ExperimentalandNumericalInvestigationofBlast-Induced ...downloads.hindawi.com/journals/sv/2019/5843516.pdf · indicate that for short-delay blasting, the principal fre- quencies are

Research ArticleExperimental and Numerical Investigation of Blast-InducedVibration for Short-Delay Cut Blasting in Underground Mining

Dan Huang Xianyang Qiu Xiuzhi Shi Yonggang Gou and Jian Zhou

School of Resources and Safety Engineering Central South University Changsha 410083 China

Correspondence should be addressed to Xianyang Qiu qiuxianyang_csu163com

Received 16 March 2019 Revised 1 June 2019 Accepted 2 July 2019 Published 1 August 2019

Academic Editor Chao Tao

Copyright copy 2019 Dan Huang et al -is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

It is essential to control the damage to the surrounding rock and engineering structures in the process of cut blasting with a singlefree surface in underground mining To reduce vibration induced by cut blasting this paper proposes short-delay cut blasting inwhich blast holes that are near each other are sequentially initiated with short-delay times Experimental tests of cut blasting wereconducted in a roadway in the Shaxi copper mine to compare the peak particle velocity (PPV) and frequency characteristics ofsimultaneous blasting and short-delay blasting Numerical modelling was then developed to study the influence of short-delaytimes on blast vibration-e accuracy of the numerical simulation was verified by the comparison of the test and simulated data ofsingle-hole blasting-e results show that the amplitude reduction ratio (ARR) value increases gradually with the increase in delayintervals and the vibration reduction for delay intervals smaller than 6ms is very limited particularly in the near field -eprincipal frequencies (PFs) for short-delay blasting are similar to those for simultaneous blasting which implies that the fre-quencies do not increase directly with the decrease of the delay intervals -e experimental tests also show that the meanfrequencies (MFs) for the 8ms delay are slightly higher than those for the 0ms delay blast In the case of ensuring the rockbreaking of cut blasting longer delay intervals of 8sim10ms are beneficial to further reduce PPV in practical blasting

1 Introduction

Hard rock fragmentation by blasting is the most widely usedand cost-effective means in mining and construction op-erations However only a part of the energy released duringblasting is utilized directly for breaking rock within thetarget range while the rest causes damage to the sur-rounding rock structures and environment owing toground vibration noise flying rocks backbreak and airblasts [1 2] Among all the negative effects ground vibrationinduced by blasting which adversely affects the stability ofsurrounding structures and residences is regarded as themost severe of blasting hazards To reduce blast-inducedvibration delay blasting which has been proved to cause lessvibration than simultaneous initiation is adopted in prac-tical blasts [3 4] However the pyrotechnic delay detonatorswidely used in blasting engineering have large delay errorsthus they are often unable to meet the requirements of fineblasting technology [5] -e newly invented and applied

electronic detonators make precise short-delay blastingpossible as the delay error is normally less than 1ms [6 7]

-e previous studies on precise delay blasting withelectronic detonators focused more on the feasibility offragmentation improvement with the improvement of delayprecision [8ndash13] Most scholars have through many fieldexperiments and trials arrived at the consensus that precisedelay blasting using electronic detonators had significantadvantages in improving rock fragmentation On the otherhand few studies have focused on the vibration effect inducedby blasting with short delays Blair [14] noted that there wasno distinct difference in peak vibration between pyrotechnicand electronic delays Xu et al [15] studied the energy dis-tribution of precise delay blasting and found that it couldcontrol the input of low-frequency energy Qiu et al [16]focused on the vibration interference and reduction mech-anisms of short-delay blasting by superimposing a single-holeblasting vibration signal However no consensus has beenreached so far on the influence of precise delay blasting with

HindawiShock and VibrationVolume 2019 Article ID 5843516 13 pageshttpsdoiorg10115520195843516

electronic detonators on blast-induced vibration In additionprevious studies on the vibration effect of precise delayblasting did not consider the influence of free surfaces

-ere is normally only one single free surface for un-derground cut blasting which increases the difficulty of theblasting construction To improve the blasting efficiency of cutblasting there can be a set of blast holes near each other thatare initiated at the same nominal delay time to create enoughcompensating space and new free surfaces for subsequentblasts Reducing the harmful vibration induced by cut blastingwith large charge weight per delay is a critical challenge inunderground mines [17] To solve this problem this paperproposes short-delay cut blasting in underground rock ex-cavation to reduce blast-induced vibration In the short-delaycut blasting the blast holes are sequentially initiated withsmall delay intervals-e delay intervals between cutting blastholes should not be too long otherwise a common blastingcrater cannot be obtained If there is significant potential toreduce vibration in the short-delay cut blasting it would be ofgreat interest to the underground mining industry -us thepurpose of this research is to investigate the possibility ofvibration reduction for short-delay cut blasting

It is well known that peak particle velocity (PPV) fre-quency and duration time are the three parameters used toassess the blast-induced vibration in rockmass [18] PPV hasbeen considered as the most suitable parameter to evaluatethe possible damage caused by blasting for a long time andcomprehensive investigations on PPV have been conductedby many researchers [19 20] In practice some empiricalcriteria mainly based on the PPV in rock mass are used toassess the blast-induced vibration Apart from PPV it is alsonecessary to understand the frequency contents of vibrationsignals In mining engineering the principal frequency (PF)is also used in some criteria and specifications to evaluate theallowable vibration limits [21 22] Wu and Hao [23] andHao et al [24] derived empirical PF attenuation relationsbased on numerical simulation and field-blasting tests ingranite mass In addition to PF the mean frequency (MF)proposed by Yang et al [25] is considered to give moreaccurate characteristic of frequency composition

Many uncontrollable factors such as rock property jointfracture and nature of the terrain have important influenceon blasting performance thus it is expensive to study thecharacteristics of blast-induced vibrations simply by field-blasting tests [25 26] With the rapid advancements incomputer technology numerical methods are used to in-vestigate the characteristics of blasting [27] -is paperstudied the vibration induced by short-delay cut blastingthrough both experimental tests and numerical simulationCut blasting tests carried out in an underground mine areused to compare the vibration of simultaneous blasting andshort-delay blasting Subsequently the related numericalmodelling is performed to systematically study the influenceof short-delay intervals on blast-induced vibration

2 Field Experiment

To compare the vibrations induced by the simultaneousblasting and short-delay blasting and to obtain the

characteristics of vibrations induced by blasting with dif-ferent delay intervals we conducted some experimental testsin Shaxi underground copper mine using four-hole schemeswith a single free surface

