BAUERSoil Improvement

BAUER Soil Improvement2 BAUER Soil Improvement2

BAUER Soil Improvementa fast and economic solution

3BAUER Soil Improvement 3BAUER Soil Improvement

In the 1960s Bauer started per-forming ground improvement. The first vibrator for vibrocom-

paction was created in 1962 under the supervision of Dr.-Ing. Karlheinz Bauer. In areas wherethe subsoil has an insufficient bearing capacity, vibrocompac-tion or vibroreplacement can be a faster and cost efficient solution in comparison to deep foundations. Soil improvement is often used for land reclamation projects as well as oil and gas or infrastructure projects.

More than 45 years experience

Some of our highlight projects:

1962 Development and construction of the fi rst Bauer vibrator for vibrocompaction, based on a hydraulic driven engine

1971 Collini-Center, Mannheim, Germany Vibrocompaction up to a depth of 12 m

1975 Las Palmas, Grand Canary Vibrocompaction of 250,000 m³ of the so called “Picon” material (a volcanic slag)

1978 Thuwal, Kingdom of Saudi Arabia Vibrocompaction with 160,000 lin.m for a new harbor construction working from a ponton

2004 Palm Jumeirah, Dubai, UAE Soil improvement of the crown, 500,000 m² vibrocompaction

2005 Peribonka Dam, Canada Vibrocompaction of 700,000 m³ of the fi lls and partially the river deposits at the main dam base up to a depth of 35 m

2009 Cleveland Clinic, Al Sowah Island, Abu Dhabi, UAE Vibrocompaction of 90,000 m² to a depth of approximately 10 m

2012 Davao City, Philippines Vibrocompaction of 100,000 lin.m up to a depth of 18 m

Ocean Reef Island, Panama Vibrocompaction of 100,000 m² up to a depth of 15 m

1988 Cardiff, United Kingdom Installation of 24,000 lin.m of stone columns with a length of 9 m to 10 m for the ring road

1990 Singapore Securing of dams against settlement and shear failure by installing 230,000 lin.m of stone columns

1995 Vancouver, Canada Delta Port, vibrocompaction of 1.5 Mio. m³ of fi ll, working from a ponton to a depth of approximately 31 m

1999 Schleuse Hohenwarte, Germany 28,000 lin.m of vibrocompaction up to a depth of 30 m

5BAUER Soil Improvement

General

Vibrocompaction

Vibroreplacement

Clay Silt Sand Gravel Stone

100%

90%

80%

70%

60%

50%

40%

30%

20%

10%

0%

Va

lue

s o

f P

(%

), b

y W

eig

ht

Particle Size (mm)

The table shows which ground conditions suit vibrocompaction and which suit vibrodisplacement (stone columns)

planned construction. In addition, a mitigation of earthquake induced liquefaction can be obtained. In com-parison to piles or barrettes (which de-scribe columnar elements that transfer loads), the subsoil will be considered as an improved soil continuum.

During the movement of the vibrator the solid part of the matrix will be fl oated and afterwards compacted,

strength values ranging from 20 to 100 kN/m² by assembling compacted

Soil improvement is a special foun-dation technique to improve the soil characteristics such as the

relative density or Young’s modulus of elasticity. The technique is required in cases where the bearing capacity of the subsoil is not adequate for the

Applicable in non-cohesive soil with a maximum fi ne content of 10 % such as sands or gravels.

Applicable in mixed grained or cohe-sive soils, such as sandy silts to fi ne-grained soils with undrained shear

Bauer offers two different techniques:

• