Contents
2024
Volume: 41 Issue 4
26 Article(s)
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Experimental Study on Material Selection for Blasting Simulation of Rock Mass Surrounding Ultra-deep Shaft
YANG Xiao-lin, XU Jie, CHU Huai-bao, SUN Bo, WANG Dong-hui, ZHANG Guang-ran, CHEN Lu-yang, GUO Peng, and WANG Shao-hua
Researching blasting similar simulation materials for ultra-deep shaft surrounding rock and conducting physical model tests are the basis for studying the dynamic response law of ultra-deep shaft surrounding rock under blasting. This paper used the monzonitic granite in Xiling subsidiary shaft of Sanshandao gold mine aResearching blasting similar simulation materials for ultra-deep shaft surrounding rock and conducting physical model tests are the basis for studying the dynamic response law of ultra-deep shaft surrounding rock under blasting. This paper used the monzonitic granite in Xiling subsidiary shaft of Sanshandao gold mine as the simulation object to prepare similar granite materials. The iron ore powder and barite powder were selected as fine aggregates, the quartz sand was selected as coarse aggregate, the rosin alcohol solution was selected as binding material, and the gypsum was selected as adjusting material. The orthogonal design method was used to prepare the simulation materials. The mechanical parameters of similar materials with different proportions were determined, and the sensitivity analysis of each influencing factor and the blasting test of the simulated materials were carried out. The results show that the selected proportion can meet the requirements of indoor blasting model tests based on the specimen's density, unaxial compressive strength and elastic modulus. The proportion of fine aggregate in the total aggregate significantly affects the density of the simulated materials. The binder concentration significantly affects the compressive strength, tensile strength, elastic modulus and cohesion of the simulated materials. The proportion of gypsum significantly affects the internal friction angle of the simulated materials. The peak strain value in the model test block under high confining pressure is more significant as a whole, and the attenuation rate of the peak strain gradually decreases with the distance increase..
BLASTING
- Publication Date: Jan. 15, 2024
- Vol. 41, Issue 4, 1 (2024)
Study on Dynamic Characteristics and Fracture Mechanism of Coal Rock under Action of Mechanical-thermal Coupling
LI Peng-long, LUO Ning, SUO Yun-chen, CHAI Ya-bo, and SUN Rui
To carry out deep coal mining safely and efficiently, the dynamic mechanical characteristics and fracture mechanism of coal rock in deep earth were investigated under the ‘three high and one disturbance’ environment. A dynamic impact test of coal rock was carried out using the self-improved 50 mm high temperature synchTo carry out deep coal mining safely and efficiently, the dynamic mechanical characteristics and fracture mechanism of coal rock in deep earth were investigated under the ‘three high and one disturbance’ environment. A dynamic impact test of coal rock was carried out using the self-improved φ 50 mm high temperature synchronous split Hopkinson pressure bar (SHPB) test equipment at temperatures between 25~200℃. A ZWT viscoelastic constitutive model was also improved to establish a dynamic constitutive equation considering the temperature effect. The influence of high temperature on crack development law and the dynamic strength of coal rock was investigated based on the coupling of the finite difference and discrete element methods. The results show four stages to the dynamic stress-strain curve of coal rock under high-temperature impact: compaction, elastic, crack propagation, and softening failure. The dynamic compressive strength and dynamic elastic modulus of coal rock significantly decrease as temperature increases. In contrast, the failure strain increases, and the absorbed energy varies in a W-shaped pattern. The fractal dimension increases linearly as the particle size decreases. The degree and complexity of the fragmentation mechanism increase as the compressive strength decreases. Although the improved dynamic constitutive model based on ZWT could adequately express the stress-strain relationship following a high-temperature impact, it does not apply to the compaction stage. According to the simulation and test results, water and adsorbed gas actively escape in the coal rock at 150℃. The coal matrix is also heated and expanded, which induces cracks. There are apparent mesoscopic cracks initially and gradually developed through cracks, mainly shear ones. The crack development of coal rock under dynamic compression at 100℃ develops through the impact surface, and the high temperature deteriorates the strength of coal rock..
BLASTING
- Publication Date: Mar. 04, 2024
- Vol. 41, Issue 4, 8 (2024)
Study on Attenuation Law of Axial and Radial Explosion Stress Wave with Different Charge Structures in Concrete
GUO Zhi-dong, LI Guang, ZHU He-chao, HU Shi-chao, ZUO Jin-jing, and YOU Shuai
To explore the attenuation law of blasting stress waves in concrete under different charging structures, the strain values at different positions of the experimental models were tested by a 16-channel dynamic strain gauge based on similarity theory. Meanwhile, the attenuation law of axial and radial blast stress waves To explore the attenuation law of blasting stress waves in concrete under different charging structures, the strain values at different positions of the experimental models were tested by a 16-channel dynamic strain gauge based on similarity theory. Meanwhile, the attenuation law of axial and radial blast stress waves in concrete under different charge structures was obtained by calculating the peak stress. The results show that the blasting stress wave exhibits a power exponential decay as the distance between the blasting centers increases. The initial pressure and maximum pressure on the borehole wall of the coupled charge structure are the highest, and the detonation wave acts on the medium for a short time. The uncoupled charge structure reduces the initial pressure on the borehole wall and prolongs the time of detonation pressure action. The coupled charging structure consumes much energy in the crushing zone, and the energy transfer is uneven. The stress wave attenuation of the uncoupled charging structure during blasting is slow, and the energy transfer is uniform..