21 Experimental Setup -e test mine the Shaxi coppermine which is located in the southeast of Hefei city in Anhuiprovince China is a newly constructed copper mine with adesigned annual ore quantity of 3300 kt-e ore grade is 059copper with a total reserve of 809million tons -e ore bodytype is porphyry copper and the surrounding rock types aremassive rock and stratified rock-e main ore body is dividedby fault F7 into two ore blocks which are called Tongquanshanore block and Fengtaishan ore block As shown in Figure 1 thetests were carried out at the minus 650m level of the Fengtaishanore block -e parameters of the rock mass are as follows thedensity is 2700 kgm3 the Poisson ratio is 03 the elasticmodulus is 5196GPa the compressive strength is 16985MPaand the tensile strength is 716MPa [17]

-e tests were carried out in a roadway with a width of50m and height of 28m First single-hole blasting tests witha single free surface were conducted to investigate thepropagation law of seismic waves -e hole diameter anddepth are 89mm and 08m respectively Next blasting testswith four holes were carried out to study the vibrations in-duced by simultaneous blasting and short-delay blasting -edelay schemes can be seen in Figure 2 A short delay of 8mswas used to compare the vibration of the short-delay blastingagainst that of simultaneous blasting with a delay of 0ms-ediameter and depth of the blast holes were 89mm and 12mrespectively In actual cases of cut blasting in undergroundmines the distance between adjacent holes is 08m A cou-pling charge structure with emulsion explosive is used in thepresent study -e detonation velocity and density for theexplosive are 3200ms and 1000 kgm3 respectively

To monitor the vibration signals three-componentseismic instruments were placed in 6 station points atdistances ranging between 10 and 100m shown in Figure 3In the present study PPV is adopted to assess the blast-induced vibration and possible damage [28ndash30] -e scaleddistance (SD) is defined as

SD R times Qminus 1E

(1)

whereR is the distance between the emitted point and receivedpoint (m) Q is the explosive charge weight (kg) and E is theattenuation coefficient A coefficient of 3 is selected in un-derground mines for E [31 32] -e PPV can be predicted as

PPV K times SDα (2)

where K is a function of the amount of energy transmitted tothe source rock from the explosion and α is an attenuationterm for the source rock Additionally a vector PPV (VPPV)defined by the largest amplitude in the entire summedwaveform is adopted in the present study [20]

VPPV MAXM2 + N2 + P2

radic (3)

where M N and P are the vertical radial and transversecomponents of particle velocity respectively

2 Shock and Vibration

22 Vibrations Induced by Single-Hole Blasting Figure 4shows the velocity time histories of single blast holetests at a distance of 15m As can be noted the radialcomponent has the largest peak values among all the threecomponents Figure 5 plots the PPV for single blast holetests determined by the largest amplitude in the entiresummed waveform and by the largest amplitude of theradial component versus scaled distance -e best fit at-tenuation equations using a least squares regression are asfollows

VPPV 4078R

Q131113888 1113889

minus 149

cms R2

08925

PPV 3455R

Q131113888 1113889

minus 152

cms R2

08768

(4)

-e Fourier transformation is adopted in this study toobtain the frequency information of the test signals [25] To

determine the attenuation of frequency the principal fre-quency (PF) proposed by Wu and Hao [23] is adopted -edefinition of PF is determined by half of the maximumspectral peak on the Fourier spectrum

PF F1 + F2

2 (5)

where F1 and F2 are determined by the intersectionpoints of a horizontal line at Fmax2 of the Fourierspectrum of the velocity time histories in which Fmax isthe peak value of the Fourier spectrum Figure 6 showsthe attenuation of PF for the radial components withscaled distance -e best-fit attenuation equation using aleast squares regression of PF for the radial componentsversus SD is

PF 42559R

Q131113888 1113889

minus 0068

Hz R2

07946 (6)

3 Comparison of Simultaneous and Short-Delay Blasting

Blasting tests with four blast holes for 0ms and 8ms delayedblasts were conducted and the velocity time histories weremeasured to contrastively investigate the characteristics ofpeak particle velocity and frequency

31 Comparisons of PPV Figure 7 shows the velocity timehistories of the blasting test with four blast holes for delaytimes of 0ms and 8ms at a distance of 20m We can seefrom the figure that the radial components produce thelargest peak values among all the three components Fig-ure 8 shows the PPV comparisons for 0ms and 8msdelayed blasts determined by the largest amplitude in theentire summed waveform versus scaled distance -e best-fit attenuation equations using a least squares regressionare

Return air shaft

Tongquanshan

Test location

Downcast shaft Return air shaft

Fengtaishan

ndash410ndash465ndash530

ndash650ndash705ndash770ndash800


ndash650ndash705ndash770ndash800 ndash850

ndash910ndash970

Figure 1 Tested Shaxi copper mine

Simultaneous blasting

d

0ms 0ms

0ms0ms

Short-delay blasting

d

0ms 0ms

0ms0ms

Figure 2 Delay schemes of blasts with four blast holes (a) Si-multaneous blasting (b) Short-delay blasting

Blast holes

50m

28m

Monitoring line

Figure 3 Blasting vibration monitoring in the blasting tests

ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)

RadialTransverseVertical

Figure 4 Velocities of single-hole blasting

Shock and Vibration 3

001

01

1

10

1 10 100Scaled distance (mkg13)

Vect

or p

eak

part

icle

vel

ocity

(cm

s)

(a)

001

01

1

10


Peak

par

ticle

vel

ocity

(cm

s)

(b)

Figure 5 PPV for single-hole blasting versus scaled distance -e largest amplitude of (a) vector summation and (b) the radial component

100

1000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)

Scaled distance (mkg13)

Figure 6 PF for single-hole blasting versus scaled distance

ndash20

ndash10

00

10

20

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)


(a)


ndash10

ndash05

00

05

10

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)

(b)

Figure 7 Velocities of simultaneous blasting and short-delay blasting (a) Simultaneous blasting (b) 8ms delayed blasting


0ms VPPV 10654R

Q131113888 1113889

minus 140

cms R2

09056

8ms VPPV 6249R

Q131113888 1113889

minus 153

cms R2

08715

(7)

As seen from Figure 8 simultaneous blasting producedlarger PPV as a function of SD compared to the 8ms delayedblast -is is mainly because the charge weight per delay forthe 8ms delay is much smaller than for simultaneousblasting and the total energy for the 8ms delay is releaseddiscretely while in the 0ms case energy is released nearlysimultaneously It is widely accepted that delay blasting caneffectively reduce vibration amplitude However in practicalblasting long-delay intervals (normally longer than 25ms)are applied for vibration reduction It is doubtful whetherdelay blasting with short-delay intervals could reduce PPVand if so to what extent short-delay blasting could reducePPV -e test in this study shows that it is efficient to reducethe PPV for the delay of 8ms

