an overview of ground motion and vibration studies - slac

1Fred Asiri

ILC- Snowmass 2005- WG 4

An Overview of Ground Motion and Vibration

Studies

2Fred Asiri


AcknowledgementsAcknowledgements•• SLAC Accelerator Physics:SLAC Accelerator Physics:

Andrei Seryi, Fredric Le PimpecAndrei Seryi, Fredric Le Pimpec•• SLAC Conventional Facility:SLAC Conventional Facility:

Clay Corvin, Javier Sevilla, Jerry AaronsClay Corvin, Javier Sevilla, Jerry Aarons•• Colin Gordon & Associates:Colin Gordon & Associates:

Hal Amick, Tao Xu, Nat WongrasertHal Amick, Tao Xu, Nat Wongrasert•• DMJM & Harris:DMJM & Harris:

Sven SvendsenSven Svendsen•• Parsons/Geovision team:Parsons/Geovision team:

Bruce Shelton, Paul MacCaldenBruce Shelton, Paul MacCaldenRobert Nigbor, Rod Merrill, Brent LawrenceRobert Nigbor, Rod Merrill, Brent Lawrence

•• Seismic Isolation Engineering (SIE inc.):Seismic Isolation Engineering (SIE inc.):Fred Tajirian, Mansour TabatabaieFred Tajirian, Mansour Tabatabaie

3Fred Asiri


Far-Field Excitation(Ambient Ground Motion

Measurement)

Acceptance Criteria

Select a Location(Representative Site)

Good Geology and Quiet

Select and LocateNear-Field

(Chillers, Pumps, etc.)

Geotechnical Studies(Soil/Rock Dynamic

Parameters)

Attenuation Characteristics of

Soil/Rock

Estimate Near-Field Excitation

(At Their Footings)

Adopt as a Concept Design Requirement

Estimate Technical Foundation Vibration

( Response to Near and Far Fields Sources)

NoYes

4Fred Asiri


Representative LC Site- Logan Ridge, California

1. View South 2. View West & Vibration Station 3. View North

Surface measurements of vibration are plotted below and are comparable with those in the LEP tunnel. They exceed the goals for X-band stability and they can be found in a variety of locations worldwide.

A typical sandstone outcrop at the site is shown below. The near surface rock is soft, competent and well blocked. High tunnel boring machine advance rates are obtainable in sandstone. It is an ideal rock for the LC.

1 2 3

5Fred Asiri


The measurements plotted above are taken in NUMI tunnel at shallow depth and in Aurora mine. Despite the surface being populated and moderately urbanized, the underground locations are relatively quiet.

Surface Projection of LC Alignment-Dekalb, Illinois

Aurora quarry mine, ILMeasurement location in NUMI tunnel, IL

The Galena-Platteville Dolomite is shown above in outcrop. Beneath the DeKalb LC site at a depth of ~300 ft these two units make up a 300+ ft thick, near horizontal, uniform, carbonate unit which has excellent rock mass characteristics that make it an ideal rock for the LC.

Representative LC Site- Dekalb, Illinois

6Fred Asiri


7Fred Asiri


@ 100 m

8Fred Asiri


Sensor

Concrete

ModulatorAverage integrated displacement at the base of the modulator and near its support.Modulator pulsed noise @ 60 Hz: < 30nm on the modulator < 12 nm on the floor (within acceptable limit)

Characterization of Vibration Sources in the Support Tunnel

The chiller (~700 lb) shown here vibrates by 2-3micron at 59Hz. If mounted rigidly, it transmits ~30nm to the floor near the support. Same chiller mounted on soft spring transmits considerably less vibration to the floor (<nm).

Chiller Vibration

Floor Vibration

9Fred Asiri


Vibration transmissibility was measured at two locations:•At SLAC along Sector 9 and 10 for Cut-&-Cover construction method

––Eocene sandstone and claystone (shear velocity of ~720 m/seEocene sandstone and claystone (shear velocity of ~720 m/se•At the Los Angeles County Metropolitan Transportation Authority (MTA) Red Line tunnels near the Universal City Station for shallow tunneling construction method

––Miocene sandstone and shale (shear velocity of ~950 m/sec)Miocene sandstone and shale (shear velocity of ~950 m/sec)

Experimentally determined the vibration transmissibility for two construction methods namely Cut-&-Cover and shallow tunneling

10Fred Asiri


s2S2

S1

R1R2R3R4R5

-50

0

50

100

150

200

-400 -300 -200 -100 0 100 200

Source

Receiver

Beam CL

S1

S2

R1R2R3R4R5

Location Plan View of Sources S# and Receptors R#Location Plan View of Sources S# and Receptors R#

