J.
Eng.
Technol.
Sci.
Vol.
No.
1, 2022, 220112
Blasting Vibration Monitoring and a New Vibration Reduction Measure Xi Yang.
Yunpeng Zhang*& Jie Wang North China University of Science and Technology.
Hebei Mining Key Laboratory of Development and Safety Technology.
Tangshan Hebei 063000.
China *E-mail: ncstzyp@163.
Highlights:
The peak particle velocity (PPV) and principal frequencies of different structures of single-story brick-concrete buildings are different.
The PPV amplification factor does not change much when the principal frequency ratio is larger than 0.
The measuring points of different heights have different sensitivities to blasting vibration waves of different principal frequencies.
PPV can be reduced by waveform interference.
Abstract.
Vibration waves generated by blasting can cause shock to buildings.
Different responses occur in different parts of the building.
Therefore, a single standard is inaccurate.
At the same time, methods to reduce vibration are needed.
In this paper, the variation of peak particle velocity (PPV) and principal frequency was analyzed.
The energy variation of blast vibration waves was analyzed by wavelet packet decomposition.
A numerical model was established to verify the new vibration reduction measure.
The results showed that the PPV on the walls increases with their height.
The PPV and principal frequency of different structures of single-story brick-concrete buildings are different.
The amplification factor of PPV does not change much when the principal frequency ratio is larger Measuring points at different heights have different sensitivities to blasting vibration waves of different principal frequencies.
Therefore, different structures will respond differently to the same blasting operation.
The PPV can be reduced by waveform interference.
However, the cycle of blasting vibration waves decreases with increasing distance.
Therefore, it is necessary to determine a reasonable interval to reduce the PPV.
This requires further research.
Keywords: blasting vibration response.
single-story brick-concrete buildings.
PPV.
principal frequency.
vibration reduction measure.
Introduction Ore mining in open pits adversely affects the surrounding environment.
Especially, vibration waves generated from blasting can cause shock to buildings around mines.
If the vibration velocity exceeds a certain threshold, it will cause different degrees of damage to buildings around a mine .
This has a direct impact on the safety of people living around the mine .
Therefore, it is Received October 8th, 2020, 1st Revision December 22nd, 2020, 2nd Revision July 29th, 2021.
Accepted for publication September 29th, 2021.
Copyright A2022 Published by ITB Institute for Research and Community Services.
ISSN: 2337-5779.
DOI: 10.
5614/j.
Blasting Vibration Monitoring and a New Vibration Reduction Measure necessary to systematically study the vibration effect produced by blasting and take effective vibration reduction measures.
Many villages and towns are situated in the vicinity of mines.
The buildings are mostly single-story brick-concrete At present, relatively few studies have been conducted on this topic.
is necessary to conduct corresponding research.
Blasting vibration waves are affected by many factors .
Li, et al.
analyzed the PPV and stress on a tunnel surface, after which they assessed the tunnelAos safety.
Xia, et al.
found that the damage degree to rock on the tunnel surface increased with the increase of PPV.
Kahriman .
predicted the PPV in a limestone quarry and eliminated environmental problems around the quarry.
Abiodun Ismail Lawal proposed an artificial neural network-based mathematical model for the prediction of blast-induced ground vibrations .
Singh, et al.
analyzed blast signatures and proposed an effective charge weight for the prediction of ground vibrations.
Smerzini, et al.
proposed a method for describing ground vibrations generated by P.
S or R seismic waves.
Xu Jingui .
found that blasting vibrations decreased with the increase of horizontal The blasting vibration velocity at the top of the slope was obviously higher than that in the other positions.
Qiu Xianyang .
revealed the timefrequency characteristics of vibration signals.
The most important ones among these factors are PPV and frequency.
Blast vibration standards have been proposed to protect buildings and limit blasting vibration.
Frequency and PPV are considered in these standards.
The United States Bureau of Mines (USBM) published RI 8507 .
and recommended blasting level criteria that set a peak particle limit based on the predominant frequency of the seismic wave.
Other countries have proposed corresponding standards .
These standards are all of them limit the PPV in different frequency ranges.
As an example, one of them is shown in Table 1.
Table 1 Permissible peak particle velocity (PPV) in mm/s at the foundation level of structures in mining areas (DGMS circular 7 of 1.
