Prediction of Ground Vibration
Prediction of Ground Vibration
Prediction of Ground Vibration
International Journal of
Rock Mechanics & Mining Sciences
journal homepage: www.elsevier.com/locate/ijrmms
a r t i c l e i n f o abstract
Article history: Blasting is generally inevitable for hard rock excavation. Vibrations, induced from blasting affect
Received 7 April 2010 adjacent and remote structures, as well as people in the neighborhood. This paper describes ground
Received in revised form motions induced by blasting near underground and surface concrete structures during the construction
15 February 2011
of upper Gotvand dam. Effects of different rock formations, different detonators and explosives are
Accepted 13 April 2011
analyzed. During underground and surface excavation, 498 ground motions, produces by 216 shots
were measured with Vibraloc vibration monitors. Scaled distance and peak particle velocity data pairs
Keywords: were carefully recorded and analyzed statistically. This analysis allowed the document of empirical
Blasting relationships between scale distance and peak particle velocity in different surface and underground
Ground vibration
regions. Finally, the particle and frequency values of further blast events were evaluated according to
Scale distance
the USBM (RI 8507) to validate the relation and predict the influence level to the neighboring concrete
ppv
Aghajari formation structures.
Bakhtiary formation & 2011 Elsevier Ltd. All rights reserved.
1365-1609/$ - see front matter & 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.ijrmms.2011.04.014
900 R. Nateghi / International Journal of Rock Mechanics & Mining Sciences 48 (2011) 899–908
Scaled distance is a normalized factor that combines distance effects of both relief during blasting and geology. Both constant
with the explosives energy to give a single number, which we can can be determined by regression analysis [7,5,6,1,15].
be plot on a graph or use easily in calculation [8]. Scaled distance
is calculated by dividing distance to the structure of concern by
the square or cube root of the weight of explosive material used in 3. Existing vibration standard and criteria to prevent damage
the blast [9]. Scaled distance concept can be used to predict the
maximum peak particle velocity, PPV, from an explosive charge, Peak particle velocity measured on the ground adjacent to the
Q, at a known distance R. Equation for a cylindrical charge is structure of concrete has been traditionally used in practice for the
measurement of blast damage to structures. Some of the suggested
V ¼ KðSDÞb , where SD ¼ DQ 1=2 ð1Þ damage criteria that are based solely on the peak particle velocity
(PPV mm/s) are listed in Table 1. These recommendations are based
where V is the peak particles velocity (mm/s), Q is the maximum
on experience and observation of cracking in residential structures.
charge per delay (kg), D the distance between blast face to
Table 2 presents PPV limit for cracking of concrete that based on
vibration monitoring point (m), K and b are factors that include
concrete age and distance. As seen in these tables, there is a
common agreement that a peak particle velocity of less than
Table 1 50 mm/Section (2 in/s) would have low probability of cracking in
Some of suggested damage criteria [13,14]. residential buildings. For commercial and engineered structures,
Wiss [18] suggested to use a conservative limit of 100 mm/s.
Predictor Effects and Maximum
damage Allowable PPV
(mm/s)
4. Site descriptions
Longefors et al. [10] No damage o 50
Fine crack 100
This study took place during construction of Gotvand dam,
Cracks 150
Serious cracks 225 located in Zagros Mountains in the south-west of Iran. The 178 m
height and 730 m length embankment dam, which regulates the
Edwards and Northwood [11] Safe zone o 50
Damage zone 100–150
water of the Karun River, also serves power generation, flood
control and irrigation needs.
