BAUERSPEZIALTIEFBAU

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ContentsThe BAUER Group ...................... 4The Diversity of Specialist Foundation Engineering ............... 6Market Segments ........................ 8

Our ExpertiseExcavation Pits .......................... 10Foundations .............................. 14Cut-off Walls .............................. 18Ground Improvement ................. 22

The MethodsPiles .......................................... 26Diaphragm Wall ......................... 28Ground Anchors ........................ 30Mixed-in-Place andCutter-Soil-Mixing ...................... 32Ground Improvement ................. 34Jet Grouting .............................. 36Grouting .................................... 38Micropiles .................................. 39

Design ....................................... 40Construction Technology ........... 41Responsibility ............................ 42

BAUER Spezialtiefbau GmbH, a member company of the BAUER Group international construction, machinery and

resources concern based in Schrobenhausen, Germany, carries out underground works all over the world, executing all

established methods and techniques of construction in thefield. The innovative strength of the BAUER Group's parent com-

pany has been a driving force in the specialist foundation engineering sector for over 50 years.

The BAUER Group

The BAUER Group4

The parent company in the specialist foundation engineeringsector, BAUER Spezialtiefbau GmbH, constructs buildingfoundations, excavation pits and cut-off walls, as well ascarrying out ground improvement, all over the world. Itsmain specialities include all kinds of bored piles, anchors,diaphragm- and cut-off walls, as well as jet grouting andvibratory techniques.

The Resources segment, established in mid-2007, focuseson products and services in the fields of water, energy,mineral resources and the environment. BAUER ResourcesGmbH is the segment's parent company, overseeing threeoperating divisions: Materials Division, Exploration andMining Services Division and Environment Division.

Bauer's Equipment segment offers an extensive range ofmachinery and tools for specialist foundation engineering ap-plications and for the mining industry. Specialist foundationengineering machinery from Bauer has been a byword fortop performance and quality and for continuous innovationin the field of specialist foundation engineering equipmentsince the late 1960s.

BAUER AG, founded in 1994, is the holding company of theBAUER Group, and provides in-house services in the fieldsof human resources, accounting, IT, facility management,legal affairs and training. The Bauer share has been listed onthe stock market since 2006.

Building with responsibility

BAUER Spezialtiefbau GmbH is a member com-pany of the BAUER Group, based in Schroben-hausen, Germany. The holding company

BAUER Aktiengesellschaft is the parent of more than100 subsidiary businesses in three segments: Cons -truction, Equipment and Resources.Bauer Spezialtiefbau carries out underground worksall over the world, implementing all the establishedmethods and techniques in the field, primarily in theconstruction of excavation pits, building foundationsand cut-off walls, as well as ground improvement.

Bauer Spezialtiefbau operates on the basis of inten-sive collaboration with its more than 50 subsidiariesand branch offices. Regional networks all over theworld allow the company to deploy machinery, man-power and know-how rapidly and flexibly to alwaysoffer optimum solutions both technically and eco-nomically. Its customers also profit enormously fromthe innovative strength of the BAUER Group as awhole, which has played a major part in driving for-ward the underground engineering sector since themiddle of the last century. Bauer Spezialtiefbau's engineers are well aware oftheir responsibilities to their customers and to the en-vironment: "Dealing with the urgent social and eco-logical issues of our age, using scarce resources in aconscientious manner, is a challenge to our skills andknow-how on a daily basis. We meet those challengesall over the world, working in tight city centre environ-ments, realising visionary infrastructure projects, andputting progressive environmental policies into prac-tice. In doing so, we are able to call upon a wealthof experience, wide-ranging specialist knowledge,state-of-the-art technical equipment, and a healthydose of creativity."

SCHACHTBAU NORDHAUSEN GmbH is a specialist busi-ness with a tradition stretching back more than 110 years.It offers expert mining and underground engineering servicesfounded on know-how in traditional techniques allied to theimplementation of state-of-the-art modern constructionengineering methods, all from a single source.

