Contents
2021
Volume: 38 Issue 3
25 Article(s)
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Calculation Model of Blasthole Pressure
ZHANG Xin, SUN Jin-shan, ZHANG Xiang-ping, JIA Yong-sheng, and YAO Ying-kang
To calculate the blasthole pressure in the numerical simulation of blasting,a simplified calculation model was propsed by analyzing the explosive detonation process and the dynamic fracture process of blasted medium.In this model,the blasting process is divided into four stages:the pressure rising,the initial elastic eTo calculate the blasthole pressure in the numerical simulation of blasting,a simplified calculation model was propsed by analyzing the explosive detonation process and the dynamic fracture process of blasted medium.In this model,the blasting process is divided into four stages:the pressure rising,the initial elastic expansion,the crack opening and gas inflow,and the medium stripping and throwing and gas escaping.By analyzing the blasting process,the approximate duration of each stage is determined respectively.By analyzing the change of explosive gas volume and based on the state equation of ideal gas,the time history function of blasthole pressure in each stage is determined.The calculation model is verified by field experiment results and the calculated results are in good agreement with the experimental results.The model takes into account the influence of many factors on the blasting process,,but without the coefficient which is difficult to determine.It can be used to determine the blasting load in theoretical analysis or numerical simulation..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 1 (2021)
Influence of Decoupling Coefficient of Water-coupled Charge on Blasting Effect
LI Shu-xuan, WANG Yan-bing, WANG Bao-zhu, and WANG Zhao-yang
In order to study the influence of different decoupling coefficients of water-coupled charge on blasting effect,a transparent and uniform cylindrical PMMA material with 250 mm in diameter and 200 mm in height was used as the test specimen.Meanwhile,a DDNP explosive was used to apply blasting load.In the test,the explosIn order to study the influence of different decoupling coefficients of water-coupled charge on blasting effect,a transparent and uniform cylindrical PMMA material with 250 mm in diameter and 200 mm in height was used as the test specimen.Meanwhile,a DDNP explosive was used to apply blasting load.In the test,the explosive quantity was fixed at 40 mg.At the same time,a water-coupled charge structure was used,and the decoupling coefficient was changed with different hole diameter and charge diameter.By comparing the number and distribution of internal cracks of the specimen and the size of crushing area,the effects of three different decoupling coefficients(1.4,2.0,2.67) on blasting effect were analyzed.It is found that appropriately increasing the decoupling coefficient of water-coupled charge can increase the number of cracks,make the crack distribution more uniform,increase the fracture area and reduce the diameter of the broken zone.Besides,there is an optimal decoupling coefficient to achieve the best blasting effect.Among the three uncoupling coefficients,the optimal decoupling coefficient is 2.67.In the test,the transparent and uniform characteristic of PMMA material are used to observe the blasting fracture behavior intuitively.The test results are very reliable and generally applicable to brittle materials..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 6 (2021)
Dynamic Effect of Civil Air-defense Tunnel Induced by Blasting of Undercrossing Subway Tunnel
ZHANG Xu, ZHOU Chuan-bo, JIANG Nan, and WU Ting-yao
The safety of adjacent existing tunnels under the effect of tunnel blasting is a key concern in blasting construction.This paper takes the blasting excavation of the tunnel between Hongshan Road Station and Xiaohongshan Station interval of Wuhan Metro Line 8 as an example to study the dynamic effect of the upper existiThe safety of adjacent existing tunnels under the effect of tunnel blasting is a key concern in blasting construction.This paper takes the blasting excavation of the tunnel between Hongshan Road Station and Xiaohongshan Station interval of Wuhan Metro Line 8 as an example to study the dynamic effect of the upper existing civil air-defense tunnel under the blasting action of the underlying subway tunnels.A finite-element numerical model of the tunnel blasting was established by LS-DYNA,and the reliability of the numerical model was verified by field vibration monitoring data.Then,the dynamic response characteristics of the civil air-defense tunnel were studied.Field tests and numerical simulation studies reveal that with the increase of the distance to blasting center,the peak particle velocity(PPV) of the civil air-defense tunnel lining decreases gradually with the maximum PPV point located directly above the explosive.The results show that the stability of the civil air-defense tunnel lining is controlled by tensile stress.Specifically,the main tensile stress of the tunnel floor and vault is in circumferential direction,and the main tensile stress of side wall is in vertical direction.The most dangerous section of the lining structure is located above the source of the explosion,and the most likely location of damage to this section is the foot of the arch facing the blast.The damage mode is tensile failure from the inside to the outside.In addition,the safety threshold of vibration velocity of the tunnel lining structure calculated by the ultimate tensile strength criterion is 14.9 cm/s..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 10 (2021)
Explosive Separation of Woven Board made of Carbon Fiber Reinforced Composite
HE Zhi-jie, WANG Meng, ZHAO Kang, and HU Kun-lun