•At SLAC along Sector 9 and 10 for Cut-&-Cover construction method

Typical Cross Section of Typical Cross Section of Accelerator Housing and Accelerator Housing and Klystron Gallery at SLACKlystron Gallery at SLACPlan Layout of Sector 9 and 10 at SLAC

11Fred Asiri


Ambient Vibration at Receiver Location R5

Source Receiver Distance, ft Attenuation at Given Frequency

10 Hz 20 Hz 30 Hz 60 Hz

S1

R1 130 0.014 0.0084 0.012 0.005

R2 134 0.012 0.012 0.014 0.004

R3 162 0.011 0.0084 0.006 0.001

R4 233 0.010 0.004 0.002 0.001

R5 289 0.005 0.002 0.0009 0.0003

0.00001

0.0001

0.001

0.01

0.1

1

1 10 100

Frequency, HzC

hang

e in

Am

plitu

de

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

Cha

nge

in A

mpl

itude

, dB

R1/S1R2/S1R3/S1R4/S1R5/S1

The figures in the above table represent the attenuation Factor for a vibration with its source near S1 propagating along the same path.

Example 1: Suppose a pump is installed at S1, and it produces a vibration at 60 Hz with an amplitude of X. The amplitude at 60 Hz that we measure at R5 would be the greater of either ambient or 0.0003X.

Example2: If we want to place a pump at S1 and not to exceed ambient at R5 (0.6µ in/sec), then we need to impose a limit on the resulting vibration at S1 of 0.6/0.0003=0.002 in /sec.

Log Mean Transmission From Drive Point S!Log Mean Transmission From Drive Point S!

12Fred Asiri


~ 40 ft

Hollywood (101)FWY

~ 90

ft

A B

LC Cross Section

4.5 m ID

~ 6 m

Vibration Measurements in the LA Metro Red Line TunnelsVibration Measurements in the LA Metro Red Line Tunnels

13Fred Asiri


S

R-0’

Tunnel A

R-300’ R-100’

Tunnel B

R-95’ R-48’

~39’

“S” Location of the 100-kg drop source

“R” Location of the sensors,

The LCC-0122 and LCC-0123 have been revised and the revisions are posted:

14Fred Asiri


0 FeetFIG10-REV-2.PDW

0 10 20 30 40 50 60 70 80 90 100 110 120

Frequency (Hz)

0.001

0.01

0.1

1

Att

enua

tion

(Res

pons

e in

Tun

nel B

/Sou

rce

in T

unne

l A)

100 Feet

300 Feet

FIG-9-REV-1.PDW

0 10 20 30 40 50 60 70 80 90 100 110 120

Frequency (Hz)

0.00000001

0.0000001

0.000001

0.00001

Mob

ility

[V

eloc

ity/F

orce

- (c

m/s

ec)/N

]

@ 20 Feet From Source

Support to Beam tunnel transmission measured in LA metro tunnels and verified with 3D modeling computer program (SASSI). At 60Hz the mobility across tunnels is ~1 nm/100 Newton's permitting moderate vibration in Support tunnel. If required, vibration due to rotating equipment can be eliminated with standard inexpensive means, e.g. 3Hz springs.

15Fred Asiri


0.00001

0.0001

0.001

0.01

0.1

0 50 100 150 200 250 300

Distance Along Tunnel B (Source in Tunnel A at 0 ft.) (ft.)

Velo

city

(cm

/sec

)

Nighbor Measured 4/9/04 Test 4 Unfiltered

Nighbor Measured 4/9/04 Test 4 Filtered

250' SASSI/Tunnel B with Liner Upper Bound Soil

250' SASSI/Tunnel B with Liner Lower Bound Soil

AB

0'

250'

Comparison of Maximum Calculated and Measured Velocities in Tunnel B, Lower Bound and Upper Bound Soil

1.E-10

1.E-09

1.E-08

1.E-07

1.E-06

1.E-05

0 10 20 30 40 50 60 70 80 90 100Frequency, Hz

Mob

ility

cm

/s/N

Calculated Mobility @ 20 ft.Calculated Mobility @ 100 ft.Measured mobility @ 20 ft.Measured mobility @ 100 ft.Parson's Report Mobility @ 20 ft.

Comparison of Calculated and Measured Mobilities

The results of the 3-D computer simulation program “SASSI” and the measured vibration data from the MTA tunnel tests are correlated.

The SASSI simulation computer program can be used to predict the attenuations of vibration emanating sources in the support tunnel to the vibration sensitive equipment in the beam tunnel.

