impact assessment of blasting on vulnerable …igs/ldh/files/igc 2015 pune/theme 15 landslid… ·...

50th

IGC

50th

INDIAN GEOTECHNICAL CONFERENCE

17th

– 19th

DECEMBER 2015, Pune, Maharashtra, India

Venue: College of Engineering (Estd. 1854), Pune, India

IMPACT ASSESSMENT OF BLASTING ON VULNERABLE LANDSLIDE AREA

Hari Dev, Birendra Pratap, Rajbal Singh and Shashank Pathak

Central soil and Materials Research Station, New Delhi, India

ABSTRACT

Ground vibrations caused by blasting operations is defined as the velocity of particles within the ground

resulting from vibratory motion. The intensity of ground vibration is measured in units of peak particle

velocity, generally, millimetres per second (mm/s). Shock waves (energy from the detonation) radiate

outwardly during any explosion and the material adjacent to the source gets crushed. A part of the energy

is used in fracturing and displacement of ground (approximately 20-30%) while the remaining part of the

energy dissipates in the form of ground and air vibrations (concussion). Under typical conditions, blasting

vibrations intensity diminishes with distance, at a rate of about one third of its previous value each time

the distance from the vibration source is doubled. Hence, extent of damage to the adjacent structures

depends on the distance from the blast source and the intensity of the explosion.

At dam site of Punatsangchhu-I H.E. Project, Bhutan, a landslide occurred on the right bank slope during

excavations by blasting at dam site. Accordingly, apart from the strengthening measures of the vulnerable

slide mass, blast vibration studies were also carried out to optimize the blast design.

This paper presents the impact assessment on vulnerable right bank slope mass during blasting carried out

at dam site on the left bank of Punatsangchhu-I hydroelectric project in Bhutan. Vibration limits

recommended by various codes and guidelines have also been discussed. Considering peak particle

velocity (PPV) of 5 mm/sec as the threshold values, vibrations have exceeded at three locations.

In the present study, distances of the monitoring points from the blast location through ground were

approximated from the cross sections drawn at upstream and downstream of dam axis. Blast vibrations

were monitored at different locations/distances and using variable quantity of explosives. In the event of

data containing variable distance, direct correlation between PPV and quantity of explosives is not

feasible. In order to develop the correlation between PPV, distance and quantity of explosives, concept of

scaled distance was utilized. Correlation co-efficient for scaled distance was derived as d/w1/2.2

(m/kg1/2.2

)

through optimization (d = distance of monitoring point from blast location approximated along the

ground/rock line in m and w = total quantity of explosive used, kg)


Hari Dev, Birendra Pratap, Rajbal Singh and Shashank Pathak; E-mail: [email protected]


Peak Particle Velocity (PPV) v/s scaled distance

Further, it is assumed that total quantity of explosives works as single source of explosion. Additionally,

the distances are approximated based on the desktop studies.

The plot between PPV (m/sec) versus scaled distance (m/kg0.45

) was drawn and the regression curve was

fitted as shown in Figure above. The best fit correlation between PPV and scaled distance was obtained as

given in the following equation :

PPV = 26.032x (d/w0.45

)-0.97

Correlation Co-efficient (R) = 0.55

Keywords: Ground Vibrations, Peak Particle Velocity, Air Overpressures, Scaled Distance

y = 26.032x-0.969

0

5

10

15

20

25

30

0 10 20 30 40

PP

V (

mm

/sec

)

Scaled Distance (m/kg0.45)

50th

IGC

50th


17th

– 19th



IMPACT ASSESSMENT OF BLASTING ON VULNERABLE LANDSLIDE AREA


Central Soil and Materials Research Station, New Delhi

E-mail: [email protected]

ABSTRACT: Ground vibrations caused by blasting operations is defined as the velocity of particles within the

ground resulting from vibratory motion. The intensity of ground vibration is measured in units of peak particle

velocity, generally, millimetres per second (mm/s). Shock waves (energy from the detonation) radiate outwardly

during any explosion and the material adjacent to the source gets crushed. A part of the energy is used in fracturing

and displacement of ground (approximately 20-30%) while the remaining part of the energy dissipates in the form

of ground and air vibrations (concussion). Under typical conditions, blasting vibration intensity diminishes with

distance, at a rate of about one third of its previous value each time the distance from the vibration source is

doubled. Hence, extent of damage to the adjacent structures depends on distance and intensity of the explosion.