32 Comparisons of Vibration Frequencies It is un-derstandable that delay blasting can reduce vibration am-plitude compared with simultaneous blasting However amajor concern regarding short-delay blasting is that thefrequencies will decrease as the time delays change from0ms (simultaneous blasting) to small delay intervals (short-delay blasting) and thus cause damage on constructions andstructures as the resonant frequencies for the structures arein the range of 4Hz to 28Hz [33] -erefore it is essential tocompare the frequencies between simultaneous blasting andshort-delay blasting A popular conception referring to vi-brations induced by delay blasting is that the frequenciesbecome higher with the decrease in the delay intervals It ishence proposed by some researchers that smaller delayintervals can be used to reduce vibrations as the higherfrequencies attenuate more readily in the ground [14]However when the delay interval between blast holes de-creases to the ultimate range a zero delay is obtained whichcould produce infinite frequencies according to the abovepopular conception -is clearly does not correspond to therealities of practical blasting thus the dependability of thepopular conception is uncertain Figure 9 shows the PFcomparisons for 0ms and 8ms delayed blasts versus scaleddistance -e best-fit attenuation equations using a leastsquares regression are

0ms PF 54693R

Q131113888 1113889

minus 086

Hz R2

08669

8ms PF 59641R

Q131113888 1113889

minus 228

Hz R2

08583

(8)

It can be seen that the 0ms and 8ms delayed blastsproduce similar principal frequencies which is inconsistentwith the popular conception -is is because the spectral

banding for small delay intervals is not as obvious as that forlarge delay intervals for which the dominant frequencies aremostly determined according to the delay intervals betweenblast holes As noted by Blair [34] it is impossible to controlthe frequencies according to the delay intervals for delaysintervals smaller than 10ms -e results shown in Figure 9indicate that for short-delay blasting the principal fre-quencies are more likely to be determined by the siteconditions rather than the delay intervals between blastholes It is interesting to note from Figure 9 that the α valuefor the 8ms delay is smaller than the 0ms delay whichindicates more readily attenuated principal frequencies

-e PF mostly gives the frequency characteristic in acertain range and couldmiss the frequency components withsmall amplitude -us besides the PF the mean frequency(MF) is also applied to obtain the comprehensive charac-teristics of the frequency composition -e MF of the am-plitude-frequency spectrum is defined as [25]

01

1

10

100

1 10 100

Vect

or p

eak

part

icle

vel

ocity

(cm

s)


Simultaneous8ms delay

Figure 8 PPV between simultaneous blasting and short-delayblasting

100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)



Figure 9 PFs between simultaneous and 8ms delay blasting


MF 1113936

mn1Fnfn

1113936mn1Fn

(9)

where Fn is the amplitude corresponding to the frequency fn

in the amplitude-frequency spectrumFigure 10 presents the MF comparisons for the 0ms and

8ms delayed blasting versus scaled distance As shown themean frequencies for the 8ms delay are slightly higher thanthose of the 0ms delay blast As seen in Figure 9 the twodelays have similar principal frequencies the higher meanfrequencies for the 8ms delay indicate that there is moreenergy in the high-frequency content compared with the0ms delay case -e possible reason for this phenomenon isthat for the 8ms delay blast when a later blast hole deto-nates initial cracks are formed around the former detonatedblast hole Hence when the compressive stress waves causedby the later detonated blast hole reach the cracks they arepartly reflected as backpropagating rarefaction waves -ereflected rarefaction waves are superimposed onto the initialcompressive stress waves and lead to lower loading pressurewith a smaller peak shorter rising time and shorter duration[25] In addition with the reduction of loading duration thespectrum of the loading moves into the region of higherfrequencies As the initial cracks are very local around theblast hole when the later blast hole detonates only a fractionof the compressive stress wave is reflected -erefore theprincipal frequency remains unchanged but the increase inthe high-frequency content makes the mean frequency of an8ms delay larger than that of a 0ms In addition it can alsobe observed from Figure 10 that the α value for the 0msdelay is larger than that for the 8ms delay-is is because thehigh-frequency content attenuates faster than low frequencyin rock mass

4 Numerical Simulation

-e experimental study described above preliminarilycompares the characteristics of blast-induced vibrations ofsimultaneous blasting and short-delay blasting Limited byexperimental conditions the systemic influence of short-delay times on blast-induced vibration is not revealed above-is is studied in this section by numerically modelling theblasting test using the LS-DYNA program whose accuracyin simulating delay blasting in a rock mass has been provenin previous studies [13 25]

41 Numerical Model According to the blasting conditionsshown in Figure 2 a three-dimensional numerical modelmeasuring 140times 80times 80m (lengthtimeswidthtimes height) is de-veloped to simulate the vibrations induced by simultaneousblasting and short-delay blasting as illustrated in Figure 11In the model the dimension and layout of the blast holes arein accordance with the experimental tests Hexahedron-shaped brick elements with eight nodes and different ele-ment sizes are used in the numerical model Suggested byKuhlemeyer and Lysmer [35] the mesh size should beshorter than 18ndash110 of the wavelength in general to reduce

any wave distortion Convergence tests are conducted todetermine the sizes of elements until the difference of themodelling results between two consecutive element sizes isless than 5 Based on the convergence test results theelement size ranges from 02m near the charge to 20m atthe border and the model has a total of 902820 elementswith 944974 nodes In accordance with the experimentalsituation nonreflecting boundaries are applied to the sixoutside surfaces of the model and free boundaries areenforced on the internal surfaces of the model In the nu-merical model the high explosive and the stemming aresolved using the Eulerianmethod and the rockmass is solvedusing the Lagrangian method

Rock masses in the immediate vicinity of the charge willundergo high pressure and large strain instantaneously In thepresent study the MAT_BRITTLE_DAMAGE (MAT_96)material model is adopted to simulate the response of rockmass It is an anisotropic brittle damage model designed for awide variety of brittle materials allowing progressive deg-radation of tensile and shear strengths across smeared cracksthat are initiated under tensile loadings -e details of thebrittle damage model can be seen in [36] -e materialproperties of rock in the test roadway are used in this sim-ulation Values for the fracture toughness shear retentionand viscosity for the rock mass are not available from theexperimental data -erefore parametric tests are carried outto adjust the appropriate values by comparing the simulatedvibration with the measured vibration waves

In the LS-DYNA software the explosives are modelledby the JohnndashWilkinsndashLee (JWL) equation which is the mostcommonly used equation for modelling high explosives dueto its simple form experimental basis and easy calculationsof hydromechanics [37] -e JWL equation is given asfollows

P A 1 minusω

R1V1113888 1113889e

minus R1V+ B 1 minus

ωR2V

1113888 1113889eminus R2V

+ωE

V (10)

100

1000

10000

1 10 100

Mea

n fre

quen

cy (H

z)



Figure 10 MFs between simultaneous blasting and short-delayblasting


where P is the detonation pressure A B R1 R2 and ω areconstants V is the specific volume and E is the specificinternal energy -e emulsion explosive used in the expo-nential tests is characterized by a density of 1000 kgm3detonation velocity of 3200ms and explosive CJ pressure of324GPa According to Qiu et al [38] the parameters as-sociated with the JWL equation are given as followsA 220GPa B 02GPa R1 45 R2 11 ω 035 andE0 42GPa

