Improvement of Different Grounds

Based on a grain size analysis a soil can be judged for its com-pactability:

Soils in zones A and B can be compacted by the deep vibratorycompaction method Vibro Compaction (also called “Vibro-flotation”), while soils of zones C and D cannot be compacted byvibration alone.

Soils in zone C are often found on sites where soil liquefactiondue to earthquakes is of concern. These soils can be compactedduring the installation of Stone Columns.

Soils in zone D are not compactable by vibration, but can be sub-stantially reinforced, stiffened and drained by installing StoneColumns.

Requirements for the soil to achieve good compaction by vibration:

• The soil must be permeable enough to allow rapid drainage ofthe pore water during the compaction process. The permeabili-ty is high enough for all granular soils with less than 12% finessmaller than sieve #200 (0.074 mm) AND less than 2 % clay.

• The friction angle of the soil must be high enough to permit the passage of the compacting shear waves. This requirement isusually satisfied if the soil is well graded.

• The sand or gravel should not be easily crushable (carbonatecontent in form of shells) or contain very platy mica mineralsthat would increase soil compressibility.

SOIL AND COMPACTION

2

% p

assi

ng

Soil Classification by Cone Penetration Testing (CPT)

Soil classification by grain size analysis is more precise than anyindirect way of soil classification.

However, as CPT sounding becomes more and more popular, thistest is used to predict not only the in situ relative density but alsothe soil type in which the sounding was made.

CPT Soil Classification Diagram after Dr. Robertson

Experience of our company with over 500 million m3 of sand andgravel compacted over the past 15 years suggests that three limitlines can be drawn that together define the zone of compactablegranular soil indicated by the green box.

Blue: Soils above this line are already dense and need no fur-ther compaction.

Red: Granular soils, including very loose fills, are hardly everfound to have an initial density of less than the value cor-responding to the red line.

Yellow: Experience shows that soils with a friction ratio Rf ofabove 0.8 % are problematic for compaction. This is be-lieved to be mainly due to high fines content but theremay also be other less well understood soil charac-teristics that coincide with a friction ratio above 0.8 %.

100

10

1

0,10 1

1012

11

8

7

6

5

4

3

21

2 3 4Friction ratio Rf (%)

5 6 7 8

Cone

bea

ring

qc

(MPa

)

9

3

Zone SoilBehaviour

1 sensitive finegrained

2 organic material3 clay4 silty clay to clay5 clayey silt to

silty clay6 sandy silt to

clayey silt7 silty sand to

sandy silt8 sand to silty

sand9 sand10 gravelly sand to

sand11 very stiff fine

grained*12 sand to clayey

sand*

* overconsolidated or cemented

Relative Density Dr

Vibro Compaction creates the most balanced relative

density profile of allcompaction methods.

Settlement as a resultof compaction of sand.

Stone Columns

Vibro Compaction

Digging out a stonecolumn and inspecting

the as built diameter isan inexpensive exercisethat generates trust in

the construction process.

0,00

5,00

10,00

15,00

20,00

25,00

30,00

35,00

40,00

45,00

50,00

0

50

100

150

200

250

300Dr=20%

Dr=80%Dr=40%

Dr=90%Dr=50% Dr=60%

Dr=70% Dr=100%

Effe

ctiv

e st

ress

(kP

a)

Cone resistance Qc (MPa)

Effects of Compaction

• The sand and gravel particles rearrange into a denser state.

• The ratio of horizontal to vertical effective stress is increasedsignificantly.

• The permeability of the soil is reduced 2 to 50 fold, dependingon many factors.

1 1.05

Vibration

Loose Flotation Dense

0.85

Settlement

VIBRO COMPACTION

The principle of sand compaction (Vibroflotation):

The compaction process, consists of a flotation

of the soil particles as a result of vibration, which then allows

for a rearrangement of the particles in a denser state.