BLASTING
- Publication Date: Sep. 15, 2024
- Vol. 41, Issue 4, 18 (2024)
Study on Fracture Characteristics and Crack Propagation Features of Fissured Rock Mass based on 3D Printed Samples
YU Lei-lei, XU Ying, GE Jin-jin, LI Hong-wei, NI Su-qian, ZHANG Zhong-yi, and SHANG Hui
To study the influence of rock fracture characteristics with different inclination angles, the notched semi-disk bending (NSCB) specimens were prepared based on the 3D printing technology for experiments on typeI static fracture characteristics of rock mass. Specifically, the straight-cut groove half-disc bending speciTo study the influence of rock fracture characteristics with different inclination angles, the notched semi-disk bending (NSCB) specimens were prepared based on the 3D printing technology for experiments on typeI static fracture characteristics of rock mass. Specifically, the straight-cut groove half-disc bending specimens (NSCB) with crack angles were prepared by 3D printing technology to investigate the influence of different pre-fabricated crack angles on rock fracture characteristics. Furthermore, the printed specimens were placed in dry ice and subjected to quasi-static three-point bending tests when their surface temperature reached -30℃ after the solidification and baking treatments. The experiment revealed the influence of pre-fabricated crack angles on fracture toughness, initiation angle, and fracture energy. The results show that the average fracture toughness of NSCB specimens containing fissures is smaller than that of standard NSCB specimens. The fracture toughness of specimens is positively correlated with the fissure inclination angle. For NSCB specimens containing fissures, the initiation angle increases with the increase of the fissure inclination angle when β is between 0° and 90°, and the crack propagation path shows a distinct ‘deflection’ phenomenon. The fissure inclination angle significantly impacts the complexity of the NSCB specimen propagation path. The crack propagation path becomes more complex when the fissure inclination angle and fractal dimension increase. From the perspective of fracture energy, the fracture energy increases with the increase of the fissure inclination angle..
BLASTING
- Publication Date: May. 20, 2024
- Vol. 41, Issue 4, 25 (2024)
Study on Parameters of Anhydrite RHT Dynamic Model
MA Kai, REN Gao-feng, GE Yong-xiang, WANG Fu-cheng, SHI Yi-hu, ZHANG Cong-rui, ZHANG Lu-wei, ZHAO Liang, and YU Yan
Numerical simulation is a vital tool for studying the dynamic characteristics of rock, with the accurate determination of models and parameters being the key to ensuring the reliability of simulation results. Among the 34 parameters of the RHT model, 19 parameters can be obtained through experimental and theoretical caNumerical simulation is a vital tool for studying the dynamic characteristics of rock, with the accurate determination of models and parameters being the key to ensuring the reliability of simulation results. Among the 34 parameters of the RHT model, 19 parameters can be obtained through experimental and theoretical calculations, but the remaining 15 are challenging to determine. Nineteen basic parameters of anhydrite were obtained through experimental analysis and theoretical calculation to identify the model parameters suitable for anhydrite. Furthermore, the LS-DYNA performed SHPB simulation tests on the 15 challenging parameters. The sensitivity of stress-strain curves to these parameters was compared, and the values were optimized. Parameters with high sensitivity were identified through orthogonal testing. Finally, simulation results were compared with laboratory test results. The findings indicate that RHT parameters B, , n, D1, nf, Pcomp and N have minimal impact on the stress strain curve, while parameters A, , , Q0, , ξ, and Af significantly influence the curve. Furthermore, the parameters with a significant impact on the stress-strain curve were determined by orthogonal tests, and the RHT model parameters fitting the SHPB impact test curve were obtained. Under varying loading strain rates, the dynamic stress-strain curves and failure patterns of anhydrite simulation tests were consistent with laboratory tests, verifying the suitability of the model parameters for anhydrite..
BLASTING
- Publication Date: Jul. 20, 2024
- Vol. 41, Issue 4, 35 (2024)
Study on Crack Propagation Mechanism and Damage Characteristics of Double-hole Cutting Blasting
ZHANG Xian-tang, CHEN Chang-qing, LIU Xiao-kang, XIA Jiao-jiao, and ZHOU Hong-min
On-site double-hole slitting blasting experiments were conducted to study the effect of controlling fracture damage by double-hole slitting blasting. A test double hole slitting blasting model was constructed using ANSYS/LS-DYNA software, and its crack propagation and changes in gas unit pressure on the hole wall were On-site double-hole slitting blasting experiments were conducted to study the effect of controlling fracture damage by double-hole slitting blasting. A test double hole slitting blasting model was constructed using ANSYS/LS-DYNA software, and its crack propagation and changes in gas unit pressure on the hole wall were compared and analyzed. The on-site results indicate that an intersecting fracture surface is formed between the two blast holes in the direction of the cutting seam after the explosion, and the half-hole residue is more obvious. Besides, the cracks will still develop towards the cutting direction by changing the cutting angle to 157°, and the guiding effect of the cutting seam is not affected by the change in angle. Meanwhile, the fracturing effect of adding empty holes between blast holes is better than that of non-empty hole slot blasting, which indicates that the existence of empty holes can effectively improve the directional fracture effect of slot blasting. The model results of the crack propagation and damage are consistent with the on-site results. By comparing and analyzing the double hole slit blasting and ordinary smooth blasting models, the superposition effect of stress waves causes the development of cracks between the holes to deflect, which forms a crack void between the two holes. Though analyzing the peak pressure of gas units around the hole wall at 0°~90°, it is found that the time when the pressure peak reaches the slit direction is earlier than that in the non-slit direction. More importantly, the pressure peak decreased significantly, and then the curve gradually tended to flatten during the slit blasting range of 0°~15°. The larger the angle, the smaller the peak change. The slit tube effectively controls the distribution of explosion energy during the explosion process, which forms stress concentration at the slit, with the maximum stress peak being about four times higher than that in the vertical direction..