Material Type 5 of the LS-DYNA (lowastMAT_SOIL_AND_FOAM) is used for the stemming -e parameters ofstemming in the simulation are listed in Table 1 [39] In thetable ρ is the density v is Poissonrsquos ratio ET is the shearmodulus c is the cohesive force μ is the friction coefficientand φ is the internal friction angle

42 Demonstration of Numerical Modelling Numericalsimulation of blast-induced vibration for a single-hole caseis firstly carried out to verify the accuracy of the model -ecomparisons of the tested radial velocity time history andsimulated waveform in the X direction for the single-holeblasting at a distance of 15m are plotted in Figure 12 It canbe seen that the simulated waves including peak velocitiesand frequencies agree well with the measured results -epeak velocity of the numerical result is slightly larger thanthat of the tested waves -is might be attributed to the factthat the numerical model assumes a continuous and ho-mogeneous medium while in reality there could be manyfractures and joints in the site Figure 13 shows thecomparison of the attenuation of PPV for tested radialvelocity time history and the simulated waves in the Xdirection versus scaled distance from the charge centreConsidering the randomness of the test site it can beconcluded that the numerical model adopted in the presentstudy is feasible in simulating blast-induced vibration inrock mass

43 Influence of Short Delays on Vibration Using the abovenumerical model with LS-DYNA numerical simulations ofthe influence of short-delay intervals on blast-induced vi-bration are carried out To form a common blasting craterthe delay intervals between blast holes in cut blasting shouldbe less than the formation time of a new free surface [17]Practical blasting and experimental tests show that theformation time of a new free surface is approximately 20 to30ms [40 41] In this study a total delay of 30ms is selectedand the delay intervals of 0ms 2ms 4ms 6ms 8ms and10ms between blast holes are considered in this simulation

Along the monitoring line shown in Figure 3 16 targetpoints spaced at every 5m are specified to record the

Z

XY

Figure 11 Numerical model used for modelling of blast-induced vibration

Table 1 Parameters of stemming

ρ (kgm3) v ET (GPa) c (MPa) μ φ (deg)2700 019 16 0018 07 35

ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)

Test resultsNumerical results

Figure 12 Comparisons of the velocities for test and numericalresults


simulated velocity time histories at which the PPV arederived Figure 14 shows the simulated velocity time his-tories corresponding to delay intervals of 0ms and 8ms atthe same distance of 20m from the charger centre As seenthe velocity time histories in the X direction have the largestpeak values among all the three components which is inaccordance with the measured waves in the test In additionit is found that the 0ms case has larger peak values than the8ms case in all the three directions which demonstrates thefeasibility of vibration reduction of short-delay blastingcompared with simultaneous blasting

Figure 15 shows the simulated PPV at recording pointsalong the monitoring line for different delay intervals It canbe seen that the PPVs attenuate very quickly with the in-crease in the distance from the charger centre irrespective ofthe delay intervals As shown we can clearly see that the 0mscase has the largest PPV values at all the recording points inthe three components -is indicates that simultaneousblasting is the most unfavourable condition for vibrationcontrol in practical blasting which we need to make everyeffort to avoid It is interesting to note that delay blastingwith any delay interval is feasible for vibration reduction asthe PPV values of the 2ms delay case are smaller than thoseof the 0ms case

To further assess the influence of short-delay intervals onthe reduction of PPV the amplitude reduction ratio (ARR)proposed by Chen et al [42] is adopted in the present studyARR is defined as follows

ARR P0 minus P

P0times 100 (11)

where P0 is the PPV value of simultaneous blasting at aspecific distance from the charge centre and P is the PPVvalue of delay blasting at the same distance It is obvious thata better vibration reduction result is obtained for a largerARR

Figure 16 shows the calculated ARR of simulated wavesversus delay intervals at different distances It can be seenthat the ARR value increases gradually with the increase in

delay interval in the time range of 0sim8ms It is widely ac-cepted that the wave superposition of blast-induced vibra-tion occurs in the peak range of velocities Delayed blastingchanges the energy releasing form as the total energy of thecharge is released in a time range rather than in an in-stantaneous time -erefore with the increase in delay in-terval the superposition of vibration waveforms induced bysuccessively detonated blast holes is reduced and thus thePPV is reduced It is noted that the ARR fluctuates for thecases of 8ms and 10ms -is might be attributed to the factthat the optimum delay interval is mainly influenced by theprincipal vibration period of vibration waveform induced bysingle-hole blasting [15] It is also observed from Figure 16that the ARR values at different distances are apparentlydifferent -e ARR values at shorter distances are smallerthan at farther distances for the same delay intervals Takingthe X direction for an example as shown in Figure 16(a) theARR values at a distance of 5m are all smaller than that of10m for the same delay intervals and the values of 10m are

001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)



Figure 13 Attenuation of PPV between test and numerical results

ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)

X directionY directionZ direction

(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)

Figure 14 Velocities of (a) 0ms and (b) 8ms cases


0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)

Simultaneous 2ms delay4ms delay 6ms delay8ms delay 10ms delay

0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)

Simultaneous2ms delay4ms delay

6ms delay8ms delay10ms delay

(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)

Figure 15 Simulated PPV at recording points along the monitoring line for different delay intervals (a) X direction (b) Y direction (c) Z direction


smaller than other longer distances As shown inFigure 16(c) the ARR values for the cases of 2ms 4ms and6ms at a distance of 5m are all less than 20 while at adistance of 80m the ARR value is 6635 for the case of8ms-is indicates that at long distances delay blasting withshort-delay intervals leads to great vibration reduction butin the near field the vibration reduction effect is not obviousTo obtain similar reduction effect relatively longer delayintervals are needed in the far field -is is because the blast-induced seismic action is realized by the response de-formation of rock mass far away from the elastic de-formation zone [43] -e propagation velocity of blast-induced seismic is far less than the velocity of elastic de-formation wave in rock mass thus the energy release of theground vibration will not change significantly for the dif-ferent delay intervals -erefore in order to obtain con-siderable vibration reduction in the whole distance range

relatively long-delay intervals are preferentially selected incut blasting in the case of ensuring the formation of acommon blasting crater

-e simulated waves are calculated by the Fouriertransform and based on equation (5) the principal fre-quencies are obtained Figure 17 shows the principal fre-quencies of simulated waves versus delay intervals atdifferent distances in the Z direction It can be seen that asthe distance increases the principal frequency decreases fora specific delay interval -is illustrates the attenuationcharacteristic of blast-induced vibration frequency which isin accordance with the tested vibration waveform in Section3 It can also be seen from Figure 17 that the PFs for differentdelays are similar which are consistent with the test results-e differences of principal frequencies between differentdelays are very small It is also observed that there is noincreasing trend for the principal frequencies as the delay

0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)

Figure 16 ARR of simultaneous blasting and delayed blasting (a) X direction (b) Y direction (c) Z direction


intervals decrease Again the numerical results show that thepopular conception that the frequencies become higher withthe decrease in the delay intervals is not suitable for blastingwith delay times smaller than 10ms However it is im-possible to use the three-dimensional model to simulate thereflection of the compressive stress waves induced by thelater detonated blast hole on the initial cracks caused by theformer detonated blast hole under current computer re-sources and therefore the MFs of different delay intervalsare not compared here

-e test and numerical results show that the PFs forshort-delay blasting are similar with simultaneous blastingIt indicates that a change in delay time from 0ms to smalldelay intervals would not increase the possibility of struc-tural resonance In addition the above test and simulationalso show that short-delay blasting could effectively reducePPV compared with simultaneous blasting-erefore it is ofgreat value to reduce PPV with similar principal frequenciesvia short-delay cut blasting

5 Conclusions

-is paper proposes short-delay cut blasting to reduce blast-induced vibration in underground mining Single-holeblasting tests with a single free surface were firstly carried outin a roadway in the Shaxi copper mine to obtain the site-specific attenuation relations of PPV and PF of vibrationwaves Cutting blasts with four blast holes for delay intervalsof 0ms and 8ms between blast holes were then conducted tocompare the characteristics of PPV and frequencies Anumerical model was developed to investigate the blast-induced vibration of short-delay blasting with a single freesurface -e measured data of single-hole blasting were usedto verify the accuracy of the numerical simulations and avery good agreement between the measured and numericallysimulated data was obtained-e numerical model with four

blast holes was used to systematically investigate the in-fluence of short-delay intervals on PPVs and PFs of vibrationwaves

-e experimental tests and numerical results show thatthe ARR value increases gradually with the increase of delayintervals -e vibration reduction for delay intervals smallerthan 6ms is very limited particularly in the near field -eprincipal frequencies for short-delay blasting are similar tothose for simultaneous blasting which implies that thefrequencies do not increase directly with the decrease of thedelay intervals -e experimental tests also show that themean frequencies for the 8ms delay are slightly higher thanthose for the 0ms case which may be caused by the re-flection of the compressive stress waves caused by a laterdetonated blast hole on the initial cracks caused by a formerdetonated blast hole

-e experimental tests and numerical simulation in thepresent study show that it is of great value to reduce PPVwith similar frequencies via short-delay cut blasting Inpractical blasting longer delay intervals such as 8sim10ms arepreferentially selected for further reducing PPV in the caseof ensuring the rock breaking of cut blasting

-e influence of the reflection effect (the reflection of thecompressive stress waves caused by a later detonated blasthole on the initial cracks caused by a former detonated blasthole) on the frequency characteristics of short-delay blastingcannot be ignored However owing to limited currentcomputing resources it is impossible to quantify the in-fluence of the reflection effect -e precise frequencycharacteristics of short-delay blasting may be determined inthe future with the help of supercomputers

Data Availability

-e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

-e authors declare that they have no conflicts of interest

Acknowledgments

-is work was supported by the National Natural ScienceFoundation Project of China (51874350) and the NationalKey RampD Program of China (2017YFC0602902) -e sup-port provided by the China Scholarship Council (CSC)during the visit of Xianyang Qiu to Curtin University isacknowledged-e authors also thank Hong Hao Yifei Haoand Jian Cui for their excellent advice

References

[1] M P Roy P K Singh M Sarim and L S Shekhawat ldquoBlastdesign and vibration control at an underground metal minefor the safety of surface structuresrdquo International Journal ofRock Mechanics and Mining Sciences vol 83 pp 107ndash1152016

[2] X Li S Wang R Malekian S Hao and Z Li ldquoNumericalsimulation of rock breakage modes under confining pressures

100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

Figure 17 PFs versus scaled distances between delay intervals


in deep mining an experimental investigationrdquo IEEE Accessvol 4 pp 5710ndash5720 2017

[3] U Ozer ldquoEnvironmental impacts of ground vibration in-duced by blasting at different rock units on the Kadikoy-Kartal metro tunnelrdquo Engineering Geology vol 100 no 1-2pp 82ndash90 2008

[4] M Vladimir and S Lazar ldquoDetermination of seismic safetyzones during the surface mining operation development inthe case of the ldquoBuvacrdquo open pitrdquoMinerals vol 8 no 2 p 712018

[5] X Z Shi X Y Qiu J Zhou Y Wang J Nie and B H LildquoTechnology and case study of ultra-large section and highshaft excavation by short-millisecond spherical-like blastingrdquoChinese Journal of Rock Mechanics and Engineering vol 35no 8 pp 1659ndash1667 2016 in Chinese

[6] X-z Shi X-y Qiu J Zhou X Chen Y-q Fan and E-w LuldquoApplication of Hilbert-Huang transform based delay timeidentification in optimization of short millisecond blastingrdquoTransactions of Nonferrous Metals Society of China vol 26no 7 pp 1965ndash1974 2016

[7] Y Changping S Jonny and J Daniel ldquoNumerical modelingfor blast-induced fragmentation in sublevel caving minesrdquoTunnelling and Underground Space Technology vol 68no 2017 pp 167ndash173 2017

[8] X P Li J H Huang Y Luo and P P Chen ldquoA study ofsmooth wall blasting fracture mechanisms using the timingsequence control methodrdquo International Journal of RockMechanics and Mining Sciences vol 92 pp 1ndash8 2017

[9] H P Rossmanith ldquo-e use of Lagrange diagrams in preciseinitiation blasting Part I two interacting blastholesrdquo Frag-blast vol 6 no 1 pp 104ndash136 2002

[10] H P Rossmanith andN Kouzniak ldquoSupersonic detonation inrockmass Part 2 particle displacements and velocity fields forsingle andmultiple non-delayed and delayed detonating blast-holesrdquo Fragblast vol 6 no 2 pp 95ndash117 2006

[11] F Vanbrabant and A Espinosa ldquoImpact of short delays se-quence on fragmentation by means of electronic detonatorstheoretical concepts and field validationrdquo in Proceedings of the8th International Symposium on Rock Fragmentation byBlasting Fragblast 8 pp 326ndash331 Santiago Chile May 2006

[12] D Johansson and F Ouchterlony ldquoShock wave interactions inrock blasting the use of short delays to improve fragmen-tation in model-scalerdquo Rock Mechanics and Rock Engineeringvol 46 no 1 pp 1ndash18 2013

[13] C Yi D Johansson U Nyberg and A Beyglou ldquoStress waveinteraction between two adjacent blast holesrdquo RockMechanicsand Rock Engineering vol 49 no 5 pp 1803ndash1812 2016

[14] D P Blair ldquoLimitations of electronic delays for the control ofblast vibration and fragmentationrdquo in Proceedings of the 9thInternational Symposium on Rock Fragmentation by Blastingpp 171ndash184 Granada Spain August 2010