Milestones in the Company’s History1790 Sebastian Bauer acquires a coppersmith’s shop

in the centre of the town of Schrobenhausen

1840 Copper cladding of the tower of St. Jakob’schurch

1870 Artesian well for the new Schrobenhausen railway station, start of piling work

1980 First international branch office opened in Saudi Arabia

1984 Opening of works complex West inSchrobenhausen; start of aggressive marketingof equipment

Trench cutter to seal the Brombachsee lake

1986 Professor Thomas Bauer (born 1955) becomessole managing director; internationalisation ofthe BAUER Group

1990 Founding of BAUER und MOURIKUmwelttechnik GmbH & Co

1992 Acquisition of SCHACHTBAU NORDHAUSEN GmbH

1994 Founding of BAUER Aktiengesellschaft as theGroup’s holding company

2001 BAUER Spezialtiefbau GmbH is demergedfrom the equipment manufacturing business tobecome the central construction companywithin the BAUER Group, carrying out projectsall over the world through its network of sub-sidiaries and branches

2006 BAUER AG is listed on the stock market,Chairman of the Management Board Professor Thomas Bauer

2007 Founding of BAUER Resources GmbH, entail-ing a restructuring of the mining and environ-mental business; market launch of the threenew segments: Construction, Equipment andResources

2009 The BAUER Group concludes the largest capi-tal investment programme in its history; inau-guration of the new head office administrationbuilding in Schrobenhausen and a new plant inEdelshausen; opening of the machinery manu-facturing plant in Conroe, Texas, USA

1928 Dipl.-Ing. Karl Bauer (1894 - 1956) constructsthe central water supply system for the townof Schrobenhausen; construction of wells andwater pipes for municipalities and industrialfirms in Bavaria

1948 Construction of a new operations centre at thesite of the current head office

1956 Dr.-Ing. Karlheinz Bauer (born 1928) becomessole managing director; company focuses itsoperations on specialist foundation engineering

1958 Invention of the injection anchor on the con-struction site of the Bayerischer Rundfunk(Bavarian Broadcasting Corporation) building inMunich; registration of patent and internationalmarketing

1959 First construction site outside Germany, inSwitzerland

1967 New hall for the workshops

1970 Design and manufacture of the first anchordrilling rig UBW 01; start of machinery manu-facture

1972 Construction of the new head office adminis-tration building

1975 Contracts in Libya, Saudi Arabia, UAE

1976 First heavy-duty rotary drilling rig BG 7

The Diversity of SpecialistFoundation Engineering

available worldwide, at home in Bavaria

Bauer Spezialtiefbau6

Buildings throughout the world are becoming not onlyever taller, but also increasingly complex. Whether forgigantic towers in tight mega-city environments or con-

tributing to futuristic infrastructure projects on a previouslyundreamt-of scale – the demands placed on foundation engi-neering specialists are increasing continuously. As a leadinginnovator in the development of underground engineeringtechniques, Bauer Spezialtiefbau is able to apply and market

its skills and strengths worldwide. An extensive global net-work, coordinated from Group headquarters in Schroben -hausen, enables Bauer's specialist know-how to be deployedin all four corners of the earth. As a result, Bauer customersaround the globe profit from the company's excellent localknowledge, from the close availability of highly qualified part-ners, from rapid availability of equipment and from compre-hensive expertise in all areas of foundation engineering.

BuildingsFrom museums to skyscrapers – many public and privatebuildings all over the world are assured of a long life restingon our foundations. We meet the challenges of urban plan-ning and construction, such as tight city centre space, closeadjoining structures and stringent ecological requirements,with tailored design concepts for foundations and excavationpits.

Market Segments

Market Segments8

We offer our customers worldwide customized, creative and cost-effective specialist foundation engineering solutions for construction engineering projects of a demanding nature. From planning through to execution – working together with our partners, we carry out top-quality

excavation pits, building foundations, cut-off walls and ground improvement works for a wide variety of applications.

InfrastructureLarge-scale excavation pits for railway stations, onshore andoffshore foundation works, piled walls for harbour installa-tions and much more – the ambitious infrastructure projectsof the modern era demand ever more complex specialistfoundation engineering solutions. We have the right equip-ment and know-how. Even in the hardest rock or in soft soil,our long-standing experience and broad-based expertisealways meet the challenge.

Water / EnergyRising energy demand means there is an increasing needfor the construction, extension, renovation and remediationof power stations, wind turbines and hydro plants, as wellas dams and locks. We carry out foundation works for majorpower station construction and extension projects. In con-structing or remediating dams and dykes, we employ spe-cialist foundation engineering equipment which is unique ofits kind in the world, enabling us to install the necessarycut-off wall systems even down to extreme depths and inhard rock.

IndustryAll industrial construction projects – whether a paper mill, asteelworks or a petrochemicals plant – pose different de-mands specific to the site. With specially tailored foundationand ground improvement works, we create the conditionsenabling industrial installations to be set up even on themost difficult ground.

Our Expertise

Excavation Pits

11

C ity centre land is scarce and expensive. Developersneed to make the fullest use of all available space –including underground installations – for services

and parking facilities. Space-saving retaining structures forexcavations make that feasible. Bauer Spezialtiefbau offersindividually tailored and optimized solutions for excavation

pit retaining walls, where necessary also incorporating tie-back anchors or struts. Water ingress from below can be re-stricted by jet grouting or grouted sealing blankets. On re-quest, Bauer Spezialtiefbau can provide turnkey solutionsincluding all excavation and groundwater control works.

PPPPP

Versatile: For the Pasing Arcaden in Munich, Bauer Spezial -tiefbau constructed a complex excavation pit covering anarea of 13,000 m². In just seven months, Bauer Spezialtief -bau created a system comprising Mixed-in-Place (MIP) retaining- and cut-off walls, soldier pile and secant bored pilewalls, where necessary with tie-back anchoring.

Excavation Pits - References

Our Expertise12

Three techniques in one: At Frankfurt Airport's Terminal 1a new pier is being added. Bauer Spezialtiefbau constructeda 790 m long and up to 12 m deep excavation pit withsoldier pile-, bored pile- and Mixed-in-Place walls, supportedwith tie-back anchors or propped with struts.

Three floors below ground: For the excavation pit andfoundations of the 23-storey Abu Dhabi Capital Hotel com-plex, Bauer Spezialtiefbau installed 500 running metres ofbored pile wall and 534 foundation piles.

Accurate and water-tight: For a large-scale sewage treat-ment plant between the Buda and Pest districts of the city ofBudapest, Bauer Spezialtiefbau constructed four water-tightcircular shafts as the start and end locations for tunnel boremachines.

Excavation pit and foundations:For the four underground levels of the 25-storey Crystal Tower in Dubai, BauerSpezialtiefbau constructed a bored pilewall supported with tie-back anchorsand installed foundation piles.

16 m below sea level: In the CentralDistrict of Beirut, Bauer Lebanon con-structed the excavation pit for a highrisetower close to the sea. Protected bythe pile wall – which was supportedwith tie-back anchors – and sealed witha grout blanket, the excavation workswere executed to a depth of 21 m ac-companied by dewatering.The surface of the secant pile wall wascleaned and joints between piles werefilled by shotcrete. left

Our Expertise

Foundations

15

T he weight of new building structures is becoming evergreater, and more and more often such buildings arebeing constructed on quite unstable ground. With pile

foundations down to great depths even high loads can betransfered safely into the bearing stratum. Bauer Spezial -tiefbau installs bored piles down to depths well in excess of

100 m and in diameters of more than 2 m – where requiredalso with base and shaft grouting or with bell-outs. Diaphragmwall panels or Mixed-in-Place elements offer further appropriateand cost-effective options to carry structural loads. BauerSpezialtiefbau can provide the optimum foundation solution forany building, bridge or transport infrastructure constructions.

Full scale tested quality: For the "Pfeilerbahn", an elevatedrailway in Hamburg, Bauer Spezialtiefbau executed 40,000running metres of Bauer Full Displacement Piles (FDP), withlengths of up to 16 m, in just 12 weeks. In advance of theworks, three large-scale field tests were set up and inten-sively monitored.

Foundations - References

Our Expertise16

Foundations for wind plants: For the foundations of ninewind power plants, Bauer Spezialtiefbau executed 26 piles in750 mm diameter and at depths down to 27 m for each.

Bridge foundations: On the 420 km eastern section ofthe East-West Highway, an Algerian segment of the futuremotorway between Morocco and Egypt, Bauer FondationsSpéciales Algeria installed the pile foundations for all 35bridges.