At dam site of Punatsangchhu-I H.E. Project, Bhutan, a landslide occurred on the right bank slope during

excavations by blasting at dam site. Accordingly, apart from the strengthening measures of the vulnerable slide

mass, blast vibration studies were also carried out to optimize the blast design. This paper presents the impact

assessment on vulnerable right bank slope mass during blasting carried out at dam site on the left bank of

Punatsangchhu-I hydroelectric project in Bhutan. Vibration limits recommended by various codes and guidelines

have also been discussed.

INTRODUCTION

Three types of waves viz. compressive, shear and

surface are generated through excitation. Three

perpendicular components of motion namely

longitudinal, vertical and transverse must be

measured to describe the motion completely. The

longitudinal component, L is usually oriented

along a horizontal radius to the explosion followed

by other two perpendicular components i.e.

vertical, V and transverse, T to the radial direction.

The three main waves can be divided into two

types; one is body wave which propagates through

the body of the rock and soil and second is surface

wave, which is transmitted along a surface (usually

the upper ground surface). The most important

surface wave is the Rayleigh, denoted by R. Body

waves can be further subdivided into two

categories compressional or tension or sound-like

waves denoted as P-wave and distortional or shear

waves denoted as S-wave. Excitations produce

predominantly body waves at small distances.

These body waves propagate outward until they

intersect a boundary such as another rock layer,

soil or the ground surface. At this intersection,

surface waves are produced. Rayleigh surface

waves become important due to large transmission

distances.

At small distances all three wave types will arrive

together and complicate wave type identification,

whereas, at large distances, more slowly moving

shear and surface waves begin to separate from the

compressional wave and allow identification.

The pattern of motion depends upon the nature of

transmitting media (soil or rock). Due to motion of

waves resulting from explosion, structures built on

or in soil (or rock) will be deformed differently.

The longitudinal (compressional) wave produces

particle motions in the same direction as it is

propagating, whereas, the shear wave produces

motions perpendicular to its direction of

propagation i.e. either horizontal or vertical. The

Rayleigh wave produces motion both in the




vertical direction and parallel to its direction of

propagation.

Vibration monitoring includes ground vibration

(transverse, vertical and longitudinal ground

vibrations) and air overpressure. Transverse ground

vibrations agitate particles in a side to side motion.

Vertical ground vibration agitates particles in an up

and down motion. Longitudinal ground vibrations

agitate particles in a forward and backward motion

progressing outward from the event point. Events

also afford air pressure by creating air blast. By

measuring air pressures we can determine the

effect of air blast on structures.

The Peak Vector Sum (PVS) of particle under

vibration is defined as:

PVS = (T2+V

2+L

2)1/2

(1)

Where,

PPV = Peak Particle Velocity

T = Peak Particle Velocity (PPV) measured by

transverse geophone

V = PPV measured by vertical geophone

L = PPV measured by longitudinal geophone

Peak Vector Sum is calculated for each point of the

sampled waveforms and gives the largest value.

This PVS is not necessarily the peak particle

velocity for an individual wave form.

Wave propagation phenomena were first

investigated by Morris [1] and his principles have

been refined ever since to attempt to determine

peak particle velocity (PPV). Maximum allowable

limit of peak particle velocity (PPV) within a

frequency range varies worldwide. For example, in

Japan the permitted vibration amplitude has to be

between 0.5 and 1.0 mm/s in residential areas,

whereas, in New Zealand anything below 5 mm/s

is acceptable.

The present paper presents the impact of blasting

operations carried out along the left bank at the

dam pit on the rock mass vulnerable to slide on

right bank of Punatsangchhu-I H.E. Project,

Bhutan. Blast vibration monitoring was carried out

at different locations along the slide prone mass.

THE PROJECT

Punatsangchhu-I hydroelectric project comprises of

a 130 m high roller compacted concrete gravity

dam across river Punatsangchhu. The extent of

excavation is of the order of more than 70 m below

rived bed level. Excavations were being carried at

the dam site for removal of river borne materials

and loose rock mass for laying the foundation of

the concrete gravity dam on the firm bed rock.

GEOLOGY OF DAM AREA

Left Bank - The left bank along the river line is

occupied by hard, fresh and blocky quartzo-

feldspathic gneiss and its variants are exposed to

the ridge top. The strike of the foliation varies from

N200

E - S200

W to N400

E- S400

W dipping at 100-

400 SE into the hill. The rocks on the left abutment

are traversed by four prominent sets of joints,

major vertical fractures cutting across the hill and

minor shears. The valley ward dipping joint (J2) is

very prominent, steep and controls the

configuration of the left bank abutment. The

vertical fractures are developed along the joints

dipping NNE and NW upstream dipping.