[15] Z Y Xu and J Yang ldquoEnergy distribution of seismic wavesfrom blasting with precise delay timing in complex envi-ronmentsrdquo Explosion and Shock Waves vol S1 pp 116ndash1212013 in Chinese

[16] X Y Qiu X Z Shi J Zhou D Huang and X Chen ldquoStudyon vibration reduction effect of short millisecond blasting byhigh-precision detonator based on HHT energy spectrumrdquoExplosion and Shock Waves vol 37 no 1 pp 107ndash113 2017in Chinese

[17] X Qiu X Shi Y Gou J Zhou H Chen and X Huo ldquoShort-delay blasting with single free surface results of experimentaltestsrdquo Tunnelling and Underground Space Technology vol 74no 2 pp 119ndash130 2018

[18] G G U Aldas ldquoExplosive charge mass and peak particlevelocity (PPV)-frequency relation in mining blastrdquo Journal ofGeophysics and Engineering vol 7 no 3 pp 223ndash231 2010

[19] J R Zhou W B Lu P Yan M Chen and G H WangldquoFrequency-dependent attenuation of blasting vibrationwavesrdquo Rock Mechanics amp Rock Engineering vol 49 pp 1ndash122016

[20] M Leidig J L Bonner T Rath and D Murray ldquoQuantifi-cation of ground vibration differences from well-confinedsingle-hole explosions with variable velocity of detonationrdquoInternational Journal of Rock Mechanics and Mining Sciencesvol 47 no 1 pp 42ndash49 2010

[21] D E Siskind M S Stagg J W Kopp and C H DowdingldquoStructure response and damage produced by ground vi-bration from surface blastingrdquo Report of Investigations 8507US Bureau of Mines Washington DC USA 1980

[22] German Standards Organization (GSO)DIN 4150 Vibrationsin Building Construction German Standards Organization(GSO) Berlin Germany 1984

[23] C Wu and H Hao ldquoNumerical study of characteristics ofunderground blast induced surface ground motion and theireffect on above-ground structures Part I Ground motioncharacteristicsrdquo Soil Dynamics and Earthquake Engineeringvol 25 no 1 pp 27ndash38 2005

[24] H Hao Y Wu G Ma and Y Zhou ldquoCharacteristics ofsurface ground motions induced by blasts in jointed rockmassrdquo Soil Dynamics and Earthquake Engineering vol 21no 2 pp 85ndash98 2001

[25] J H Yang W B Lu Q H Jiang C Yao and C B ZhouldquoFrequency comparison of blast-induced vibration per delayfor the full-face millisecond delay blasting in undergroundopening excavationrdquo Tunnelling and Underground SpaceTechnology vol 51 pp 189ndash201 2016

[26] K Liu H Hao and X Li ldquoNumerical analysis of the stabilityof abandoned cavities in bench blastingrdquo InternationalJournal of Rock Mechanics and Mining Sciences vol 92pp 30ndash39 2017

[27] J Cui H Hao and Y Shi ldquoDiscussion on the suitability ofconcrete constitutive models for high-rate response pre-dictions of RC structuresrdquo International Journal of ImpactEngineering vol 106 pp 202ndash216 2017

[28] X Z Shi and S R Chen ldquoDelay time optimization in blastingoperations for mitigating the vibration-effects on final pitwallsrsquo stabilityrdquo Soil Dynamics and Earthquake Engineeringvol 31 no 8 pp 1154ndash1158 2011

[29] M Khandelwal and T N Singh ldquoEvaluation of blast-inducedground vibration predictorsrdquo Soil Dynamics and EarthquakeEngineering vol 27 no 2 pp 116ndash125 2007

[30] C H Dowding Blast Vibration Monitoring and ControlPrentice-Hall Englewood Cliffs NJ USA 1985

[31] I A Elseman ldquoMeasurement and analysis of the effect ofground vibrations induced by blasting at the limestonequarries of the Egyptian cement companyrdquo in Proceedings ofthe International Conference for Environmental HazardsMitigation pp 54ndash71 Egypt September 2000

[32] C Kuzu ldquo-e importance of site-specific characters in pre-diction models for blast-induced ground vibrationsrdquo SoilDynamics and Earthquake Engineering vol 28 no 5pp 405ndash414 2008

[33] D E Siskind M S Stagg J W Kopp and C H DowdingldquoStructure response and damage produced by ground vi-bration from surface mine blastingrdquo USBM Reports of In-vestigation 8507 1980


[34] D P Blair ldquoBlast vibration control in the presence of delayscatter and random fluctuations between blastholesrdquo In-ternational Journal for Numerical and Analytical Methods inGeomechanics vol 17 no 2 pp 95ndash118 1993

[35] R L Kuhlemeyer and J Lysmer ldquoFinite element methodaccuracy for wave propagation problemsrdquo Journal of the SoilMechanics and Foundations Division vol 99 no 5 pp 421ndash427 1973

[36] S Govindjee G J Kay and J C Simo ldquoAnisotropic mod-elling and numerical simulation of brittle damage in con-creterdquo International Journal for Numerical Methods inEngineering vol 38 no 21 pp 3611ndash3633 1995

[37] LSTC LS-DYNA Keyword Userrsquos Manual Version 971 Liv-ermore Software Technology Corporation Livermore CAUSA 2007

[38] X Y Qiu Y F Hao X Z Shi H Hao S Zhang andY G Gou ldquoNumerical simulation of stress wave interaction inshort-delay blasting with a single free surfacerdquo PLoS Onevol 13 no 9 Article ID e0204166 2018

[39] Y Wang X Z Shi Y G Gou and T Guo ldquoBlast holestemming length effects of rock blasting with parallel doublefree surfacerdquo Journal of Vibration and Shock vol 35 no 15pp 80ndash85 2016 in Chinese

[40] L He D W Zhong and J F Si ldquoExperimental study onreasonable delay time of millisecond delay blasting nearsloperdquo Engineering Blasting vol 22 no 1 pp 8ndash13 2016 inChinese

[41] A H Xahykaeb Physical Process of Blasting in Rock Trans-lated by Liu Dianzhong Metallurgical Industry Press BeijingChina 1980

[42] S H Chen Y F Yan G F Qi X K Zhang and W ZhangldquoAnalysis of influence factors of interference vibration re-duction of millisecond blastingrdquo Rock and Soil Mechanicsvol 32 no 10 pp 3003ndash3008 2011 in Chinese

[43] D C Lin Q Zhang and C H Bai ldquoAn experimental study onground vibration from millisecond blasting with two sourcesnear to the ground surfacerdquo Engineering Blasting vol 6 no 4pp 1ndash5 2000 in Chinese