Duvall and Fogelson [7] Major damage (95%) 50
benches alternating with gentler slopes corresponding to the waveform Blast vibration monitor with an integrated tri-axial
softer interbeds. The sandstones of the AJ formation are composed geophone and air blast system. The blasting analysis software
of the well-rounded siliceous-limy grains with approx. 70% lime provided features for graphical output of the wave forms in each
and 30% quartz. The AJ formation, of late Miocene to lower of the three axes and comparison between measured peak
Pliocene age, overlies the Mishan formation [19]. Geotechnical particle velocities and frequency content with various accepted
properties of the intact rocks are described in Table 3. standards developed by the U.S. Bureau of Mines and others. Each
transducer measured velocities on three mutually perpendicular
axes (Vx, Vy, Vz) corresponding to a radial, transverse, and vertical
6. Test procedure component. All three seismographs were used in a line with
different distant for each blast and as shown in Fig. 3, a three
Drilling and blasting were selected as the excavation method sharp pins and wall attachment device was used to coupling of
for underground and surface excavation from the beginning of the the instrument to the ground or concrete lining [4].
project. During latter years to reach the time schedule for filling
the reservoir Different activities (formwork and concreting,
grouting and excavation) were conducted adjacent to each other. 8. Statistical analysis of measured results
To minimize negative effects of blast excavation, ground motions
were monitored during blasting with three vibration monitors 8.1. Power house excavation
near main concrete structures. Distances between shot points and
monitoring stations were determined by survey equipment. The Powerhouse structures are nearly located in 1 km distance
scaled distances are derived from the combination of distances from the south-west of dam body. It is approximately 350 m in
between source and measurement points and maximum charge length and 250 m in width. The extension was excavated during
per delay and were used to determine dynamic site factors (K&B). construction of the main powerhouse and installation of hydro
These relations were then employed for designing blasting mechanical equipments. Therefore these blasting required extra
patterns near these structures. In addition the frequency content caution because of the existing building. Field observations and
was also measured for comparison with the USBM (RI 8507) exploratory drilling showed the powerhouse to be excavated in
standard for cracking of weak wall covering. the AJ formation, which consists of sequence 0.2–1.5 m layers of
sandstone, clay and siltstone as shown in Fig. 5. ANFO and non-
electric detonators were used for more excavation but for excava-
7. Blast monitoring equipment tion under water level dynamite and emulsion type explosive and
electric detonators were used. Blasting patterns often consist of
Three Vibroloc blasting seismographs and analysis software 45 holes in three rows with 8 m length and 76 mm diameter and
were used in this study. Vibraloc is a complete and easy to use
Fig. 2. Geology of the project area [19]. Fig. 3. Wall and ground attachment device.
Table 3
Summary results of laboratory testing: geo-mechanical properties [21].
Rock formation Rock type UCS Tensile Dry Young’s Porosity Wave velocity
(MPa) strength density modulus (GPa) (%)
(MPa) (g/cm3)
Vp Vs
Fig. 6. Statistical regression of recorded data from bench blasting in plunge pool.
R. Nateghi / International Journal of Rock Mechanics & Mining Sciences 48 (2011) 899–908 903
2.5 m burden and 3 m spacing array (Fig. 4). Some 130 events rectangle shape tunnel with the height of 17.3 m and a vertical
from 52 blasts were recorded and statistical analysis was applied shaft (Fig. 7). These structures are located in Bakhtiary formation
to blast vibration data pairs, peak particle velocity and scaled that consists of thin layers of conglomerate with thin interbeded
distance to specific velocity attenuation equation and dynamic layers of mudstone. To reach the scheduled time for filling of the
site factors. Fig. 5 shows the curve of regression analysis and dam, rectangle tunnels and vertical shafts were excavated first.
respective parameters in this region.
Then during concreting of these parts the bugle shapes monitored. For increasing accuracy of scale distance and regres-
were excavated by head and bench blasting from entrance of sion analysis only ANFO and non-electric detonators were used
tunnels. Because ultimate parts of bugle shape tunnels were for excavation. Fig. 8 shows regression analysis and dynamic site
excavated very close to concrete lining, primary blasts were factors in this region.
Fig. 10. Statistical regression of recorded data from underground blasting in Waterway.
Fig. 11. Particle velocity versus frequency values in USBM standard (Powerhouse).