Our Expertise 17

Precisely to customer specification: For the "WeddingTower" in Moscow with a height of 250 m and featuringstoreys wrapped around the stairwell core, the customerplanned foundation piles with two concentric reinforcementcages. Bauer Technology Russia met the challenge, con-structing 130 cased piles in 1,500 mm diameter at a depth of 30 m in just five months.

An extraordinary project – an extraordinary effort: The"Exzenterhaus" in Bochum will become the city's new land-mark. Inside the high-rise block – a former wartime bunker –a Bauer BG rig was deployed to install foundation piles inorder to discharge the high building loads.

In mid-river: Near the Macken Street Bridge in Dublin, adrilling rig installed piles for pylon foundations in a sheet pilewall supported pit 10 m below the river level.

Our Expertise

Cut-off Walls

19

under waste disposal sites, tank farms or other industrialinstallations. As required, they protect the structure itself, thesurrounding area, or indeed the entire region. Bored, grab-excavated or trench cutter excavated walls effectively pre-serve the stability of dams and dykes.

W ater - the base of all life on earth and as such a re-source which needs to be preserved and protect-ed. Its elemental force is well known, whether as a

flowing course or standing mass, or in the form of ground-water. Cut-off walls are installed to seal up dams and dykesof water courses, or to encapsulate polluted groundwater

To reduce the flow through the ground under the MeroweDam in Sudan, Bauer Spezialtiefbau installed 8,000 m² ofbored pile wall and 5,000 m² of diaphragm cut-off wall. The1.20 m thick cut-off wall sockets several metres into ultra-hard rock.

Cut-off Walls - References

Dyke sealing by the Cutter-Soil-Mixing (CSM) system:The remediation of the approx. 230 km long Herbert HooverDike around Lake Okeechobee in Florida demands the useof high-tech expertise. Despite layers of rock and embeddedclay strata, Bauer Foundations USA is constructing a CSMcut-off wall at an average depth of 25 m. below

Innovative measurement: The dam at the Söseltal drinkingwater reservoir was showing signs of leakage at high water.A 9 m deep jet grouted continuous wall was installed alonga length of 330 m. The verticality of each bore hole was veri-fied by a technique developed in-house by Bauer.

Our Expertise 21

Double capacity: The capacity of the Hinze dam reservoirnear Brisbane was more than doubled to around 300 mil-lion m³. Bauer Foundations Australia executed the damsealing works in the form of a 840 mm thick and down to50 m deep two-phase cut-off wall. above

Protection against oil: In the Canadian province of Alberta,oil sands are being mined over a vast area. To protect an ad-jacent river, Bauer Foundations Canada excavated a 2.6 kmlong cut-off wall down to a depth of 50 m.

At the limits of technical feasibility: For the Peribonkadam project north-east of Montreal, Bauer Spezialtiefbauexecuted 85,000 m² of vibro-compaction, contact-, curtain-and stabilization grouting as well as 23,500 m² of trenchcutter cut-off wall to a maximum depth of 120 m in ultra-hard granite.

Our Expertise

Ground Improvement

23

I ntensive building activities in the metropolitan areas inmost of the industrialized countries are causing real es-tate prices to rise continuously. As a consequence, even

sites on difficult ground, with low load-bearing capacity, arebecoming more and more interesting to developers. BauerSpezialtiefbau enables such sites to be built on. Ground im-

provement techniques such as vibro-compaction-, vibro-displacement densification and vibro-cast-in-place- or soilstabilization columns are efficient and cost-effective solu-tions where structural loads need to be transferred over awide area or slopes need to be stabilized and secured.

