ground improvement brochure

8/2/2019 Ground Improvement Brochure

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www.roger-bullivant.co.uk

NRG

CONE TAMPING

SYSTEM

SOIL MODIFICATION,

STABILISATION

AND RECYCLING

VIBRO

DISPLACEMENT

GROUND IMPROVEMENT


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A P P L I C AT I O N

Vibro displacement using vibro stone columns is a method ofenhancing ground bearing capacity and limiting settlement.Typical applications include support of foundations, slabs,hardstandings, pavements, tanks or embankments. Soft soilscan be reinforced to achieve improved specificationrequirement whilst slopes can be treated to prevent slip failure.Both natural soils and made ground can be improved.

On low to medium rise buildings and industrial developmentstypical allowable bearing capacities are in the range 100kN/m2

to 200kN/m2, while beneath tanks or embankments applied loadsare often in the region of 100kN/m2. Dependent on groundconditions, the technique may be suitable to support heavierloads.

On completion of ground improvement, foundations may beconstructed at nominal depths (minimum 0.60m), while floor slabsand areas of hardstanding may be constructed after proof rollingof the surface following removal of surface disturbed soils.

D E S C R I P T I O N

Specially designed and constructed RB high powered vibratingmandrels penetrate the ground requiring improvement, in avertical plane to a design depth. The resulting bores are thenfilled with suitable aggregate or stabilised soil, which iscompacted in layers typically 0.3 - 0.6m increments. The

shape of the poker tip is designed to ensure excellentcompaction of stone or stabilised soil column and the taperedmandrel profile specifically maximises compaction of thesurrounding ground.

S I T E R E Q U I R E M E N T S

In granular soils ground bearing capacity is enhanced by theintroduction of columns of compacted stone or columns ofcompacted stabilised soil, together with densification of thegranular soil around each column.

In cohesive soil, enhancement of ground bearing capacity isachieved by the reinforcing effect of columns of compactedstone or compacted stabilised soil within the clay mass. Inboth cases design is based on the performance of thecomposite column/soil system. There is load sharing betweenthe columns and the soil, as the columns do not work incomplete end bearing as piles do.

In ground of variable density or variable consistency,installation of stone columns or columns of stabilised soilprovides an effective means of ensuring the groundperformance is made more uniform, thereby limiting differentialsettlement.

The presence of ground water on site can obviously influencethe choice of treatment application, but the speed of inflowand ground type are factors to be considered.

VIBRO

DISPLACEMENT

RB4

001Rig

Installingstonecolum

n

MORE ECONOMICAL

than piling or deep excavation worksENVIRONMENTALLY FRIENDLY

RAPID INSTALLATION

Immediate follow on

works


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M E T H O D

Penetration to the required treatment depth is achieved by thevibratory action of the mandrel, together with extra pull downprovided by the rig. On reaching the required depth themandrel is fully extracted and a small charge of aggregate orstabilised soil is introduced into the resulting bore from thesurface. The poker then re-penetrates the bore to within ashort distance of the original depth, thus compacting theintroduced aggregate or stabilised soil. The poker is againextracted and further aggregate or stabilised soil is added.This is compacted as before during re-penetration to within ashort distance of the previously penetrated depth and theprocedure is repeated until each column is completed to thesurface.

M A N D R E L D E S I G N D ATA

A range of mandrel shapes is available to meet differing soilconditions (refer to data below). RB has a range of in-housedesigned and built rigs.

4 0 0 1 T E C H N I C A L D ATA

GROSS WEIGHT: 19 tonnes

POWER RATING: 315kW at 1800rpm

VIBRATOR RATING: 47 tonnes at 1650rpm (28 Hz)

MAIN CONTROL: Full radio remote

B E N E F I T S

G buildings may be supported on conventional shallow,nominally reinforced foundations and ground bearing floorslabs

G rapid installation immediate follow-on works

G no spoil produced

G economy when compared with piling or deep excavationwork

G environmentally friendly, encouraging regeneration ofbrownfield sites, and promoting sustainability by thepossible use of reclaimed or recycled aggregates

Insertionofvibratingconemandrelto

engineereddepth.

Byuseofsidetippingloadshovel,stoneischargedinto

thedisplacedvoid.

Byre-introductionoftheconemandreladensestone

columnisconstructed.

NO SPOIL PRODUCEDENCOURAGES REGENERATION OF

BROWNFIELD SITES

PROMOTES SUSTAINABILITY

Possible use of reclaimed or

recycled aggregates


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Dynamic compaction and consolidation using the NRG conetamping system is a method of enhancing ground tosubstantial depths by repeated, controlled energy input, bydropping specially designed tampers to achieve measuredground improvement.

This special technique has been developed by Roger BullivantLimited, based on traditional slower methods developed inFrance, which use flat bottomed tampers which are known tocreate significantly more vibration, noise and disturbance.

Using RB equipment, treatment can be effective to provide

allowable bearing capacities typically in the range 50 to150kN/m2. In the right conditions higher capacities may beachievable. The technique is appropriate to provide support forfoundations, slabs, hardstandings, tanks, or embankments, orsimply to reduce levels on site.