In order to study the explosive separation of woven board made of carbon fiber reinforced composite,a new idea of embedding a detonating cord in a groove on both sides of the composite board was adopted.By combining numerical simulation with experiments,the separation of composite board with no confining medium added,cIn order to study the explosive separation of woven board made of carbon fiber reinforced composite,a new idea of embedding a detonating cord in a groove on both sides of the composite board was adopted.By combining numerical simulation with experiments,the separation of composite board with no confining medium added,copper shell constraint added and lead shell constraint added at the groove opening was compared and analyzed.According to the Tsai-Wu tensor strength criterion,the damage degree of composite board under three constraint conditions was judged respectively,and the pressure and velocity of the surface element of composite board under each condition were further discussed.The results show that the composite board without dielectric covering groove is successfully separated by covering metal shell at the opening of groove on both sides.The metal shell can prolong the duration of high pressure of detonation products and improve the dispersion speed of surface element particles,and the constraint effect of lead shell on explosion energy is better than that of copper shell.The total explosion energy of composite plate restrained by lead shell is 1.06 times that of copper shell and 1.5 times that of the composite plate without shell.In a certain range,the research results can provide a new technical solution for spacecraft interstage separation..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 26 (2021)
Rock Blasting Excavation Technology for Unlined Spillway of Namkong 1 Hydropower Station in Laos
WU Shi-ran, LIU Guang-xin, CHEN Yu-quan, LU Wen-bo, ZHANG Ke, and CHEN Ming
The quality of spillway excavation has an important influence on the safety of the later project operation.Based on the rock mass excavation of an unlined spillway of Namkong 1 Hydropower Station in Laos,different blasting excavation techniques were proposed and adopted for four key parts.The field excavation results sThe quality of spillway excavation has an important influence on the safety of the later project operation.Based on the rock mass excavation of an unlined spillway of Namkong 1 Hydropower Station in Laos,different blasting excavation techniques were proposed and adopted for four key parts.The field excavation results show that the deep hole pre-splitting blasting technique can well solve the problem of excavation shaping control of spillway high slope.The profile is clearly visible after blast with the half hole ratio and the maximum fluctuation meeting the design requirements.In addition,the energy dissipation-accumulation control blasting technique has been successfully applied in the stilling basin floor excavation,which has achieved good excavation shaping effect and greatly accelerated the construction progress.For the excavation of the special part of the tail of the stilling basin,the deep-hole pre-splitting one-time excavation shaping technique is adopted for the upstream and downstream surface,while the horizontal pre-splitting and vertical hole contour excavation technique is adopted for the top horizontal surface,which can solve the excavation shaping control problem of shaping of the tail sill.For the small bench blasting area with the requirements of excavation quality,such as the drop sill section of gate chamber,the blasting technique of small diameter and small bench is preferred than that of large diameter and small bench..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 31 (2021)
Selection and Optimization of Interval Charge Structure of Surrounding Holes in Tunnel Excavation Blasting
LIU Jiang-chao, GAO Wen-xue, and ZHANG Sheng-hui
There are air and water in the bore hole worked as interval media when the water-decked charge blasting is used in the process of tunnel excavation,and the explosion stress is more complex than single air interval.In order to select the appropriate charge structure and determine the reasonable blasting parameters to guThere are air and water in the bore hole worked as interval media when the water-decked charge blasting is used in the process of tunnel excavation,and the explosion stress is more complex than single air interval.In order to select the appropriate charge structure and determine the reasonable blasting parameters to guide the site construction,taking Wenquan tunnel blasting excavation as an example,the numerical simulation method is used to simulate and analyze the blasting stress of the peripheral hole with water-decked charge,then the appropriate charge structure is selected for parameter optimization,and finally verified by the field test.The results show that in the case of the same amount of charge,the peripheral hole with water-decked charge blasting can transfer the explosion energy to the hole wall more evenly,and the surrounding rock around the hole and the rock above the holes is damaged smaller than the air-decked charge blasting,which means that the same blasting effect can be achieved,and the powder factor can be reduced by using the water-decked charge blasting.It is suitable to use 0.9 kg charge with three cartridges,0.5 m water at the bottom of the hole,0.8 m water at the mouth of the hole,and 0.3 m cartridge interval when the peripheral hole with water-decked charging structure..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 38 (2021)
Analysis of Stemming Length of Borehole in Blasting
ZHANG Yan-jun, CHEN Yan-wu, LEI Mei-rong, and ZHANG Dong-rang
