical range of charge parameters for blasting contour holes iThe contour forming effect of a hard rock tunnel is of significant importance in enhancing the stability of surrounding rock and reducing support costs.This paper aims to optimize the singlehole charge and charge structure for tunnel contour holes.The theoretical range of charge parameters for blasting contour holes in tunnels is proposed initially.Subsequently,blasting tests were conducted on a hard rock tunnel using singlehole charges of 1200 g,900 g,750 g,and 600 g respectively,with all tunnel contours analyzed by a laser scanner.Finally,a fracture mechanics model was employed to simulate the contour blasting of the hard rock tunnel with different singlehole charges.The results indicate that when charging parameters are within a reasonable range,smaller singlehole charges result in fewer cracks between blasting holes and less damage to the surrounding rock.Although decreasing the charging amount from 1200 g to 600 g reduces overexcavation volume from 6.53 m3 to 2.02 m3,it also increases underexcavation volume caused by hole position error from 0.15 m3 to 0.26 m3 along the tunnel contour.Furthermore,compared to the damage mechanics model,the fracture mechanics model proves superior in simulating contour blasting for hard rock tunnels as evidenced by good agreement between calculated results and experimental data regarding half hole numbers on the tunnel′s contour..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 15 (2024)
Research on Advanced Cutting Control Blasting of Complex Lithologic Tunnel
YANG Zhi-long, ZHONG Dong-wang, BAI Wen-liang, ZHAO Yun-peng, MA Jian-jun, LI Teng-fei, HE Li, SI Jian-feng, and CAI Lu-jun
In response to the poor excavation effect of traditional blasting in complex lithology tunnels,a method called advanced cutting control blasting is proposed based on the research of traditional smooth blasting and presplitting blasting.This method involves conducting the blasting around weak surrounding rock areas aftIn response to the poor excavation effect of traditional blasting in complex lithology tunnels,a method called advanced cutting control blasting is proposed based on the research of traditional smooth blasting and presplitting blasting.This method involves conducting the blasting around weak surrounding rock areas after tunnel contouring hole blasting.A quasithreedimensional model was established,and numerical simulations were conducted using the fluidstructure interaction(ALE) algorithm and ANSYS/LSDYNA finite element analysis software to compare the advanced cutting control blasting method with traditional presplitting and smooth blasting methods.The results show that compared to smooth blasting and presplitting,advanced cutting control blasting reduced the depth of damage around the tunnel contour by 6.85% and 10.08%,respectively.Based on simulation results,field blast test plans were designed,and comparative tests between smooth surface blasting and advanced cutting control blasting methods were carried out.The blast results demonstrated that after adopting the advanced cutting control method,the tunnel contour had good shaping effects without block falling or collapse in weak surrounding rock areas,while overexcavation was effectively controlled.Threedimensional crosssectional scanning data and statistical results of postblast sections indicated that compared to wellperforming smooth surface blasting,maximum overexcavation decreased by 35.98%,average overexcavation decreased by 25.60%,concrete consumption decreased by 26.3%,and flatness standard deviation increased by 24.29%.This method has been verified through field practice as it reduces overexcavation while mitigating blast damage in complex lithology areas,thereby improving tunnel retaining rock flatness..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 23 (2024)
Field Test of Long Footage Burn Cut Blasting Excavation and Control of Overcut and Undercut in Medium Section Tunnel
GONG Wei-yi, YAO Ying-kang, and DU Yu-xiang
Due to the limitations in construction scope,blasting a mediumsection tunnel is challenging as it often results in short circular footage and significant over and under excavation.To reduce costs and increase efficiency,it is essential to focus on long footage excavation and fine control of over and under excavation.IDue to the limitations in construction scope,blasting a mediumsection tunnel is challenging as it often results in short circular footage and significant over and under excavation.To reduce costs and increase efficiency,it is essential to focus on long footage excavation and fine control of over and under excavation.In this study,a straight hole cutting blasting scheme was designed for a medium section tunnel project and 40 cycles of blasting excavation field tests were conducted.The results revealed that when designing the long footage blasting parameters for a medium section tunnel based on the blasting design manual,issues such as high block rate and uneven face frequently arise.However,by appropriately increasing the charge of the cut part(the proportion of charge of the cut part increased from 12.8% to 18.1% in our field test),better blasting effects were achieved.Additionally,by reducing the charge amount of peripheral holes and adjusting their distance from each other,smooth blasting effect was effectively ensured.During the field test,adjustments were made to the charge amount of peripheral holes based on preliminary design for blasting parameters.This resulted in good contour forming effects with a halfhole rate exceeding 90%.However,an average overcutting value of 18.6 cm was observed across all 40 excavation sections during the blasting cycle.The main cause for this overcutting was identified as platform irregularities along the contour line.To address this issue,it is necessary not only to reduce external drilling angles but also control platform width alongside reasonable parameter designs for surrounding holes.The straight hole cutting scheme proved compatible with threearm rock drilling truck construction methods while enabling mechanized longshot blasting excavations.Nevertheless,precise control over overcutting and undercutting remains challenging along with cost management during blast construction.It is necessary to optimize and improve the operation technology of drilling personnel and the management mode of site construction..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 32 (2024)
Experimental Study on Dynamic Compressive and Tensile Mechanical Properties of Steel Fiber Reinforced Concrete
PENG Song-lin, JIA Yong-sheng, DONG Qian, YE Zhang-fan, YANG Xuan, and KANG Jia
In order to investigate the influence mechanism of steel fiber content on the dynamic compression and tensile mechanical properties of concrete,this study conducted dynamic compression and dynamic Brazilian splitting tests on concrete samples with varying impact pressure and steel fiber volume contents(0%C50 element coIn order to investigate the influence mechanism of steel fiber content on the dynamic compression and tensile mechanical properties of concrete,this study conducted dynamic compression and dynamic Brazilian splitting tests on concrete samples with varying impact pressure and steel fiber volume contents(0%C50 element concrete,2%,3%,and 4%) using a Hopkinson pressure bar(SHPB) device.Additionally,highspeed photography was employed to reveal the dynamic evolution process of cracks.The test results demonstrate that under the same impact pressure,both the dynamic compressive strength and dynamic splitting tensile strength of steel fiber reinforced concrete samples exhibit a positive correlation with the content of steel fiber.Furthermore,there is also a positive correlation between energy absorption capacity and degree of crushing,indicating that steel fibers effectively inhibit concrete crushing while preventing excessive energy absorption and dissipation in these samples.The upper limit for energy absorption rate in steel fiber reinforced concrete samples ranges from 30% to 36%.Notably,compared to its effect on dynamic compressive strength,steel fibers significantly enhance the dynamic splitting tensile strength of concrete.For applications requiring highstrength or antiviolence characteristics in combination with costeffectiveness,technical controllability,and test data analysis;incorporating a reasonable range for toughening can be achieved by including 2%~3% steel fiber content into highstrength concrete.Moreover,it is important to note that the action mechanism of steel fibers differs when considering their effects on both dynamic splitting and compression failure in concrete samples.Steel fibers significantly impede crack propagation during dynamic splitting processes;however,separation between the fibers themselves leads to ineffective toughening during dynamic compression.".
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 40 (2024)
Design and Practice of Rock Plug Blasting in Cryogenic Environment
CHI Xiang, and YAO Chun-yu
The Yinsong Water Diversion Project is a largescale water diversion project aimed at solving the urban water supply problem in the central region of Jilin Province.The rock plug blasting at the intake is a key control engineering aspect of the project.The rock plug has a trumpetshaped opening with a top width of 28.4The Yinsong Water Diversion Project is a largescale water diversion project aimed at solving the urban water supply problem in the central region of Jilin Province.The rock plug blasting at the intake is a key control engineering aspect of the project.The rock plug has a trumpetshaped opening with a top width of 28.4 m,bottom width of 7.0 m,and thickness of 15.76 m.The construction site is located in a cold zone with temperatures ranging from -10℃ to -15℃ during the freezing period,resulting in an ice cover thickness of approximately 0.5 m.There are limited reference cases for implementing rock plug blasting operations under such lowtemperature frozen conditions.To address the technical challenges faced,both 1∶1 scale rock plug blasting tests and lowtemperature tests on explosive materials were conducted.The results of the 1∶1 scale rock plug blasting test were consistent with the original design,as confirmed through postblast inspections which showed that the shape and dimensions of the intake met design requirements and achieved expected goals.This verified the feasibility of groove excavation hole layout,charge structure,amount of explosives used,and initiation network as planned in the design.The lowtemperature test on explosive materials resolved issues related to phase separation and loss of sensitizing bubbles for ordinary emulsion explosives under lowtemperature frozen environments.It also examined reliability by using physically treated solid particles for sensitized highwaterresistant emulsion explosives; experimental measurements met technical requirements.All communication,timing synchronization,and networking functions for highprecision digital electronic detonators operated normally.The highenergy detonation of the explosive charge was effectively controlled by implementing protective measures such as setting end caps and using epoxy resin.The sensitivity to detonation did not show any significant changes.Through a comparison with conventional blasting holes,it was observed that the equipment subjected to lowtemperature testing met the design requirements satisfactorily.Based on the results of these two experiments,optimization of the blasting scheme was carried out.During actual operations,issues such as protruding ice formations on the inner walls of boreholes and difficulties in loading explosive charges were successfully resolved.The initiation network employed three main lines encircling the lining connection section,each distinguished by a different color.Electronic detonators were grouped according to their corresponding colorcoded main line connections.This circular arrangement of blast initiation lines effectively prevented water leakage at low temperatures,ensuring waterproof integrity within connecting components and facilitating subsequent drilling and charging operations.To alleviate pressure buildup after blasting,relief holes were excavated in the upper ice layer above rock plugs for pressure release purposes.The resulting crosssection after blasting closely matched the design specifications without any noticeable collapse at tunnel entrances or excessive vibration levels at critical monitoring points during blasting operations.This study demonstrates that effective control over blast vibrations and environmental protection can be achieved through wellexecuted rock plug blasting techniques..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 51 (2024)
Research on Intelligent Blasting Design and Management Control System of Hydropower Station Slope
ZHENG Xiang, QIU Hao-yang, WANG De-ming, CHEN Jun-tao, ZHAO Feng-ze, and CHEN Ming
The blasting construction of water conservancy projects is characterized by its long duration and large scale.However,traditional methods for blasting design and construction control are inadequate to meet the requirements of current water conservancy project development.Therefore,it is crucial to study and establish aThe blasting construction of water conservancy projects is characterized by its long duration and large scale.However,traditional methods for blasting design and construction control are inadequate to meet the requirements of current water conservancy project development.Therefore,it is crucial to study and establish a platformbased,networked,and intelligent blasting design and control system with significant engineering significance.To achieve this goal,this research adopts a frontend and backend separation method using the Angular framework and SpringBoot framework based on BIM(Building Information Modeling),WebGIS(Geographic Information System),and developed blasting design software.The system comprises an intelligent blasting design module,threedimensional visualization module,digital blasting control module,as well as an intelligent safety evaluation and prediction/warning module.This integration enables intelligent blasting design along with comprehensive auditing functions throughout the entire process.Importantly,the system can select control points on the excavation contour line for intelligent blasting design based on actual site conditions.It generates blast design schemes that undergo review using a model parameterized dynamic joint cropping method before being uploaded.This approach promotes standardization,informatization,and digital management of the entire blasting process while enhancing realtime interactive collaboration among various units involved in designing,constructing,supervising hydropower stations.The application of this system in slope blasting and excavation projects at Yebatan Hydropower Station demonstrates its effectiveness in carrying out blast designs while improving control efficiency.Consequently,it provides valuable technical support for slope blasting designs during hydropower station excavations..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 60 (2024)
Experimental Study on Presplitting Blast of Underground Caverns in Fractured Rock Mass
CHEN Xing-gen, GUAN Fu-su, FU Zhao-kai, NA Xiao-ping, HAO Li-jun, and LI Hong-tao
The geological structure of the Ying Liangbao hydroelectric underground powerhouse is complex due to the development of surrounding rock fissures,messy lithology,and a rock body with "hard,broken,miscellaneous" characteristics.Excavation and molding pose difficulties while presplitting blasting has poor efThe geological structure of the Ying Liangbao hydroelectric underground powerhouse is complex due to the development of surrounding rock fissures,messy lithology,and a rock body with "hard,broken,miscellaneous" characteristics.Excavation and molding pose difficulties while presplitting blasting has poor effects.To address this issue,we conducted a systematic blasting test combined with presplitting for central groove construction on layer III of the powerhouse.In initial tests,both sides of the wall exhibited significant breakage after blasting and traces of presplitting holes were not clearly visible when linear charge density was nearly 100 g/m lower than standardized calculation values.Acoustic testing data revealed that average longitudinal wave velocity in the rock mass body was 4.03 km/s indicating overall poor integrity.Additionally,segmental wave velocities along axial depths from 0~1.5 m,1.5~3.9 m and 3.9~7.4 m were found to be 2.59 km/s,3.58 km/s and 4.70 km/s respectively suggesting segmented integrity differences in depth direction.Based on these findings an average singlehole linear charge density for presplitting blasts during excavation was determined to be between 0 .123~0.284 kg/m with different densities selected according to varying depths while small charge rolls were evenly spaced for each section.The results obtained through testing and application have been positive ensuring basic formation of wall surfaces while significantly increasing halfporosity levels..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 67 (2024)