16Fred Asiri


Science Vibration and Stability Needs for Warm LCScience Vibration and Stability Needs for Warm LC––Assumptions:Assumptions:

The total beam jitter at the IP is 50% of the beam size, with thThe total beam jitter at the IP is 50% of the beam size, with the e following uncorrelated contributions:following uncorrelated contributions:

30% from the main linac, 30% from the beam delivery, 25% from 30% from the main linac, 30% from the beam delivery, 25% from the final doublet, and with 15% injection jitter, RSS is ~ 50%the final doublet, and with 15% injection jitter, RSS is ~ 50%–– Assuming the above jitter budget:Assuming the above jitter budget:

The vertical vibration of the linac quadrupoles needs to be lessThe vertical vibration of the linac quadrupoles needs to be lessthan 12 than 12 nm above several Hznm above several Hz––Ground stability:Ground stability:

Considering that the normal operations include a 9 month run Considering that the normal operations include a 9 month run cycle, followed by a 3 month period for maintenance & alignment,cycle, followed by a 3 month period for maintenance & alignment,

An annual relative drift rate at the beam pedestal support floorAn annual relative drift rate at the beam pedestal support floorshould be less than +/should be less than +/-- 2 mm over a distance of 200 meters.2 mm over a distance of 200 meters.

What are the Science Vibration and Stability Needs for the Cold LC?

17Fred Asiri


Vibration Criteria at the invert of Beam HousingVibration Criteria at the invert of Beam HousingThe RMS value of the imported (i.e. added) The RMS value of the imported (i.e. added) broadband vibration integrated above 3 Hz should broadband vibration integrated above 3 Hz should be less than a factor of two (2) times the prebe less than a factor of two (2) times the pre--existing ground vibration amplitude, excluding existing ground vibration amplitude, excluding the resonant the resonant ““spikespike”” vibrations synchronous with vibrations synchronous with collider repetition rate.collider repetition rate.With the resonant spikes included, the RMS With the resonant spikes included, the RMS amplitude above 3 Hz should be less than a factor amplitude above 3 Hz should be less than a factor of three (3) times the preof three (3) times the pre--existing ground existing ground vibration amplitude.vibration amplitude.

Beam Housing Foundation Vibration CriteriaBeam Housing Foundation Vibration Criteria--WarmWarm

Its assumed that the preIts assumed that the pre--existing RMS value of the existing RMS value of the vertical component of vertical component of ground vibration amplitude ground vibration amplitude is less than is less than two nanometers two nanometers integrated above 3 Hz.integrated above 3 Hz.

Hz

Inte

grat

ed, m x 3

With sync. spikes

Hz

m2 /H

z integrate

Hz

Inte

grat

ed, m x 2

Without sync. spikes

18Fred Asiri


Vibration Criteria at the invert of Beam HousingVibration Criteria at the invert of Beam HousingThe RMS value of the imported (i.e. added) The RMS value of the imported (i.e. added) broadband vibration integrated above 3 Hz should broadband vibration integrated above 3 Hz should be less than a factor of two (2) times the prebe less than a factor of two (2) times the pre--existing ground vibration amplitude, excluding existing ground vibration amplitude, excluding the resonant the resonant ““spikespike”” vibrations synchronous with vibrations synchronous with collider repetition rate.collider repetition rate.With the resonant spikes included, the RMS With the resonant spikes included, the RMS amplitude above 3 Hz should be less than a factor amplitude above 3 Hz should be less than a factor of three (3) times the preof three (3) times the pre--existing ground existing ground vibration amplitude.vibration amplitude.

Beam Housing Foundation Vibration CriteriaBeam Housing Foundation Vibration Criteria--ColdCold

Its assumed that the preIts assumed that the pre--existing existing RMS value of the vertical RMS value of the vertical component of ground vibration component of ground vibration amplitude is less than amplitude is less than 5 nanometers5 nanometers integrated above integrated above 3 Hz3 Hz. and . and less than 20 nanometersless than 20 nanometersintegrated above integrated above 0.5 Hz.0.5 Hz.

Hz

Inte

grat

ed, m x 3

With sync. spikes

Hz

m2 /H

z integrate

Hz

Inte

grat

ed, m x 2

Without sync. spikes

DRAFTED FROM WARM

19Fred Asiri


What should be done next? What should be done next? To measure ambient ground noise (natural, far-field) for the ILC Sample Illinois

sites at or near the Interaction Point We are planning to conduct this task

To identify and toTo identify and to characterize the major vibration sources (cultural, near-field) for the cold machine sub systems

Cryogenics systems (Compressors), LCW cooling system, rotating mechanical and electrical equipment (L-Band Modulator)

To adopt the vibration criteria (goals) and to determined the stability parameters for the cold machine (similar to the one for the warm machine)

Vibration budget for the cold machine is higher, but so the imported noises To utilized 3utilized 3--D computer modeling and to modify the parameters for the ILC D computer modeling and to modify the parameters for the ILC

Sample site Sample site SASSI models can be used to parametric predict transmissibility functionsMitigate vibration effects by trying different options, tradeoffThis can lead to better optimization of design requirements, as well as to better

manage the ILC vibration budget

an overview of ground motion and vibration studies - slac

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