In order to investigate the appropriate stemming length of borehole in blasting and the propagation law of stress wave in the borehole,theoretical analysis and numerical simulation were used to analyze the mechanism of the borehole stemming mechanism.On the basis of the basic hypothesis,a calculation model of the stemmIn order to investigate the appropriate stemming length of borehole in blasting and the propagation law of stress wave in the borehole,theoretical analysis and numerical simulation were used to analyze the mechanism of the borehole stemming mechanism.On the basis of the basic hypothesis,a calculation model of the stemming length was established by studying the stemming dynamics and compression deformation of the stemming.Furthermore,the rationality of this model was verified.To simulate the explosion stress nephogram of the single hole and dynamic response curve at the bottom of the blasthole and free face of the blasthole with a stemming length of 0.35 m when rectangular coupling charge at the bottom of the continuously coupled hole,a mechanical model with a regional size of 1.5 m×1.5 m,a hole depth of 0.62 m and a hole diameter of 0.04 m was established by using the finite element analysis software.The results show that the stress wave propagates outward in the form of spherical wave,and the stress appears first in the center area of the blasthole charge and reaches the maximum.The stress wave is finally released after reflection and superposition.Especially,the stress at the bottom of the hole reaches its peak rapidly in a very short time,then oscillates up and down,and gradually stabilizes at a certain value.It is a very short period of time for the stress wave caused by the explosion that reaches the free face.However,the stress on the free face reaches the peak value quickly,and then decreases rapidly until the stress wave is released completely.This method can provide reference for the analysis of blasthole stemming and be applied in blasting analysis of coal mine blasting face..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 45 (2021)
Study on Hydraulic Blasting Technology of Tuanshan Tunnel
YU Zhi-qi, ZHU Rong, and KE Bo
During tunnel blasting construction,conventional blasting methods have low explosive utilization rate,produce more dust and cause great environmental pollution.In order to improve these shortcomings,taking the Tuanshan Tunnel blasting construction as the background,a hydraulic blasting scheme is adopted.The tunnel is eDuring tunnel blasting construction,conventional blasting methods have low explosive utilization rate,produce more dust and cause great environmental pollution.In order to improve these shortcomings,taking the Tuanshan Tunnel blasting construction as the background,a hydraulic blasting scheme is adopted.The tunnel is excavated by a single side heading method,and the blasting scheme is designed,in which the blast hole diameter is 42 mm.The single wedge cutting is adopted.The distance between peripheral holes is 40 cm and the resistance line distance is 50 cm.The distance between auxiliary holes is 100~120 cm,and the resistance line distance is 80~100 cm.The distance of holes on the tunnel floor is 60~70 cm,and the resistance line distance is 50~60 cm.The smooth surface blasting is adopted for the periphery,the smooth blasting controlled by microseismic is adopted for unfavorable geology and shallow buried sections,and the settlement and horizontal convergence of tunnel vault are monitored after blasting.Compared with conventional blasting,the results show that hydraulic blasting can increase the energy utilization rate of explosives,enhance the blasting effect,shorten the construction time,increase economic benefits,reduce dust,and protect the environment.The monitoring results show that the hydraulic blasting has less damage to the surrounding rock mass of the tunnel,which can better maintain the stability and ensure the safety of subsequent construction..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 50 (2021)
Application Study on Reducing Ore Dilution by Delayed Blasting
LIANG Bing
With the increase of depth,the ore bodiy in Wunugetushan Cu-Mo Mine has serious interpenetration,and the position of ore body line is not accurate,which leads to the mixed explosion of ore and rock,and increases the ore loss and dilution rate.Blasting parameters have great influence on ore loss and dilution in open-pitWith the increase of depth,the ore bodiy in Wunugetushan Cu-Mo Mine has serious interpenetration,and the position of ore body line is not accurate,which leads to the mixed explosion of ore and rock,and increases the ore loss and dilution rate.Blasting parameters have great influence on ore loss and dilution in open-pit mining.According to the on-site blasting construction situation of the Wunugetushan Cu-Mo mine,the marker method was used to monitor the blasting displacement to select a reasonable initiation position.The delay time was determined by the blasting delay time experiment,and the blasting sequence was controlled to change the instantaneous free surface in the process of blasting.Four separate blasting tests of ore and rock were carried out,and a comparative statistical analysis of blasting toes rate and the power consumption of the coarse crushingwas carried out.The results show that the optimal blasting network design plan is 9 ms between holes,25 ms between rows,65 ms in the back row and 100 ms delayed interval at the separation boundary of ore and rock.The vertical distance between the top of the blasting pile on both sides of the ore and rock and the bottom of the boundary between the ore and rock is 2~3 m,which achieves the effective control of the movement direction of rock and realizes the purpose of the separation of ore and rock.The research results are of great significance for optimizing blasting parameters,reducing crushing costs,and reducing ore loss and dilution..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 58 (2021)
Application of Detonating Cord and Detonating Nonel Tube Detonating Network in Joint Blasting of Multiple Explosive Zones
LIU Bo, HU Jing-yun, and SHI Xiu-zhi