Study on Effect of Blasting Vibration on Stability of Safety Roof Pillar for Openpit to Underground Transition in Longshou Mine
ZHAO Er-cheng, WEI Zhao-jun, SHEN Yan-cheng, LIU Ji-xiang, LI Ju-hong, ZHANG Chun-yang, and TIAN Xiao-long
This study aims to investigate the stability evolution of the safety roof pillar during the transition from openpit to underground mining in Longshou mine under the influence of blasting vibration.A numerical calculation model was established based on the current mining area conditions.The most critical position of thThis study aims to investigate the stability evolution of the safety roof pillar during the transition from openpit to underground mining in Longshou mine under the influence of blasting vibration.A numerical calculation model was established based on the current mining area conditions.The most critical position of the safety roof pillar was determined through calculations,and a twodimensional numerical model for this position was developed using toplevel mining as an example.By calculating blasting parameters and equivalent elastic boundaries,we obtained the peak blasting load transmitted from cutting holes,auxiliary holes,and peripheral holes to the excavation surface.Subsequently,numerical calculations were conducted to assess the stability of the safety roof pillar after applying an equivalent blasting load to the excavation face.The results indicate that each delayed blast caused displacement and vibration velocity peaks,with maximum displacement observed at monitoring points inside the safety roof pillar closest to the blast site.Vibration velocity spreads spherically around the blasting operation position into surrounding rock mass.Based on criteria related to blasting vibration velocity and rock damage assessment,it can be concluded that overall there is no or only slight damage present in the safety roof pillar.Additionally,analysis reveals that maximum principal stress remains lower than tensile strength of rock mass without any significant formation of a tensile fracture plastic zone on the safety roof pillar.In general,the designed thickness of the safety roof pillar meets requirements for openpit to underground mining.However,due to actual geological complexities beyond what is captured by the numerical model,it is essential to continuously observe and monitor changes in the safety roof pillar to ensure its stability during ongoing mining operations..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 75 (2024)
Research on Application of Compound Wedge Cut in Large Section Tunnel Excavation
QIAN Zhi-qiao, ZHAO Ming-sheng, CHI En-an, WANG Zhen-yi, CUI Wei-wei, and WU Yong-xiang
The blasting effect of cut holes has a significant impact on the overall quality of blasting in large section tunnels. To address the challenges associated with difficult excavation and low utilization rate of blast holes,this study employs a fluid structure coupling algorithm based on ANSYS/LSDYNA to compare and analThe blasting effect of cut holes has a significant impact on the overall quality of blasting in large section tunnels. To address the challenges associated with difficult excavation and low utilization rate of blast holes,this study employs a fluid structure coupling algorithm based on ANSYS/LSDYNA to compare and analyze the internal effective force and damage range between single wedge cut blasting and compound wedge cut blasting. The research findings confirm that compound wedge cut blasting yields better results compared to single wedge cut blasting,providing an explanation for this improved performance. The results indicate that in single wedge cutting,peak stress occurs at the bottom of the hole,gradually decreasing from the bottom to the stemming section before dropping sharply from the stemming section to the palm surface. In contrast,double wedge cutting exhibits higher peak stress values at the bottom of the first level cutting hole compared to single wedge cutting. The damage area crosssections are found to be similar for both types of cutting models. However,in single wedge cutting models,rock from the blockage section to the palm face area remains unbroken and disconnected. Conversely,in compound wedge cutting models,there is complete connectivity throughout the entire groove cavity. Based on these numerical simulation results,an improved blasting scheme was implemented for a specific highway tunnel project. Onsite experiments were conducted accordingly.Compound wedge cuts proved more effective in addressing issues such as low utilization rate of blast holes in large section tunnels and multiple large blocks after blasting..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 86 (2024)
Simulation and Application of Mediumlength Hole Blasting with Nonpillar Sublevel Caving Method based on Aegis
ZHU Guo-jun, XU Shuai, ZHONG Yi-lu, and YANG Bo
The nonpillar sublevel caving method is extensively employed in underground metal deposits due to its advantages of high mining efficiency,simple structure,and enhanced safety.In order to address the issues associated with the laborious design process and insufficiently intuitive simulation effect of mediumlength holThe nonpillar sublevel caving method is extensively employed in underground metal deposits due to its advantages of high mining efficiency,simple structure,and enhanced safety.In order to address the issues associated with the laborious design process and insufficiently intuitive simulation effect of mediumlength hole blasting using traditional pillarless sublevel caving methods,this study conducted a simulation and application research on the medium deep hole blasting process based on the Aegis blasting design and analysis software.Firstly,this paper introduces the module composition and functions of the software while summarizing the simulation analysis process.Secondly,two key technologies were investigated:utilizing model boundaries to confine the blasting space and employing staggered states of blasting energy to verify borehole network parameters.Finally,numerical simulations were performed on mediumlength hole blasting in a specific underground mine with nonpillar sublevel caving method using this software.The research findings suggest that the explosion energy in a single row of blast holes is concentrated and fills the entire explosion chamber.The design of continuously coupled charging structure and a powder factor of 0.3 kg/t is deemed reasonable in this context.It appears that there exists a tangential state for the blasting cavity walls between adjacent blast holes,indicating that the energy between rows may not be sufficient to completely break the rock mass.The distance between blast holes,which is approximately 2.2 m,seems slightly larger.Multiple routes were analyzed to predict the distribution of blasting fragmentation masses,all showing a high proportion of large blocks,consistent with field engineering practice results.For instance,based on photos taken after one blasting event,it was observed that large blocks accounted for 18.03% of the total pile volume.Simulation results from Aegis software analysis indicate that the large spacing between blast holes may be a primary factor contributing to this high block rate.Furthermore,through conducting 12 blasting tests on six mining routes within an experimental section and verifying these results through simulation analysis,consistent outcomes regarding proportions of block size and mass were obtained.This effectively supports the practical application efficiency of the software onsite.Overall,these findings contribute valuable insights into optimizing blasting techniques in rock excavation projects by considering factors such as explosion energy concentration and hole spacing to achieve desired fragmentation outcomes while minimizing undesirable block formation..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 96 (2024)