International Journal of

AerospaceEngineeringHindawiwwwhindawicom Volume 2018

RoboticsJournal of

Hindawiwwwhindawicom Volume 2018


Active and Passive Electronic Components

VLSI Design



Shock and Vibration


Civil EngineeringAdvances in

Acoustics and VibrationAdvances in



Electrical and Computer Engineering

Journal of

Advances inOptoElectronics

Hindawiwwwhindawicom

Volume 2018

Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Control Scienceand Engineering

Journal of



Journal ofEngineeringVolume 2018

SensorsJournal of



RotatingMachinery


Modelling ampSimulationin EngineeringHindawiwwwhindawicom Volume 2018


Chemical EngineeringInternational Journal of Antennas and

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Navigation and Observation


Hindawi

wwwhindawicom Volume 2018

Advances in

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Submit your manuscripts atwwwhindawicom

electronic detonators on blast-induced vibration In additionprevious studies on the vibration effect of precise delayblasting did not consider the influence of free surfaces

-ere is normally only one single free surface for un-derground cut blasting which increases the difficulty of theblasting construction To improve the blasting efficiency of cutblasting there can be a set of blast holes near each other thatare initiated at the same nominal delay time to create enoughcompensating space and new free surfaces for subsequentblasts Reducing the harmful vibration induced by cut blastingwith large charge weight per delay is a critical challenge inunderground mines [17] To solve this problem this paperproposes short-delay cut blasting in underground rock ex-cavation to reduce blast-induced vibration In the short-delaycut blasting the blast holes are sequentially initiated withsmall delay intervals-e delay intervals between cutting blastholes should not be too long otherwise a common blastingcrater cannot be obtained If there is significant potential toreduce vibration in the short-delay cut blasting it would be ofgreat interest to the underground mining industry -us thepurpose of this research is to investigate the possibility ofvibration reduction for short-delay cut blasting

It is well known that peak particle velocity (PPV) fre-quency and duration time are the three parameters used toassess the blast-induced vibration in rockmass [18] PPV hasbeen considered as the most suitable parameter to evaluatethe possible damage caused by blasting for a long time andcomprehensive investigations on PPV have been conductedby many researchers [19 20] In practice some empiricalcriteria mainly based on the PPV in rock mass are used toassess the blast-induced vibration Apart from PPV it is alsonecessary to understand the frequency contents of vibrationsignals In mining engineering the principal frequency (PF)is also used in some criteria and specifications to evaluate theallowable vibration limits [21 22] Wu and Hao [23] andHao et al [24] derived empirical PF attenuation relationsbased on numerical simulation and field-blasting tests ingranite mass In addition to PF the mean frequency (MF)proposed by Yang et al [25] is considered to give moreaccurate characteristic of frequency composition

Many uncontrollable factors such as rock property jointfracture and nature of the terrain have important influenceon blasting performance thus it is expensive to study thecharacteristics of blast-induced vibrations simply by field-blasting tests [25 26] With the rapid advancements incomputer technology numerical methods are used to in-vestigate the characteristics of blasting [27] -is paperstudied the vibration induced by short-delay cut blastingthrough both experimental tests and numerical simulationCut blasting tests carried out in an underground mine areused to compare the vibration of simultaneous blasting andshort-delay blasting Subsequently the related numericalmodelling is performed to systematically study the influenceof short-delay intervals on blast-induced vibration

2 Field Experiment

To compare the vibrations induced by the simultaneousblasting and short-delay blasting and to obtain the

characteristics of vibrations induced by blasting with dif-ferent delay intervals we conducted some experimental testsin Shaxi underground copper mine using four-hole schemeswith a single free surface

21 Experimental Setup -e test mine the Shaxi coppermine which is located in the southeast of Hefei city in Anhuiprovince China is a newly constructed copper mine with adesigned annual ore quantity of 3300 kt-e ore grade is 059copper with a total reserve of 809million tons -e ore bodytype is porphyry copper and the surrounding rock types aremassive rock and stratified rock-e main ore body is dividedby fault F7 into two ore blocks which are called Tongquanshanore block and Fengtaishan ore block As shown in Figure 1 thetests were carried out at the minus 650m level of the Fengtaishanore block -e parameters of the rock mass are as follows thedensity is 2700 kgm3 the Poisson ratio is 03 the elasticmodulus is 5196GPa the compressive strength is 16985MPaand the tensile strength is 716MPa [17]

-e tests were carried out in a roadway with a width of50m and height of 28m First single-hole blasting tests witha single free surface were conducted to investigate thepropagation law of seismic waves -e hole diameter anddepth are 89mm and 08m respectively Next blasting testswith four holes were carried out to study the vibrations in-duced by simultaneous blasting and short-delay blasting -edelay schemes can be seen in Figure 2 A short delay of 8mswas used to compare the vibration of the short-delay blastingagainst that of simultaneous blasting with a delay of 0ms-ediameter and depth of the blast holes were 89mm and 12mrespectively In actual cases of cut blasting in undergroundmines the distance between adjacent holes is 08m A cou-pling charge structure with emulsion explosive is used in thepresent study -e detonation velocity and density for theexplosive are 3200ms and 1000 kgm3 respectively

To monitor the vibration signals three-componentseismic instruments were placed in 6 station points atdistances ranging between 10 and 100m shown in Figure 3In the present study PPV is adopted to assess the blast-induced vibration and possible damage [28ndash30] -e scaleddistance (SD) is defined as

SD R times Qminus 1E

(1)

whereR is the distance between the emitted point and receivedpoint (m) Q is the explosive charge weight (kg) and E is theattenuation coefficient A coefficient of 3 is selected in un-derground mines for E [31 32] -e PPV can be predicted as

PPV K times SDα (2)

where K is a function of the amount of energy transmitted tothe source rock from the explosion and α is an attenuationterm for the source rock Additionally a vector PPV (VPPV)defined by the largest amplitude in the entire summedwaveform is adopted in the present study [20]

VPPV MAXM2 + N2 + P2

radic (3)

where M N and P are the vertical radial and transversecomponents of particle velocity respectively



VPPV 4078R

Q131113888 1113889

minus 149

cms R2

08925

PPV 3455R

Q131113888 1113889

minus 152

cms R2

08768

(4)



PF F1 + F2

2 (5)


PF 42559R

Q131113888 1113889

minus 0068

Hz R2

07946 (6)




Return air shaft

Tongquanshan

Test location


Fengtaishan





ndash910ndash970



d

0ms 0ms

0ms0ms


d

0ms 0ms

0ms0ms


Blast holes

50m

28m

Monitoring line


ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)




001

01

1

10


Vect

or p

eak

part

icle

vel

ocity

(cm

s)

(a)

001

01

1

10


Peak

par

ticle

vel

ocity

(cm

s)

(b)


100

1000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)



ndash20

ndash10

00

10

20

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)


(a)


ndash10

ndash05

00

05

10

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)

(b)



0ms VPPV 10654R

Q131113888 1113889

minus 140

cms R2

09056

8ms VPPV 6249R

Q131113888 1113889

minus 153

cms R2

08715

(7)