Compaction of granular soils by depth vibrators is

known as Vibro Compaction. The method is also known

as “Vibroflotation”. Natural deposits as well as artifici-

ally reclaimed sands can be compacted to a depth of up

to 70 m. The intensity of compaction can be varied to

meet bearing capacity and settlement limitation criteria.

Other improvement effects such as reduction of settle-

ments are achieved at the same time.

The following diagrams illustrate the compaction process:

4

5

Penetration

The vibroprobe pene-trates to the required

depth by vibration andjetting action of water

and/or air.

3,10 m

Pattern No.: A

A1

A3

CPT or dynamic probing locations

A2

B1

B3

B2

C1

C3

C2

D1

D3

D2

E1

E3

E2

B C D E

4,30 m

3,40 m3,70 m

4,00 m

2,86 m 2,82 m 2,94 m 3,07 m 3,20 m 3,33 m 3,46 m 3,59 m 3,72 m

Test Pattern

Construction of a “hidden dam” thatstabilizes the hinter-land against land-slides.

Compaction

The vibroprobe isretracted in 0.5 m inter-

vals. The in situ sandor gravel is flowing to-wards the vibroprobe.

CompletionAfter compaction the

working platform has tobe levelled and eventu-

ally roller compacted.

• The friction angle typically increases by 10 degrees.

• Settlements of the compacted soil mass are in the range of 2 %to 15 %, typically 5 %.

• The stiffness modulus can be increased 2 to 5 fold.

On large projects the optimal compaction grid spacing has to bedetermined by test grids.

The compaction effect in the test grids should be as close as pos-sible to the treatment in the later production areas.

In order to achieve this it is advisable to arrange the test gridsclose to each other.

The distance between grid A (3.10 m) and grid B (3.40 m) should be(3.10 m + 3.40 m)

d = .–2 –23

= 2.82 m.

VIBRO COMPACTIONWhile the principle of Vibro Compaction (flotation of

grains into a denser state by vibration) is a simple

concept, the application of the technology in an optimal

manner is still an art that few have mastered.

The difficulty lies in the many parameters that can be varied andthe narrow band in which those parameters have to be adjustedto deliver the desired results. Some of the parameters that can bevaried are type of vibrator, grid spacing, holding time per depthinterval, water pressure, location and type of water jets.

The examples on these pages show some of the works we havesuccessfully undertaken.

Offshore Vibro Compaction

This offshore application of the Vibro Compaction process wasused on the North Lantau Expressway, Hong Kong for the com-paction of a loose sandfill in preparation for the placement of arockfill seawall on this sandfill.

6

The access to the new Hong Kong Airport:A major infrastructure project. Extensive marine and land compaction works were carried out by the Vibroflotation Group.

Members of theVibroflotation Groupwere involved in mostof the compaction pro-jects related to thenew Hong KongAirport

Central Reclamation Hong Kong: Thesand fill was improved by a VibroCompaction treatment prior to otherconstruction activity.

Hong Kong Airport: The Hong KongInternational Airport was constructed inlarge part from rock fill generated byblasting a local bluff.Sand fill areas with high loads were treated by Vibro Compaction. In 1995this 12 million m3 project was the lar-gest in the world.

7

Port of Monaco

A layer of up to 20 mthick cobble fill had tobe compacted workingoffshore through 32 m

of water. Penetrationwas achieved through

the cobble fill with average grain sizes of

around 10 cm andmaximum sizes of

25 cm in diameter.

Lausitz, Germany

The photo shows a V32vibroprobe on its way

down to a world recorddepth of over 68 m

(223 ft). More than 500million cubic metres ofsand have been com-pacted to protect the

slopes of the open pitexcavations in East

Germany.

Penny’s Bay Hong Kong: The world’s largest Vibro Compactionproject. Penny’s Bay Reclamation (more than 40 million m3 up to40 m deep).

Land Based Vibro Compaction

Dry Bottom Feed Stone

Columns were invented in

Germany in the early 1970’s.

