Decoupled charge can change the action mode of explosive products on rock,so as to obtain different effects of rock fragmentation.In order to study the influence of charge decoupling coefficient on rock crack propagation by blasting under initial stress,a kind of transparent material conforming to the mechanical properties of hard rock was used to carry out similar model tests of blasting under bidirectional equal load.The test results show that:The propagation of the longest radial crack is along the direction of maximum principal stress in the model specimen with equal confining pressure; nder the initial stress state,the decoupling coefficient has an obvious effect on the crack propagation.Both the length of the longest radial crack and the average length of radial main cracks on the model specimens decrease with the increase of decoupling coefficient.And the maximum and average diameters of circumferential fractured zone decrease with the increase of decoupling coefficient; Under the initial stress state,the diameter of the crushed zone increases first and then decreases with the increase of decoupling coefficient.During blasting excavation of deep rock mass,the relationship between the propagation length of the radial main crack and decoupling coefficient can be used to design parameters of controlled blasting,so as to reduce the overcutting and undercutting on surrounding rock and enhance the efficiency of tunneling blasting.The research results are of great significance to enrich the theory of deep rock blasting and engineering practice.

Abstract: Because of its safety and high efficiency,blasting demolition technology has become the preferred technology for demolition of high-rise buildings.In recent years,urban high-rise buildings have gradually shown the characteristics of large scale,complex environment and various structures.Aiming at solving the problem of limited collapse space in the blasting demolition of buildings in complex urban environment,the basic principle of longitudinal span-by-span collapse blasting demolition technology is analyzed with several typical engineering cases of blasting demolition.Meanwhile,the design principles of related blasting parameters are discussed and summarized.The trapezoidal blasting incision should be adopted in the longitudinal span-by-span collapse mode,the closure angle of the incision should be no less than 25°,and the support area with sufficient stiffness should be reserved in the rear row.Furthermore,the extension time of longitudinal partition should be 0.3~0.6 s,and the partition delay time of frame-shear structure buildings with a large longitudinal span or stiffness should be properly extended.Through three examples of blasting demolition of buildings,the feasibility of the simulation and analysis of the longitudinal and span collapse blasting design scheme of buildings by dynamic finite element software is expounded.In simulation calculation,the failure of main components of buildings is controlled by tensile stress or principal strain failure.By a contrastive analysis,longitudinal span-by-span collapse blasting technology has the advantages of small accumulation range of blasting pile,good crushing and disintegration effect,and reduction of building touchdown vibration.It is suitable for the blasting demolition of the buildings with small height-width and large length-width ratios,and it has broad application prospects.In practical engineering,the best blasting scheme should be determined according to the comprehensive comparison of site environmental conditions,building structure characteristics and technical risks.

Blasting loads may cause severe damage to reinforced concrete(RC) structures.Adding basalt fiber(BF) into concrete is a means to improve the blast resistance of reinforced concrete members.Beam is a vital bearing and connecting member in a reinforced concrete structure.Improving the blast resistance performance of the beam can enhance the overall impact resistance of the frame.Three beams with different basalt fiber volume ratios(0%,0.1%,and 0.2%) were selected to investigate the anti-explosion performance of basalt fiber reinforced concrete(BFRC) beams under blasting loads.The accelerometers and strain gauges recorded test beams′ dynamic responses.Meanwhile,the embedded piezoelectric smart aggregates(PSA) were used to monitor the internal damage developments of the beams.The observations show that under the action of blasting loads,compared with ordinary RC beams,the peak strain and acceleration of the BFRC beam are lower.Correspondingly,there are less surface cracks of the beam and a smaller spalling area.Wavelet packet energy method is used to compute the indices for estimating the internal damages of the BFRC beams under different explosives and analyze the change of anti-explosion performance of the concrete beams with different basalt fiber volumes.The test results show that the basalt fiber can improve the anti-explosion performance of concrete beams,and the damage degree of beams decreases significantly when the basalt volume content is 0.2%.

In order to reveal the influence law of graphite ore grade on its dynamic mechanical properties,SHPB tests were carried out on graphite ore samples with five grades of 1.57%,5.19%,10.79%,12.65% and 19.50% under the action of constant amplitude impact loads.Based on the analysis of microscopic fabric characteristics of the graphite ore,the peak strength(σd),dynamic elastic modulus(Ed),peak strain(εd) and energy consumption density(ASE) of the samples were analyzed.The results show that the change of the dynamic mechanical properties of the graphite ores with different grades is the result of the change of mineral composition and graphite flake distribution characteristics.With the increase of graphite ore grade,the dynamic mechanical properties of the sample are obviously weakened,but there is a limit of the weakening degree.The σd,Ed,and ASE have a good negative exponential function fitting relationship with graphite grade(correlation coefficients R2 is 0.977,0.930 and 0.973,respectively).With the increase of graphite ore grade,the σd,Ed,and ASE decrease gradually in a gentle trend and eventually reach a stable value.However,with the increase of graphite ore grade,the εd increases approximately linearly at the initial stage.When the grade reaches 12.65%,the εd increases significantly,and then decreases slowly,but the decrease degree of εd is very small.On the whole,it still shows a good increasing law of weak power function(R2 is 0.810) for εd with the increase of graphite ore grade,indicating that the general weakening trend of the dynamic mechanical properties of the samples with the increase of graphite ore grade has not changed.