Optimization and Application of Blasting Parameters of Deep Hole Bench Blasting in Open Pit Mine
ZHANG Yan-hao, LIU Shao-guang, and LOU Xiao-ming
In deep hole bench blasting in openpit mines,several issues arise including high consumption of explosives per blast,large bulk and foundation ratio,increased overall cost,inadequate loose blasting pile for shovel loading,and excessive blasting vibrations that affect slope stability.This study focuses on the controlleIn deep hole bench blasting in openpit mines,several issues arise including high consumption of explosives per blast,large bulk and foundation ratio,increased overall cost,inadequate loose blasting pile for shovel loading,and excessive blasting vibrations that affect slope stability.This study focuses on the controlled blasting project of deephole benches in Duobaoshan openpit mine.Theoretical analysis was conducted to establish an analytical formula for the stress field caused by holebyhole blasting.The parameters such as hole and row spacings,minimum bottom resistance line,and delay time between holes were determined based on this formula.The LSDYNA software was utilized to analyze the blasting stress and crushing range under these parameters.Furthermore,six groups of industrial field tests were carried out at Duobaoshan open pit mine using different blasting parameters.These tests aimed to determine the variation patterns of powder factor,fragmentation size,and looseness characteristics among different explosives.The optimized parameters for controlled deep hole bench blasting in Duobaoshan openpit mine were verified and determined through these experiments.The main research findings are as follows:(1)Under the coupling charge condition of Duobaoshan openpit blasts and utilizing theoretical derivation and analysis of stress fields from holebyhole initiation method,it was found that the influence of stress field distribution is limited to front and rear holes with a delay time between holes set at 17 ms.(2)UAV tilt photography technology along with mobile phone photography can be employed to collect data on detonation piles′ characteristics and lumpiness size at blast sites.Analysis based on collected data provides effective insights into looseness levels.(3)For the 178 mm of the hole diameter and 17 ms of the holes′ delay time of the deep hole bench blasting in Duobaoshan openpit mine,the powder factor is 0.60 kg/m3 and the hole row spacing is 7 m×5 m under the conditions that the blast lumpiness is less than 60 cm and the looseness is greater than 1.45 shovel loading..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 104 (2024)
Rock Blastability Evaluation based on K-Means Clustering and Entropy Weight TOPSIS Method
YE Hai-wang, LEI Bing-xiang, ZHOU Han-hong, YU Meng-hao, LEI Tao, WANG Qi-zhou, LI Ning, and Doumbouya Sekou
The distribution of blasting fragmentation in open pit mines has a direct impact on subsequent excavation,transportation,and crushing operations.To effectively control the fragmentation distribution of blasted rocks in different regions of graphite mines,a new model for evaluating rock blastability was developed using The distribution of blasting fragmentation in open pit mines has a direct impact on subsequent excavation,transportation,and crushing operations.To effectively control the fragmentation distribution of blasted rocks in different regions of graphite mines,a new model for evaluating rock blastability was developed using the Kmeans unsupervised cluster learning method and entropy weight TOPSIS evaluation method.Evaluation indexes including rock density,dynamic energy dissipation rate,dynamic compressive strength,average strain rate,and brittleness index were selected.Through entropy weight calculation,it was determined that the degree of rock breakage is most influenced by the brittleness index and least influenced by the average strain rate.The model was then applied to an actual graphite mine to assess its effectiveness.The rock blastability was divided into 10 grades based on this evaluation model.The average particle size of rocks under different grades was calculated and it was observed that as blastability grade increased,so did the average particle size.This finding demonstrates clear classification characteristics and validates the efficacy of our model.From the perspective of rock mass type of graphite ore,the rock explosibility is ranked from easy to difficult:schist,gneiss,granodiorite,mixed rock.Combined with the analysis of microscopic observation results of graphite ore,it can be seen that the lithology changes from schist to mixed rock,and the graphite crystalline content in the rock decreases,and the graphite ore explosibility grade is also higher and higher.Additionally,there exists a linear positive relationship between density/energy dissipation rate/dynamic compressive strength with rock blastability while negative correlation is observed with respect to average strain rate/brittleness index..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 112 (2024)
Modelling of Relationship between Drilling Parameters of Underground Blasting with Rock Blastability in Phosphate Mines
SHENG Yi-ming, CHAI Xiu-wei, CHANG Zhi-feng, LIU Jian, LI Zhi-quan, and XIANG Bin
Rock blastability classification is a prerequisite for determining labour quotas,designing blasting programmes and controlling the unit consumption of explosives.In order to realize a realtime grading of rock explodability,a measurement of insitu drilling parameters of carbonbearing muddy dolomite during the excavatRock blastability classification is a prerequisite for determining labour quotas,designing blasting programmes and controlling the unit consumption of explosives.In order to realize a realtime grading of rock explodability,a measurement of insitu drilling parameters of carbonbearing muddy dolomite during the excavation process of Ph31 ore body and roadway in the Shukongping phosphorus mine has been carried out based on the KJ2121 fullhydraulic boring drilling truck.Combined with the indoor uniaxial compressive strength test,the relationship model between the uniaxial compressive strength Rc and the drilling speed V,the drilling hole diameter D and the rotary pressure M was respectively established and verified.Finally,the model is substituted into the solidity coefficient f relationship equation to derive a model for the relationship between the blasthole drillfollowing parameters and the rock blastability classification.The results of the study show that the average rate of difference between the uniaxial compressive strength calculated by the relational model and the results of the indoor uniaxial compression tests is 5.5%,which demonstrates the reasonableness of applying the model to the realtime prediction of rock blastability.This model provides a more convenient and fast method for realtime grading prediction of rock blastability.The results show that the dolomitic banded phosphorite,mud banded phosphorite and dense banded phosphorite are medium explosive,carbonbearing mud dolomite is difficult to explode..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 120 (2024)
Study on the Influence of Different Charge Structures on Morphology of Explosion Pile based on GDEM-BlockDyna
ZHANG Ken, YU Yan, LIU Ben, ZHANG Jian-hua, HUANG Gang, LI Jiang-jiang, and Eric Munene Kinyua