The total blasting charge was large when simultaneous blasting of multiple blasting areas in underground mines, it was difficult to set up blasting network,and the network was more complex after setting up blasting network,especially when the blasting area was far from each other.The compound detonating network of detoThe total blasting charge was large when simultaneous blasting of multiple blasting areas in underground mines, it was difficult to set up blasting network,and the network was more complex after setting up blasting network,especially when the blasting area was far from each other.The compound detonating network of detonating cord and detonating nonel tube has the advantages of large detonating power,fast detonation transmission speed,long detonation distance,simple network structure and reliable connection,which can effectively solve the problem of blasting network formation when multiple remote blasting areas are simultaneously detonated.Three blasting areas in two sections of a mine need to be detonated at the same time,and the amount of blasting ore is 61,000 tons.The compound detonating network of detonating cord and detonating tube was adopted,and 1278 detonating tubes were successfully detonated with 120 m long transmission detonating cord,and the amount of blasting charge was 20.3 t.Through the analysis of blasting vibration,safe explosion distance and blasting fragmentation,it is considered that the blasting effect is good.Through practice,the detonating network of detonating cord-detonating nonel tube has strong networking ability,reliable network connection,clear and intuitive,easy to check the connection quality,and reduces the cost of blasting,which can provide reference for engineering blasting of similar mines..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 62 (2021)
Numerical Simulation Research on Delayed Double-hole Bench Blasting Effect
YANG Jing-yu, YANG Jun, and RONG Kai
In order to study the influence of delay time on bench blasting,a numerical simulation study on precise delay blasting of a double-hole and double-slope bench was carried out by ABAQUS.The main contents of the research include the stress wave propagation law,the development of tensile and compression damage and the vibIn order to study the influence of delay time on bench blasting,a numerical simulation study on precise delay blasting of a double-hole and double-slope bench was carried out by ABAQUS.The main contents of the research include the stress wave propagation law,the development of tensile and compression damage and the vibration effects of the double-hole bench structure with different delays.The results show that the closer to the free surface,the greater the peak stress and peak particle vibration velocity in the rock mass,and the more obvious the damage area.Meanwhile,on the top surface of the bench,with the increase of distance to blast source,the peak particle vibration velocity in Y direction(horizontal) at each measuring point showed a decreasing increasing-decreasing trend.At the same time,the measuring point with the maximum Y direction(horizontal) velocity is located at 150 mm(1.25 times the hole spacing).The peak particle velocity of the Z-direction(vertical) decreases gradually with the increase of distance to blasting source.Besides,with the increase of time delay between holes,the volume of rock damage unit(D>0.6) decreases in a small range and then increases continuously.When the delay time is 60 μs,the vibration velocity reaches the peak value.With the further increase of delay,the damage volume decreases gradually and tends to a stable value.At the same time,the stress of the measuring point between two holes in the rock reaches the peak value when the delay time between the holes is 60 μs,and the vibration velocity at the top of the bench gradually decreases and tends to be stable at 50 μs.Therefore,it can be considered that 60 μs(0.5 ms/m) is the best delay time for this model..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 67 (2021)
Study on Response Characteristics of Underground Roadway on Adjacent Blasting Dynamic Load
YAN Yao-feng, WANG Gong-zhong, YAN Min-jia, CHAI Xiu-wei, XU Liang, PENG Ya-li, and JIN Sheng-li
In the process of underground mineral resources exploitation,underground space group and tunnel excavation,drilling and blasting construction has irreplaceable advantages.However,the influence of dynamic load of adjacent excavation blasting on the existing underground space cannot be ignored.In order to improve the safIn the process of underground mineral resources exploitation,underground space group and tunnel excavation,drilling and blasting construction has irreplaceable advantages.However,the influence of dynamic load of adjacent excavation blasting on the existing underground space cannot be ignored.In order to improve the safety and stability of surrounding rock mass of the underground space after drilling and blasting and optimize the excavation and blasting scheme,combined with the characteristics of a phosphate mining roadway,the finite element software ANSYS/LS-DYNA was used to model and calculate the dynamic response distribution on the roof,floor and roadway side of the existing roadway at different distances from the explosive source(the distance from the explosive source to the roadway was 10 m,14 m,18 m and 22 m,respectively).The calculation results show that the failure of rock near the existing roadway section was mainly caused by tensile stress,and the compressive stress played an auxiliary role.The reasonable layout range of adjacent roadway was within the range of 14~18 m to effectively ensure the safety and stability of the stope structure.The inverted trapezoidal section was helpful to guide and diverge the explosion stress wave and improve the safety and stability of the existing roadway..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 75 (2021)
Blasting Demolition of Brick-concrete Structure Building by Piecewise and Inward Collapse
LIU Chang-bang, JIA Yong-sheng, HUANG Xiao-wu, SUN Jin-shan, YAO Ying-kang, and WU Yue