R. Nateghi / International Journal of Rock Mechanics & Mining Sciences 48 (2011) 899–908 905
Fig. 12. Particle velocity versus frequency values in USBM standard (Plunge Pool).
Fig. 13. Particle velocity versus frequency values in USBM standard (Intake).
906 R. Nateghi / International Journal of Rock Mechanics & Mining Sciences 48 (2011) 899–908
9. Waterway tunnels vibrations have greater potential for damage than high-frequency
vibrations for a certain velocity. In order to predict the influence
As watch the intake structures, the waterway tunnels are of the PPV level on the neighboring structures, the peak particle
located in Bakhtiary formation. However interbeded of mudstone
layers are thicker in comparison to the rock mass. The extended Table 4
plant waterway tunnels were excavated of the simultaneous with Summary of the results of the regression analysis.
concreting of basic plant, so care was require. All blasts were done
Location Formation Blasting type Equation R value
with electric detonators and one scale combination of dynamite
and emulsion and uniform pattern in head and bench blasting. Power house Aghajari Bench blasting PPV ¼ 169.5 SD 0.869 64.7
As shown in Fig. 9, blasting pattern consist of 116 holes in V-cut Plunge pool Aghajari Bench blasting PPV ¼ 660.7 SD 1.71 79.8
array with 3 m length and 54 mm diameter holes that explode Intake Bakhtiary Bench blasting PPV ¼ 346.7 SD 1.63 81.3
with 11 electric delay detonators. PPV versus SD relation and Waterway Bakhtiary V-Cut PPV ¼ 416.8 SD 0.955 53.4
Fig. 14. Particle velocity versus frequency values in USBM standard (Waterway).
R. Nateghi / International Journal of Rock Mechanics & Mining Sciences 48 (2011) 899–908 907
velocity and frequency values of all blast events are evaluated 12. Results
according to the United States Bureau of Mines (USBM) with the
safety factor about 1.5. The graphs of measured maximum It is important to assess the dynamic effect before the begin-
particle velocity versus frequency values of some events at USBM ning of construction activities and at the time of construction.
are given in Figs. 11–14. These time history records show that the Therefore monitoring construction vibrations have to be started
PPV values of the recorded events did not exceed damage limits of prior to the beginning of construction work at a site and be
USBM. Some of the PPV values recorded at the underground continued during construction to provide the safety and service-
excavation were higher than predicted values, so for underground ability of sound and vulnerable structures.
blasts near concrete lining blasting patterns were designed with The measurement of ground vibration induced by blasting is
safety factor 3. However, as can be seen in Figs. 11–14 almost all significantly important in controlling and eliminating of blast
dominant vibration frequencies in all blasts are higher than 20 HZ damages to structures. Since the particle velocity is still one of the
for this site, and no damage risks caused by low-frequency and most important grounds vibration predictors for regulating the blast
resonance condition have been observed. design, an empirical relationship with good correlation has been
established between peak particle velocity and scaled distance.
Based on the vibration tests done in Aghajari formation,
11. Summary constant dynamic factors of the rock mass which are related to
vibration velocity, are changed between 170–660 and 0.87–1.71.
This paper presents some guidelines for preconstruction sur- Based on the vibration tests done in Bakhtiary conglomerate,
vey, prediction, measurement, analysis and control of structure constant dynamic factors of the rock mass, which are related to
vibrations generated by blasting activities at a site. Within the vibration velocity, are changed between 350–420 and 1.63–0.955.
scope of this study, at the large number of measurements from As a result of this vibration test in Bakhtiary conglomerate
different blasting material and detonators in different rock rocks, ground vibration induced by underground blasting is at
formation at upper Gotvand dam were employed to develop the least three times more than vibration induced by bench blasting
attenuation relations. These relations for the four regions com- in the same rock.