This study focuses on the impact of charge structure on the distribution of blast pile morphology in a limestone mine.A combination of theoretical analysis,GDEMBlockDyna numerical simulation,and onsite optimization tests were conducted to investigate the morphological distribution of step blasting and blast reactors.This study focuses on the impact of charge structure on the distribution of blast pile morphology in a limestone mine.A combination of theoretical analysis,GDEMBlockDyna numerical simulation,and onsite optimization tests were conducted to investigate the morphological distribution of step blasting and blast reactors.The change in blast pile morphology with different charge structures was analyzed.The results indicate that the looseness and throwing distance of the blast pile initially increase and then decrease with an increase in the upper charge proportion of the interval section.The height of the explosion pile generally decreases but shows an initial decrease followed by an increase when there is a large air interval proportion.Additionally,the slope angle of the blast pile increases with an increase in charge proportion in the upper section of the interval section but decreases when this proportion becomes too large.These findings demonstrate that explosive pile patterns vary according to charge structure.Furthermore,through numerical simulation methods,effective optimization can be achieved for charge structure,leading to improved onsite explosion patterns and economic benefits for mining operations..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 127 (2024)
Blasting Fragmentation Prediction based on PSO-BPNN Model
LIU Ying, MAO Yu, XU Shi-chao, LI Bin, ZHANG Hong, GU Yun, ZHANG Ji-kui, and JIANG Nan
The impact of fragmentation size and gradation on the stability and permeability of rockfill in hydraulic engineering is of great significance.Accurate prediction of fragmentation size has become a key focus in rock blasting research.In this study,a PSOBPNN model is developed based on the Backpropagation Neural NetworThe impact of fragmentation size and gradation on the stability and permeability of rockfill in hydraulic engineering is of great significance.Accurate prediction of fragmentation size has become a key focus in rock blasting research.In this study,a PSOBPNN model is developed based on the Backpropagation Neural Networks(BPNN) with optimized network weights and biases using the Particle Swarm Optimization(PSO) algorithm.The model is trained and tested using representative blasting data,and its reliability and applicability are validated through its application in the Hunyuan Pumped Storage Power Station project in Shanxi.Results demonstrate that the PSOBPNN model exhibits short computation time and high reliability for predicting fragmentation size,with a maximum relative error between the model output and actual average fragmentation size of 6.56%.Therefore,this model demonstrates high predictive accuracy and applicability,providing precise guidance for construction of rockfill dams at the Hunyuan Pumped Storage Power Station in Shanxi province..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 136 (2024)
A Noise Reduction Smooth Model of Vibration Signal of Open-pit Deep-hole Blasting based on CEEMD
TIAN Jie, ZHANG Yun-peng, YAN Peng, SUN Wen-cheng, and YANG Xi
Due to the complex terrain and geological conditions in the blasting area,as well as errors in monitoring instruments,reflections of vibration propagation medium,and interference from magnetic fields,a significant amount of noise is often present in the original blasting vibration signals collected.To address this issuDue to the complex terrain and geological conditions in the blasting area,as well as errors in monitoring instruments,reflections of vibration propagation medium,and interference from magnetic fields,a significant amount of noise is often present in the original blasting vibration signals collected.To address this issue,a signal noise reduction smooth model based on complementary ensemble empirical mode decomposition(CEEMD) is proposed.Firstly,the measured blasting vibration signal is decomposed using CEEMD and an algorithm for lowpass filtering is established based on the obtained intrinsic mode function(IMF) component from the decomposition.Additionally,an objective function is constructed to calculate the optimal solution according to similarity and smoothness criteria for filtering algorithms.The resulting filtering algorithm model represents an optimal denoising smooth model for blasting vibration signals.To verify our noise reduction smooth model,a simulation signal is constructed and applied to actual openpit deephole blasting vibration signal research.Finally,the noise reduction effects of empirical mode decomposition(EMD) method,wavelet threshold method,CEEMDwavelet threshold method,and filter algorithm model BP3 are quantified and compared using two indexes:signaltonoise ratio and rootmeansquare error.It has been confirmed that the proposed noise reduction smooth model effectively reduces noise in openpit blasting vibration signals.The findings demonstrate that our CEEMDbased noise reduction smooth model for openpit deephole blasting vibrations possesses excellent denoising capabilities while preserving essential characteristic information from the original signals.Furthermore,the denoising effect of the proposed model surpasses that of EMD method,wavelet threshold method,and CEEMDwavelet threshold method..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 143 (2024)
Numerical Simulation and Construction Design of Blasting Demolition of Doublecylinder Old Ammonium Nitrate Granulation Tower
KONG Qing-liang, XIA Zhi-yuan, WANG Gang, LIU Ming-feng, QIAN Ming-yuan, YANG Fan, and GAO Peng-fei
In order to demolish a 57 m high doublecylinder ammonium nitrate granulation tower in a complex environment,this study analyzes the structural characteristics of the tower,including its large potential energy and uneven mass distribution.A blasting method was designed with intermediate initiation and sequential detonaIn order to demolish a 57 m high doublecylinder ammonium nitrate granulation tower in a complex environment,this study analyzes the structural characteristics of the tower,including its large potential energy and uneven mass distribution.A blasting method was designed with intermediate initiation and sequential detonation towards both sides to achieve a controlled collapse effect through “directional blasting+internal convergence”.The blasting design includes trapezoidal cut notches with strictly controlled perimeter and height.The bottom supporting walls are partially retained,and highly symmetric directional windows were created at specific heights.The demolition was carried out using highprecision nonel detonators combined with delayed initiation inside the holes and external relays outside the holes.Through theoretical analysis and calculations,the final blast notch length was determined as 13.5 m with a height of 3.5 m.To validate the design scheme,LSDYNA simulation software was used to establish a threedimensional finite element model of the granulation tower for precollapse analysis.Simulation results show that the collapse process takes approximately 8.8 seconds without any significant forward movement or toppling during collapse,indicating that the overall blasting parameters selected in this scheme are reasonable and can achieve the desired demolition effect..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 151 (2024)
Research Progress on Synthesis of Carbon Nanomaterials by Gaseous Detonation
CHEN Duan-huaa, LI Xiao-jie, YAN Hong-hao, WANG Xiao-hong, and WANG Yu-xin