Aiming at the technical problems of the irregular brick concrete structure building demolition by blasting and the lack of directional collapse space,a demolition method of in-situ collapse combined with directional toppling' was proposed based on a blasting demolition engineering practice of a 7-story ‘凹’ style brAiming at the technical problems of the irregular brick concrete structure building demolition by blasting and the lack of directional collapse space,a demolition method of in-situ collapse combined with directional toppling' was proposed based on a blasting demolition engineering practice of a 7-story ‘凹’ style brick-concrete structure building.By innovative design of blasting cut,hole network parameters and blasting network,an expected blasting demolition effect was achieved.Using ANSYS/LS-DYNA finite element analysis software,the process of building collapse was simulated and the scientific nature of the design scheme was verified.The results show that the middle part of the building touches the ground first,and the two sides of the building are collapsed piecewisely and inwardly.There is basically no recoiling phenomenon,and it can collapse according to the design scheme.The simulation results are basically consistent with the blasting results.In the corner on both sides and north-south and central area,the explosion pile overflowed the original site of the building,so it is necessary to pay attention to the collapse space margin at this location,and take effective safety protection measures.By the method of piecewise and inward collapse,the demolishing of the special-shaped brick-concrete structure building has achieved the purpose of reducing the collapse accumulation range of the building and improving the disintegration effect..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 82 (2021)
Blasting Demolition of Water Stop Wall at Butt End of Immersed Tube in Yuliangzhou East Line of Xiangyang City
DU Shao-qing, ZHAO Gen, LI Wei-chao, and WANG Jin-xu
It is difficult to demolish the water stop wall at the butt end of immersed tube by machinery,and it is more economical and efficient to demolish it by blasting.However,it is still difficult to demolish it by blasting when it is close to the important structure and requires high construction technology.Combined with thIt is difficult to demolish the water stop wall at the butt end of immersed tube by machinery,and it is more economical and efficient to demolish it by blasting.However,it is still difficult to demolish it by blasting when it is close to the important structure and requires high construction technology.Combined with the example of blasting demolition of water stop wall at the butt end of immersed tube tunnel on Yuliangzhou east line in Xiangyang,the paper introduces the blasting demolition construction technology of water stop wall under the complex conditions of large water depth,thin wall, narrow construction working face,close to the protected buildings and the existence of first-class soil and water conservation organisms.Before the blasting demolition of the two water stop walls,the geological drill is used to arrange the blast holes on the top of the water stop wall with the a width of 1.2 m and the maximum underwater depth of more than 18 m.According to the design explosive consumption of 1.28 kg/m3,the East branch water stop wall was demolished,and the expected demolition effect was achieved.The maximum peak vibration velocity of the permanent support of diaphragm wall adjacent to the explosion source was 8.16 cm/s,the maximum peak vibration velocity of the first section of immersed tube to be floated near the explosion source was 3.7 cm/s,and the maximum overpressure peak of water hammer wave was 0.786 MPa.Based on the summary of Dongcha blasting and considering the actual situation of Dongjin water stop wall,the blasting scheme of Dongjin is optimized.The designed explosive consumption is adjusted from 1.33 kg/m3 to 1.02~1.33 g/m3,which not only the expected demolition effect is achieved,but also the blasting vibration and water shock wave are further weakened.The maximum peak vibration velocity of the permanent support of the diaphragm wall is 7.49 cm/s,The maximum peak velocity of the buried section closest to the explosion source is 5.03 cm/s,and the maximum overpressure peak value of water hammer wave is 0.592 MPa,all of which have no influence..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 88 (2021)
Research on Forward Thrust and Ground Impact Vibration of Chimney Demolition by Directional Blasting
FEI Hong-lu, WANG Shuai, and QIAN Qi-fei
The forward thrust of the chimney demolition by directional blasting determines the collapse range and the threshold of collapse impact vibration of the chimney.In order to find the forward thrust mechanism of the directional toppling of chimney,mechanical analysis was conducted by considering three touchdown postures The forward thrust of the chimney demolition by directional blasting determines the collapse range and the threshold of collapse impact vibration of the chimney.In order to find the forward thrust mechanism of the directional toppling of chimney,mechanical analysis was conducted by considering three touchdown postures of a reinforced concrete chimney,which leads to the calculation formulas for the forward thrust distance and collapse range of the directional blasting of the chimney.At the same time,the characteristics of the ground impact vibration induced by the chimney collapse was analyzed to verify the accuracy and reasonableness of the previous theoretical derivation based on engineering examples.The research results show that the established theoretical model can describe the chimney forward thrust process very well.And the calculation result can provide a reference for the safety protection design of similar blasting projects due to its conservation.In addition,it is more reasonable to use criterion 1 as the mechanical basis when the chimney has a forward thrust because it is difficult to accurately obtain the friction coefficient of the supporting parts in actual demolition projects.And it is also more reliable to study the impact vibration of the chimney on the basis of the forward thrust analysis..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 95 (2021)