The use of the special shaped tampers greatly increases theefficiency of the ground improvement. For given energy input,the degree of improvement and the effective depth ofimprovement is increased relative to traditional flat bottomedtampers. Vibration generated is also reduced as the energy isdirected into the ground, rather than laterally. Roger BullivantLtd has also developed purpose-made machines, whichenable dropping of tampers in free fall within leaders. This

greater accuracy in drop regime leads to a higher proportion ofthe energy applied for a given drop height, relative toconventional dynamic compaction, where tampers areattached to a crane rope, as well as significantly increasingproductivity.


Suitable ground conditions include natural granular soils, madeground and refuse. The technique may also be used as part ofan earthworks operation, where fill is required to be placed inlayers. The fill, which may consist of unmodified as dugmaterial, or soils which are modified or stabilised by use ofadditives, such as quicklime or cement, may be compactedusing the NRG cone tamping system.

Several tamping passes may be required to achieve thedesired effect, and careful monitoring and testing forms anessential part of the ground improvement. On-goingmonitoring may include taking levels on a grid pattern beforeand after each tamping pass, undertaking trial drops todetermine the optimum treatment regime, monitoring imprintdepths and measuring pore water pressures (whereappropriate). As part of the monitoring of imprint depths,accurate measurements are taken of the penetration of thetamper achieved by application of particular energy. By thismeans, direct assessment of allowable bearing capacity is

made. Analysis of levels enables the amount of void closure andhence the degree of densification.

NRG CONE

TAMPING SYSTEM

RB9000SeriesRig

RB9000SeriesandJS200Rigs,workingin

tandem

COST EFFECTIVE

best value solutionSUITABLE FOR CONTAMINATED SOILS

HIGH PRODUCTIVITY

minimises contract period


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M E T H O D

A selection of different shaped NRG tampers with a variety ofweights is available depending on the densification and

consolidation requirements and ground conditions.On some sites it is necessary to provide a working platform toenable the works to proceed and to provide a source materialto infill imprints which may be formed as part of the tampingoperation. The working platform may be formed by applicationand mixing of additives such as quicklime or cement to thesurface materials using the RB Wirtgen WR 2500K soilstabilisation system.

Where treatment to substantial depth is necessary, initialtamping is undertaken using single pointed tampers up toapproximately 2.5m long with a mass up to 10 tonnes. Thiswould be on a grid pattern, with the objective of densifyingdeeper layers. Subsequent tamping would normally beundertaken using multipointed tampers, which are designed toimprove the shallower layers, either on a closer grid pattern, orwith dropping at immediately adjacent positions (continuoustamping see Fig 1).

Imprints resulting from the tamping may be infilled either withon-site materials, where it is suitable, or with soil modified orstabilised by use of additives such as quicklime or cement.The source of infill material is often the working platform asreferred to above.

On completion of the main tamping, a single pointed NRGcone may be used to form instant excavations for foundationbases. At this stage, accurate measurements of NRG conepenetration for a given energy are taken to confirm thatnecessary allowable bearing capacity has been achieved.

Details of some of the available tampers are shown in Fig 2.

The NRG cone system may be used in combination with vibrostone columns to further enhance ground improvement alreadyachieved by installation of stone columns, or columns ofstabilised soil.

This involves dropping of single pointed NRG long cones intopreviously constructed stone columns, or columns ofstabilised soil.

This will burst the upper section of the column to enablefurther improvement of the ground. The resulting imprints arefilled either with suitable granular materials such as crushedrock, natural aggregates, crushed concrete or stabilised soil.

B E N E F I T SG cost effective, best value solutionG no spoil produced an important environmental factor on

sites with contaminated soilsG total area treatment enables flexibility with positioning of

buildingsG high productivity minimises contract periodG reduced vibration enables treatment closer to adjacent

structures than is possible with traditional dynamiccompaction.

NO SPOIL PRODUCED

REDUCED VIBRATION

compared with traditional dynamic

compactionTOTAL AREA TREATMENT

StandardLo

ngCone

FlowerPotCone

Multi-PointCone

Typical tampers

Fig 2

Fig 1

Typicalschematicofworkingpattern


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Roger Bullivant Limited has a range of techniques for modifying

and stabilising soils including the ability to recycle previously

unusable material. The objectives are to control soil moisture

content, provide workable materials, increase soil strength,

reduce settlement, ensure volume stability and durability, or to

encapsulate contaminants as required.


The RB Wirtgen WR 2500K soil stabilisation system, provides a

rapid method of introducing powder additives in a controlled

method and dosage to create a material with an end-product asspecified by the client. The additive may be either placed on the

ground ahead of the machine, prior to pulverisation and mixing,

or it may be placed by means of an integrated hopper, such

that additive is introduced concurrent with granulation. Water

may be introduced simultaneously with the additive.

The advantages of an integrated hopper are:

1 Metered dosages of additive and water (if required) may be

accurately applied

2 The zone where additive is introduced is fully shielded to

prevent loss of additive into the environment.


