Aruchanalam Q & A

8/12/2019 Aruchanalam Q & A

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Would you please define and explain what peak particle velocity is?

Peak particle velocity refers to the maximum speed of a particular particle as it oscillates about a point of

equilibrium that is moved by a passing wave. It is a term used to describe vibration, or elastic movement,resulting from excitation by seismic energy as it passes a particular point. We usually measure this speed

in "inch or inches per second." he reason we use this measurement is that it has been shown in

numerous studies over the years to be the best indicator of whether damage to a residential structure is

possible or likely.

What is Scaled Distance?

!caled distance is a relationship used to relate similar blast effects from various explosive weights at

various distances. !caled distance gives a blaster an idea of expected vibration levels based upon priorblasts detonated at a proect. It is calculated by taking the distance in feet from the blast #source$ to the

receiver and dividing it by the square root of the maximum pounds of explosives detonated per delay. It is

for estimation and may supplement actual seismograph measurements.

Why isn't the seismograph reading taken inside the home?

he interior measurements represent "structure" motion and are not considered the same. In many cases

the vibration levels measured within the home are less. %esearch on the effects of blast vibration upon

structures has been conducted while recording the blast vibration on the ground, outside of the structure,

and usually in the area of the closest portion of the structure to the blast. &ibration recording by the 'nited

!tates (ureau of )ines and many other individual researchers, over many years, with many structures,

has allowed those researchers to observe, and predict with a very high degree of certainty, how typical

residential*type structures respond to blast vibration. +urther seismograph standards are based upon

exterior ground vibration levels which take into account the structures response to vibration. he

measurements on the exterior also allow for consistency. he geophone or transducer #sensor of the

seismograph$ is attached and secured by spiking, burying or other physical attachment that cannot be

accomplished within someones home. he outside measurement is consistent and allows comparison of

the measurements on a day by day basis.

How can you guarantee that my property will not be damaged by the blasting at this site?

%egulations that govern most quarries, mines and construction proects place limits on vibration to protect

nearby structures whether that structure is ten feet or thousands of feet away from the blast. he blast is

designed to meet these regulatory limits, and monitoring of every blast is done in order to ensure


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compliance to the limits. )aintaining levels below limits provides off*site vibration levels that will not cause

new defects or aggravate existing defects.

What are the vibrations limits recommended within the US !ureau of "ines reports?

he '!() recommended limits are published in %eport of Investigations -o. /01. he "2*curve or

!iskind curve" is the information most often cited, which was published in 340 as a result of an extensive

study conducted in the late 3410s. he study was completed using numerous blasts, throughout several

states, while monitoring at different types of structures. he graph shows recommended limits to reduce

the damage potential for structures when comparing ground velocity with its associated frequency. he

'!() curve is like a speed limit. If vibration levels do not exceed the curve, damage is not likely. +or

those cases over this limit it does not automatically mean vibration has caused damage5 however, it does

indicate a thorough evaluation should be made. he graph shows the limits recommended by the '!()

to preclude cosmetic damage to plaster and drywall, the most fragile building materials.

It was determined by the evaluation that each of the structure types #single, 3 6 and 7*story homes$ have

a varying natural frequency. (last vibration matching the frequency of the structure of concern may

amplify the shaking within the house. If the particle velocity is high enough, cracks can occur or may be

extended. his cosmetic, threshold damage potential is alleviated when the limits are maintained. 8s the

frequency of the ground motion changes from low to high #3*90 :ert;$ the structure responds less and the

limits increase. 8 safe level of 0./0 ips for plaster and 0.1/ ips for drywall that exists for 9 * 3/ :ert;

increases as the frequency increases to a maximum velocity of 7.00 ips.

# know there has been research on safe blasting levels$ but that study was not done in the state

where # reside

(uilding materials that are in your home did not necessarily come from your state either. he criteria in

place are designed to protect building materials regardless of where those materials are located. hose

materials dont change as they are designed to meet minimum 8!) published standards which are

incorporated into


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the closer to a structure the operation progresses. his is all designed to limit vibration leaving the proect

site.

# feel vibration #s that not causing damage since # feel it?

People feel vibration and are very perceptive to a very small amount of ground motion. :owever, people

cannot put a value on the amount of motion created, which is necessary to assess whether damage

occurs. hat is the key issue in determining damage potential. Was there sufficient vibration to create

damage> here is no disagreement to feeling vibration, but homes take quite a lot of vibration before

damage occurs. :omes are built to move and react to everyday activity and environmental motion. ?oor

slamming, thunderstorm activity and wind all produce vibration that we feel and take for granted since

they are "cultural" events. he level of vibration in these events equals or exceeds the vibration from

blasting or other vibration activity. (uilding materials can withstand specific vibration levels before

damage occurs.