They are particularly useful if

washout of soil to the surface

is to be prevented or where

handling of process water for

the Wet Top Feed method is

problematic.

Dry Bottom Feed Stone Columns have been successfully used onlarge infrastructure projects like earth dams, highway embank-ments, airport runways, port facilities and under large industrialstructures such as oil tanks and silos. They are a common choicefor foundations in liquefiable soils in earthquake prone areas.

The V-Rex

The V-Rex is a state-of-the-art custom built machine forDry Bottom Feed StoneColumns rigs.

Some of the advanced fea-tures include:

• Built in data acquisition

• Easy mobilisation/demo-bilisation

• Modular leader exten-sions

• Process control computer,combined with electronicwinches, drives rig duringcolumn installation on“autopilot”.

DRY STONE COLUMNS

V-Rex rigFoundation for a leisure

center in Germany.

Foundation for a bridge in Leipzig, Germany.

8

St. André Marseille, France.Slope stability reinforcement usingthe land type gravel pump.

9

The need for a fast and very efficient method of forming shallowto medium depth dry bottom feed stone columns lead to thedevelopment of the stitcher.

Advantages of the Vibro Stitcher:

• Simple operation. No high tech gravel transport system involved.

• Vibroprobe can be pushed down with force to preload thecolumn while producing it and to speed up the process.

• Verticality of the Vibroprobe can be controlled and corrected bythe excavator, manually or automatically.

Stone Columns and Liquefaction Prevention

Loose sandy soils below the water table liquefy during an earth-quake. To prevent this, stone columns can be installed and havea threefold effect:

• They drain the soil.

• They compact loose sand and gravel layers.

• They reinforce layers that cannot be compacted and facilitate drainage (mainly very silty sands to sandy silts)

Installation

Adding gravel through atremie pipe alongside

the Vibroprobe createsthe Stone Column.

Penetration

The vibroprobe pene-trates to the required

depth by vibration andjetting action of air.

The VibroStitcher

Stitcher installingDry Bottom FeedStone Columns inCrosby, UK

Completion

The column diametermay vary depending on

the initial stiffness/densi-ty of the soil. Differential

settlements are greatlyreduced by allowing

more gravel to be placed in weaker soil

regions.

The required diameter atany depth interval can

be sensed by observingthe vibroprobe’s motor

current, which is anexcellent indicator of the

confinement of themachine in the soil.

Shallow groundimprovement for roadworks by Dry StoneColumns, using theVibro Stitcher.

OFFSHORE STONE COLUMNS

Breakwater: 4830 No. stone columns, 16 m average length,77280 lin m, 60665 m3 (1 m diameter), average square spacing 2.7 m.Quaywall: 4500 No. stone columns, 10 m average length,45000 lin m, 35300 m3 (1 m diameter), average square spacing 2.85 m.

For many years there has been a need for the installa-

tion of high quality stone columns in an offshore envi-

ronment. Previous attempts to install offshore stone

columns often relied on the assumption that a mattress

of gravel dumped on the seabed could be worked into

the soil by moving a vibroprobe up and down.

No adequate means of quality control were available to demon-strate the integrity of columns installed in such a way. Proper docu-mentation involving monitoring of column diameter variation withdepth derived from measured batches of gravel placed at defineddepth intervals was totally out of reach. With the new Marine GravelPump technology the problem of installing high quality offshorestone columns has been solved. The Marine Double Lock GravelPump guarantees integral columns by continuously pressurisedstone discharge. Offshore platforms or dams under cyclic loadingor earthquake loading can now be founded cost efficiently andreliably on stone columns.

The stone columns for the foundation of a breakwater and quay-wall in Patras serve as drainage for excess pore pressures thatbuild up during construction of the seawall and also provideadditional strength under earthquake loading. The 1.0 m diame-ter stone columns in a 2.7 m to 3.3 m grid extend up to 20 minto the soft silty and clayey marine sediments. The water depthat the treatment location reaches up to 32 m. Both the break-water and the quaywall are treated with stone columns, as de-tailed below:

Port of Patras, Greece, construction of a seawall onloose liquefiable sandy and silty sediments.