Bypass: On the B180 trunk road nearWaldenburg in Saxony, Bauer Spezial -tiefbau executed 31,000 m of soil sta-bilization columns, 1,100 soil nails and5,600 m² of protective steel wire mesh.below

Ground Improvement - References

Perlen, Switzerland: The construction of a logistics centre called for the installa-tion of 225,000 running metres of plastic drains down to a depth of 25 m and29,000 running metres of vibro-displacement densification. Despite the difficultground conditions, the works were completed in 25 weeks. aboveWhile the hospital worked: For a hos -

pital extension in Fulda, Bauer Spezial -tiefbau executed 6,000 m of vibro-dis-placement densification. The hospitalhad to be able to keep working whilethe work was being carried out. below

Uniform end-bearing capacity: InGermersheim on the Rhine, Bauer Spe -zialtiefbau compacted the sand andgravel backfill of a former harbour basin.After the installation of 23,400 runningmetres of vibro-compaction densificationdown to a depth of 13.5 m, the areacan be utilized as a container terminal.right

Our Expertise 25

Large-scale deep vibration: In theport of Balboa on the Pacific coast ofPanama, Bauer Fundaciones Panamacompacted some 15 hectares of newlyreclaimed land down to a depth of 22 m. The improved ground is beingutilized to extend the second largestcontainer terminal in Latin Americaand will in future be capable of with-standing all kinds of loads that suchuse demands.

Foundations vibrated: At Estinnesin Belgium, vibro-displacement densifi-cation was deployed to construct thefoundations for several wind turbines.Owing to the hard intermediate layers,each vibro-displacement column hadto be pre-drilled with a Bauer BG 9.left

The Methods

Piles

27

B ored piles are cylindrical bodies made of concrete (with or without reinforcement) which are installed inthe ground by a variety of methods. They transmit

high structural loads into lower, load-bearing soils. When in-stalled in rows or in secant configuration they can form a

supporting wall for an excavation pit or cut in the terrain, orblock off groundwater. The length, diameter, material, shapeand layout of the piles can be varied according to their in-tended use.

MethodsKelly PileThe kelly-method is used to produce uncased, partially orfully cased or slurry-supported bored piles. The soil is exca-vated by a drilling tool mounted at the tip of a telescopickelly bar. When the fully cased pile technique is used, the in-section of the full depth casing is simultaneous to the exca-vation, until the final depth is reached.

Double Rotary System (DRS)The DRS links the CFA-method with the kelly casing method.The result is a fully cased bore, produced by a continuousflight auger (DRS 620, 880 mm). This method is particularlyadvantageous where the groundwater level is high with therisk of soil collapse.

Full Displacement Pile (FDP) The FDP-system has a key advantage over the CFA-methodin that it transports virtually no drilling spoil to the surface. Itis suitable in displaceable soils. The drill rod has an auger asstarter, followed by the displacement body and an extensioncasing. During drilling and extraction, the surrounding soil isdisplaced. Concreting and reinforcement is executed as inthe case of the CFA-pile.

Continuous Flight Auger (CFA) PileThe CFA-method is a rotary drilling method which permitshigh drilling performance (CFA 630, 750, 880 mm). Thismethod employs a continuous flight auger as the drilling tool.When the final depth is reached, concrete is pumped frombottom to top through the hollow stem auger. The reinforce-ment is installed subsequently, where necessary assisted byvibration.

The Methods 29

Diaphragm WallD iaphragm walls have a static and / or sealing function

and can serve as cut-off walls for dams or excavationpits, as foundations or as enclosures of structures.

They are executed as concrete or steel-reinforced concretewalls, built from ground level. They are considered very re-sistant to deformation and virtually water-impermeable. Theyare excavated in sections by crawler cranes using suitablediaphragm wall grabs or cutters, with the aid of a stabilizingfluid, between previously fabricated guide walls, which serve

primarily to guide the excavator, allow fluctuations in levelof the stabilizing fluid and carry temporary loads from the re-inforcement or stop end elements. When the final depth isreached, temporary or permanent stop ends are installed inthe trench, the stabilizing fluid is desanded and reinforce-ment cages are installed. Then the concreting is carried out.In the course of excavating the adjoining panel, temporarystop ends are removed for re-use.

MethodsDiaphragm Wall (grabbed)Two different grab systems, suitable for wall thicknesses of600 mm to 1500 mm, are available for trench excavation.The grab is lowered into the trench and the soil is discontin-uously transported. Larger blocks or sections of rock arepunched through, excavated or displaced using modifiedgrabs or heavy-duty chisels. Measuring systems can be in-stalled to verify verticality.On mechanical grabs, a roller system operates the jaws.To increase the closure force, the closing cable is reeved fiveto six times.Hydraulic grabs work with a hydraulic cylinder. They havevery high closure forces and work with lower noise and lessvibrations than mechanical grabs.