pared in Table 4. Vibration frequency in all blasts is higher than 20 Hz for this
Fig. 15 compares the expected value and attenuation relations site so there is no potential for damage risk caused by resonance
in two basic formations. As seen in this figure for Aghajari from blasting waves and self-structural frequencies of structures.
formation the dynamic site factors K and b changes respectively
between 170–660 and 0.87–1.71. Because of blasting patterns and
explosive material and device (detonators, exploder, etc.) were Acknowledgments
unique in measured blasts, these variations are the outcome of
changes of thickness and dip of layers, aperture of major joints This work was supported by the Iran water and power resources
and bedding and less related to explosive parameters. But for development co and Sepasad engineering co. The author would like
Bakhtiary conglomerate difference between two relations mainly to thank for financial support for carrying out this research work.
refers to inexistence of prefer free face in underground excavation
in comparison with bench blasting. Predicted rock dynamic
factors (K and b) in Bakhtiary conglomerate are about 350 and Appendix
1.63 from bench blasting and 420 and 0.955 from underground
excavations. See Table A1 for details.
Table A1
3.79 102 Under construction 20 156 Thr 4 Mar 2010 12:26:03 Waterway T4 559 1
6.21 102 Under construction 20 109 Thr 4 Mar 2010 12:26:03 Waterway T4 569
1.36 102 Under construction 18 190 Mon 8 Mar 2010 12:36:09 Waterway T4 559 2
2.61 178 Over than 48 h 18 183 Tue 9 Mar 2010 05:38:53 Waterway T4 559 3
1.86 178 Over than 48 h 18 111.3 Wed 14 Apr 2010 13:37:41 Waterway T4 559 4
5.98 178 Over than 48 h 18 95 Wed 14 Apr 2010 13:37:41 Waterway T4 569
23.82 178 Over than 48 h 20 95 Mon 10 May 2010 13:39:05 Plunge Pool 569 5
20.16 178 Over than 48 h 20 71 Mon 10 May 2010 13:39:05 Plunge Pool 574
1.22 178 13 h 27 138 Wed 19 May 2010 13:33:03 Plunge Pool 559 6
1.44 51 13 h 27 154 Wed 19 May 2010 13:33:03 Plunge Pool 569
1.30 51 13 h 27 149 Wed 19 May 2010 13:33:03 Plunge Pool 574
12.69 178 Over than 48 h 40 164 Fri 7 May 2010 06:24:03 Plunge Pool 559 7
908 R. Nateghi / International Journal of Rock Mechanics & Mining Sciences 48 (2011) 899–908
Table A1 (continued )
7.72 178 Over than 48 h 40 163 Tue 18 May 2010 13:11:36 Plunge Pool 569
8.76 178 Over than 48 h 38 80 Sun 9 May 2010 18:49:27 Powerhouse 559 9
32.63 178 Over than 48 h 38 38 Sun 9 May 2010 18:49:27 Powerhouse 569
27.74 178 Over than 48h 38 55 Sun 9 May 2010 18:49:27 Powerhouse 574
9.14 178 Over than 48 h 36.5 38.6 Wed 31 Mar 2010 01:46:42 Powerhouse 559 10
13.43 178 Over than 48 h 36.5 38.3 Wed 31 Mar 2010 01:46:42 Powerhouse 569
7.31 178 Over than 48 h 28 38.6 Sat 1 7 Apr 2010 13:39:12 Powerhouse 559 11
14.66 178 Over than 48 h 28 38.3 Sat 1 7 Apr 2010 13:39:12 Powerhouse 569
18.04 178 Over than 48 h 9 26 Sat 20 Feb 2010 16:29:37 Intake 559 12
23.55 178 Over than 48 h 9 18.5 Sat 20 Feb 2010 16:29:37 Intake 569
36.14 178 Over than 48 h 15 20 Sun 7 Mar 2010 12:41:13 Intake 559 13
23.25 178 Over than 48 h 15 13 Sun 7 Mar 2010 12:41:13 Intake 569
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