10

Quality Control

While in a land based operation a stone column can be assessedwith load tests, or a borehole can be drilled into the column tocheck for continuity, such controls are not readily available underwater.

When recording onlyAmpere and depthinformation there is nocontrol to ensure thatgravel is placed at therequired location.Problems such asblockage of the graveltransport tube or lossof gravel on the seabed may not be detec-ted.

This danger does notexist in a land basedoperation, where ex-cessive spillage of gravel on the surfacecan be visually control-led.

Traditional data loggers are not able to generate the data re-quired to provide adequate control. However, a new data loggingmethod has now been developed which produces an outputshowing the stonecolumn diameter, mea-sured from the actualplaced volume of stones at the respect-ive depth. An exampleof such an output ispresented on the right.

On the graph to theright the stone columndiameter is plottedagainst depth. This isaccomplished by thecomputer through a re-cording of the time anddepth when each gravelbatch has been sentthrough the DoubleLock mechanism.

Sketch of Marine GravelPump

The patented Marine DoubleLock Gravel Pump has a snor-

kel hose (6), which is at-tached at the air exhaust lock(16b) to the receiver tank (8).

Snorkel hose (6) and locks(16a, 16b, 9) are operated insuch a way that while gravel

flows through hose (5) there is always atmospheric

pressure in the receiver tank(8), and even for 200 m

water depth a 7.5 bar com-pressor can transport the

gravel from blow tank (4) atthe surface to the receiver

tank (8) at depth.

A separate high pressurecompressor feeds directly

into the pressure tank (10).Since either lock (9) or locks(16) are closed, there is at alltimes a sufficient pressure tosurmount the water and soilpressures in the gravel tube

(11) at the tip (18) of thevibroprobe (17).

11

Wet Top Feed Stone

Columns were invented

in Germany in the early

1960’s. They are faster to

install and need less

sophisticated equipment

than Dry Bottom Feed

Stone Columns. However,

the installation technique

requires more experience

than Dry Bottom Feed

Stone Columns.

Where to Use the Wet Top Feed Stone Column Method?

• Where the compaction of sandy and gravelly layers is requiredand those layers are located above the water table. Compactionis generally better accomplished with the wet method than withthe dry method, as the flushing water assists in compaction ofthe sandy soil around the column.

• Where particularly clean stone columns are required. The flushing water cleans the columns during installation.

• Wherever there are no contaminants in the soil and the soil isnot a highly plastic clay leading to the problem of handling themud in the process water.

• Where space is available for a 500 m2 (= 5000 ft2) settlementpond.

• Where the installation crew has sufficient experience in themore demanding installation methodology.

WET STONE COLUMNS

Stone columnsWest Kowloon, Hong Kong.

12

Oregon, 195000 lin mof Wet Top Feed StoneColumns.

Penetration

The vibroprobe pene-trates to the required

depth by vibration andjetting action of water.

Installation

Adding gravel throughthe washed out annular

space alongside theVibroprobe creates the

stone column.

13

A Word on Ecology

The stone column is possibly the most “natural” foundationsystem in existence. Stone columns consist entirely of gravel, asubstance that is found naturally in the subsoil. No additives aremixed into the stone columns. They are therefore not only envi-

ronmentally neutral but alsomore durable than any otherfoundation system that wouldinvolve the use of cement orsteel.

Stone column foundation for a hotelat Coco Beach, Puerto Rico.

Hong KongNorth LantauExpressway, Tai Ho SectionMTRC traction substation8.000 m3 of stonecolumns.

CompletionThe surface is leveledand roller compacted.

Vibro Concrete Co-

lumns can be classi-

fied as cast-in-situ

displacement piles.

This type of pile has

a high bearing capa-

city due to a high

shaft friction and

the enlarged base

that can be installed

when dry concrete is

used.