)ne blast may be low and below regulated levels$ but blast after blast will slowly add up and

eventually wear my house down and damage it after several years.

he 'nited !tates (ureau of )ines studied the repeated effects of vibration on structures. hey

concluded that as long as the vibration levels were below regulated limits, cumulative or repeated effects

that produce fatigue were not seen. heir conclusions summari;ed that a home could withstand blasting

twice per day at 0./0 inch per second for 7 years before the first crack would be expected to be

extended, let alone a new crack created. In the same study, they found that there were forces acting on

the structures that were greater than the levels from the blasting operation. hese factors were changes

in temperature and changes in humidity. hese forces occur every day and are constantly putting strain

on the structure in excess of the vibration. !ince these occur over many years daily during the life of the

structure, with greater effect there is little vibration will do within the regulatory limits.

Why is it that some blasts feel stronger while others are mild in comparison?

:uman perception is not a good measure of blast effects. (lasting and other vibration producing activities

do not take place in the same location each time. he change in distance may affect the actual vibration

levels and this would be supported by seismograph measurements. Whether or not the person is

expecting the blast or whether they are inside or outside at the time of the blast may affect perception as

well. In the case of construction blasting the actual blasts may change the explosives type or amount

necessary to break rock being excavated. In addition, the si;e of the blast, orientation and direction of

initiation may also affect perception. 8lso, the airblast may cause an additional effect. he ground

vibration travels faster than the airblast #noise$ associated with the detonation, and each affect the


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structure differently. 8s airblast is highly affected by environmental conditions, mainly wind, the effects

change with each blast.

Why do # feel two vibration *+olts* a few seconds apart?

When a blast is detonated, there are two primary effects * one is ground vibration and the other is air

overpressure, or airblast. he ground vibrations move very quickly, arriving at nearby structures within a

few seconds typically. he airblast waves move comparatively slowly, at about 3,000 feet per

second. his can be compared to seeing lightning and then hearing the thunder. he light travels

extremely quickly compared to the sound wave. In the case of vibration, the ground motion is the faster of

the two components. his creates two separate pulses as the vibration affects the structure and then the

airblast.

,his blasting is going to ruin my well How are you going to protect my well?

here are two maor areas to consider with wells and natural water supplies. @ne alleged cause of well

problems commonly claimed is from rock fracturing. o cause fracturing or shifting of rock strata, blasting

operations must be within close proximity to the well. )any people believe that if the energy can be felt

then it is also fracturing the rock at that distance. his is not the case. +racturing of the rock takes place

within about 30 feet of the drilled borehole. @utside of that radius, the energy that remains is elastic in

nature and is felt as ground vibration. +or the overall blast the fracture ;one is a bit bigger but not past a

few hundred feet, depending also upon the si;e of the blast. his is the reason drillers put boreholes on a

specific spacing pattern and use multiple holes in a blast. In other words, the fracturing of the rock only

occurs within a very small area around the drilled blast hole.

+or the vibration component of a blast, well studies dealing with ground vibration produced from surface

mining provide solid research. -umerous studies were developed to analy;e the relationship between

ground vibrations, well components and the aquifer. hese studies all concluded that vibration damage to

wells and well components requires much higher velocities than the regulated levels currently set by state

and local governments. %esearch shows that wells are resilient to vibration and levels at the surface are

reduced at the depth of the well. his precludes damage to submerged pumps and plumbing and the well

casing.

What is vibration & air over pressure?

Ground-borne vibration can be generated by a number of sources, including road

and railways, construction activities such as piling, blasting and tunnelling.


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Vibration can be defined as regularly repeated movement of a physical object

about a fixed point. The parameter normally used to assess the ground vibration is

the peak particle velocity ppv! expressed in millimetres per second mm"s!.

#n order to completely define ground vibration, the amplitude and fre$uency of the

motion are measured in the three orthogonal directions generally in terms of

velocity which is considered to be the best descriptor for assessing human comfort

and the potential damage response of structures. The vibration velocity signals are

summed in real time! and the maximum amplitude of this vector sum is defined as

the %eak Vector &um %V&!.

Vibration can cause varying degrees of damage in buildings and affect vibration-

sensitive machinery or e$uipment . #ts effect on people may be to cause

disturbance or annoyance or, at higher levels, to affect a person's ability to work.