Gaseous detonation synthesis is a novel approach for the production of carbon nanomaterials.This method offers several advantages over other techniques,including rapid reaction kinetics,diverse product types,high yield,exceptional purity,straightforward operation,and costeffectiveness.These benefits make it highly suiGaseous detonation synthesis is a novel approach for the production of carbon nanomaterials.This method offers several advantages over other techniques,including rapid reaction kinetics,diverse product types,high yield,exceptional purity,straightforward operation,and costeffectiveness.These benefits make it highly suitable for promoting the industrialscale manufacturing of carbon nanomaterials.To elucidate the current research and development status of gaseous detonationsynthesized carbon nanomaterials,this paper provides an overview of the necessary instruments and equipment,experimental procedures,theoretical calculations,and product characterization methods employed in this synthesis technique.Additionally,it summarizes the technologies and methodologies used to synthesize various carbonbased materials such as carboncoated nanometallic particles,carbon nanospheres,carbon nanotubes(CNTs),carbon dots(CDs),and carbon nanocapsules via gaseous detonation synthesis.The morphology of these synthesized products is analyzed along with their structural features and performance characteristics.Furthermore,this study explores the potential applications and technological advancements associated with these newly developed gaseous detonationsynthesized carbon nanomaterials to lay a solid theoretical foundation for rational design optimization and largescale production of nanostructured materials in line with industry standards in explosive engineering.Current research indicates that the synthesis of detonation should be integrated with both macroscopic detonation theory and microscopic particle growth.The investigation of detonation wave engine and the analysis of detonation cell structure have become prominent areas of study,particularly in understanding the relationship between macroscopic detonation cells and the microscopic synthesis process of nanomaterials.However,a significant challenge remains in comprehending the growth mechanism of particles synthesized through detonation on a microscale,necessitating the utilization of molecular dynamics and lattice Boltzmann calculation methods for resolution..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 160 (2024)
Study on Explosive Disconnection Effect of Titanium Alloy Plate
WANG Jie-chun, WANG Meng, ZHAO Meng-qiao, CHEN Gang, and ZHU Yu
The simulation test of blade loss in an aero engine plays a crucial role in casing containment design.The main challenge lies in controlling the breaking of rotor blades when they reach their maximum allowable speed.To investigate the optimal separation structure for rotor blades with artificial separation,two types ofThe simulation test of blade loss in an aero engine plays a crucial role in casing containment design.The main challenge lies in controlling the breaking of rotor blades when they reach their maximum allowable speed.To investigate the optimal separation structure for rotor blades with artificial separation,two types of TC4 titanium alloy plates with Ⅴshaped grooves,one with a single hole and another with double holes at the center,were designed using explosive separation method.The selected size for the TC4 titanium alloy plate was 100 mm×80 mm×23 mm.The AUTODYN numerical simulation software's Smoothed Particle Hydrodynamics(SPH) algorithm was employed to conduct simulation calculations.Experimental comparisons were made on the damage and additional kinetic energy caused by five different schemes involving these two structures.Results indicated that scheme Ⅱ and Ⅴ failed to break off successfully,while scheme Ⅲ resulted in significant damage to the template.On the other hand,schemes Ⅰ and Ⅳ demonstrated better ability to separate the template.Under identical charge conditions,it was observed that the displacement of doublehole structured plates after fracture was significantly greater than that of singlehole structured plates with Ⅴgrooves on both sides.Further analysis revealed that the Ⅴshaped slotted structure could reduce plate damage,enhance explosive energy efficiency,and minimize additional kinetic energy exerted on the plate.Moreover,compared to doublehole structures,this slotted structure also reduced peak speed by 20% and escape speed by 40%..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 170 (2024)
Influence of Air Overpressure induced by Blasting Excavation of Phase Ⅱ Diversion Upper Horizontal Adit of Meizhou Pumped Storage Power Station on Accident Gate
ZHENG Jing-xing, HUANG Wen-feng, CHEN Ming, CHEN Guang-ze, PAN Xin-hao, and ZHENG Jian-yue
Air overpressure generated from the blasting excavation may affect the safety of surrounding structures.The blasting operation area of the horizontal tunnel of the second phase of Meizhou Pumped storage power station is only 81 m away from the steel accident gate of the upper drainage tunnel of the second phase projectAir overpressure generated from the blasting excavation may affect the safety of surrounding structures.The blasting operation area of the horizontal tunnel of the second phase of Meizhou Pumped storage power station is only 81 m away from the steel accident gate of the upper drainage tunnel of the second phase project,which has been built and put into the operation in the first phase.However,the blasting may affect the operation stable of the accident gate.Therefore,taking the blasting excavation of the horizontal hole above the water diversion of the second phase of Meizhou pumped storage power station as the object,the field monitoring of blasting air overpressure was carried out.The distribution rule of blasting air overpressure and its influence on the safety of the emergency gate in the upper reservoir of Meizhou pumped storage power station were analyzed,which provided support for analyzing the influence of blasting air overpressure on the safety of the emergency gate in the upper reservoir.The blasting air overpressure monitoring data show that the air overpressure level in front of the accident gate about 80 m away from the blasting master surface is distributed at 0.63~3.46 kPa,which is much smaller than the suggested corresponding blasting safety control standard of 100 kPa.The protective facilities before the gate can effectively reduce the air overpressure at the gate position,and the measured air overpressure in the fourth and fifth blasting is reduced by more than 55%.When the single and total charge volume are effectively controlled,the measured air overpressure value is much smaller than the suggested control standard value.Besides,there is no abnormality in the field macro investigation and other detection data,the blasting construction does not affect the safe operation of the accident gate on the reservoir..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 177 (2024)
Analysis of Dynamic Characteristics of Old Masonry Structure under Blastinginduced Earthquake
HUANG Jun, XIA Jie-ning, and LUO Song
In urban centers,there are numerous old masonry buildings that possess poor seismic performance and may suffer damage under the effects of blasting.To investigate the dynamic characteristics of these structures when subjected to blasting,a strong motion instrument was installed near a blasting site on an old masonry buIn urban centers,there are numerous old masonry buildings that possess poor seismic performance and may suffer damage under the effects of blasting.To investigate the dynamic characteristics of these structures when subjected to blasting,a strong motion instrument was installed near a blasting site on an old masonry building.This allowed for observation of both instantaneous and cumulative damage effects on the structure.By analyzing records of blasting acceleration and velocity in both time and frequency domains,it is concluded that the dynamic characteristics of the masonry structure can be better identified using blasting velocity rather than acceleration.Additionally,it is found that the transverse resonance of the masonry structure is most influenced by the blasting seismic velocity.Furthermore,both blasting seismic velocity and acceleration can approximately identify low order translational and torsional frequencies of the masonry structure.However,when calculating natural vibration frequency,it is observed that using blasting velocity yields a lower value(1.8%~3.4% lower) compared to calculations based on ground pulsation methods.This discrepancy arises because blast vibrations provide a more accurate reflection of structural response under larger vibrations.Moreover,frequent blasts may induce nonlinear responses in old masonry structures.By monitoring changes in natural vibration frequency over time due to longterm exposure to blasts,it is determined that with increasing blast frequency,firstorder torsional frequency decreases by 4%,secondorder transverse frequency decreases by 3.6%,and secondorder longitudinal frequency decreases by 5.2%.These reductions occur even though individual blasts meet safety regulations,thus highlighting the importance of considering cumulative damage effects from longterm exposure to blasts for old masonry structures with poor seismic capacity during safety monitoring..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 185 (2024)