0ms PF 54693R

Q131113888 1113889

minus 086

Hz R2

08669

8ms PF 59641R

Q131113888 1113889

minus 228

Hz R2

08583

(8)




01

1

10

100

1 10 100

Vect

or p

eak

part

icle

vel

ocity

(cm

s)




100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)





MF 1113936

mn1Fnfn

1113936mn1Fn

(9)










P A 1 minusω

R1V1113888 1113889e


ωR2V

1113888 1113889eminus R2V

+ωE

V (10)

100

1000

10000

1 10 100

Mea

n fre

quen

cy (H

z)










Z

XY




ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)







ARR P0 minus P

P0times 100 (11)




001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)




ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)


(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)



0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia



VPPV 4078R

Q131113888 1113889

minus 149

cms R2

08925

PPV 3455R

Q131113888 1113889

minus 152

cms R2

08768

(4)



PF F1 + F2

2 (5)


PF 42559R

Q131113888 1113889

minus 0068

Hz R2

07946 (6)




Return air shaft

Tongquanshan

Test location


Fengtaishan





ndash910ndash970



d

0ms 0ms

0ms0ms


d

0ms 0ms

0ms0ms


Blast holes

50m

28m

Monitoring line


ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)




001

01

1

10


Vect

or p

eak

part

icle

vel

ocity

(cm

s)

(a)

001

01

1

10


Peak

par

ticle

vel

ocity

(cm

s)

(b)


100

1000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)



ndash20

ndash10

00

10

20

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)


(a)


ndash10

ndash05

00

05

10

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)

(b)



0ms VPPV 10654R

Q131113888 1113889

minus 140

cms R2

09056

8ms VPPV 6249R

Q131113888 1113889

minus 153

cms R2

08715

(7)



0ms PF 54693R

Q131113888 1113889

minus 086

Hz R2

08669

8ms PF 59641R

Q131113888 1113889

minus 228

Hz R2

08583

(8)




01

1

10

100

1 10 100

Vect

or p

eak

part

icle

vel

ocity

(cm

s)




100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)





MF 1113936

mn1Fnfn

1113936mn1Fn

(9)










P A 1 minusω

R1V1113888 1113889e


ωR2V

1113888 1113889eminus R2V

+ωE

V (10)

100

1000

10000

1 10 100

Mea

n fre

quen

cy (H

z)










Z

XY




ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)







ARR P0 minus P

P0times 100 (11)




001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)




ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)


(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)



0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


001

01

1

10


Vect

or p

eak

part

icle

vel

ocity

(cm

s)

(a)

001

01

1

10


Peak

par

ticle

vel

ocity

(cm

s)

(b)


100

1000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)



ndash20

ndash10

00

10

20

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)


(a)


ndash10

ndash05

00

05

10

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)

(b)



0ms VPPV 10654R

Q131113888 1113889

minus 140

cms R2

09056

8ms VPPV 6249R

Q131113888 1113889

minus 153

cms R2

08715

(7)



0ms PF 54693R

Q131113888 1113889

minus 086

Hz R2

08669

8ms PF 59641R

Q131113888 1113889

minus 228

Hz R2

08583

(8)




01

1

10

100

1 10 100

Vect

or p

eak

part

icle

vel

ocity

(cm

s)




100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)





MF 1113936

mn1Fnfn

1113936mn1Fn

(9)










P A 1 minusω

R1V1113888 1113889e


ωR2V

1113888 1113889eminus R2V

+ωE

V (10)

100

1000

10000

1 10 100

Mea

n fre

quen

cy (H

z)










Z

XY




ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)







ARR P0 minus P

P0times 100 (11)




001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)




ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)


(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)



0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


0ms VPPV 10654R

Q131113888 1113889

minus 140

cms R2

09056

8ms VPPV 6249R

Q131113888 1113889

minus 153

cms R2

08715

(7)



0ms PF 54693R

Q131113888 1113889

minus 086

Hz R2

08669

8ms PF 59641R

Q131113888 1113889

minus 228

Hz R2

08583

(8)




01

1

10

100

1 10 100

Vect

or p

eak

part

icle

vel

ocity

(cm

s)




100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)





MF 1113936

mn1Fnfn

1113936mn1Fn

(9)










P A 1 minusω

R1V1113888 1113889e


ωR2V

1113888 1113889eminus R2V

+ωE

V (10)

100

1000

10000

1 10 100

Mea

n fre

quen

cy (H

z)










Z

XY




ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)







ARR P0 minus P

P0times 100 (11)




001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)




ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)


(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)



0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


MF 1113936

mn1Fnfn

1113936mn1Fn

(9)










P A 1 minusω

R1V1113888 1113889e


ωR2V

1113888 1113889eminus R2V

+ωE

V (10)

100

1000

10000

1 10 100

Mea

n fre

quen

cy (H

z)










Z

XY




ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)







ARR P0 minus P

P0times 100 (11)




001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)




ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)


(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)



0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia







Z

XY




ndash08

ndash04

00

04

08

0 10 20 30 40

Velo

city

(cm

s)

Time (ms)







ARR P0 minus P

P0times 100 (11)




001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)




ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)


(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)



0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia





ARR P0 minus P

P0times 100 (11)




001

01

1

10

1 10 100

Peak

par

ticle

vel

ocity

(cm

s)




ndash20

ndash10

00

10

20

0 10 20 30

Velo

city

(cm

s)

Time (ms)


(a)

ndash10

ndash05

00

05

10

0 10 20 30 40 50

Velo

city

(cm

s)

Time (ms)


(b)



0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


0

2

4

6

8

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

02

04

06

08

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(a)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)



(b)

0

1

2

3

4

0 20 40 60 80

PPV

(cm

s)

Distance (m)


0

01

02

03

04

30 40 50 60 70 80 90

PPV

(cm

s)

Distance (m)


(c)






0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia





0

10

20

30

40

50

60

70

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

10m40m

5m20m80m

(a)

10m40m

5m20m80m

0

20

40

60

80

0 2 4 6 8 10

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

(b)

10m40m

5m20m80m

0 2 4 6 8 10 12

PPV

redu

ctio

n ra

tio (

)

Delay interval (ms)

0

20

40

60

80

(c)





5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




5 Conclusions






Data Availability




Acknowledgments


References



100

1000

10000

1 10 100

Prin

cipa

l fre

quen

cy (H

z)


0ms2ms4ms

6ms8ms10ms

















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia
















































RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia















RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia




RoboticsJournal of




VLSI Design



Shock and Vibration







Journal of



Volume 2018



Volume 2018


Journal of




SensorsJournal of



RotatingMachinery





Propagation






Hindawi


Advances in

Multimedia


Documents

ExperimentalandNumericalInvestigationofBlast-Induced ...downloads.hindawi.com/journals/sv/2019/5843516.pdf · indicate that for short-delay blasting, the principal fre- quencies are