Right Bank - At right bank, the exposures are

restricted. On the right bank of dam, the ongoing

excavation for stripping has revealed very limited

exposure of rock above cable car bench (EL.1260

m) from U/s 50 m to D/s 100 m of dam axis. The

area in the upstream and downstream of this rock

ledge comprises thick overburden/hill wash debris.

This available rock ledge exposes jointed and

blocky quartzo feldspathic gneiss, which is fresh in

the middle portion and slightly to moderately

weathered (W2-W3) in the upstream and

downstream extremities. The general strike of the

foliation varies from N100

E – S100

W to N400

E-

S400

W dipping at 100-40

0 SE. However, the rocks

on the right bank exhibit tight S- shape folding,

which has disturbed the normal foliation thus

showing rolling dips at many places. The exposed

rocks on the right abutment are traversed by four

prominent sets of joints and minor shears. Wide

topographic depressions filled with thick

overburden/slide debris are noticed in the

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IGC

50th


17th

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downstream and upstream portions of the rocky

outcrop. The geological section of dam axis is

shown in Fig. 1.

Fig. 1: Geological section of dam axis

THE PROBLEM

On completion of excavation and dressing of

slopes for right abutment blocks No. 14 and 13 up

to EL 1110 from the river bed level of 1151 m,

benching down of block no. 12 was under progress

when movement and subsidence of right abutment

from 150 m u/s to 140 m d/s of dam axis between

EL 1110 m and 1400 m occurred. The probable

reason of slide was attributed to shear zones.

During benching down, removal of toe material on

the right bank in block nos. 12 and 13 (Fig. 1)

triggered the movement of geological mass along

the shear zone. Due to the geological situation the

right abutment of the dam is prone to sliding along

various shear planes [2]. Figure 2 shows the extent

of slide on the right bank.

Excavation in the river bed was immediately

stopped. Investigation and instrumentation in the

affected right bank slope was started to assess the

damages and to suggest the remedial measures.

Inclinometers were installed at critical locations in

consultation with the designers in the slide area to

monitor the movement of ground. Optical targets at

critical locations were also installed to monitor the

surficial movement.

Fig. 2: Extent of slide and imposed dam section

Cement grouting was started as immediate

rehabilitation measure to strengthen the

damages/displaced mass. Right bank slope was

unloaded by removing some overburden mass and

creating more benches. Cement grouting, micro

piling and cable anchoring was initiated at various

levels as the long term stabilizing measure.

Reinforced concrete piles of 2.0 m diameter are

also being provided at different levels for

strengthening of vulnerable slope. Excavation is

still required for laying the foundation of concrete

gravity dam which will be taken up after

completion of strengthening measures.

In view of the nature of slide mass, excavation

using blasting may further trigger the landslide.

Hence, it was decided to complete the restoration

measures. After sizeable rehabilitation measures,

controlled blasting was allowed along the left bank

abutment and simultaneously, intensity of blast and

ground vibrations were monitored by CSMRS for a

period of one month to assess the impact of

blasting.