In order to solve the charge failure problems due to water gushing or freeze in the blasting process of an open-pit mine in plateau water-bearing frozen rock area for many years,Jiama open-pit mine in Mozhugongka County,Lhasa City is taken as the research object for coupling analysis in an temperature and water field.Based on the theories of elasticity,Darcy′s law and mathematical physical methods,the temperature change model of the mining area with drilled blast holes is established by the finite element simulation software COMSOL-Multiphysics.Then the numerical simulation results are verified by the field test results of the SG-DTS-84U optical fiber thermometer.After verification,it is found that the simulation results are in good agreement with the field test results,which confirms the correctness of the simulation results.On this basis,the relevant parameters of the numerical model are changed to study the change law of the temperature field after blasthole formation in different external environments.That is,in order to further find a fundamental solution to the technical problems of frozen hole charging,the influence process of different surface temperatures and seepage velocities within 24 hours under the coupling effect of temperature and water field on the change law of the temperature within the hole is analyzed.The research results show that the frozen depth in the blasthole is mainly controlled by the surface temperature and seepage water velocity.The temperature of the blast hole is greatly affected by the external temperature when the depth is less than 6 m,and the temperature of the blast hole is mainly affected by the seepage water velocity and the original temperature of the blast hole wall when the depth is more than 6 m.After the blast hole is formed,the temperature in the hole gradually tends to be stable after 8 h,and its temperature decreases with the increase of depth.When the seepage water velocity is less than or equal to 5 m/h,the change of seepage velocity has an impact on the development of the temperature field in the mining area.On the contrary,when the seepage water velocity is greater than 5 m/h,the change of the seepage velocity has a weakened effect on the temperature field in the blasthole.

The design and disaster prevention of open-pit mining of mineral resources by bench blasting in cold regions have become key issues in the safe extraction of energy in Western China.In order to study the propagation mechanism of stress waves in the blasting process of a surface mine in plateau cold regions,the definition of ice-filled rock mass is given first,and the basic characteristics of ice-filled rock mass and its difference with frozen soil are defined.Secondly,the propagation process of stress waves in ice-filled rock mass is reproduced by RFPA2D-dynamic and wave peak migration visualization is achieved.At the same time,the reflection and transmission of stress waves at the interface between the cracked ice and the bedrock are analyzed.Furthermore,the influence of the quantity,spacing,and thickness of the cracked ice on the propagation process of stress waves is discussed.The numerical simulation results show that the propagation effect of the explosion stress waves is the best in intact bedrock,second in ice-filled rock mass,and the worst in air-filled cracked rock mass.Compared with the intact bedrock,the cracked ice existing in cracks reduces the stress wave amplitudes,and the attenuation of the stress waves in the rock rod model changes from 6.1% to 7.1%.The propagation of stress waves in the ice-filled rock mass is affected by the thickness and quantity of the cracked ice more than the,with a transmission coefficient of 0.925.When,the thickness and quantity of the cracked ice increases,the amplitude of the transmitted stress waves decreases.Take the attenuation degree of stress wave as y,it follows y=0.6527+0.03687x with the thickness of the cracked ice,and y=0.0715+0.0026x with the quantity of the cracked ice.The research results provide a theoretical research basis for blasting parameter design and disaster prevention of surface mine in plateau cold region.

Aiming at the safety problem of second-step mining blasting in Lilou Iron Mine,the finite element software ANSYS/LS-DYNA is used to establish a corresponding blasting simulation scheme.According to the actual stope specifications,the length of the backfill body on both sides is 20 m,and the length of the middle mining body is 30m.The size of the bottom roadway is 4 m 4 m.The height of the backfill body and the ore body are both 25 m,and the thickness and row spacing are both 2 m.When arranging blast holes,it is considered to set 0.5 m、1.0 m、1.5 m and 2.0 m thick protective layer(that is,the ore body between the bottom of the blasthole and the boundary of the filling body) inside the ore body near the boundary of the backfill body,and both bottom and top initiation are used.After simulating the second-step recovery blasting under different schemes,the element most affected by blasting is selected at the corresponding position of the boundary of the backfill body for comprehensive analysis of stress,vibration velocity and displacement,so as to evaluate the overall stability of the backfill body under different schemes.The simulation results show that increasing the thickness of the protective layer in an appropriate range can effectively reduce the impact of blasting on the filling body.At the same time,under the top initiation scheme,the detonation position of the explosive is far away from the filling body,and the stress wave attenuation is more obvious.When the thickness of the protective layer is set to 1.0 m under the top initiation scheme,the effective stress peak value,the peak vibration velocity,and the peak value of the combined displacement of each monitoring point during the blasting process are 0.03 MPa,9.35 cm/s,and 0.07 mm respectively,all of which are in the safety range of the filling body.However,the thickness of the protective layer needs to be increased to 1.5 m when the bottom initiation scheme is adopted to keep each monitoring point in a safe state.In contrast,the thickness of the protective layer of the top initiation scheme is smaller,which has a better effect on the ore recovery rate.The simulation scheme of the top initiation method and the thickness of the protective layer of 1.0 m is verified through the field industrial tests by arranging a vibration meter around the stope.And the peak particle vibration velocity at the backfill boundary is fitted according to the relevant data and the Sadowsky formula.The peak velocity is 9.37 cm/s,which is consistent with the peak vibration velocity of the corresponding monitoring point in the simulation results.And the blasting effect on site is relatively positive,which further verifies the reliability of the simulation results and the rationality of the simulation scheme.