There are two main types of Vibro Concrete Columns:

1. Vibro Concrete Columns (VCC) with pumped concrete.

2.Dry Vibro Concrete Columns (DVCC) where the concrete is a drymix.

Advantages of the DVCC Method over the VCC Method

The dry concrete is much less a liquid than the pumpable con-crete that is used for the standard VCC method.

This allows the vibroprobe to transmit more vibration waves andthereby compaction energy through the concrete into the soil.The DVCC method is therefore advisable for projects where theload bearing capability of a pure stone column is not sufficientand compaction of the soil around the pile is desired (e.g. to pre-vent liquefaction in an earthquake). The DVCC pile offers thecombined effect of high load bearing and soil compaction.

An enlarged gravel base can be formed to give the concretecolumn enhanced bearing capacity. It is also possible to build apartial stone and concrete column.

VIBRO CONCRETE COLUMNS

VCC constructed usinga truck mounted con-

crete pump.

14

15

DVCC with dry con-crete. Installation isdone in the sameway as a normalstone column. The advantage is tobe able to build anenlarged base and tobe able to vary thecolumn diameter.

Installation of VCC

1Locate rig over VCC point.

2Vibrate down to depth.

3Start the concrete pump.

4 Build the enlarged base.

5 Pull with constant speed

while observing limitvalues for concrete pump

pressure.

VCC in centralBerlin

VCCs are comparable intheir quality and field

of application withContinuous Flight Auger

(CFA) piles, with theadded benefit that forVCCs over 90 % of thesoil is displaced in-situ

rather than dug out.This assures a highershaft friction and less

waste disposal.

Possible Disadvantage of the DVCC Method

Although comparison tests in the same soil have not yet been carried out, columns installed with pumpable concrete (VCC) mayhave a higher maximum internal strength due to the character-istics of the concrete mix. However, very often the internalstrength of the pile is not the critical factor and the better com-paction of the surrounding soil may lead to higher overall loadbearing capacity of the DVCC columns.

1 2 3 4 5

Arearatio A/Ac1

1

2

3

4

5

6

2 3 4 5 6 7 8 9 10

Impr

ovem

ent F

acto

r η

ϕc = 45.0°ϕc = 42.5°

ϕc = 40.0°ϕc = 37.5°

ϕc = 35.0°

µc = 1/3

2.00 m

CL

SM-ML

2.00 m

Ø = 8.00 m p = 209.00 kN/m2

ϕ = 23.0°, c = 20.00 kN/m2

γ/γ ' = 16.0/7.0 kN/m3

E = 5.0 MN/m2, dc = 0.9 m

ϕ = 29.0°, c = 5.00 kN/m2

γ/γ ' = 17.0/7.0 kN/m3

E = 8.0 MN/m2, dc = 0.6 m

2.00 m 2.00 m

0.00 m

3.00 m

1.00 m

7.00 m

0.9

m0.

6 m

THE DESIGN

The graph shows the settlement reduction with differentpercentages of soil being replaced by stone columns.

Screenshot of the DC software.

A depth factor has been added to takeinto consideration the positive effect oflarger confinement of the stone column

with increased depth.

The design comprises the assessment of bearing capacity,

settlement, stability and liquefaction potential of a soil

after Vibroflotation Ground Improvement.

For Vibro Compaction the design is very straightforward: Assessthe required improved soil strength and stiffness after compac-tion and calculate otherwise as for any unimproved soil. The onlydifficulty lies in the evaluation of the degree of compaction poss-ible in different soils. This can only be assessed with extensiveexperience in local soil conditions and the use of appropriatesounding techniques. For stone columns the design is much morecomplex. Stone columns are a soil reinforcement, and their beha-vior is closely linked to the behavior of the soil surrounding thecolumns. Specific calculation methods for stone columns havebeen developed and calibrated using full scale tests, allowingstone columns to be designed with the same confidence as pilesbut with the advantage of better resistance to earthquake loads.