BLAST VIBRATION STUDIES

After stabilization of right bank slope and

completion of restoration measures, controlled

blasting was permitted along the left bank and

ROAD

ROAD

1050.00

1425.00

1420.00

1415.00

1410.00

1405.00

1400.00

1395.00

1390.00

1385.00

1380.00

1375.00

1370.00

1365.00

1360.00

1355.00

1350.00

1345.00

1340.00

1335.00

1330.00

1325.00

1320.00

1315.00

1310.00

1305.00

1300.00

1295.00

1290.00

1285.00

1280.00

1275.00

1270.00

1265.00

1260.00

1255.00

1250.00

1245.00

1240.00

1235.00

1230.00

1225.00

1220.00

1215.00

1210.00

1205.00

1200.00

1195.00

1190.00

1185.00

1180.00

1175.00

1170.00

1165.00

1160.00

1155.00

1150.00

1145.00

1140.00

1135.00

1130.00

1125.00

1120.00

1115.00

1110.00

1105.00

1100.00

1095.00

1090.00

1085.00

1080.00

1075.00

1070.00

1065.00

1055.00

1050.00

1425.00

1420.00

1415.00

1410.00

1405.00

1400.00

160.00140.00120.00100.0080.0060.0040.0020.000.00

1395.00

1390.00

1385.00

1380.00

1375.00

1370.00

1365.00

1360.00

1355.00

1350.00

1345.00

1340.00

1335.00

1330.00

1325.00

1320.00

1315.00

1310.00

1305.00

1300.00

1295.00

1290.00

1285.00

1280.00

1275.00

1270.00

1265.00

1260.00

1255.00

1250.00

1245.00

1240.00

1235.00

1230.00

1225.00

1220.00

1215.00

1210.00

1205.00

1200.00

1195.00

1190.00

1185.00

1180.00

1175.00

1170.00

1165.00

1160.00

1155.00

1150.00

1145.00

1140.00

1135.00

1130.00

1125.00

1120.00

1115.00

1110.00

1105.00

1100.00

1095.00

1090.00

1085.00

1080.00

1075.00

1070.00

1065.00

1060.00

1055.00

RIVER EDGE (RIGHT BANK)

DH-20(P)

DH-26(P)DH-25 DH-31

De

si gn

pr o

f il e

Grouting Gallery

Fol= 10°- 12° ( 7°)/N220-230

Rock mass

yet to expose

J=

70

° -7

5° (7

0°

)/ N2

30

- 2 60

PDH-33 (PROJECTED)

?

EXCAVATED PROFILE AFTER SLIDE

NATURAL SURFACE PROFILE

EXCAVATED PROFILE BEFORE SLIDE

NATIONAL HIGHWAY

DHM-2DHM-7

DHM-8

CABLE CAR BENCH

DHM-11(PROJECT ED)

GABBION WALL

DHM-15

ROCK LINE

180.00 200.00 220.00 240.00 260.00 280.00 300.00 320.00 340.00 360.00 380.00 400.00 420.00 440.00 460.00 480.00 500.00 520.00 540.00 560.00 580.00 600.00 620.00 640.00 660.00 680.00 700.00 720.00

1060.00

1 2

3 4 5 6 7 8 9

10 11 12 13 14

RE

TA

ININ

G W

AL

L

J.N

25°

W-S

25°E

/75

°NE

(72

°)

J.N

50W

- S5

0°E

/75°

NE

(70

°)

FOL.N20E-S20°W/20°SE(17°)

J.N70°E-S70°W/70°NW(25°)

SINKING ZONE

SINKING ZONE

SINKING ZONE

(COLONY ROAD)

(COLONY ROAD)

(COLONY ROAD)

S 80° W

?

N 80° E

SINKING LINE

?

?

?

?

?

?

?

?

PDH- 35(CAN NOT BE PROJECTED)

PDH- 34

38°-40°(

31°-3

6°)/N

50°

DHM-1 (CANNOT BE

PROJECTED WRT SHEAR ZONE)

PDH-40 (CANNOT BE

PROJECTED WRT SHEAR ZONE)

(40°(16°)/N330°)

SZ-1

?

?

?

?

FAULT / SHEAR ZONE

?

?

?

DH-30(CAN NOT BE PROJECTED)

DHM - 22 DHM - 23

-0'-0

LEFT BANK RIGHT BANK

REDUCED DISTANCE (m)SECTION 0-0'

N 56349.21

E 49369.23E 49566.35

N 56390.43 N 56243.60

?

?

?

? ?

? ?

?

?

?

?

?

?

?

?

C B A

40°(16°)/N330°




monitoring of vibrations was suggested to be

carried on the right bank slope to study the impact

of blast on the vulnerable slide mass. Typical

locations such as right bank toe in dam pit area,

grouting gallery, national highway level, cable car

bench and colony area were chosen as monitoring

points. Real time monitoring of ground and air

vibrations were monitored.

Peak particle velocity and air overpressures

resulting from blast vibrations were recorded at

various locations. The data pertaining to blast such

as total quantity of explosives and blast holes were

also obtained from the agency responsible for

construction of dam. A correlation between the

quantity of explosives, distance and peak particle

velocity was arrived at through regression analysis.

Blast vibration monitoring was carried out at 18

locations on the right bank of dam site focusing on

the vulnerable slide mass. A total of 49 blast

vibration data was recorded. Blast locations and

ground motion monitoring points have been

depicted in Fig. 3. Installation of instrument and

monitoring of vibrations is shown in Figs. 4a and

4b.