In the process of upward medium-length hole blasting in underground mines,the damage of surrounding rock at the brow is mainly caused by the blast of the last row of blast holes.The angle of blast holes,the length of air decking and the spacing of blast holes are important and easily adjustable blasting parameters that affect the control effect of the brow.To ensure the integrity of the brow and the safety of the blasting working face,the optimization of these aforementioned blasting parameters are studied.Taking the blasting in the underground stope of Tonglushan Mine as the engineering background,the blasting numerical models with different blast hole angles,air decking lengths and blast hole spacings are calculated and analyzed by the blasting crater theory and LS-DYNA.The calculation results show that the smaller the blast hole angle is,the better the integrity of the rear brow is protected.The air decking can effectively reduce the brow damage.When the hole spacing is 1.0 m,the smooth brow contour can be ensured.Considering the control effect of brow and the site conditions,the optimal blast hole angle,the optimal air decking length,and the optimal blast hole spacing are determined as 80°,0.6 m and 1.0 m,respectively.According to the analysis results,the field blasting tests were carried out in Tonglushan.The field results show that the integrity of the rock mass in the brow region,roof and two sides are good,and the rock damage is minimal.Besides,the blasting fragmentation is uniform,and the blasting effect is positive.

In order to explore the rationality of the parameter selection for the numerical model of limestone under the action of impact load,a numerical analysis method for the impact failure of limestone was constructed based on the Holmquist-Johnson-Cook(HJC) constitutive model.At the same time,static tests were carried out on the limestone drilled in Tongzi tunnel,and the basic physical and mechanical parameters were obtained.First,the rock sample limit surface parameters,pressure parameters and rate effect parameters were obtained through triaxial confining pressure experiments,Hopkinson pressure bar and other experiments.Then,LS-DYNA numerical simulation and SHPB tests were carried out,and the results were compared.Finally,the sensitivity analysis of 21 parameters of the limestone HJC constitutive model was carried out with the dynamic peak stress as the objective function.The results show that the numerical calculation is in good agreement with the stress-strain curve and the failure form obtained from the SHPB laboratory tests,indicating the rationality of the parameters of the limestone HJC constitutive model in this paper.The strength of the limestone is sensitive to the parameters fc,A,B,and N,and either the maximum change rate of its intensity increase or decrease exceeds 10%.

In the process of open pit mining,deep hole blasting parameters directly affect the blasting effects(boulder yield and bottom toe) and the blast cost which accounts for a large proportion of the overall cost of open-pit mining.In order to standardize the process of drilling and blasting and to improve the actual production efficiency and economic benefit,optimization tests of deep hole blasting parameters were carried out in Laolongshan limestone mine.In the first stage,blasts were conducted with hole diameter of 90 mm and four different blast hole layout patterns(hole spacing burden) of 4.0 m×3.8 m,4.0 m×4.4 m,4.2 m×4.4 m and 4.5 m×4.4 m.In the second stage,the hole diameter was adjusted to 110 mm,and the hole spacing and burden were increased to 5.0 m×4.8 m and 5.2 m×5.5 m.The crushing hammer is used for secondary crushing of boulders after blasting to meet the requirements of fragmentation.Finally,the most reasonable values of blasting hole spacing and burden were tested according to minimum overall cost of blasting and secondary crushing.By comparing the costs before and after the blast experiments,the optimum hole spacing and burden are 4.0 m and 3.8 m for hole diameter of 90 mm and 5.0 m and 4.8 m for hole diameter of 110 mm.