BLASTING
- Publication Date: Dec. 27, 2023
- Vol. 41, Issue 4, 45 (2024)
Research on Catastrophe Instability Criterion of Surrounding Rock under Blasting Action in Shallow-buried Tunnel with Unsymmetrical Pressure
MA Rong-zeng, LI Wen, DU Ze-hui, PENG Ya-xiong, and WU Li
To address the instability problem of shallow-buried tunnel with unsymmetrical pressure under blasting, the potential energy equation of surrounding rock was derived by considering both blasting damage and water weakening effect. Using the cusp catastrophe theory and its calculation method, a catastrophe instability crTo address the instability problem of shallow-buried tunnel with unsymmetrical pressure under blasting, the potential energy equation of surrounding rock was derived by considering both blasting damage and water weakening effect. Using the cusp catastrophe theory and its calculation method, a catastrophe instability criterion of surrounding rock mass in a shallow-buried tunnel with unsymmetrical pressure under blasting was established. Then, the effects of water weakening, blasting damage and unsymmetrical pressure on the instability of the surrounding rock mass were discussed. Taking Dayangan tunnel in the national high-speed G5615 (Tianbao-Malipo section) as an example, a catastrophe criterion k of surrounding rock mass under different working conditions was calculated according to the physical and mechanical parameters of surrounding rock and the results of the field acoustic wave test. Meanwhile, a shallow-buried tunnel's surrounding rock stability state with unsymmetrical pressure was determined. The results show that the necessary condition for abrupt instability in shallow-buried tunnels with biased pressure under blasting is the abrupt failure criterion k<1, indicating a potential state of abrupt instability. The degree of bias pressure is the critical internal factor affecting tunnel instability surrounding rock mass. Additionally, the greater the degree of bias pressure, the more prone the tunnel is to sudden instability. The practical evaluation results are consistent with the field observations, verifying the practicability and validity of the criterion..
BLASTING
- Publication Date: Sep. 15, 2024
- Vol. 41, Issue 4, 54 (2024)
Mechanism and Quantitative Characterization Method of Rock Clamping Effect in Medium-deep Hole Blasting of Steeply Inclined Narrow Vein Mining
WANG Zhi, AN Long, SUN Xing, and FU Zhou-yun
Since the problems of significant rock clamping effect and ore depletion were caused by deep hole blasting in steeply inclined thin veins, a combination of on-site investigation, PMMA (organic glass) blasting model experiment and numerical simulation was used to explore the mechanism and a quantitative characterizationSince the problems of significant rock clamping effect and ore depletion were caused by deep hole blasting in steeply inclined thin veins, a combination of on-site investigation, PMMA (organic glass) blasting model experiment and numerical simulation was used to explore the mechanism and a quantitative characterization method of rock clamping effect by taking a gold mine in Gansu Province as the engineering background. Firstly, to analyze the distribution pattern of blasting cracks under different mining conditions of thin ore veins, a PMMA blasting model experiment was conducted. The results show that reducing the mining width of the thin ore veins reduces the radius of blasting crushing and fracture areas around the blast hole and suppresses the development of blasting cracks. Furthermore, different blasting conditions of thin ore vein mining were simulated. The results show that as the mining width of thin ore veins decreases, the blasting energy reflected and superimposed at the blasting-free surface decreases, and the volume of blasting rock decreases accordingly. Meanwhile, more blasting energy is dissipated as kinetic energy, which could not be effectively used to break the rock. Finally, a quantitative characterization method for the clamping coefficient of thin ore vein blasting was proposed based on the analysis of blasting energy. A clamping coefficient was defined by the ratio of the total energy peak at the center point of the blasting free surface under semi-infinite and narrow amplitude working conditions, and this index characterized the size of the clamping effect. As a result, a prediction model for the blasting clamping coefficient was established through the mining width and rock mechanics parameters. The study of this paper can provide a theoretical basis and technical support for the optimization design of deep hole blasting parameters in steeply inclined thin ore veins..
BLASTING
- Publication Date: Sep. 15, 2024
- Vol. 41, Issue 4, 61 (2024)
Experimental Study on Dynamic Compressive Mechanical Properties of Shale in Western Hubei
WANG Jiang-yi, DONG Qian, YAN Xiao-ming, TONG Hao, RAO Xiao-qiang, YAO Ying-kang, and WEI Dong
The dynamic compression mechanical characteristics of the surrounding rock mass of the shale formation tunnel in western Hubei province need detailed exploration. A Split Hopkinson Pressure Bar (SHPB) and a high-speed camera were employed to conduct impact tests on shale samples at five different bedding angles (the anThe dynamic compression mechanical characteristics of the surrounding rock mass of the shale formation tunnel in western Hubei province need detailed exploration. A Split Hopkinson Pressure Bar (SHPB) and a high-speed camera were employed to conduct impact tests on shale samples at five different bedding angles (the angle between the direction of impact loading and the normal of the bedding planes of the specimen, including 0°, 30°, 45°, 60°, and 90°). Meanwhile, the research team also studied the influence mechanism of bedding angles, impact pressure, and strain rate on the dynamic compression mechanical characteristics and failure mode of shale with different dynamic loading strain rates under different impact pressures. The research results indicate that the dynamic compressive strength of shale has an approximately U-shaped pattern with increasing bedding angles under different impact pressures and strain rates. Among them, the shale with bedding angles of 0° and 90° has relatively higher compressive strength, while the shale with a bedding angle of 60° has the most minor compressive strength. Furthermore, the dynamic compressive strength of shale with different bedding angles increases as the impact pressure and strain rate increase. The macroscopic failure modes of shale are mainly divided into tensile failure, shear failure, and mixed failure. Significantly, the macroscopic failure modes of samples with bedding angles of 0° and 90° under different strain rates are mainly tensile failure. The primary macroscopic failure mode of the sample shows a transition process of shear failure mixed failure tensile failure' as the strain rate increases when the bedding angle is 30°. The primary macroscopic failure mode of the specimen evolves from shear failure to mixed failure as the strain rate increases when the bedding angle is 45° and 60°. The energy absorption ratio of shale samples first increases and then decreases as the bedding angle increases under the same impact pressure. Additionally, the energy absorption ratio and the degree of sample damage are simultaneously maximum as the bedding angle is 60°. The degree of fragmentation of shale samples with different bedding angles increases, and the energy absorption ratio gradually tends to be consistent as the impact pressure and strain rate increase..