Optimization of Blasting Schemes for Demolition of Cross-road Bridges in Complicated Conditions
QI Peng, SHANG Xiu-rui, LIU Chuan, ZHANG Jian-hua, and JIANG Ting-ting
The Dajinglong bridge in Fujian province needs to be demolished by blasting due to road reconstruction,which is a reinforced concrete structure with length of 187 m and width of 24 m.There are 5 rows of piers and 6 spans,and span length is 30 m.The surrounding conditions are complicated.The maximum vertical distance beThe Dajinglong bridge in Fujian province needs to be demolished by blasting due to road reconstruction,which is a reinforced concrete structure with length of 187 m and width of 24 m.There are 5 rows of piers and 6 spans,and span length is 30 m.The surrounding conditions are complicated.The maximum vertical distance between the bridge and the road under the bridge is 29 m.It is necessary to accurately control the hazards such as blasting flying rock,blasting vibration,and touch ground vibration.Through theoretical analysis and numerical simulation with ANSYS/LS-DYNA to simulate three pre-selected schemes,symmetrical initiation,one-way initiation and intermediate initiation.Comparing the blasting pile and the magnitude of the touch ground vibration,it is found that the intermediate initiation method is the best scheme.By comparing the simulation results of the delay time between different rows,the original design of the short-delay blasting scheme was optimized,and finally the blasting scheme with intermediate initiation and long-delay time was adopted.At the same time,measures such as pre-paved buffer layer,multi-layer winding protection and sand embankment protection are adopted to control blasting hazards.The on-site blasting outcomes show that good blasting results have been achieved after adopting the optimized scheme and vibration control measures.The actual blast pile shape of the bridge is roughly consistent with the simulation results.The peak vibration velocity of each monitoring point is relatively close to the simulation results,and meets the requirements of the surrounding important facilities..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 104 (2021)
Study on Rockfall Control in Blasting Mining of Changjiu Shenshan Limestone Mine
CHEN Ming-ying, LIU Jian-cheng, XIONG Jun-wei, YIN Yue-jiang, LU Wen-bo, and CHEN Ming
The control of blasting rockfall is the crucial guarantee for safety production in the blasting process of mining exploitation.A comprehensive method of theoretical analysis and model research is used to study the control of blasting rockfall in Changjiu Shenshan Limestone Mine.The mechanism of rockfall in the blastingThe control of blasting rockfall is the crucial guarantee for safety production in the blasting process of mining exploitation.A comprehensive method of theoretical analysis and model research is used to study the control of blasting rockfall in Changjiu Shenshan Limestone Mine.The mechanism of rockfall in the blasting process is summarized.A simplified kinematic model is established,and the distance of rock movement is calculated and the influence range is predicted.The results show that without any control measures,the maximum movement distance of the rockfall can reach more than 150m,and the influence scope covers the surrounding houses,fields and highways.According to the engineering practices and production demands of Changjiu Shenshan Limestone Mine,millisecond loose blasting method with preserved dike,holding rockfall net and ditch safety system are proposed from the source and the process respectively to control the hazards of blasting rockfall movement.In the meantime,measures relocating out of precautionary areas within 300m of the mine right line are taken.The technology provides reference for rockfall protection engineering and blasting projects in other complex environments..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 113 (2021)
Experimental Study on Dust Suppression by Explosion Water Mist in Open Bench Blasting
YANG Nian-hua, GUO Yao, BAI He-qiang, and ZHANG Zhao
Due to the large amount of dust and wide range of pollution caused by open-pit deep-hole blasting,it is urgent to study an efficient and reasonable blasting dust suppression technology for green mine construction.Through field test,the paper reveals that the dust sources of deep-hole bench blasting in open-pit mainly iDue to the large amount of dust and wide range of pollution caused by open-pit deep-hole blasting,it is urgent to study an efficient and reasonable blasting dust suppression technology for green mine construction.Through field test,the paper reveals that the dust sources of deep-hole bench blasting in open-pit mainly include three parts:ejection of blasting-hole stemming,breaking and crushing of rock,and scattering of surface.Besides,the dust production is closely related to groundwater,lithology and blasting mode.Therefore,a three-dimensional water mist suppression model was designed by using water bags to stemming the holes and be exploded into water mist in front of the bench surface of the blasting and throw area.Through the special tests of the water bags explosion,a reasonable design parameters of water bag explosion were obtained,the optimal explosive consumption for water bag explosion is 0.4~0.5 kg/m3.The field tests and applications show that the reasonable water bags spacing is 5~10 m,the delay time of water bag blasting is 1.0~1.5 s than that of hole explosion,and the stemming length of water bags is less than 4 m.The comprehensive test results reduce the concentration of blasting dust by more than 50%,and the method of dust suppression by explosion water mist is simple and effective..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 130 (2021)