In order to explore the influence of buffer thickness on the production efficiency of rope shovel in a blast,buffer thickness values of 8 m,10 m,12 m and 15 m are respectively designed with a hole diameter of 251 mm and a bench height of 7.5 m in the production blasting block.Based on the statistical analysis of the rope shovel production efficiency,the blasting fragmentation distribution and the blasting muck pile height,the best buffer thickness is determined.The results show that when the buffer thickness is 10 m at different excavation depths,there is the best fragmentation distribution with the largest proportion of 400~600 mm.Moreover,the height of the blast muck pile can reach 12.6 m,which conforms to the optimal height range and loading efficiency of the rope shovel.Meanwhile,the optimum number of blast hole rows is 10,for it has a significant impact on the buffer blasting effect.If there are more than 10 rows of blast holes,the blasting effect and the loading efficiency of the rope shovel will be affected.At this time,the blasting parameters of the blast holes after the 10 rows should be adjusted.Last but not least,buffer blasting improves the effective operation time by 1 hour and reduces the ore dilution rate by 3%,which can create an economic benefit of 450 million US dollars during the full life of Husab uranium mine.It is the first time to promote buffer blasting technology to large block blasting with multiple rows(20 to 30 rows),which is not only in line with the objective needs of large-scale mine production,but also an inevitable trend after large-scale equipment is used.Meanwhile,it promotes the refined blasting of Husab Mine more,and can also provide important field data for similar mine blasting at home and abroad.

Nowadays,the development of digitization and artificial intelligence has penetrated all walks of life.The emergence of "digital blasting" in the blasting industry promotes the development of blasting towards digitization,refinement and visualization.The application of intelligent technology in the field of engineering blasting have become a development trend.In order to improve blasting effect and reduce the blasting cost,a new method for calculating explosive charge is proposed.By training the SVM model to predict the strata and embedding the intelligent drilling rig system,the accurate positioning and real-time identification of lithologic parameters are obtained. A borehole database is established to store and manage the borehole lithology distribution data obtained from the intelligent drilling rig.These data can be visually displayed by generating two-dimensional and three-dimensional histograms.According to Delaunay′s criterion,the polygon of hole location and blasting range is triangulated,and the affected area of each hole is calculated.Then,according to the lithologic stratification and affected area of each hole,the charge quantity required by each rock layer of each hole is calculated,and the charge quantity required by each rock layer is accumulated to obtain the total charge quantity required by each hole.The charge calculation based on intelligent lithology identification is realized by C++ programming,which has been applied in the 918 section of an open-pit coal mine in Xilinhot,Inner Mongolia.

Demolition by blasting is still the first choice for tall buildings due to the characteristics of economy,efficiency and low safety risk.However,the improvement of construction technology,safety and environmental protection requirements has brought new challenges to the demolition of urban blasting because of the complex surrounding environment and complex building structure forms.In order to optimize the blasting scheme,at present,the forward numerical simulation research is mainly based on the blasting theory and numerical model,while the analysis of the collapse process which is of great significance to the study of collapse mechanism is rarely done.To explore the orientation of blasting demolition of frame shear structure building movement and the collapse of the law of the dumping process,combining with a 22 floors frame-shear structure for blasting demolition of buildings,builting a set of economy applicable image acquisition system,successfully taken out a set of suitable for dumping process analysis of high-definition pictures in a row,using the existing mature AutoCAD software platform and combined with secondary development,An image analysis framework is established to extract the spatio-temporal data of a specific observation point.Through calculation and analysis,the time history curves of displacement,velocity,acceleration,instantaneous velocity and instantaneous acceleration of the observation points are drawn,which reveal the downward motion law of the blasting dumping vibration of the frame-shear structure building,and the disintegration mechanism of the structure failure caused by the impact overload of more than 20 g at the internal joints of the building during the falling process.The motion trajectory formula of the observation point on the roof front during the toppling process of a similar frame-shear structure building is fitted.According to the height of the front point of the roof during the toppling process,the horizontal displacement of the roof during the toppling process can be predicted,and the collapse range of the building can be predicted finally.The related analysis process,data results and collapse prediction model can provide reference for the prediction of the collapse range of buildings with similar structures.

Aiming at the problems of high risk and long construction period in demolishing a L-shaped building by manual pre-cutting and separate blasting,a one-time overall blasting demolition scheme with different collapse directions was designed for a 7-story L-shaped brick-concrete structure building.ANSYS / LS-DYNA dynamic finite element software was used to carry out numerical simulation for checking on the feasibility of the scheme.The failure mechanism of the main components of the building was revealed by analyzing the motion time-history curve of the top nodal points and the whole building′s collapse process,and the blasting effect was predicted.By dividing the building into three areas,designing the blasting incisions and the initiation network,and raising the height of the approximately trapezoidal blasting cut,the building was automatically divided into two parts at the corner.The north side of the building collapsed northward,and the south side of the building toppled westward,which made the building fully disintegrated upon touching the ground.The formation and closure of the actual blasting cut,the collapse process of the structure,the collapse range and shape of the building were basically consistent with the numerical simulation results,which means a good actual blasting effect.The time of collapse and disintegration was about 7 s.There was no recoil phenomenon in the reverse direction of collapse.The overall height of the blasting pile was about 8.9 m,and the blasting pile at the corner collapsed to the east about 2.1 m.Combined with the numerical simulation results,the suggestions of protection measures were presented to control the harmful effects of blasting and ensure the safety of the east protection target.