Reduction of Settlements

Based on Priebe’s design diagram and assuming 25 % of the soilbeing replaced by stone columns (factor A/Ac =4) and a frictionangle for the column material of 40°, it follows that n = 2.6 , i.e.a 2.6-fold reduction in settlements as compared to the unim-proved ground. DC-Software and The Vibroflotation Group havejointly developed a Windows® program called DC-Vibro. This soft-ware is based on the Priebe method including the depth factor. Afree trial version of this software can be downloaded from theInternet on DC-Software’s site www.dc-software.de. With DC-Vibroany arrangement of structures can be input and for every crosssection an individual multilayer soil model and varying columndiameter over depth profile can be assumed.

16

17

Increase in Slope Stability

Stone columns have a threefoldeffect in soil:

1. Compaction of compatiblelayers.Layers of clean sand and gravel and slightly silty sand(up to 20 % fines content)are compacted during theprocess of stone columninstallation.

2.Reinforcement of the soil.Column and soil form a rein-forced matrix with instantlyincreased shear resistanceand stiffness modulus. Thehigh friction angle of thecolumn material gives an immediate overall increase in shearstrength to the composite of soil and column.

3.Drainage.The columns accelerate drainage (consolidation) of the cohesivesoil, i.e. the columns work as vertical drains and thereby ac-celerate reduction of harmful excess pore pressures.

The screenshot(finite elementssoftware: plaxis®)shows possibleslope failurewithout stonecolumns.Safety factoragainst slope failure: F = 1.06

After slope stabili-sation with stonecolumns: F = 1.60

Prevention of Soil Liquefaction

The compaction of the in-situ soil is the most important positiveeffect of vibrocompaction or stone columns for the prevention ofliquefaction in granular soil layers. In soils with a silt content of over

10 % the most impor-tant effect of the stonecolumn is the reduc-tion of the total cyclicshear stress in the soil.The graph left showsthat the required sound-ing resistance can bevariable over depth aslong as a proper consi-deration of the varyingfines content is made.In order to achieve thesame safety factoragainst liquefaction inan SM-ML a SPT blowcount of 11 is sufficient,while in the clean sanda value of around 20 isrequired.

Liquefaction Analysis

SPT optimized for constant factor of safety

Hole No.=XY-123Water Depth0=0 ft

SoilDescription

Fine to med.sand, tr. silt

Gravelly sand

SM-ML

Fine sand, tr. silt

Silty sand

Factorof

Safety

ShearStressRatio

(shaded area:liquefied zone)

Settlement

0 (ln.) 1

RawSPT

Unitweight

Fines%

Surface Elev.=0 Magnitude=6Acceleration=0.25g

00,50

11

0(ft)

121 211 121 211 121 212 121 213 121 215 121 216 121 216 121 217 121 217 121 218 121 211 114 211 114 4019 121 4019 121 219 121 220 121 213 116 2513 116 2513 116 25

CRR CSR

2

10

20

30

40

50

wet dry

Stone Columns reinforce and compactthe soil. Liquefaction

can be prevented.

Soil

Colu

mn

τc

τ

τs

γ

Stone column construc-tion should be closelymonitored and designadapted to suit actual

soil conditions.

The shear stress is partially taken over by

the stone column.

Digital quality controlfor dry bottom feedstone columns.Variation of depth,ampere, pull downforce, gravel batchesand inclination x andy with time.

Foundation engineering is the civil engineering disci-

pline with the highest potential for variance between

assumed behaviour and actual as-built behaviour. This

stems from the large uncertainties in the character-

istics of the building material, the in-situ soil. No mat-

ter how much field and laboratory exploration data is

available, the unknowns and uncertainties will always

be greater than for steel, concrete and other construc-

tion materials.

Detailed measurements and observations are therefore of para-mount importance and an efficient quality assurance/controlsystem is obligatory. Modern data acquisition systems intelligent-ly combined with equipment built to allow for the exact measure-ment of process parameters (such as a precise gravel consump-tion by volume over depth) are now available.