SAFETY CRITERIA

Ground Vibration: A small part of the blast energy

is utilised for breakage and displacement of the rock

mass, the rest of the energy accounts for ground

vibrations, air blasts, noises, back breaks, flyrocks,

dusts etc. [3-6]. The structural damages produced

by ground vibration are commonly correlated with

the peak particle velocity and safety criteria are

suggested accordingly. However, the mechanism

of damage cannot be explained only in terms of the

peak particle velocity. Persson [7] developed the

damage criteria for Swedish hard rock. Li and

Huang [8] discussed damage criteria for rock

tunnels with slight, medium and serious damage

conditions.

Director General of Mines Safety [9] has laid out

permissible levels of vibration at the foundation

level structures when carrying out blasting

operations in mining areas (DGMS (Tech) (S&T)

Circular No: 7 of 1997). Typical blasting limits

for various types of buildings in different

countries have been described by Roy [10].

Fig. 3: Blast locations and ground vibration

monitoring points

a) National Highway Location

b) Grouting Gallery Location

Fig. 4: Blast Vibration Monitoring in Progress at

Right bank of Dam site area.

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Maximum allowable peak particle velocity for the

RCC frame structures, brick/plastered houses and

mud houses as per DGMS [9] and Bureau of Indian

Standards (IS 14881:2001) [11] criteria are shown

in Fig. 5.

a) DGMS Safety Criteria

b) BIS Safety Criteria

Fig. 5: DGMS and BIS safety criteria for ground

vibrations

Air Vibration (IS 14881: 2001): Limits are based

upon wall response necessary to produce strains

equivalent to those produced by surface coal mining

induced ground motions with peak particle velocity

of 19 mm/s (Table 1). These limits are presented

below as function of instrument’s frequency

weighing scales as different sound–weighing scales

are employed by different monitoring instruments.

Most cases of broken glass are reported to have been

observed at air over pressures of 136 – 140 dB

(measured with a linear transducer).

Table 1: Table showing BIS safety criteria for air

overpressure

Lower Frequency Limit of

measuring System (Hz – 3 dB)

Maximum

Levels (dB)

0.1 or lower – flat response 134 peak

2 or lower – flat response 133 peak

6 or lower – flat response 7 peak

RESULTS AND DISCUSSIONS

The vibration recording instrument was set to

record the vibration in the normal range of geo-

trigger level starting 0.50 mm/sec to 254

mm/sec and Mic trigger level ranging from 100 to

148 dB (L). All the records were individually

viewed and interpreted. The recorded PPV and air

blast (air overpressure) was compared with the

general guidelines set by the DGMS and BIS.

Permissible limits of PPV being followed

worldwide were also referred. The guidelines for

permissible limits of PPV and air blast are

generally for the different kinds of buildings

including monumental structures. However,

Environmental guidelines [12] by Department of

Natural Resources and Environment Minerals and

Petroleum, Victoria suggests limits for PPV and

airblast (Air over pressure) as 5 mm/sec and 115

dB, respectively for sensitive sites (new sites).

In the present study, distances of the monitoring

points from the blast location through ground were

approximated from the cross sections drawn at

upstream and downstream of dam axis. The

distances, quantity of explosives and the

corresponding PPV pertaining to various blasts are

given in given Table 2.




Table 2: Blast vibrations data

Blast

Location

along Left

Bank

Monitoring Point on Right

Bank

Quantity of

Explosives,

kg

PPV

mm/se

c

Air Over

Pressure

Location Approximated

Distance, m

Dam, EL

1097 m

NH, EL

1217 m

245 1351 2.32 144.2

Dam, EL

1095 m

Dam Pit,

EL 1115 m

112 932 10.0 > 148 dB

Dam, EL

1097 m

Grouting

Gallery ,

EL 1168 m

193 1029 2.65 > 148 dB

Dam and

Power Intake,

EL 1095 m

Bjimthong

Colony EL

1330 m

539 846 1.64 134.7

Dam and

Power Intake,

EL 1097 m

Cable car

bench, EL

1260 m

280 675.5 1.03 143.7

Dam and

Power

Intake, EL

1120m

Grouting

Gallery ,

EL 1168 m

193 774.5 8.6 113.8

Dam and

Power

Intake, EL

1120 m

Dam Pit,

EL 1115 m

112 1383 24.5 > 148 dB

Dam, EL

1096 m.