Asymmetry,irregularity,many buildings(structures) to be protected around,and the difficulty to topple in a direction constitute the complex environment for the demolition of a building(named Pacific Tower) with “L” shape in north-south direction.To ensure the successful collapse of the building and effectively control the harmful effects of blasting,the pre-demolition method of mechanical cutting partition and the method of increasing the incision height were adopted.Pacific Tower adopted the plan of one-time blasting demolition,which includes the combination of in-hole/out-hole delays and zonal sequential directional collapse.In pre-demolition,the building was divided into rectangular and special-shaped areas by mechanical cutting partition method.The rectangular blasting incisions were distributed in the 1st ~ 3rd floors,and the special-shaped blasting incisions in the 1st~3rd and the 8th~9th floors.In addition,the powder factors were 1.67 kg/m3 and 1.6 kg/m3 for the stand column and the shear wall,respectively.The blast holes were arranged in one row.And they were initiated in sequence by long-delay nonel detonators in the holes and short-delay nonel detonators out of the holes.The rectangular area was oriented to the southwest,while the special-shaped area was oriented to the west with three-layer folding blasting,with a delay interval of 1900 ms between the two areas.There were several measures proposed to control the damage effect of blasting.Firstly,cover protection was adopted at the position of incisions.Secondly,a 6 m high buffer layer made by waste residue was put in the collapse position of the building.Thirdly,double layer shelving was set up for passive protection for the key areas.The building collapsed successfully and fully disintegrated.Now that flying rocks,air shock wave and blasting vibrations were all within the safe ranges,and the surrounding environment was not affected,good blasting effect was obtained.

One 150 m high and two 210 m high chimneys have been successfully demolished by blasting with 40 m high trapezoidal cuts in an insufficient collapse space.Directional collapse blasting was carried out for three times by combining in-hole and out-hole delays.The protection measures included laying a cushion in the direction of chimney collapse,piling up an impingement dike,excavating a vibration damping ditch,putting a dense screen at the blasting cut and overlaying geogrids.Blast vibrations monitoring proved that the flying objects and blast vibrations were both controlled within the safety allowable range and no damage was caused to surrounding structures.The blasting effect shows that high blasting cuts can effectively solve the problem of limited collapse space,and avoid the influence of factors such as soot platform at the bottom of the chimney and flue entrance on the collapse direction.At the same time,this technique can also limit the flyting distance of the splash on the ground and reduce the ground contact vibration and blast vibration.In addition,the chimney lining can be effectively treated by blasting boreholes through the concrete walls of the chimney into the lining and insulation layer.Another good practice is to pretreat the directional windows and guide windows by a drilling and coring machine,which can reduce explosive charge and promote the breakage of the blasting cuts so as to ensure the exact direction of collapse.

The structure of a limestone kiln consists of an external metal plate,internal firebricks and middle filled loess.The foundation of a limestone kiln is built by reinforced concrete with low bar ratio and internal mortar pieces masonry with a square large volume composite structure with gray channel space.It is difficult to drill blast holes with a conventional  38 manual rock drill because of its metal outer wall.The safety of gas cut also cannot be guaranteed.Meanwhile,the internal lining of the foundation is of poor quality,with large porosity and isolated gravel distribution.Therefore,a directional blasting technology scheme is adopted to blow up a gap on the foundation of the limestone kiln and make it unstable and collapse under the action of gravity.In order to improve the construction efficiency and safety,and make the explosive energy evenly distributed in the structure,a large hole drilling rig is used to drill  90 holes on three sides(front,left and right sides) of the designed gap by reasonable design of blasting parameters.The blast holes are charged with  32 emulsion explosive bundles and tightly stemmed.The successful blasting demolition of the limestone kiln proves that it can achieve a good blasting effect,ensure the safety of blasting,and improve construction efficiency.

Natural disasters such as rainstorm,flood and typhoon occur frequently in China in recent years.Blasting technology has been widely used in emergency rescue projects all over the country.In view of the risk of blasting demolition and flood discharge construction of cohesive soil dams in flood season,Chuhe dam blasting demolition project in 2020 it taken as the analysis example.The problem of collapsible collapse in the excavation of cohesive soil embankment under high water level for a long time can be solved by designing a drilling rig with mud suction and soil discharge performance.Through the analysis of four existing models of explosion in soil,the calculation model of blasting cavity volume, i.e.the spherical charge explosion similarity theory model,is suitable for blasting demolition of soil buildings.Based on this model,the blasting cavity volume required for the project is calculated as 160% of the volume of strong throwing blasting charge by blasting tests and the convenience of engineering operation.Combined with the theory of enhanced throwing blasting cavity and the size of the cohesive soil dam,the hole depth is determined as 3.6 m.According to the previous experience of blasting compacted soil,the powder factor,hole spacing and charge amount of enhanced throwing blasting are determined as 0.83 kg/m3,2.5 m and 84 kg/cavity,respectively.Thus the charge amount of cavity expanding is calculated as 0.40 kg.The results show that the semi empirical formula based on the similarity theory of spherical charge explosion can meet the application needs of blasting demolition of soil buildings.It is proved that the construction method of cavity expansion and strong throwing blasting technology based on mud suction and dumping drill is feasible and effective in the demolition of soil buildings in flood control and rescue.