To put vibration levels in context, below is a list of common tasks and the level of

vibration they produce(

Activity Vibration (mm/s Peak Particle

Velocity(PPV))umping *p to +

ammering nail *p to /

&liding door *p to /

&hutting door *p to 0

1ir overpressure is energy transmitted from a blast site within the atmosphere in

the form of pressure waves. 1s these waves pass a given position, the pressure of

the air rises very rapidly then falls more slowly then returns to the ambient valueafter a number of oscillations. The maximum excess pressure in this wave is

known as the peak air overpressure, generally measured in decibels, using the

linear or unweighted! scale to obtain an unfiltered reading of the change in

pressure. The unit used is d2 3inear.


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Vibration generating activities which can cause annoyance and are typically

monitored form an environmental impact perspective include(

2lasting at mine, $uarrying and rock removal during road construction and

building basement development.

%iling

4emolition

5oad 6 rail traffic

2last vibration is very dependent on the sites geological condition, distance to the

blast and the blasting techni$ue and amount of explosives used. #t can be designed

to ensure vibration and air overpressure levles are within acceptable limits. 2last

design can be modified by(

7umber of blast holes

8eight of explosive

1mount of stemming

4elay timing

Typical levels measured during construction activities are shown below(

Construction Activity Typical roun! Vibration "evel

Vibratory roller *p to /.mms 9 +m

ydraulic rock breakers :. mm"s 9 m, .: 9 +m, ./ 9

m;ompactor +mm"s 9 m,


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Truck traffic rough surface!


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than one area within a site then more than one monitoring location may be

necessary. #n some situations access to a vibration sensitive building may not be

practicable. #n this case, consideration can be given to the selection of a location

away from the building in a general line with the area to be blasted and at whichmonitoring could be regularly undertaken. &uch locations may be at or just within

the site boundary.

2ritish &tandard A0B( %art /, /CC discusses the measurement of vibration in

buildings in general terms with more specific advice for damage investigation

given in 2& A0B( %art +, /CC0 and for human perception in 2& D:A+, /CC+.

8hen vibration limits are set, they usually refer to recordings taken at ground level

at specified properties usually the closest!. 2&A0B(%art / states "Where the

purpose is to monitor with regard to imposed vibration, the preferred position is at

the foundation, a typical location being at a point low on the main load-bearing

external wall at ground floor level when measurements on the foundations proper

are not possible". The reason for this is that structural damage criteria from around

the world specify vibration limits that apply at foundation level. #ndeed the vast

majority of damage noted in studies does not occur on upper floors in structures

but mainly on lower floors where the strains are greatest due to the confinement of

the foundation.

#f transducers are placed on the ground alongside the building being monitored, the

recorded vibrations can be significantly affected by surface or near-surface features

which may have a very localised affect. 1t high levels of vibration which occur at

certain fre$uencies, it is also possible for transducers to leave the ground. 1gain

2&A0B(%art / suggests that when monitoring on the ground, a stiff steel rod

should be driven into the ground, through the loose surface layer, and the

transducer attached to ensure close contact with the ground. 1lternatively it can be

fixed to a rigid surface plate such as a well-bedded paving slab. &ome e$uipment


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manufacturers suggest placing a small sandbag on top of the transducer if it is

simply placed on a hard surface.

Eor more information on monitoring see the Aood Buarry website

%eulations an! 'tan!ar!s

Vibration standards come in two varieties( those dealing with human comfort and

those dealing with cosmetic or structural damage to buildings. #n both instances,

the magnitude of vibration is expressed in terms of %eak %article Velocity %%V!

and millimetres per second mm"s!.

Guidance relevant to acceptable vibration at the foundation of buildings is

contained within 2& A0B /CC0!( ?valuation and measurement for vibration in

buildings %art +( Guide to damage levels from ground-borne vibration. This states

that that there should typically be no cosmetic damage if transient vibration does

not exceed /mm"s at low fre$uencies rising to +mm"s at /= and mm"s at

:= and above. These guidelines relate to relatively modern buildings and are

normally be reduced to F or less for more critical buildings. ;ritical buildingsinclude premises with machinery that is highly sensitive to vibration or historic

buildings that may be in poor repair, including residential properties.

The German standard 4#7:/ provides limits below which it is very unlikely that

there will be any cosmetic damage to buildings. Eor structures that are of great

intrinsic value and are particularly sensitive to vibration, transient vibration should

not exceed 0mm"s at low fre$uencies. 1llowable levels increase to Bmm"s at =

and /mm"s at /= and above.