BLASTING
- Publication Date: Sep. 15, 2024
- Vol. 41, Issue 4, 73 (2024)
Bench Blasting Parameters Optimization with Air-decked Charge Structure based on Fragmentation Control
YE Hai-wang, YU Meng-hao, LIU Cong, CHEN Jia-tao, ZHOU Fa-ming, WANG Hao, YANG Bao-zhong, and LEI Tao
This study presents a comprehensive approach to solve the problem of low ore recovery caused by the difficulty in separating small-particle size ore from soil after blasting in a limestone building stone mine. Firstly, a correlation model between blasting fragmentation and dynamic damage of rock mass was established baThis study presents a comprehensive approach to solve the problem of low ore recovery caused by the difficulty in separating small-particle size ore from soil after blasting in a limestone building stone mine. Firstly, a correlation model between blasting fragmentation and dynamic damage of rock mass was established based on field measurement data and numerical simulation results, which can determine dynamic damage thresholds corresponding to various rock particle sizes. Secondly, the numerical simulation test of bench blasting in a three-dimensional fractured rock mass was carried out by using different air-decked charging stages and borehole distribution parameters, which can improve the particle size yield of 0.3~0.9 m and control the bulk ratio to obtain the best blasting parameters. Finally, the field blasting tests were conducted to optimize the charge structure and borehole distribution parameters based on numerical simulation results. The results show a negative exponential function relationship between the blasting block size and the dynamic damage value of the limestone. Specifically, the dynamic damage thresholds corresponding to the blasting size of 0.3 m and 0.9 m are 0.793 and 0.286, respectively. Using only an air-decked charging structure alone can increase the particle size ratio of 0.3~0.9 m and significantly raise the bulk rate. Conversely, combining an air-decked charging structure with a reduced hole spacing markedly enhances the particle size ratio of 0.3~0.9 m while maintaining a stable bulk rate. Optimal blasting results are achieved using a two-stage air interval charging structure and a strategic reduction in hole distribution parameters. The field application results show a 20.09 percentage point increase in the 0.3~0.9 m particle size ratio, with the bulk rate remaining virtually unchanged. Additionally, the unit consumption of explosives decreased by 10.29%..
BLASTING
- Publication Date: Jun. 20, 2024
- Vol. 41, Issue 4, 84 (2024)
Research on Demolition Technology of Unstable Rock Mass based on High Precision 3D Model
ZHAO Xu-kun, WU Long-hai, KE Bo, SU Cheng-zhe, XIONG Jian, YU Ming-wei, TAN Hai, ZHANG Qi-xuan, PAN Ruo-han, HUANG Jia-jun, and LIU Zhi-hao
Researching controlled blasting technology for hazardous rock bodies in complex environments holds significant theoretical importance and provides valuable reference points for enhancing highway construction efficiency and mitigating potential risks. This study focuses on the Gulin-Jinsha highway construction project, Researching controlled blasting technology for hazardous rock bodies in complex environments holds significant theoretical importance and provides valuable reference points for enhancing highway construction efficiency and mitigating potential risks. This study focuses on the Gulin-Jinsha highway construction project, aiming to eliminate the dangers posed by hazardous rock bodies during construction. Six scanning stations were established using 3D laser scanning technology to create a high-precision 3D Digital Terrain Model (DTM) of the hazardous rock bodies. Additionally, four object detection lines were deployed using a high-density electrical method to achieve 3D visualization of the geological features in the hazardous rock area. A fracturing test was conducted based on the high-precision 3D model. The designed depth of the shell hole was 70% of the height of the hazardous rock body, with fracturing pipes connected in series and each pipe carrying a total charge of 720 g. The results demonstrated that the constructed high-precision 3D model accurately reflects the morphological characteristics of the hazardous rock body, providing reliable information for the blasting design. The fracturing pipes showed effective fracturing performance, facilitating the removal of the hazardous rock body during subsequent stages. This method offers a viable reference for similar projects, showcasing the potential for efficient and safe removal of hazardous rock bodies in complex environments..
BLASTING
- Publication Date: Aug. 23, 2024
- Vol. 41, Issue 4, 91 (2024)
Research and Application of Parametric Design Optimization Method for Medium-deep Holes in Underground Mines
CHEN Xin
A parameterized hole placement design method for medium-depth holes was proposed to solve the problems of large subjectivity of manual interaction, cumbersome and complex adjustment of hole placement and difficulty in ensuring the uniformity of hole bottom distance. Firstly, a mathematical model in underground mines waA parameterized hole placement design method for medium-depth holes was proposed to solve the problems of large subjectivity of manual interaction, cumbersome and complex adjustment of hole placement and difficulty in ensuring the uniformity of hole bottom distance. Firstly, a mathematical model in underground mines was constructed using the parameterized hole layout idea combined with the blasting boundary space constraints and blasting parameter requirements. Furthermore, the mathematical model was solved using the operation research method to get the optimal hole design on a digital mining software platform. Finally, the model was used in an underground mine. The result shows that the standard deviations of the bottom distance for the manually laid holes are 0.08 m, 0.10 m, 0.07 m and 0.07 m, respectively, while those for the automatically laid holes with the parameterized method are 0.02 m, 0.03 m, 0.02 m and 0.02 m, respectively. The hole laying time is shortened from 4 hours to 5 min. The proposed method significantly reduces the workload of the designing technicians and maximizes the guarantee of inter-hole laying between holes. It maximizes the uniformity of the bottom distance and avoids the randomness and error-prone nature..