Dominant excitation frequency/ Hz <8Hz (A) Buildings/structures not belonging to the mine owner Domestic houses/structures (Mud/ Kuchcha, brick and cemen.
Industrial buildings Objects of historical importance and sensitive structures (B) Buildings belonging to the mine owner with limited life span Domestic houses/structures Industrial buildings 8-25Hz >25Hz Xi Yang, et al.
The PPV and frequency in these standards are definite values.
However, the PPV and frequency of different structures of the buildings respond differently to the same blasting.
At the same time, the PPV and frequency at different heights are also different.
Building types are mentioned in these standards.
However, structures of buildings are not mentioned.
The damage to structures of buildings by PPV and frequency is different.
people also respond to them differently.
This needs to be further clarified.
Since blasting vibration can damage houses, it must be investigated how we can reduce its impact.
Various methods and techniques have been developed to reduce blasting vibrations .
The water jet technique has been frequently applied in many different fields .
It was developed by Jung-Gyu Kim .
to block the propagation of vibrations from tunnel blasting.
At the same time, many different vibration control methods have been developed .
These methods can be classified into four major categories: passive control .
, semi-active control .
, active control .
, and hybrid control .
However, these methods require additional facilities, or the structure of the building must be changed.
This increases the investment capital required.
Blasting vibration waves respond differently to different structures of the building.
Different vibration control methods should be adopted for different structures of a building, or the vibration of the building should be reduced by reducing the blasting vibration waves.
However, the effect of blasting excavation cannot be reduced.
Therefore, new vibration reduction measures should be considered.
In this paper, blast vibration monitoring was conducted for different structures of single-story brick-concrete buildings.
The variation of PPV and principal frequency was analyzed.
The energy variation of blast vibration waves was analyzed by wavelet packet decomposition.
A numerical model was established to verify the new vibration reduction measure that can be used to protect buildings near mines.
Experimental Site and Experimental Details Single-story brick-concrete buildings are situated near an opencast mine in the east of Hebei Province.
China, as shown in Figure 1.
The mine produces millions of tons of iron ore every year.
Ground vibrations from blasting have been a continuous problem for the mine and the surrounding buildings.
Hole-by-hole detonation technology has been adopted in the mine.
The explosive weight in each hole is between 100 kg and 480 kg.
Different explosive weights are adopted in different locations according to work requirements.
The monitoring equipment was a TC-4850 blasting vibration intelligent monitor produced by the Chinese Academy of Sciences.
It can accurately monitor the Blasting Vibration Monitoring and a New Vibration Reduction Measure waveform, the principal frequency and the PPV of the blasting vibration waves.
The monitoring points are shown in Figure 2.
Figure 1 Monitoring location.
Monitoring points on inner wall O.
Monitoring points on external wall Figure 2 Monitoring points of single-story brick-concrete building.
Vibration Monitoring on the Structures In total, six tests were conducted.
The principal frequency and PPV of the blasting vibration waves are shown in Table 2.
The X direction is perpendicular to the Y and Z directions.
The Y direction points toward the blasting site.
The Z direction is perpendicular to the ground.
The PPV of monitoring points 3, 4, 5, 6 in the X direction are presented in Figure The PPV of monitoring points 3, 4, 5, 6 in the Y direction are shown in Figure The PPV of monitoring points 3, 4, 5, 6 in the Z direction are shown in Figure The PPV near the corner of a wall increases with height.
However, this is not obvious in the Z direction.
Xi Yang, et al.
Table 2 PPV and principal frequency.
Number Points PPV /mmAs-1 Principle PPV /mmAs-1 Principle /Hz PPV /mmAs-1 Principle /Hz Blasting Vibration Monitoring and a New Vibration Reduction Measure Figure 3 PPV of monitoring points 3, 4, 5, 6 in the X direction.
Figure 4 PPV of monitoring points 3, 4, 5, 6 in the Y direction.
Figure 5 PPV of monitoring points 3, 4, 5, 6 in the Z direction.
Xi Yang, et al.
The PPV of monitoring points 7, 8, 9, 10 in the X.
Z directions are presented in Figures 6, 7, and 8 respectively.