The reasonable matching of explosive and rock can effectively increase the energy utilization rate of explosive and improve the blasting effect.To study the influence of the matching relationship between explosives and rock on the blasting effect,rock samples from different platforms were collected from an open-pit coal mine in Xinjiang.Through rock static mechanics tests,uniaxial compressive strength,elastic modulus,Poisson′s ratio and tensile strength of different rocks were obtained.Through the SHPB dynamic rock impact test,the influence law of different impact loads on rock stress,strain and rock failure characteristics was obtained.Based on the adjustment of the ratio of different components of the mixed emulsion explosive,five different formulations of the mixed emulsion explosive with different properties were obtained through the detonation velocity test and density test of the mixed emulsion explosive.Based on the theory of explosive and rock energy matching,an explosive and rock energy matching model based on BP neural network was established.The trained PSO-BP neural network was tested by test samples.The average errors of the three groups of prediction are 5.09%,7.26% and 4.79% respectively.Finally,the energy matching model of explosive and rock is applied to the 1252 West platform,1228 East platform and 1180 West platform of an open-pit mine in Xinjiang.The results show that,compared with the traditional explosive formula and blasting parameters,the explosive selected by the matching relationship between the energy of mixed explosive and rock properties can not only reduce the single consumption of explosive,but improve the blasting effect indexes such as bulk rate and backsplitting distance.

In view of the application situation and problems of mixed emulsion explosive in the cold and high-altitude area,especially the short storage period of the mixed emulsion matrix,easy crusting on the surface,high storage safety risks,poor on-site sensitization quality,too many invalid large bubbles,the state of "tofu dregs",and so on.In order to solve the problems above,the water-phase and oil-phase formula design and field sensitization are optimized,which reduces the number of major hazard sources in the mining area,improves the intrinsic safety of the matrix,improves the storage stability of the matrix and the sensitization effect of explosives.At the same time,it will not have a negative impact on the current production process,explosive performance and blasting effect of mixed emulsion explosives.These improvements can effectively solve the technical problems in the production and application of mixed emulsion explosives in cold and high altitude environment.The results show that when the water content of emulsion matrix increases from 14% to 17%,the natural storage period of emulsion matrix increases from 25 days to 40 days,and the detonation velocity is measured as 3900~4000 m/s which is at a comparable level with the test result of 3700~4200 m/s before any adjustment.The field tests indicate that the blasting effect has meet the demands.By adjusting the content of citric acid and introducing foaming promoter E in the water formula,the density of the explosive is finally controlled as 1.15~1.20 g/cm3.In addition,the field sensitizing quality of the explosive has been improved obviously.The natural storage time of the emulsion matrix is significantly increased from 45 days to 70 days by using the polymer emulsifier EPE-3021.

In order to improve the high-temperature resistance of powder emulsion explosive,the super absorbent polymer(SAP) after absorbing water was added.Then the temperature rise curves of the mixed explosive in the high-temperature blast holes were measured by thermocouple,and the detonation velocities of the mixed explosive in the blast holes were measured by corresponding instrumentation.The results show that the SAP after absorbing water can absorb heat and release water vapor in the high-temperature blast hole,which greatly reduces the temperature-rising rate of the mixed explosive due to the large specific heat capacity of water.In addition,since the SAP after absorbing water will secrete water after mixed with the powder emulsion explosive,the mixed explosive is heated evenly and can be maintained below 100℃.The heat resistance of the mixed explosive is significantly improved with the increasing of the SAP content.Because the density of the mixed explosive is higher than that of the normal powder emulsion explosive,the detonation velocity of the mixed explosive containing 10% SAP is equivalent to that of the wet powder emulsion explosive(3980 ms-1),and is 6% to 11% higher than that of the powder emulsion explosive(3733 ms-1),even though the SAP will absorb heat and hinder the propagation of detonation waves during detonation reaction.With the gradual increase of the SAP content,the detonation velocity of the mixed explosive decreases greatly and even fails to explode,and the particle size of the SAP has a significant effect on the detonation velocity.By comprehensive consideration,SAP with particle size of 10 mm accounting for 10% of to the powder emulsion explosive is a better choice,which can not only improve the safety of the mixed explosive in high-temperature blast holes,but also does not affect the explosive power of the mixed explosive.