Diaphragm Wall (cut)Trench cutters are used to produce diaphragm walls in thick-nesses of 500 mm to 3200 mm. As they transport the spoilcontinuously, they are particularly suitable for depths of morethan 40 m. Trench cutters operate with two opposite-runningcutter wheels which, depending on configuration, are suit-able for a wide variety of strata, including even ultra-hardrock. The soil material is cut by the rotation of the wheels,crushed, mixed with slurry and transported to the surface bya suction pump. Hydraulic steering flaps control the cutter inboth horizontal directions. The penetration depth and speedare regulated by controlled activation of the cutter weight.

The Methods

Ground Anchors

31

T he idea of installing retaining systems without tie-backanchoring is almost inconceivable nowadays. Bauerrevolutionized the special geotechnical works with its

invention of the ground anchor in 1958. Excavation pitswith no obstructive strutting have been the standard eversince. Today ground anchors are used to secure pile walls,sheet piles, Mixed-in-Place walls or diaphragm walls, aswell as steep slopes, support embankments and quay walls.Installing ground anchors is a technically elegant, cost-effec-

tive and, above all, operationally efficient solution for manyconstruction projects. Whether for temporary or permanentuse, in single-rod or strand anchor configuration, in the dryor protecting against pressing groundwater, the Bauerground anchor is usable in all kinds of soil and in rock.Experienced, continuously trained drilling crews, high-perfor-mance special equipment and comprehensive quality controlensure rapid, technically fault-free execution of Bauer groundanchors.

MethodsTemporary anchors, in single-rod orstrand anchor configuration, which canbe removed fully or partially, are used tosecure retaining walls for a maximum oftwo years. They are quick to install andhighly cost-effective. The load-bearingbehaviour of each anchor is tested andlogged during the acceptance procedure.Strand anchors are delivered to the sitein coils, which means they can also beused in tight operating environments.

Permanent anchors are ground an-chors usable for longer than two years,and thus part of a permanent structure.Permanent anchors are executed asstrand anchors, single-rod corrugatedtube anchors or single-rod pressure tubeanchors. The steel tendon and anchorhead are protected against corrosion byspecial measures. Each hollow space inthe anchor head is filled in with perma-nently plastic corrosion-proof compound.

The Methods

Mixed-in-Place and Cutter-Soil-Mixing

33

Why haul away soil and bring in new materials whenthe soil can be used for construction? The Mixed-in-Place(MIP)- and Cutter-Soil-Mixing(CSM)-methods

developed by the BAUER Group avoid the need for labour-in-

tensive transport coordination, cut costs, reduce emissionsand so relieve the strain on residents in the neighbourhood.Both methods offer efficient, cost-effective and environmen-tally friendly alternatives in the appropriate ground.

MethodsThe MIP-method is particularly suitable in non-cohesivesoils for the construction of cut-off walls as groundwater orpollution control, for remediating dykes and dams, or for theinstallation of structural retaining structures to secure ter-races in the ground and excavation pits. In the MIP-method,the surrounding soil is broken up with a single or triple auger,turned over and the pores filled in with binder suspension.The individual units are combined to form walls by the stepback method. In this, it is the size of the auger(s) which ulti-mately dictates the unit size. Reinforcing elements can beinstalled in the fresh MIP-mix for structural strengthening.

The CSM-method combines features of the diaphragm walltechnique (page 29) and the MIP-method, as well as offeringsome additional benefits: the use of modified, high-perfor-mance cutters means soil mixing is possible even at verygreat depths and in very densely packed soils. The methodalso enables even greater wall thicknesses and higher levelsof reinforcement to be attained. Accordingly, in addition tothe applications described for the MIP-method, the CSM-method is suitable in particular for securing very deep exca-vation pits or for reinforcing high dams and dykes.

N UATO S-

The Methods

Ground Improvement

35

Continually rising real estate prices mean that evenground with less than adequate load-bearing capaci-ty is becoming ever more attractive to developers.

Ground improvement can be achieved by the highly produc-

tive methods of vibro-compaction-, vibro-displacement den-sification, vibro-cast-in-place- or soil stabilization columns.Selection of the most suitable method depends primarily onthe ground at the site and on the loads to be carried.