The PPV decreases first and then increases with height.
The PPV on the ground is larger than the PPV on the walls near it, while the PPV on the walls increases with height.
Figure 6 PPV of monitoring points 7, 8, 9, 10 in the X direction.
Figure 7 PPV of monitoring points 7, 8, 9, 10 in the Y direction.
Figure 8 PPV of monitoring points 7, 8, 9, 10 in the Z direction.
Blasting Vibration Monitoring and a New Vibration Reduction Measure The PPV on a high wall is larger than the PPV on the ground.
As shown in Table 3, the PPV on the roof is larger than the PPV on the ground.
The PPV on the roof is also larger than the PPV on the windows.
This is a PPV amplification phenomenon related to height.
The PPV on a window is larger than on a corner when the height is the same.
Because blasting vibration waves cause different responses in different structures, the PPV and principal frequency of different structures of single-story brick-concrete buildings are different.
The vibration resistance of different structures is also different.
Therefore, a single standard is Table 3 Number Point 1 (Roo.
2 (Windo.
6 (Corne.
10 (Groun.
1 (Roo.
2 (Windo.
6 (Corne.
10 (Groun.
1 (Roo.
2 (Windo.
6 (Corne.
10 (Groun.
1 (Roo.
2 (Windo.
6 (Corne.
10 (Groun.
1 (Roo.
2 (Windo.
6 (Corne.
10 (Groun.
PPV on different structures.
PPV/mmAs-1 PPV/mmAs-1 PPV/mmAs-1 Principal frequency ratio is shown in Eq.
where fw is the vibration principal frequency of the ground, f is the vibration principal frequency of different structures.
The amplification factor is shown in Eq.
Xi Yang, et al.
A A CC
where is the amplification factor, vh is the PPV at different points, v h is the PPV on the ground.
The amplification factor and principal frequency ratio in the X.
Z directions are shown in Figures 9, 10, and 11 respectively.
The amplification factor increases rapidly when the principal frequency ratio is less than 0.
The amplification factor does not change much when the principal frequency ratio is larger than 0.
The principal frequency may be close to the natural frequency of different structures.
Figure 9 Amplification factor and principal frequency ratio in the X direction.
Figure 10 Amplification factor and principal frequency ratio in the Y direction.
Blasting Vibration Monitoring and a New Vibration Reduction Measure Figure 11 Amplification factor and principal frequency ratio in the Z direction.
As shown in Figure 12, the energy ratio of the measuring points was obtained by wavelet packet decomposition.
The size of each frequency band was 7.
81 Hz .
requency band 1 was from 0 Hz to 7.
81 Hz, frequency band 2 was from 7.
Hz to 15.
In the low frequency band .
requency bands 2, 3, .
, the energy ratio at a low point was large.
In the high frequency bands .
requency bands 7 and .
, the energy ratio at a high point was large.
This shows that the measuring points at different heights have different sensitivities to blasting vibration waves of different principal frequencies.
Therefore, different structures respond differently to the same blasting operation.
Figure 12 Energy ratio of the measuring points.
Xi Yang, et al.
Vibration Reduction Measures Previous vibration reduction methods require additional facilities, or the structure of the building must be changed.
This increases the investment capital required.
Waveform interference does not require more investment capital.
As shown in Figure 13, the two waveforms will be reduced after superposition.
How do we implement this method? First.
Ls-dyna is used to establish a model, as shown in Figure 14.
The model width is 100 m.
The height is 24 m.
Second.
MAT_HIGH_EXPLOSIVE_ BURN material is used for the explosive.
The JWL equation for describing explosions is shown as Equation 3.
The parameters of the explosive are shown in Table 4.
MAT_PLASTIC_KINEMATIC material is used for rock.
The parameters of rock are shown in Table 5.
P A A.
R1V
)e A R1V A B .
A A R2V
)e A R2V A AE0 where P is detonation pressure.
V is the relative volume.
E0 the initial specific internal energy, and A.
R1.
R2 and O are independent constants describing the JWL equation.
Thirdly, the meshing is shown in Figure 15.
The bottom of the model is a nonreflective boundary.
Lastly, the simulation time is 50,000 s.
The velocity time history at point A in the model of one 500-kg explosive package is shown in Figure 16.