Coking of pulverized coal furnace in thermal power stations is a common phenomenon of coal-fired industrial boiler.Since the establishment of Qianbei Power Station in Jinsha,Guizhou,the average annual coking frequency of boilers has reached 52 times per year,which has seriously affected the normal production of the power station.In order to ensure production,blasting decoking is adopted during the overhaul of the 3# boiler in the power station.The boiler coke is mostly attached to the water-cooled wall of the pulverized coal boiler.So,the first job is to analyze the blasting environment,furnace space,the causes of coking and the components of the coke.Based on the analysis,a plan of multiple times of exposed blasting with a small charge of 0.6~1.5 kg is adopted.When the coke body is directly broken by blasting,the blast vibrations also contribute to the coke removal.According to the different positions of the coke body in the furnace,three different packaging modes are used for horizontal support,pre-slide rod and steel rope traction.In terms of safety measures,it is proposed that the time of blasting operation should be controlled within 3 min and emergency measures such as recovery of charge bag,cooling and recharging or waiting for natural explosion in high temperature environment should be taken when accidents occur.Through careful design and construction,the blast has obtained ideal results,which provides practical experience for similar coke removal projects.

It is very crucial to arrange the wreck strip.To accurately cut and disassemble the sunken ship and ensure the success of explosive cutting;through the comparison between the original hull design drawings and the actual hull,the cutting explosive strips are accurately arranged at the weak points of the hull,and the detonator detonator initiation network is adopted.In order to ensure that all explosive strips are detonated,double detonators are used in each group of detonating explosive packages; It shall be wrapped with double-layer waterproof cloth and bound and fixed with hemp rope every 1m to ensure that the medicine strip is not easy to be impacted and scattered by seawater after being lowered.It has proved that through the deep-water test and initiation experiment of the detonator detonator,the detonator detonator used in the sea area with a depth of 30m can detonate safely and resist the stray current on the ship.To ensure the full disassembly of the ship′s bottom plate,the detonating cord is used to increase the initiation energy during the processing of the bottom explosive strip.The explosive amount per meter of the explosive strip in the original similar engineering example is optimized,Through the analysis of salvage after blasting,it is feasible to cut the 2~ 3 cm thick steel plate into joints with a charge of 30.24 kg per meter;It is safe and reliable to detonate with double detonators; Hemp rope binding and double-layer waterproof measures are adopted to effectively prevent seawater impact;it is effective to adopt the staggered strip layout method;the actual theoretical calculation will not produce surge,which is consistent with the measured results; The instant of blasting has little impact on seabed organisms;the explosion cutting of the sunken ship meets the design requirements and provides certain reference for the cutting and disassembly of similar underwater sunken ships.

In order to eliminate the potential hazards of waste explosives and ensure the public safety of the capital,the Beijing public security organs have conducted a centralized destruction of 198 waste shells.The key destruction procedures,including the screening and destruction method of waste explosives,the selection of destruction site,the design of destruction blasting parameters and explosion pit,the stevedoring and transportation of waste shells,are analyzed and assessed.The propagation law of the destruction blasting vibrations is obtained through on-site monitoring and time-frequency analysis by HHT(Hilbert-Huang transform) method.The results show that the equivalent TNT weight of the waste shells is 47.72 kg.An abandoned mine pit has topographical advantages to be selected as the explosion destruction site for waste shells.And the explosion pits are located close to the rock slope in a reasonable layout.By using a delay time of 5 ms,the safe and successful completion of destruction blasting and the limit control of harmful effects are ensured.The seismic waves generated by the destruction blasting have the characteristics of low propagation speed,slow attenuation,and low frequencies.Compared with the underground blasting vibrations,K and α is smaller obviously under the condition of shallow buried blasting.The dominant frequency of the destruction blasting vibrations is mainly distributed in the low frequency band of 4~20 Hz,and the main vibration frequency decreases slightly with the increase of distance.The air shock wave can easily cause sudden changes of the amplitudes and frequencies of the measured vibration waveforms near the explosion area.The design,construction,and vibration monitoring and analysis of the destruction blasting can provide a reference for similar projects.

Ground vibrations induced by blasting in a shallow buried diversion tunnel can easily cause damage to existing buildings above under complex geological conditions.Controlled blasting is a key technical difficulty to reduce the impact on existing buildings under the premise of ensuring engineering efficiency.In this paper,the influence of blasting excavation on ancient buildings and the characteristics of vibration attenuation are studied by using numerical simulation and on-site vibration monitoring,based on the project of water diversion tunnel under the highway(through Shoushan Temple,Shoufeng Temple section).The results show that the vibration velocity decreases with time and distance from blast center due to the action of plastic zone elements.The combined effect of the angle between the incident p-wave and the vertical direction and the distance from the blast source leads to that the vibration velocities in vertical direction are greater than other directioins.The simulation errors of peak vibration velocites of Shoushan Temple and Shoufeng Temple are 3.7% and 2.3%,respectively,which are consistent with the field test data.According to the monitoring data,due to the large damping of rock mass,the signals have a certain selective absorption effect,and the transmission process of the signals in rock mass produces energy loss,and the vibration velocity is constantly attenuated.The simulation results are consistent with the monitoring results.In addition,the linear fitting method is used to obtain the Sadovsky formula for seismic wave attenuation,which indicates that the numerical simulation method is feasible to predict the vibration effect in advance.