BLASTING
- Publication Date: Mar. 21, 2024
- Vol. 41, Issue 4, 101 (2024)
Research on Zoning Layout Method and Application of Contour Holes for Blasting of Jointed Rock Mass Tunnel
ZHANG Kai, TAO Tie-jun, TIAN Xing-chao, LIU Xuan, QIN He, and ZHANG Ming-wei
The rock mass joints can affect the propagation of explosive stress waves. The angle between their direction and the surrounding holes and the relative position changes have different effects on the blasting effect. Based on the attenuation law of stress waves at different jointed angles, a method was proposed for zoniThe rock mass joints can affect the propagation of explosive stress waves. The angle between their direction and the surrounding holes and the relative position changes have different effects on the blasting effect. Based on the attenuation law of stress waves at different jointed angles, a method was proposed for zoning the surrounding holes of tunnel blasting in jointed rock masses. The parameters of the surrounding holes are optimized when the angle between the joint and the surrounding hole is 30°, 60°, 90°, and 0° (parallel). The zoning layout method was validated by combining LS-PREPOST numerical simulation and on-site tests regarding rock damage depth and blasting vibration speed. The results show that the rock mass's damage depth and blasting vibration speed under the zoning arrangement of surrounding holes are significantly better than that of the original layout plan of surrounding holes. Based on the geological conditions of the research section of the Bayueshan Tunnel of the Tongliang Anyue Expressway, the angles between the joints and the surrounding holes are set to 30°, 60°, and 90°, respectively. The spacings between the surrounding holes are set to 43 cm, 50 cm, 58 cm, and 60 cm when the joints parallel the surrounding holes. The average over-excavation value can be controlled at 18cm after blasting, and the over-consumption of concrete is controlled within 100% per linear meter..
BLASTING
- Publication Date: Mar. 21, 2024
- Vol. 41, Issue 4, 107 (2024)
Application of RTK Line Lofting Technology in Borehole Arrangement for Bench Blasting
YAN Shi-liu, CHEN Yun-cheng, ZHU Wei, and LI Tie-long
With the continuous development of precision step blasting technology in open pit mines, the disadvantages of traditional layout methods in layout precision and construction efficiency are becoming more and more prominent. In order to improve the precision and efficiency of hole layout, the theory of hole layout is comWith the continuous development of precision step blasting technology in open pit mines, the disadvantages of traditional layout methods in layout precision and construction efficiency are becoming more and more prominent. In order to improve the precision and efficiency of hole layout, the theory of hole layout is combined with RTK line lofting technology. According to the designed values of the chassis resistance line, hole spacing and row spacing, the RTK line lofting method is used to measure the size of the chassis resistance line and determine the line coordinates and layout direction of the first row of holes. Then, each row of holes can be laid out for construction by setting parameters such as mileage, mileage increment, deviation and deviation direction in the RTK manual book. Finally, a single person can achieve high-precision and high-efficiency hole laying while recording the hole position and measuring the design hole depth. This paper introduces a construction method of RTK line lofting and hole layout in detail, applies it to the actual construction, and gets a good effect. Applying this method provides a new idea for the precision, standardization and high efficiency of the open-pit bench blasting construction, improves the construction efficiency and precision while saving workforce, and reduces the cost of open-pit blasting..
BLASTING
- Publication Date: May. 01, 2024
- Vol. 41, Issue 4, 116 (2024)
Computer-aided Design of Blast Hole Distribution and its Application
SONG Hao-tian, ZHANG Wan-zhi, SI Xiao-li, XU Bang-shu, and WANG Wei
There are hundreds of blast holes in a tunnel blasting. Since the traditional manual drawing of the blasting scheme is laborious and depends on the experience of blasting engineering, a digital method for the planar and three-dimensional spatial distribution of blast holes was proposed based on formula derivation to stThere are hundreds of blast holes in a tunnel blasting. Since the traditional manual drawing of the blasting scheme is laborious and depends on the experience of blasting engineering, a digital method for the planar and three-dimensional spatial distribution of blast holes was proposed based on formula derivation to study an intelligent design method for tunnel blasting blast holes. Subsequently, the programming of blast hole parameters was achieved by utilizing computer programming techniques, which can lead to the development of an intelligent blast hole design system. The results show that the parametric expression method of tunnel contour, cut holes, peripheral holes and auxiliary holes can realize their rapid creation and meet the needs of tunnel blasting. By establishing a correlation between the coordinates of the blast hole opening and bottom, a refined expression of the spatial distribution of the blast hole can be realized, and intuitive guidance for on-site drilling operations can be provided. Furthermore, a computer programming method can realize an intelligent and fine design of a blast hole layout. After tunnel blasting, the residual marks of the blast holes are complete, the contour of the tunnel excavation is smooth, and the overall excavation effect is good. The research results can improve the efficiency and intelligence of tunnel blast hole design..
BLASTING
- Publication Date: May. 07, 2024
- Vol. 41, Issue 4, 122 (2024)
Numerical Simulation on Blasting Demolition of 130 m Multi-tube Sleeve Chimney Under Complex Environment
ZHAO Meng-qiao, CHEN Lei, WANG Meng, LUO Ning, QUAN Shu-en, and LIU Tong
For the blasting and demolition project of a 130 m multi-tube sleeve chimney, the LS-DYNA finite element software was used to simulate the blasting incision by unit failure using a separated common-node model. The collapse process of the multi-tube sleeve chimney was numerically simulated, analyzed and compared with thFor the blasting and demolition project of a 130 m multi-tube sleeve chimney, the LS-DYNA finite element software was used to simulate the blasting incision by unit failure using a separated common-node model. The collapse process of the multi-tube sleeve chimney was numerically simulated, analyzed and compared with the actual blasting effect. The results show that the effective stress is mainly concentrated on the edge of the remaining part of the support when the blasting notch is forming. However, the notch closure stage of the falling speed is different due to the length and slenderness ratio and the nature of the material of the outer chimney and the inner sleeve are different. The simulation shows that the external chimney and the steel inner tube would be collisional at the notch closure stage as the internal and external detonation simultaneously. Choosing the detonation method with a delay of two seconds between internal and external components will achieve the ideal collapse effect..