The PPV of point A is 100cm/s.
Figure 13 Waveform interference.
Figure 14 The model of one 500-kg explosive package.
Blasting Vibration Monitoring and a New Vibration Reduction Measure Table 4 Parameters of explosive.
Density .
/cm.
Detonation speed .
A (GP.
B (GP.
Table 5 Density .
/cm.
YoungAos (GP.
PoissonAos Rock parameters.
Yield (MP.
Tangent (GP.
Hardening Figure 15 Meshing.
Figure 16 Velocity time history at point A in the model of one 500-kg explosive Firstly.
Ls-dyna is used to establish another model, as shown in Figure 17.
The model width is 100 m.
The height is 24 m.
The 500-kg explosive is divided into two 250-kg explosives.
The two 250-kg explosive packages detonate at the same Two explosives are separated by air.
Secondly, the Gruneisen equation for describing air under high pressure is shown in Equation 4.
The air parameters are shown in Table 6.
The material parameters of rock and explosive are the same as in the previous model.
Thirdly, the meshing is shown in Figure 18.
The bottom of the model is a non-reflective boundary.
Lastly, the simulation time is 50,000 s.
Xi Yang, et al.
The velocity time history at point B in the model with two 250-kg explosive packages is shown in Figure 19.
The PPV at point B is 90 cm/s.
It is less than that at point A, because the waveforms of the two 250-kg explosive packages interfere with each other, as can be seen from Figure 21.
The waveform interference is affected by the initial phase of the blasting vibration wave if the initial phases of the two blasting vibration waves are opposite, as shown in Figure 21.
The two explosive packages should be detonated at the same time.
If the initial phases of the two blasting vibration waves are the same, the initiation detonation time of the two explosive packages should be half a cycle apart.
However, the cycle of blasting vibration waves decreases with increasing distance.
The PPV can be reduced by taking different intervals between two explosive packages according to the cycle of different locations, so the cycle is changed in a blasting vibration Therefore, it is necessary to determine a reasonable interval to reduce the PPV.
This requires further research.
A 0C 2 A.
A .
)A A
A ]
A3 2
A ( S1 A .
A A S 2
A S3
A A1
( A A .
A (A 0 A aA ) E0 where A0 is initial density, 0 is the Gruneisen parameter.
E0 is initial internal energy.
C is the curve intercept.
S1.
S2.
S3 are curve slope coefficients, is the dynamic viscosity coefficient, a is a first-order volume correction of 0 and .
Figure 17 The model of two 250kg explosive packages.
Table 6 Density .
/cm.
239y10-3 Air parameters.
9y10-4 Figure 18 Meshing.
Blasting Vibration Monitoring and a New Vibration Reduction Measure Figure 19 Velocity time history at point B in the model with two 250-kg explosive packages.
Figure 20 Points C and D.
Figure 21 The waveform interference of the model with two 250-kg explosive Conclusion The PPV on a wall increases with its height.
The PPV and principal frequencies of different structures of single-story brick-concrete buildings are different.
The vibration resistance of different structures is also different.
Therefore, a single standard is inaccurate.
Xi Yang, et al.
The amplification factor of the PPV does not change much when the principal frequency ratio is larger than 0.
This is maybe because the principal frequency is close to the natural frequency of different structures.
Measuring points at different heights have different sensitivities to blasting vibration waves of different principal frequencies.
Therefore, different structures will respond differently to the same blasting operation.
It is necessary to propose a PPV limit standard for different structures of single-story brick-concrete buildings or other This can better balance mine production and building safety.
This requires further research.
PPV can be reduced by waveform interference.
Waveform interference is affected by the initial phase of the blasting vibration wave.
If the initial phases of the two blasting vibration waves are opposite, the two explosive packages should be detonated at the same time.
If the initial phases of the two blasting vibration waves are the same, the initiation detonation time of the two explosive packages should be half a cycle apart.
However, the cycle of blasting vibration waves decreases with increasing distance.
It also changes in the blasting vibration wave.
Therefore, it is necessary to determine a reasonable interval to reduce PPV.
This requires further research.
Acknowledgement This research was mainly supported by the National Natural Science Foundation of China .
and National Key Technologies Research & Development Program .
7YFC0804.
References