Study on Attenuation Law of Blasting Vibration in a Small Clear Distance Highway Tunnel
LI Xiao-shuai, GAO Wen-xue, SU Li-ping, ZHANG Xiao-jun, HU Yu, and XUE Rui
In order to study the vibration response of the interlaid rock in the small clear distance tunnel under the blasting load,a field blasting vibration test was carried out based on the blasting project of the Xiaolongmen tunnel.The improved variational mode decomposition(VMD) and multiscale permutation entropy(MPE) algoIn order to study the vibration response of the interlaid rock in the small clear distance tunnel under the blasting load,a field blasting vibration test was carried out based on the blasting project of the Xiaolongmen tunnel.The improved variational mode decomposition(VMD) and multiscale permutation entropy(MPE) algorithm were employed to denoise the blasting vibration signal.Subsequently,the differences in vibration characteristics between the left arch waist(noninterlaid rock area) and right arch waist(interlaid rock area) of the tunnel were analyzed,along with a comparison and analysis of seismic wave attenuation characteristics generated by cut hole blasting and surrounding hole blasting.The results demonstrate that the improved adaptive VMDMPE algorithm enables automatic determination of modal number K and penalty factor α while effectively eliminating noise from the vibration signal,reducing subjective decisionmaking influence.During posterior excavation tunnel face blasting,interlaid rock exhibits significant amplification effects on blast vibrations.Peak particle velocity(PPV) values are higher in interlaid rock compared to noninterlaid areas.However,vibrations attenuate faster within interlaid rock regions.Additionally,analysis reveals that lowfrequency vibrations below 40 Hz account for a substantial proportion of energy within interlaid rock areas when comparing frequency characteristics at measuring points between noninterlaid and interlaid regions.Attention should be given to these lowfrequency vibrations as they are more likely to induce resonance in supporting structures,posing higher risks of damage or destruction within interlaid rock zones.By analyzing the blasting vibration characteristics of the cut hole and the surrounding hole,it can be found that the vibration velocity generated by the surrounding hole blasting in the surrounding rock behind the tunnel face is greater than that of the cut hole blasting within the range of the scale distance(SD) which is less than or equal to 11.57 m kg1/3 due to the effect of 'corner weakening' and the influence of the seismic wave propagation path.After exceeding the critical value of SD,the vibration velocity generated by the cut hole blasting is greater..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 194 (2024)
Prediction of Blasting Vibration Velocity in Openpit Mine based on MD-PCA-BP Model
ZHAO Mo-xi, YANG Yu-min, ZHOU Chuan-bo, ZHANG Sheng, CHEN Wen-zhong, YANG Mao-sen, and ZHANG Yu-qi
In order to address the problem of predicting blasting vibration in complex geological conditions at openpit mines,an improved BP neural network prediction model based on Mahalanobis distance discrimination(MD) and principal component analysis(PCA),namely MD-PCA-BP model,is proposed.By combining the monitoring data ofIn order to address the problem of predicting blasting vibration in complex geological conditions at openpit mines,an improved BP neural network prediction model based on Mahalanobis distance discrimination(MD) and principal component analysis(PCA),namely MD-PCA-BP model,is proposed.By combining the monitoring data of blasting vibration at Changtan openpit mine in Inner Mongolia,outliers in the monitoring data are eliminated using the Mahalanobis distance discrimination method.Then,the principal component analysis method is employed to reduce the dimensionality of factors affecting blasting vibration and obtain three principal component factors.The scores of each principal component factor are calculated,and finally a nonlinear relationship between blasting vibration and principal component scores is constructed through BP neural network to establish the prediction model based on MD-PCA-BP.The results show that the fitting degree between predicted values and measured values of blasting vibration velocity prediction model established based on MD-PCA-BP reaches 0.94,indicating high prediction accuracy of this model.When compared with Sadovsky empirical formula,two improved elevation empirical formulas,MDBP model,PCABP model,and BP model,most of the prediction errors of MD-PCA-BP model are within 10%,demonstrating higher reliability and accuracy compared to empirical formulas and unimproved BP prediction models.The blast vibration prediction model based on MD-PCA-BP exhibits good predictive performance for blast vibration velocity in complex terrains..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 203 (2024)
Study on Attenuation of Underwater Explosion Shock Waves by Bubble Curtain
DU Ming-ran, WANG Tian-zhao, LIANG Jin, LU Shao-feng, LI Ji-rui, WANG Yin-jun, CHEN Yu-hang, and CHEN Zhi-fan
The shock wave generated by underwater explosions has a significant destructive impact on the surrounding environment.Therefore,it is crucial to implement bubble curtain protection for blast area safety.This study aims to investigate the influence of the number of bubble curtain layers on attenuating underwater explosiThe shock wave generated by underwater explosions has a significant destructive impact on the surrounding environment.Therefore,it is crucial to implement bubble curtain protection for blast area safety.This study aims to investigate the influence of the number of bubble curtain layers on attenuating underwater explosion shock waves.An underwater explosion model with free water and varying numbers of bubble curtain layers was established using AUTODYN finite element software.Through experimental validation of the numerical model,a formula for calculating peak overpressure of the shock wave was derived,and the impact of different numbers of bubble curtain layers on shock wave attenuation in water was compared.The results demonstrate that employing a bubble curtain can effectively reduce peak overpressure from an underwater blast shock wave,achieving an attenuation ratio as high as 83%.Furthermore,increasing the number of bubble curtain layers can further enhance this attenuation effect,reaching more than 94% reduction in peak overpressure.Specifically,when comparing twolayered and onelayered bubble curtains at a distance of 12 m from the detonation center behind the bubble curtain,there is a reduction in peak overpressure by 61.94%.Similarly,using a threelayered bubble curtain leads to an additional decrease in peak overpressure at this distance by 11.38% compared to using a twolayered one.However,when utilizing fourlayered curtains instead of threelayers ones,there is only a marginal decrease in peak overpressure(6.42%) at this same distance.In conclusion,implementing a bubble curtain significantly weakens shock waves within water bodies during explosive events.Moreover,fewer layers within the bubble curtain result in greater attenuation effects.However,diminishing returns are observed with each subsequent increase in layer count..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 212 (2024)