Risk Elimination Blasting of Crushing Station Foundation Pit and Toe Rock Disposal Blasting
LI Xi-ming, LI Zhen-min, JIA Shuai, and ZHANG Zhi-guo
In view of a series of problems such as excessive residual foundation after foundation pit blasting in a crushing station of a mine and the collapse of foundation pit slope in the construction process,blasting method was adopted to eliminate risks and deal with toe rock.Based on the analysis of the failure mode of the In view of a series of problems such as excessive residual foundation after foundation pit blasting in a crushing station of a mine and the collapse of foundation pit slope in the construction process,blasting method was adopted to eliminate risks and deal with toe rock.Based on the analysis of the failure mode of the foundation pit slope and the causes of the dumping type combined with the site geological structure,three feasible blasting technical schemes were proposed.Through the analysis and demonstration of the risk elimination scheme,it was determined to adopt the pre-splitting blasting method to carry out half bench blasting and cut off the dangerous rock on the west slope at the horizontal crack of the bench.Simultaneously,the foundation pit dumping platform was brought into the first blasting,and the toe rock was incorporated into the second stage blasting.In the construction process,the perforation equipment combined with construction conditions was reasonably selected,the construction efficiency was effectively improved,perforation cost was reduced,the measures of scheme 1 and scheme 2 were reasonably used to deal with the toe rock of southwest corner of foundation pit,the second stage slope drilling quantity was effectively reduced,and the construction efficiency was improved.The process adopted the air-decked charging technology,millisecond initiation technology and patent technology a charge structure for deep hole presplitting blasting'.In the case of not affecting the overall stability of the slope,the problem of under-excavation of the north slope in the construction process was solved.Through the fine construction,the risk was eliminated successfully,and the toe rock problem was solved,which created a good construction condition for the follow-up construction,shortened the construction period,and saved the construction investment..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 136 (2021)
Time-frequency Analysis of Blasting Vibration Signal based on FDM
WANG Hai-long, BAI Hao-bo, and WANG Sheng-hua
A time-frequency analysis method based on Fourier Decomposition Method(FDM) has been introduced to improve the accuracy of time-frequency analysis of blasting vibration signals.Firstly,the original simulated signals were decomposed based on FDM theory,and the correlation coefficient and energy ratio between the modal cA time-frequency analysis method based on Fourier Decomposition Method(FDM) has been introduced to improve the accuracy of time-frequency analysis of blasting vibration signals.Firstly,the original simulated signals were decomposed based on FDM theory,and the correlation coefficient and energy ratio between the modal component and the original signal were calculated,so as to screen the dominant components.Then,the Hilbert transform was applied to the screened components to obtain the time-frequency spectrum.At the same time,the original simulated signals were decomposed based on EMD,EEMD and CEEMDAN methods,and the modal mixing effect of the decomposition results was evaluated by using the energy ratio theory.In addition,the corresponding time-frequency spectrums were obtained by using Hilbert transform,and the time-frequency resolutions of the FDM,EMD,EEMD and CEEMDAN methods were compared.Finally,the proposed method was applied to time-frequency analysis of measured blasting vibration signals.The results show that FDM can effectively solve the problem of modal aliasing,and the decomposition results have a better time-frequency resolution by the Hilbert transform.The proposed method is advantageous to the acquisition of local features and the time-frequency-energy relations of the blasting vibration signals,so as to improve the accuracy of time-frequency analysis of tunnel blasting vibration signals..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 143 (2021)
Prediction of Ground Blasting Vibration in Qianbaizaoshan Iron Mine
HUANG Yu-hua, ZHANG Hai-jun, and XU Guo-quan
Ground vibration is one of the most severe and complex environmental problems in blasting operations.Blasting vibration can have adverse effects on reserved slopes and structures,which would consequently affect the integrity of the building structures.Hence,an accurate prediction of ground vibrations during blasting prGround vibration is one of the most severe and complex environmental problems in blasting operations.Blasting vibration can have adverse effects on reserved slopes and structures,which would consequently affect the integrity of the building structures.Hence,an accurate prediction of ground vibrations during blasting process is of great significance.The main purpose of the research is to make highly precise predictions of the ground vibrations caused by mine blasting,and to reduce the impact of ground vibrations on the surrounding environment.In this study,an artificial neural network(ANN) model was put forward to predict blasting vibrations of Qianbaizaoshan Iron Mine.Besides,vibration data from 29 blasts were collected,and 8 ANN models were established for PPV prediction.In order to evaluate the established network,the coefficient of determination(R2),Root Mean Squared Error(RMSE) and Mean Square Error(MSE) were chosen as the network performance evaluation indexes.It is found that the 2-6-1 network has the best performance when R2 is 0.92,RMSE is 0.4 and MSE is 0.23.In order to prove the superiority of ANN forecasting method,four empirical models and multiple linear regression(MLR) models were used to predict PPV.The results show that the ANN model has better prediction performance than the empirical and MLR model..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 152 (2021)