BLASTING
- Publication Date: Apr. 02, 2024
- Vol. 41, Issue 4, 128 (2024)
Experiment and Numerical Analysis of Crack Propagation in Mortar Blocks under Dynamic and Static Loads
SHI Meng-meng, and FAN Zhan-feng
To investigate the rock mass crack propagation pattern in deep-buried tunnels during drilling and blasting excavation, two combined model tests (labeled as Model 1 and Model 2) consisting of multiple cement mortar blocks were carried out. The dimensions of the models were both 180 cm×80 cm×25 cm (length widthTo investigate the rock mass crack propagation pattern in deep-buried tunnels during drilling and blasting excavation, two combined model tests (labeled as Model 1 and Model 2) consisting of multiple cement mortar blocks were carried out. The dimensions of the models were both 180 cm×80 cm×25 cm (length width height). Among them, the matrix size was 60 cm×80 cm×25 cm, and two sides had single and multiple joints. Furthermore, a thorough analysis was conducted to determine the influence of dynamic loads stemming from nine cumulative explosions on the crack propagation in a matrix by applying various static stresses, particularly on the direction of the applied static loading. The experimental results reveal that cracks emerge on both Model 1 and Model 2 surfaces along the direction of static stress loading when the static stress increases from 0.5 MPa to 5 MPa. The crack propagation direction forms an angle on the loading direction, and the main crack is longer than 60 cm. A blasting funnel contour with about 30 cm diameter is formed on the bottom of Model 1, which does not fall off. In comparison, a funnel with about 52 cm diameter and a 10 cm depth is formed on the bottom of Model 2, which has fallen off. Numerical analysis verified that the static stress has a guiding effect on the propagation direction of blasting cracks, which is consistent with the model test results. The difference was that the length of the main crack calculated by numerical calculation was smaller than that of the model test. Finally, the reason for this deviation was analyzed..
BLASTING
- Publication Date: May. 20, 2024
- Vol. 41, Issue 4, 136 (2024)
A Method for Collecting Bus Current of Electronic Detonators
TANG Quan-ming, LIU Yuan-yuan, LI Xia, ZHONG Yi, and LI Ying
A patented technology for bus current acquisition of electronic detonators is introduced, which uses a low-cost hardware solution to achieve high-precision and wide-range current acquisition. This technology is designed to monitor and acquire data related to the working current, communication current, charging current,A patented technology for bus current acquisition of electronic detonators is introduced, which uses a low-cost hardware solution to achieve high-precision and wide-range current acquisition. This technology is designed to monitor and acquire data related to the working current, communication current, charging current, and detonator bus current load for electronic detonators, thus enabling these devices' status monitoring, data communication, and bus protection. This system focuses on the innovative, low-cost circuit design concept and the methods employed to ensure high-precision, high-resolution, and wide-range current acquisition. The typical working current of the electronic detonator control module ranges between 10~30 uA, and data is transmitted to the detonation controller via a current carrier. The communication current typically falls within the 0.5~2 mA range, and the ignition energy storage capacitor is charged through the bus with a peak charging current of 1~2 mA. The detonation controller determines the working status of the electronic control module by acquiring bus current data, which includes communication and charging status, to determine the module's working condition. In the current acquisition method discussed, low-side resistors are used to sample the current, replacing a differential comparator with three low-cost operational amplifiers. Furthermore, a 12 bit AD converter integrated into the MCU replaces an external 16-bit AD converter, which reduces hardware costs by over 80%. By segmenting the current collection, the system maintains the required accuracy for small current sampling and expands the current sampling range by 30 times, covering the rated current of the bus. The absence of an external AD conversion module significantly improves the sampling efficiency..
BLASTING
- Publication Date: Dec. 10, 2024
- Vol. 41, Issue 4, 145 (2024)
Time-frequency Analysis of Non-Stationary Vibration Signals based on EP-CEEMDAN Algorithm
SUN Miao, QU Ling, YUAN Li-ping, WU Jing, and SHEN Yu-guang
The intrinsic mode confusion of empirical mode decomposition (EMD) and the ensemble empirical mode decomposition (EEMD) can only suppress mode confusion to a limited extent, as the white noise added by EEMD cannot be fully neutralized, which compromises the completeness of the original signal. Additionally, both methodThe intrinsic mode confusion of empirical mode decomposition (EMD) and the ensemble empirical mode decomposition (EEMD) can only suppress mode confusion to a limited extent, as the white noise added by EEMD cannot be fully neutralized, which compromises the completeness of the original signal. Additionally, both methods fail to avoid interference from endpoint effects. Modal confusion and endpoint effects lead to distortions in the time-frequency analysis results obtained from the Hilbert transforms of EMD and EEMD. A complete ensemble empirical mode decomposition with adaptive noise and endpoint processing (EP-CEEMDAN) is proposed to address these issues. Simulation experiments were conducted to compare EMD, EEMD, and EP-CEEMDAN decomposition results on simulated vibration signals. Through multiscale permutation entropy detection and marginal spectral analysis, it was verified that EP-CEEMDAN has better control over endpoint effects and mode confusion, proving that EP-CEEMDAN is a more effective adaptive algorithm than EMD and EEMD. Finally, EP-CEEMDAN was applied to the processing of measured non-stationary vibration signals, where adaptive white noise was added at the endpoints of the vibration signals during each stage of decomposition. The method successfully generated various intrinsic mode functions (IMF) by calculating a unique residual signal. The EP-CEEMDAN algorithm effectively suppresses IMF endpoint divergence and modal confusion, while the time-frequency spectrum obtained through the Hilbert transform offers high resolution in both time and frequency domains. This result can be used for vibration feature recognition in non-stationary vibration signals..