Analysis of Attenuation Effect of Multi-layer Bubble Film on Underwater Shock Wave
LIANG Yun, WU Hong-bo, CHEN Yong-jia, LI Ji-rui, HUANG Guo-shu, MA Cheng-shuai, ZHANG Zheng, YE Feng-ming, and ZENG Hui-lian
In order to analyze the attenuation effect of multilayer bubble film on underwater explosive shock wave,an underwater explosion test was conducted to obtain shock wave parameters with a No.8 industrial electric detonator as the explosion source.The bubble film was designed with different specifications and different lIn order to analyze the attenuation effect of multilayer bubble film on underwater explosive shock wave,an underwater explosion test was conducted to obtain shock wave parameters with a No.8 industrial electric detonator as the explosion source.The bubble film was designed with different specifications and different layers of air insulation structure.Furthermore,the shock wave overpressure peak value and specific shock wave energy were compared based on the shock wave parameters.The results show that the attenuation rate of shock wave overpressure peak increases with the increase of bubble film number,with the attenuation rates of 1#,2#,3# and 4# bubble film increasing from 48.32%,86.08%,87.87% and 90.34% to 89.10%,91.33%,91.45% and 92.37%,respectively,which implies that the normal film has less influence on the attenuation of underwater shock wave without air interlayers.Specifically,a larger bubble diameter can reach a better attenuation effect with the same number of layers,which indicates that the bubble plays an important role in attenuating shock waves.In addition,the specific shock wave energy consumption of the bubble film is more than 98.50%.In practical applications,bubble film can be used as a protective material,which can effectively reduce the harmful effects caused by shock waves on the protected objects..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 223 (2024)
Application of LiquidOxygen Phase Change Gas Expansion Technology in Tunnel Excavation
FANG Ying, LI Guo-liang, ZHU Zhen-hai, LIU Jie, and KONG Yu-xia
This study aims to address the challenge of rapid tunnel excavation without the use of explosive.A new oxygen expansion rock breaking technology suitable for general tunnel excavation such as cutting,expanding,auxiliary and peripheral holes is explored,researched,and summarized.The drilling and blasting parameters optiThis study aims to address the challenge of rapid tunnel excavation without the use of explosive.A new oxygen expansion rock breaking technology suitable for general tunnel excavation such as cutting,expanding,auxiliary and peripheral holes is explored,researched,and summarized.The drilling and blasting parameters optimized for tunnel excavation are also provided in detail.The experimental study section consists of granite with a compressive strength ranging from 90 to 100 MPa,developed cleavage cracks,and average blastability.Through field tests and continuous improvement,an average cycle footage of 2.5 m per twoday cycle is achieved for a tunnel area of approximately 65 m2,meeting the requirements for rapid excavation when explosives cannot be used.The research demonstrates that the new gas expansion rockbreaking technology can effectively excavate tunnels in hard rock masses.It offers advantages such as safe operation,high efficiency in rock breaking,no involvement with civil explosives or dangerous chemicals used in explosive production,absence of explosion shock waves and low vibration amplitude.This technology provides a solution to situations where civil explosives are prohibited due to complex environmental conditions or slow progress using mechanical methods..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 232 (2024)
Research on Inhibitory Characteristics of Phytic AcidCytidine on DLMethionine Dust Explosion Flames
WANG Hao, ZHANG Ying, ZHOU Lin, and ZHAO Qi
Feed and its additive dusts have a high combustion heat,which poses significant risks of dust explosions during production,thereby threatening life and property safety.Currently,premix inhibitors are widely used as explosion suppression measures.However,traditional inhibitors are inedible and cannot be added to feed duFeed and its additive dusts have a high combustion heat,which poses significant risks of dust explosions during production,thereby threatening life and property safety.Currently,premix inhibitors are widely used as explosion suppression measures.However,traditional inhibitors are inedible and cannot be added to feed dust to achieve explosion suppression.Therefore,this study focuses on the dust of DLmethionine(DLM),a primary additive in feed,and investigates the effect of selfsynthesized phytic acidcytosine(PACY),an edible biomassbased compound with nutritional value and environmental friendliness,on the flame propagation characteristics of DLM dust explosions.The flame propagation process was recorded through highspeed photography and visualized in a vertical pipe while calculating the flame velocity.Additionally,thermocouples were used to monitor changes in flame temperature.The results indicate that as the mass fraction of PACY increases,the luminosity of DLM dust explosion flames consistently decreases,severely disrupting the flame structure.After adding 20% PACY,there is a reduction of 50.0%,52.2%,and 46.7% in peak velocity(from 27.66 m/s to 13.83 m/s),average velocity(from 14.39 m/s to 6.88 m/s),and peak temperature(from 1014℃ to 540℃) respectively.Moreover,when the mass fraction of PACY reaches 30%,ignition of the dust cannot occur indicating significant inhibitory effects provided by PACY..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 238 (2024)
Study on Explosion Equivalent and its Influencing Factors of DT-3 under External Flame Stimulation
XU Fei-yang, ZHANG Jing-jing, KANG Li-min, YAO Ya-dong, XIA Man-man4, MA Zhi-yong, GUO Guang-fei, WU San-zhen, and XU Sen
To study the explosion equivalent of DT-3 and its influencing factors caused by fire stimulus during storage,transportation and use,the propagate detonation ability of that was studied by the extremely insensitive to detonating substances(EIDS) gap test.Highspeed cameras and a shock wave pressure acquisition system weTo study the explosion equivalent of DT-3 and its influencing factors caused by fire stimulus during storage,transportation and use,the propagate detonation ability of that was studied by the extremely insensitive to detonating substances(EIDS) gap test.Highspeed cameras and a shock wave pressure acquisition system were utilized to obtain information on the deflagration processes and shock wave hazards of DT-3 under external flame effect.Additionally,an infrared thermal imager was employed to determine the highest temperature of the surface fireball.Further calculations were conducted to determine the explosive TNT equivalent of 18 kg and 120 kg DT-3 samples.The experimental results indicate that direct exposure to a strong shockwave does not cause DT-3 propagation detonation.However,different packing strengths can lead to deflagration events under external fire conditions,potentially resulting in an overall detonation reaction.The average TNT equivalents for standard packaged 18 kg and 120 kg DT-3 samples were found to be 0.629 and 0.0293 respectively.Furthermore,there is no positive correlation between the scale effect and shock wave impact.Under fire stimulus conditions,package design strength significantly influences the explosive characteristics of DT-3.To enhance safety measures,it is recommended that package design strength be reduced within acceptable limits for actual usage in order to effectively mitigate the risk of detonation hazard..
BLASTING
- Publication Date: Aug. 29, 2024
- Vol. 41, Issue 2, 245 (2024)
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