Numerical Simulation of Dynamic Response for Gas Explosion in Urban Pipe Gallery
DENG Cheng-yun, CUI Hai-long, ZHONG Dong-wang, LI Teng-fei, WANG Yan-hong, HE Li, and SI Jian-feng
In order to better optimize the anti-explosion design of urban pipe gallery structure,it is very necessary to study the dynamic response characteristics of gas explosion of pipe gallery.Using the finite element software ANSYS/LS-DYNA,the finite element calculation model of the pipe gallery structure was established,andIn order to better optimize the anti-explosion design of urban pipe gallery structure,it is very necessary to study the dynamic response characteristics of gas explosion of pipe gallery.Using the finite element software ANSYS/LS-DYNA,the finite element calculation model of the pipe gallery structure was established,and the equivalent internal energy method was used to simulate the gas explosion loading.Based on this model,the failure and response characteristics of the pipe gallery structure were analyzed by studying the propagation attenuation law of shock wave excited by gas explosion and its dynamic influence on the pipe gallery structure.The results show that the peak pressure of gas explosion shock wave decreases gradually with the increase of propagation distance,and the duration of overpressure becomes shorter at the same time.The reflection and superposition of the shock wave on the wall of confined space cause the peak pressure to increase slightly in the later stage of propagation,but the whole attenuation is in a polynomial form.The explosion damage is mainly concentrated in the corner of the gas warehouse or the position where the structure changes suddenly.The pressure relief port is set on the top of the gas warehouse,which can effectively avoid the damage effect of the concrete in the upper passage warehouse.The higher stiffness of the corner of the pipe gallery leads to a weaker vibration response,while the resultant vibration velocity in the middle of the wall can reach 0.4 m/s.Under the condition of full warehouse gas explosion,the local concrete of pipe gallery structure has through-wall cracks,but there is no overall structural damage..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 159 (2021)
Construction of Virtual Simulation System for Emergency Rescue of Blasting Fume Poisoning Accident during Roadway Excavation
ZHANG Fei-yan, WEN Jia-yu, and HAN Ying
The experiment teaching platform for blasting safety during roadway excavation based on virtual simulation technology has been running online and realized three experimental teaching contents:tunnelling blasting scheme design,blasting construction,blasting hazard monitoring and analysis.However,the emergency rescue of The experiment teaching platform for blasting safety during roadway excavation based on virtual simulation technology has been running online and realized three experimental teaching contents:tunnelling blasting scheme design,blasting construction,blasting hazard monitoring and analysis.However,the emergency rescue of blasting accidents during roadway excavation has not yet been involved.Therefore,taking the blasting fume poisoning which is a typical accident in the process of blasting as an example,the virtual simulation system for emergency rescue was studied and constructed by using the 3D Max software modeling and Unity 3D software development in this paper.Finally,a blasting fume poisoning accident was demonstrated on the computer to show the self-rescue and mutual rescue of workers and rescue by rescue workers.The system is an expansion and extension of the experiment teaching platform for blasting safety during roadway excavation.It can be used for the experimental teaching of undergraduates and graduate students majoring in safety engineering and civil engineering,as well as the training and teaching of relevant technical personnel in the fields of mining and engineering blasting..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 166 (2021)
Thoughts on Safety Management of Miniature Civil Explosives Magazine
XIA Man-man, and ZHENG De-ming
According to the current national laws,regulations,standards and specifications on miniature civil explosives magazine,the problems existing in the ground storage of miniature civil explosives magazine,such as the insufficient safety distance of the internal and external areas,the unqualified building structure,the unqAccording to the current national laws,regulations,standards and specifications on miniature civil explosives magazine,the problems existing in the ground storage of miniature civil explosives magazine,such as the insufficient safety distance of the internal and external areas,the unqualified building structure,the unqualified lightning protection facilities,the failure of the civil explosive articles to be placed safely according to the regulations,and the inadequate safety management etc,are sorted out.In view of the above safety management problems,the existing safety risks and accident cases are given as examples,and analyzes the root causes of a series of accidents.It is recommended that the Ministry of Public Security should make clear provisions on the number of miniature civil explosives magazine used by blasting units in revising the Safety Code for Miniature Civil Explosives Magazine(GA838—2009).The competent department can strictly control and effectively play the role of the dangerous goods on-site supervision and management organization.From the formulation and revision of laws,regulations and standards to the implementation of civil explosives industry opinions,should be widely solicited to ensure the effectiveness of management..
BLASTING
- Publication Date: Jan. 01, 1900
- Vol. 38, Issue 3, 172 (2021)
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