BLASTING
- Publication Date: Jan. 15, 2024
- Vol. 41, Issue 4, 150 (2024)
Damage Characteristics and Impact Assessment of Blasting-induced Vibration on High-density Structures Adjacent to Diversion Tunnels
RAO Yu, XIE Zhi-guo, LU Jin-bin, ZHAO Gen, MA Kai, and GUO Yi-wei
Vibration is a primary detrimental effect generated by blasting operations, and accurately evaluating its impact remains crucial and challenging. Based on the blasting excavation of a tunnel under the Central Yunnan Water Diversion Project, this study combines numerical simulation and field investigation to assess the Vibration is a primary detrimental effect generated by blasting operations, and accurately evaluating its impact remains crucial and challenging. Based on the blasting excavation of a tunnel under the Central Yunnan Water Diversion Project, this study combines numerical simulation and field investigation to assess the damage characteristics of buildings affected by various factors. The results show that blasting vibration causes “X-shaped” cracks at the four corners of windows and doorways, while uneven settlement leads to 45° diagonal cracks. Subsequently, time-frequency analysis was performed on vibration data from buildings at varying distances from the blast source. The findings indicate that forced vibration predominates in building foundations, with minimal free vibration and quickly attenuating after the blasting load ends. As horizontal distance increases, the main frequency and blasting vibration energy exhibit a downward trend based on Fast Fourier Transform (FFT) analysis. However, the main frequency is less sensitive to distance changes than energy. Additionally, the sensitivity of energy to distance varies across different frequency bands. Generally, energy in each frequency band rapidly attenuates close to the blast source, with slower attenuation as distance increases. Furthermore, as the distance from the last source increases, there is a shift in energy from higher to lower frequency bands towards lower frequency bands, and the effect of low-pass and high-filter results in distinct variations in energy attenuation within different frequency bands. Finally, the study highlights a significant disparity between human perception of blasting vibrations and building safety standards. Based on this observation, a comprehensive evaluation method is proposed to combine structural damage assessment with considerations of the human settlement environment..
BLASTING
- Publication Date: Aug. 23, 2024
- Vol. 41, Issue 4, 156 (2024)
Vibration Characteristics of Gas Pipeline near Blasting in Silt-rock Strata
YIN Tao, JI Ling, GUO Zi-ru, ZHOU Chuan-bo, LI Hong-wei, ZHENG Chang-qing, and HE Zhi-wei
Since uneven stress on the cutter head can easily lead to surface collapse accidents when a shield machine passes through the silt-rock strata, the rock stratum can be blasted and broken by drilling blast holes on the ground surface before the shield machine arrives. However, the seismic waves generated by the blastingSince uneven stress on the cutter head can easily lead to surface collapse accidents when a shield machine passes through the silt-rock strata, the rock stratum can be blasted and broken by drilling blast holes on the ground surface before the shield machine arrives. However, the seismic waves generated by the blasting would threaten the safe operation of adjacent gas pipelines. In order to study the vibration characteristic of adjacent gas pipelines during blasting in silt-rock strata, the rock breaking project of silt-rock strata in the shield section of Hengqin Station and Hengqin North Station of Zhuhai Metro was selected as the research background. Firstly, the on-site blasting vibration was tested. Then, the ANSYS/LS-DYNA software was used to simulate the blasting process and invert the physical and mechanical parameters of the materials at the blasting site. Finally, the vibration characteristic of the gas pipeline was analyzed. The research results show that the PPV (peak particle velocity) on the pipeline decreases with the increase of the horizontal distance from the explosion source in the axial direction of the gas pipeline. Meanwhile, the maximum PPV position is perpendicular to the center line of the blast holes. Furthermore, the surface PPV above the gas pipeline decreases along the pipeline axis as the horizontal distance from the explosion source increases, and the maximum PPV position is also perpendicular to the center line of the blast holes. Besides, there is a functional relationship between the surface soil PPV2 along the axial direction of the gas pipeline and the PPV1 on the outer wall of the gas pipeline, which is V2=0.60V1+1.29. More importantly, the PPV of the gas pipeline's inner and outer of the gas pipeline are basically the same..
BLASTING
- Publication Date: Apr. 02, 2024
- Vol. 41, Issue 4, 167 (2024)
Experimental Study on Fusion Delay Detonation Network in Small Section Excavation
QIN Shao-bing, XU Zi-dong, WANG Dao-yin, QIN Zi-hang, and GE Yong-xiang
The construction of a blasting network is challenging, with high risks and costs associated with blasting equipment. Considering the geological structure, physical and mechanical properties of the excavation target, and the detonation characteristics of the detonating cable, a delayed detonation network was designed toThe construction of a blasting network is challenging, with high risks and costs associated with blasting equipment. Considering the geological structure, physical and mechanical properties of the excavation target, and the detonation characteristics of the detonating cable, a delayed detonation network was designed to combine a digital electronic detonator and a detonating cord. This design replaced the digital electronic detonator with the detonating cord in auxiliary and peripheral holes within the same section. In contrast, a single digital electronic detonator was used to initiate detonation to reduce the networking complexity and improve the overall reliability of the network. Field tests conducted at Guangshan iron mine and Gemstone phosphate mine verified the applicability of this method in different mineral environments. The results show that the fusion delay detonation network can significantly reduce detonation equipment costs, simplify initiation network construction, improve cutting effectiveness, and reduce safety risks during excavating small-section roadways in iron mines. However, during the underground phosphate rock test, the unique geological structure and the properties of phosphate rock prevented the designed network from achieving the expected results, indicating a need for further research..