#n #reland, the 7ational 5oads 1uthority 751! have issued Auidelines for the

reatment of -oise and &ibration in -ational %oad !chemes and have

indicated Table +-751 Guidance!typically deemed acceptable vibration levels in
http://www.goodquarry.com/article.aspx?id=19&navid=1http://www.nra.ie/Publications/DownloadableDocumentation/Environment/file,3482,en.PDFhttp://www.nra.ie/Publications/DownloadableDocumentation/Environment/file,3482,en.PDFhttp://www.goodquarry.com/article.aspx?id=19&navid=1http://www.nra.ie/Publications/DownloadableDocumentation/Environment/file,3482,en.PDFhttp://www.nra.ie/Publications/DownloadableDocumentation/Environment/file,3482,en.PDF


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order to minimise the risk of building damage during road construction as shown

below(.

#n practice, construction vibration limits may be found in planning permission

conditions for large projects which are likely to generate potentially significant

vibration, limits are usually set which are below the thresholds of structural and

cosmetic damage in order to limit nuisance. #n addition ?%1 #%%; 3icenced

facilities such as large $uarries and mining operations typically have vibration

limits of B-/+mm"s daytime and :mm"s night time

2& A0B /CC0 as referred to above gives guide values with respect damage

classifications for residential structures in terms of peak particle velocity and

fre$uency. These values are based on the lowest vibration levels above which

damage has been credibly demonstrated. 2uilding 5esearch ?stablishment 25?!

4igest 00 )uly /CC!( 4amage to structures from ground borne vibration is also a

useful document in vibration assessment. 2ritish &tandard D:A+, /CC+, Guide to

evaluation of human exposure to vibration in buildings /= to B =! and 2ritish

&tandard ++B( %art 0, /CCA, 7oise and vibration control on construction sites, %art

0.;ode of practice applicable to surface coal extraction by opencast methods are

also applicable in this respect.

Eor additional information standards see the8cceptable levelson the Good

uarry website

#uman %esponse to Vibration
http://www.goodquarry.com/article.aspx?id=18&navid=1#buildingshttp://www.goodquarry.com/article.aspx?id=18&navid=1#buildings


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uman response to blast induced ground vibration is a relatively complex

phenomenon and is dependent upon a range of factors of which the actual vibration

magnitude is only one and not necessarily the most important. #t is well recognised

that the human body is very sensitive to the onset of vibration albeit very poor atdistinguishing relative magnitudes. 1lthough sensitivity to vibration varies

significantly between individuals, a person will generally become aware of blast

induced vibration at levels of around . mms-/peak particle velocity, however

individuals are very poor at distinguishing between vibrations of differing

magnitudes.

This threshold of perception of vibration is very much lower than the onset of even

cosmetic damage plaster cracking at typically least


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Consultnet Vibration onitorin 'ervices

Hur ;onsultant have been involved in vibration monitoring and control on #relandJs

largest mining and construction projects during the past twenty years, our services

include(

>onitor and measure vibration and air overpressure from construction

blasting or piling activities

>onitor and measure vibration and air overpressure from mine and $uarry

blasting

1dvice on vibration prediction and mitigation

;ommunity interface and complaint management

At Consultnet we use the Instantel Minimate monitors for routine vibration and air

overpressure monitoring activities

&ee also-onsultnet .oise "onitoring Services

"inks to other sources o inormation on environmental vibration*

#uman response to vibration in resi!ential environments

Good uarry (lasting C &ibration Information

ueensland -oise and vibrationfrom blasting
http://www.consultnet.ie/environmental%20noise.htm#Consultnet_Noise_Consultancy_Services_http://www.defra.gov.uk/environment/noise/research/pdf/human-response-vibration-residential-environments.pdfhttp://www.goodquarry.com/article.aspx?id=1&navid=1http://www.epa.qld.gov.au/publications/p01382aa.pdf/Noise_and_vibration_from_blasting.pdfhttp://www.epa.qld.gov.au/publications/p01382aa.pdf/Noise_and_vibration_from_blasting.pdfhttp://www.epa.qld.gov.au/publications/p01382aa.pdf/Noise_and_vibration_from_blasting.pdfhttp://www.consultnet.ie/environmental%20noise.htm#Consultnet_Noise_Consultancy_Services_http://www.defra.gov.uk/environment/noise/research/pdf/human-response-vibration-residential-environments.pdfhttp://www.goodquarry.com/article.aspx?id=1&navid=1http://www.epa.qld.gov.au/publications/p01382aa.pdf/Noise_and_vibration_from_blasting.pdf


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3inks to acoustics and vibrationweb resources

8coustics and &ibration888 Virtual 3ibrary

*& based 7#H& on &ibration

*& based ?3;H&on ;onstruction 7oise and Vibration

1ustralian information on -oiseand (est Practice in -oise and

&ibration-oise C &ibration and 8irblast


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Aruchanalam Q & A