These techniques may be adopted in natural and/or made

ground. Granular, cohesive and even contaminated soils can be

successfully treated. The selection of appropriate additives and

dosage depends on soil type and end product requirements.

SOIL MODIFICATION,

STABILISATION AND

RECYCLING

Modifiedtractorbeingusedformixingbinders

Soilstabilisatio

nforHGVparkonindustrialdevelopment

usingtheRBWirtgenWR2500K

The complete stabilisation process

MINIMISES QUARRYING AND

TRANSPORTATION

AVOIDS UNNECESSARY REMOVAL OF

CONTAMINATED MATERIALS

PROVIDES EXCELLENT

WORKING PLATFORM


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When used on contaminated sites, one of the objectives may be toencapsulate the contaminants, or to treat the material to neutralisethem. This process is generally under guidance of The EnvironmentAgency and in compliance with the requirement of the RB Limited

Mobile Plant Licence.

M E T H O D

Use of the RB Wirtgen WR 2500K soil stabilisation systemfacilitates pulverisation of a soil layer, placement of additives andwater (where required) and mixing of additives into the pulverisedlayer. The treated layer must then be compacted by an appropriatemethod. Compaction could be by conventional rolling, or bytamping using specially designed shaped tampers (see NRG conetamping system).

Where relatively small dosages of additive are used (eg less than3%), soil properties may be almost instantaneously modified, toprovide a workable material (SOIL MODIFICATION). However, overa longer period of time, provided there is sufficient available

additive to react with the soil, there may be ongoing enhancementof soil properties (SOIL STABILISATION).

In cohesive soils, the commonly used additive is quicklime, whilstin more granular soils, the additives are typically cement orpulverised fuel ash. Other additives or blends of additive may beused.

Provision of workable materialsBy application of appropriate additives an unsuitable material maybe rendered suitable for incorporation into earthworks. Thistechnique normally involves modification rather than soilstabilisation.

A convenient method may be to place a layer of the unsuitablematerial on the ground surface, which may then be pulverised

using the RB Wirtgen WR 2500K machine while appropriateadditive is applied, prior to compaction of the layer. Compactioncould be by conventional rolling or by tamping with NRG cone.

Working platforms

Provision of working platforms may be required where soft soilsoccur at the surface or where surface soils are wet. Additive maybe used to control moisture content of the soil, which may be allthat is required to provide a workable material. It may be necessaryto introduce further additive to modify the soil. For this applicationsoil modification with comparatively low dosages of additive isusually sufficient.

Enhancement of bearing capacityIntroduction of appropriate additive results in an enhancement of

soil properties, which in itself increases the strength of the soilsand also provides more workable materials which can be bettercompacted to maximise bearing capacity and to minimisesettlement. This technique may be used to provide enhancedmaterials to incorporate into conventional earthworks, or may beused to provide permanent hardstanding areas, or load transferplatforms.

Encapsulation of contaminants

By use of appropriate additives, soil stabilisation techniques maybe used to encapsulate certain contaminants. This may be anadditional benefit to enhancement of soil properties.

B E N E F I T S

G enables re-use of on site soils, includingcontaminated materials, bringing environmentalbenefits

G provides a cost effective alternative to use ofconventional aggregates (minimises quarrying andtransportation)

G avoids unnecessary removal of unsuitablematerials and contaminated soils.

ENVIRONMENTAL BENEFITSRE-USE OF ONSITE SOILS

including contaminated materialsCOST EFFECTIVE

RB WIRTGEN WR 2500K

Schematicdiagrams

howingd

ust-freesoil

stabilisationwithlimeorcement

Wet

soil

Integratedspreading devicewith hopper andcellular wheelsluice

Variablemixingchamber withmilling andmixing rotor

Soil mixturewithreducedwatercontent

Working direction


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Regional Offices

HEAD OFFICERoger Bullivant Limited

Walton Road

Drakelow

Burton-on-Trent

Staffs DE15 9UA

T 01283 511115

F 01283 512233

SCOTLAND

T 01259 272050

F 01259 272051

NORTH EASTT 0191 5372542

F 0191 5193097

YORKSHIRE

T 01924 224300

F 01924 898165

NORTH WEST

T 01772 323385

F 01772 626814

MIDLANDST 01283 511115

F 01283 512233

SOUTH WALES

T 01639 895641

F 01639 899035

SOUTH WEST

T 01373 865012

F 01373 865559

SOUTH EAST

T 01322 286565

F 01322 286566

Other Products & Services

Piling

House Foundations

Mini-piling

Underpinning

Concrete Products

Testing

Conservatory & Extension Bases

Quality Control

Testing is an essential part of theoverall package and is carried out

by RB Testing Services andindependent testing houses toISO9001.

TESTING & QUALITY CONTROL

Zone Test/

Static Load Testing

ISO14001CertificateNumberEMS 74925

Roger Bullivant Limited

E: marketing@ roger-bullivant.co.uk W: www.roger-bullivant.co.uk

ISO9001 Certificate NumbersFS 62321

&FM 13004

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