Bjimthong

Colony EL

1330 m

539 807 2.41 136.1

Dam and

Power Intake,

EL 1095 m

Cable car

bench, EL

1260 m

280 630 0.762 142.6

Left Bank,

Dam and

Power Intake,

EL 1096m

Right bank,

NH, EL

1217 m

245 411 1.02 141.5

Left Bank

dam

NH, EL

1221 m

238 1317 4.32 147.1

Dam and

Power Intake,

EL 1105 m

NH, EL

1227 m

325 472 1.78 138.2

Dam and

Power Intake,

EL 1105 m

NH () EL

1217 m

220 1662.5 0.254 106

Dam and

Power Intake,

EL 1105 m

PHEP-I

Colony, EL

1375 m

687 1172 2.16 134.6

Power Intake NH, EL

1226 m

347 341 0.889 139.7

Dam and

Power Intake,

EL 1120 m,

1100 m, 1205

m & 1216 m

Below NH,

EL 1212 m

361 741 1.9 137.3

Dam and

Power Intake

EL 1115 m

Near

Plunge

Pool, EL

1135 m

186 638 2.92 146.3

Power Intake,

EL 1205 m

and 1119 to

1123 m

Cable car

bench, EL

1265 m

330 132 0.762 139

Blast vibrations were monitored at different

locations/distances and using variable quantity of

explosives. In the event of data containing variable

distance, direct correlation between PPV and

quantity of explosives is not feasible. In order to

develop the correlation between PPV, distance and

quantity of explosives, concept of scaled distance

was utilized. Correlation co-efficient for scaled

distance was derived as d/w1/2.2

(m/kg1/2.2

) through

optimization (Where, d = distance of monitoring

point from blast location approximated along the

ground/rock line in m and w = total quantity of

explosive used in kg).

Hence, a plot between PPV and scaled distance

was drawn as shown in Fig. 6.

Fig. 6: PPV v/s scaled distance

Further, it is assumed that total quantity of

explosives works as single source of explosion.

Additionally, the distances are approximated based

on the desktop studies.

The plot between PPV (m/sec) versus scaled

distance (m/kg0.45

) was drawn and the regression

curve was fitted as shown in Figure 6. The best fit

correlation between PPV and scaled distance was

obtained as given in equation 2 (with correlation

coefficient of 0.55):

PPV = 26.032x (d/w0.45

)-0.97

(2)

Air overpressure has generally exceeded the

permissible values as per IS 14881: 2001. At

occasions, the instrument has indicated out of

range values which means that the intensity air

blast was beyond 148 dB.

y = 26.032x-0.969

0

5

10

15

20

25

30

0 10 20 30 40

PP

V (

mm

/sec

)

Scaled Distance (m/kg0.45)

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CONCLUSIONS

Safe PPV is project specific and it depends upon

the topography, geology, blasting practices etc.

Maximum PPV of 24.5 mm/sec was recorded at

dam pit (right bank). The quantity of explosives

corresponding to the maximum PPV was of the

order of 1383 kg (969 blast holes). The monitoring

point was very near to the blast location

approximately 112 m. Considering peak particle

velocity (PPV) of 5 mm/sec as the threshold

values, vibrations have exceeded at three locations.

Air overpressure has exceeded the permissible

limits in most of the blasts with some of the data

exceeding 148 dB also.

Best fit correlation between PPV and scaled

distance was obtained as PPV=26.032x(d/w0.45

)-0.97

with correlation co-efficient (R) as 0.55. Due to

approximation in distances and limited data,

present attenuation law is of limited utility for

preliminary safe blast design. Proposed correlation

may be further validated with more data.

Ground vibrations must be monitored during

blasting at right bank for necessary modifications

in the blast design, charge, pattern and delay etc. in

order to arrive at safe blast design.

ACKNOWLEDGEMENTS:

The blast vibration monitoring work was possible

due to cooperation and active participation of

WAPCOS Ltd.

REFERENCES

[1] MORRIS, G., 1950 - Vibrations due to

blasting and their effects on building

structures. The Engineer, 394/95; 414-418.

[2] Peter Jewitt (2014), Interim Report (PS02),

‘Geological Aspects related to the Sliding on

the Right Abutment’, 30 January.

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[5] Singh, D.P., Singh, T.N. and Goyal, M. (1994)

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[6] Wiss, J.F. and Linehan, P.W. (1978) ‘Control

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[7] Persson, P.A.: The relationship between strain

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