MethodsVibro-Compaction Densification (VCD)Granular or weakly cohesive sediments such as gravel andsand often have very uneven layer densities in their naturalstate. With VCD this can be increased to around 80 %. Inthe process, the soil is "floated" by a water or air flush, thevibrator sinks and a settlement depression is formed atground level. This is filled with added material. By extractingthe vibrator in stages, a compacted zone 2 to 4 m in diame-ter is created.

Vibro-Displacement Densification (VDD)In cohesive soils it is not possible to rearrange the grains.In the VDD, the added material is transported directly tothe vibrator tip, compacted by multiple displacementstages and pressed into the surrounding soil. This createsa crushed rock or gravel column which improves the sur -rounding cohesive soil due to the greater rigidity of theinstalled added material. Selection of the most suitablemethod depends primarily on the ground at the site andon the loads to be carried.

Vibro-Cast-in-Place Columns (VCIPC)The VCIPC-method is efficient and cost-effective in primarilycohesive, and also organic ground with very low load-bearing capacity. Thanks to the use of high-grade pumpedconcrete, the VCIPC have a high internal strength, regardlessof the surrounding ground. VCIPC are classified accordingto DIN 1054 as unreinforced piles for the transmission ofstructural loads into deeper ground.

Soil Stabilization ColumnsSoil stabilization columns are slim load-bearing elements witha minimum diameter of 15 or 18 cm. A lance is vibrated intothe load-bearing horizon or to the pre-determined depth andextracted again. While this is happening, mortar is pumpedinto the soil under pressure. The soil stabilization columnscombine load discharge transfer via skin friction and end-bearing with the effect of additional ground improvement bythe full displacement method.

The Methods

Jet Grouting

37

T he jet grouting method is a specialist technique forunderpinning, reinforcing or deepening building founda-tions, for sealing or stiffening blankets and for dam

sealing. To produce jet grouting bodies a drill rod is drilledinto the ground. When the specified depth is reached, anenergy-rich liquid – water or water-binder slurry – is jetted

through a nozzle at the bottom end of the rod. Simultaneousextraction and rotation of the drill rod causes the liquid jet toerode the soil. A portion of the soil is flushed out with theliquid. With the binder slurry remaining in the soil, a cylindri-cal plastic concrete body is produced.

MethodsA variety of jet grouting- or high pressure injection(HPI)-methods are used depending on the nature of the soil andthe function:

B-method (Binder slurry for cutting; one-phase-method): ingranular soils for small and medium-sized column diameters.

BA-method (Binder slurry for cutting with Air assistance;two-phase-method): in granular soils for medium-sized tolarge column diameters.

WB-method (Water for cutting and filling in with Binderslurry; two-phase-method): in cohesive soils for small tomedium-sized column diameters.

WAB-method (Water for cutting with Air assistance andfilling in with Binder slurry; three-phase-method): in cohesivesoils for medium-sized to large column diameters.

G routing is used in specialist foundation engineeringto introduce the grout material (water with hydraulicbinders and possibly additives) and solutions (soft

gel, silicate gel) into the soil. A basic distinction is made

between displacement grouting (compaction grouting, hy-draulic fracturing) and grouting without displacement of thehost material not involving ground displacement (permeation,fissure grouting, bulk-filling).

Grouting

The Methods38

MethodsCompensation GroutingSuitable drilling rigs are used to execute spread bores fromshafts beneath buildings, fill them with a sleeve grout and in-stall the tubes-à-manchettes. By targeted injection of groutmaterial into the tubes-à-manchette the soil is broken upand pretensioned. Controlled multiple grouting operations,with electronic uplift monitoring of the buildings compensatefor settlement.

Compaction GroutingIn the compaction grouting process a comparatively stiff,special mortar is pumped in stages from bottom to top intothe mostly loose ground in order to compact it withoutbreaking it up. Probes verify the success of the compactiongrouting.

Permeation GroutingPermeation grouting enables deep-level sealing blankets tobe produced in sand and gravel. Single sleeve pipes arevibrated into the ground or installed in bores in a preset gridconfiguration. Through the valve the grout is injected. Inthe vicinity of the valves spherical or elliptical grout bodiesare created which form a continuous, tight blanket.