In order to explore the difference of vibration characteristics between high-pressure gas cracking and explosive blasting.The equivalent relationship between different gas pressure and explosive was established according to the blasting energy method of compressed gas and water vapor vessel,and the vibration test of high pressure gas blasting and explosive blasting in rock mass was designed and carried out.Based on the test results,the duration and vibration velocity of the 2 types of blast vibration were analyzed,and the wavelet packet transform technique was used to compare the distribution pattern of the energy of the 2 vibration signals in the frequency domain.The results show that the vibration duration of high-pressure gas cracking is much longer than that of explosive blasting,and the duration of both blasting vibrations decreases with the increase of distance.High-pressure gas blasting vibration duration decreases with the increase in burst pressure,but the duration of explosive blasting vibration increases with the large increase in mass.The peak vibration velocity of high-pressure gas cracking is smaller than the explosives blasting,but with the increase of distance,the peak value of 2 kinds of blasting vibration tends to be close,and high-pressure gas cracking vibration velocity than explosive blasting decay slowly.The main frequency bands of the two blast vibration signals shift to lower frequencies as the distance increases,and the proportion of energy in the main frequency band gradually decreases.Compared to explosive blasting,high-pressure gas cracking vibration signals are much lower and narrower in frequency,more concentrated in the frequency domain,and have a higher percentage of energy in the main frequency band.

A chemical storage tank area stores most of the inflammable and explosive toxic and dangerous chemicals.Once leakage occurs,it will cause ignition and explosion accidents,and the consequences will be unimaginable.Based on the dynamic Bayesian network method,an LNG and LPG storage tank area was selected to determine the evolution process of the accident domino effect,the time nodes of the accident process and the influence between different levels.With the help of Bayesian computing software,the domino effect analysis method of dynamic Bayesian network is proposed,and the thermal radiation value is calculated twice.Then,the extended probability of domino accident of each storage tank in four time periods of 0~37.55 min,37.55~47.55 min,47.55~52.55 min and 52.55~57.55 min was obtained by using the equipment damage probability model.Considering emergency measures for individual and multiple tanks,different levels of confidence are set to allocate different degrees of emergency rescue force to make the storage tank reach the safe state.Based on this,the accident probability of each accident storage tank at the critical moment is obtained under the condition of sufficient and limited emergency rescue force after the initial accident.The results imply that under the condition of sufficient emergency rescue force and limited emergency rescue force,priority should be given to taking emergency measures for the storage tank that has the greatest impact on the safety of the chemical industry park,which can greatly reduce the risk of ignition and explosion.

Civil explosive industry is a significant industry to promote the modernization construction and social development.Thus the rapid development of the national infrastructure construction increases the demand for civil explosive goods rapidly.Because of dangerous characteristics,there is the possibility of explosion in the process of their production,transportation,storage and use,which seriously threatens the safety of people′s lives and property and social stability.In order to further understand the dangers of civil explosive goods explosion accidents,targeted civil explosive goods safety management,and effective prevention and control,with 102 cases from 2012—2021 as the statistical object,using the mathematical statistics method of accident year,province,accident level,occurrence and cause,and predict the Grey Markov prediction model in 2022—2023.The results show that the most explosive accidents in 2012,2014,2014 and 2016,the least deaths in 2020 and the largest proportion; Hunan,Hubei and Shaanxi are high provinces in production and use,and mechanical impact and friction in production and transportation are the main causes of explosive explosions in 2022 and 2023 are 6 and 5 respectively,with 18 and 17 deaths respectively.The results are of great significance to strengthen the safety management of civil explosive articles and reduce the occurrence of civil explosive accidents.

In order to strengthen the information supervision on the blasting operation site and plug up the management loopholes,technical means such as setting up a video recorder on the blasting operation site,digitally recording the entire blasting operation area and the whole process of blasting operation,providing law enforcement recorders for safety officers to closely monitor the actual operation of the blasters on site,and establishing electronic archives and image data of each batch of blasting operation projects are adopted.The real situation of the operation site is completely preserved to facilitate traceability of the site management.In the current economic situation,the use of video recorders,law enforcement recorders and other technical means for the information supervision of blasting operation site,on the one hand,reduces the economic burden of blasting operation units,on the other hand,promotes the standardization and skill innovation of blasting operation,which is conducive to the discovery of existing safety hazards,reducing the probability of safety accidents,avoiding the loss of civil explosives,and improves the terminal management and control ability of enterprises.