BLASTING
- Publication Date: Jun. 20, 2024
- Vol. 41, Issue 4, 174 (2024)
Linear Regression Analysis on Sadovsky Formula for Open-pit Bench Blasting
DU Jun, HUA Liang-kui, LI Mei-jie, WANG Hong-qiang, and WANG Ming-wei
With the continuous development of blasting equipment, the popularization of high-precision detonator detonators and electronic detonators have been widely used in open-pit bench blasting. However, the definition is vague in the selection of the maximum amount of initiating charge and the distance from the detonation sWith the continuous development of blasting equipment, the popularization of high-precision detonator detonators and electronic detonators have been widely used in open-pit bench blasting. However, the definition is vague in the selection of the maximum amount of initiating charge and the distance from the detonation source to the vibration measurement point for the linear regression analysis of the Sadovsky formula when the vibration measurement point is close to the blasting area, and the dispersion position of the blast hole cannot be ignored. A proportional distance was used to measure close-range blasting vibrations by hole blasting. The total charge with a delay interval smaller than 8 ms or the charge quantity nearest to the vibration measurement point was selected as the maximum blasting charge in a section. The distance between the detonation source and the vibration measurement point was selected as the three-dimensional distance between the center of the hole range of the maximum blasting charge and the vibration measurement point or the three-dimensional distance between the hole and the nearest vibration measurement point. The one with a smaller proportional distance was selected for linear regression by comparing the group proportional and single proportional distances. The results show that it has relatively accurate linear regression using this method for the same direction or near the direction of the vibration point value after the noise reduction process..
BLASTING
- Publication Date: May. 07, 2024
- Vol. 41, Issue 4, 181 (2024)
Optimization of Gas Tunnel Blasting Scheme and Study on Gas Transportation Law at Working Face
WANG He, TIAN Cheng-lin, WANG Qing-biao, SUN Yong, LIU Zhong-lei, WEI Yuan-jin, LIANG Long, and BI Yuan-jia
In order to study the gas diffusion-transport law and the influence of ventilation on the gas concentration of high gas tunnel after blasting, an optimization blasting scheme under gas conditions was carried out, and a gas diffusion-transport characteristic near the working face was investigated under both ventilated aIn order to study the gas diffusion-transport law and the influence of ventilation on the gas concentration of high gas tunnel after blasting, an optimization blasting scheme under gas conditions was carried out, and a gas diffusion-transport characteristic near the working face was investigated under both ventilated and unventilated conditions in a project. The study shows that the residual rate of the blast hole and the utilization rate of the blast hole are above 90%, and the over-excavation control effect is better with an expected blasting footage of 1.2 m and an uncoupling coefficient of 0.76. Under the condition of unventilated condition by numerical simulation, the gas accumulation near the arch top and the arch waist at the tunnel's working face is severe as the gas concentration is close to 30%. Meanwhile, the gas concentration is higher in the area 7 m away from the working surface, and the gas concentration gradient is smaller in the area beyond 7 m after the gas state is stabilized. The gas concentration can be reduced to the safe range around 30 days after ventilation. However, gas accumulation quickly occurs at the arch foot and the arch waist on the other side of the air duct, especially the gas accumulation at the arch foot is more prominent, and the gas concentration is close to 20%. There is a ventilation blind area at the arch foot of the same side of the air duct, and the gas accumulates in a small range as the concentration is about 5%. The monitoring and prevention of the above areas should be strengthened. The field measured gas concentration distribution and gas influence range are consistent with the simulation results, and the research results can provide a reference for similar gas tunnel blasting construction and ventilation optimization..
BLASTING
- Publication Date: Apr. 16, 2024
- Vol. 41, Issue 4, 187 (2024)
Computational Research on Volatilization and Explosion Mechanism of Paint——Example of a Shipyard Explosion
LI Yi, WU Long-hai, SHEN Li-yuan, HUANG Chu-yuan, ZHAO Qi, and CHEN Xian-feng
Taking the explosion of a shipyard as an example, the investigative techniques had been comprehensively utilized (such as on-site investigation, interview, numerical simulation, theoretical calculation, trace analysis, etc.) to conduct in-depth research on the development of the accident, consequences and mechanism of Taking the explosion of a shipyard as an example, the investigative techniques had been comprehensively utilized (such as on-site investigation, interview, numerical simulation, theoretical calculation, trace analysis, etc.) to conduct in-depth research on the development of the accident, consequences and mechanism of the explosion. An on-site survey of the involved hull revealed fresh welding slag remaining on the starboard main deck in the area of the No.7 empty cabin utility hole. In addition, the empty compartment No.7 on the starboard side was identified as the explosion's origin based on the ignition source traces, the extent of the hull damage, and the cracking direction. The root of the explosion accident was restored according to results from a comprehensive on-site investigation. The paint and thinner would volatilize and produce massive organic combustibles during painting operations, forming explosive mixtures when mixed with air and accumulating in the empty compartment's limited space. The explosive gas mixture contacted spattered weld slag at the utility hole, causing an explosion in the empty compartment No.7 on the starboard side, which triggered explosions in the remaining compartments. As a result of the breeding-development-dissipation of the shock wave, the explosion first intensified and then gradually reduced damage to the surrounding of the NO.7 empty cabin as the center. The simulation with the CFD analysis software FLUENT revealed that the explosion mixture diffused 10% outward through the utility hole in 12 h. According to the diffusivity analysis results, the gas mixture's volumetric concentration was calculated to be 7.3%, which is sufficient for a combustion explosion. The equivalent amount of TNT for the explosion was 188 kg, which was inverted to 203 kg depending on the extent of damage to the buildings at the accident site after the explosion. It is in good agreement with the TNT equivalent of the explosion obtained from calculations based on the physical parameters of the gas mixture, which proves the practicability of the calculation..
BLASTING
- Publication Date: May. 20, 2024
- Vol. 41, Issue 4, 197 (2024)
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