The Methods

Micropiles

39

M icropiles serve to introduce compression loads intothe ground or to transfer tensile forces (such ascreated by uplift). They can be installed in any soil

types as well as in rock and transmit the force into the soilby skin friction and / or end-bearing. Commonly applied

execution methods are drilling and driving with percussionor vibration, if necessary using ultra-compact equipmentwhich permits working in tight spaces. This means micro -piles can also be installed within existing buildings.

Method

Depending on requirements, micropiles are deployed assingle piles, pile groups or -walls on new-build, renovation orbuilding reconstruction projects. Bauer produces micropileswith diameter from 114 mm to 300 mm, using cased or un-cased drilling techniques. The pile shaft is made of cementslurry, mortar or concrete. The external load-bearing capacitycan be increased by single or repeated multiple grouting.Internal load-bearing capacity is safeguarded by means ofbearing elements comprising single rods, rod groups, cas-ings, profiles or reinforcement cages.

C arefully thought-out planning is essential to cost-effective construction. The Design Department ofBAUER Spezialtiefbau GmbH carries out all neces-

sary steps, from the initial draft through to highly complexgeotechnical site surveys and provides state-of-the-artdesign software and useful databases. Whether at head of-fice or in the planning offices of the company's subsidiaries,

the Design Department offers a package of design servicesall from a single source, in the form of feasibility studies,preliminary designs, advance surveys, alternative concepts,or complete execution planning. All its services are basedon extensive specialist foundation engineering know-howand long experience in the execution of foundations andexcavation pits.

Design

Design40

Construction Technology

Construction Technology

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Passion for progress is the Bauer slogan – and theTechnical Services Department of BAUER Spezialtief -bau GmbH is a living example of this spirit. As an in-

house service provider, the department supports the branchoffices and subsidiaries in all geotechnical, measurement andbuilding materials technology matters, especially when inno-vative solutions are called for. Highly qualified techniciansand engineers analyze building materials and conduct qualityand suitability testing or quality control of concrete, suspen-

sions or other materials. Its work incorporates loading testsof a wide variety of kinds, such as pile- and anchor tests, aswell as geotechnical or geodetic surveys carried out underthe toughest conditions. It carries out intensive research anddevelopment in cooperation with leading universities, insti-tutes and consulting engineers in order to ensure a constantflow of new developments and to continually optimize exist-ing products and techniques.

Health and SafetySafety on construction sites is vital in order to maintain highlevels of concentration and efficiency. Bauer Spezialtiefbaustaff is highly trained, undergo regular refresher courses tokeep their skills and know-how up to date and use thorough-ly serviced equipment. The health and safety managementsystem employed by Bauer Spezialtiefbau is routinely certi-fied to OHRIS standard.

Quality ManagementSpecialist foundation engineering products play a key role,but are for the most part hidden away. The certified qualitymanagement system of the BAUER Group ensures that clearly defined yet highly flexible processes are implementedglobally throughout the Group – from order acquisition andprocessing through to after-sales. This learning, continuouslyimproving system guarantees the customers of the BAUERGroup absolute top quality.

ResponsibilityEnvironmental ManagementThe construction industry inevitably has an impact on the environment. The challenge faced by all construction compa-nies is to keep any such impact to a minimum. BAUERSpezialtiefbau GmbH operates an EMAS-certified environ-mental management system and submits itself to environ-mental auditing procedures. Bauer Spezialtiefbau is alsocommitted to collaborative, efficient working practices in theexecution of its projects, which further helps to conserveresources.

Ethical ManagementBAUER Spezialtiefbau GmbH has established a binding pro-gramme of values. As a founding member of the Germanconstruction industry's ethical management association EMBWertemanagement Bau e.V., it requires its employees to actin a manner conforming to the highest ethical standards. Theethical management practices of BAUER Spezialtiefbau GmbHare routinely audited and regularly recertified.

BAUER Spezialtiefbau GmbHBAUER-Straße 186529 Schrobenhausen, GermanyTelephone: +49 8252 97-0Telefax: +49 8252 97-1496BST@bauer.dewww.bauer.de

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