Quality Control for Dry Bottom Feed Stone Columns

In order to be able to print out column diameter variations withdepth, it is necessary to measure precisely the volume of each gravel batch and the depth, at which it was placed in the ground.

The Double Lock Gravel Pump is the optimal machine for an exactgravel volume control. This volume measurement is particularlyuseful for offshore (marine) stone column installation, where avisual control of the gravel consumption or gravel loss on theseabed is not possible.

QUALITY ASSURANCE

18

Analog quality control for dry bottomfeed stone columns.

(Appendix to ParticularSpecification Clause 6.91(6) )

Appendix 6.3

Deep Compaction Requirement

Top of Surcharge(Vibro-Compaction Platform)

Finished Formation Level

Cone PenetrationTip resistance (qc)

The “Envelope” ofCompaction Criteria

(CompactedSand)

>17MP

a

>17MP

a

> 10 MPa

02

10

20

Depth (m)

Typical requirement for PostCompaction CPT sounding.

Vibro Compaction

19

Quality control for drybottom feed stone

columns.Variation of time,

ampere, pull downforce and column dia-

meter with depth.

The Aging Effect

An increase of CPT result isclearly visible after a waiting

period of eleven days incomparison to only five days

(sand compaction on HongKong Airport project).

Quality Assurance for Vibro Compaction

Quality control for a Vibro Compaction consists of the followingsteps:

• Before compactionDetermine Pre-Compaction CPT or SPT sounding.Establish the Pre-Compaction ground level of the compactionarea.

• During compactionRecord ampere variation with depth during every compactionpoint installation.

CPT results before and after compac-tion. The non compacted layers resultfrom a silt content exceeding 10 %.

Digital data logger showing depth vari-ation with time on the left and amperagevariation with time on the right.

Analog data logger showing ampere overtime (blue) and depthover time (red).

• After compactionDetermine Post-Compaction CPT or SPT sounding and adjust forPost Compaction ground levels.

www.v ib ro f lo ta t ion . com

Head Office:

The Vibroflotation Group, Henderson House, Langley Place, Higgins Lane, Burscough, Lancashire L40 8JB, England, UKphone: +44-1704-895686 · fax: +44-1704-895581e-mail: info@vibroflotation.com

Representatives:

Asia: Vibroflotation Asia Ltd., 3/F., Harcourt House, 39, Gloucester Road, Wanchai, Hong Kongphone: +852-2730-2378 · fax: +852-2730-3935e-mail: ychiffoleau@vibroflotation.com

D: Gevib mbH, Schwarzbacherstr. 19, D-01945 Gutebornphone: +49-35752-50007-0 · fax: +49-35752-50007-17e-mail: adegen@vibroflotation.com

F: Vibro France, 18, rue des Pyrénées, Silic 582-Wissous, F-94663 Rungis Cedexphone: +33-1-56704200 · fax: +33-1-56340388e-mail: mbrucy@vibroflotation.com

Vibroflotation Europe, 140, rue Serpentine Z.I. Jalassières, F-13510 Eguillesphone: +33-442-297521 · fax: +33-442-590153e-mail: jmdebats@vibroflotation.com

UK: Vibrofoundation Ltd., Henderson House, Langley Place, Higgins Lane,Burscough, Lancashire L40 8JB, England, UKphone: +44-1704-895686 · fax: +44-1704-895581e-mail: acourts@vibroflotation.com

USA: Vibrofoundation Inc., 2082 Michelson Drive, Suite 305, Irvine, CA 92612phone: +1-949-833 0444 · fax: +1-949-8330446 e-mail: wdegen@vibroflotation.comand401 E. Jefferson St., Suite 108, Rockville, Md 20850phone: +1-301-315 06 70 · fax: +1-301-315 06 73 e-mail: btarralle@vibroflotation.com

For further contacts and information please visit our website: www.vibroflotation.com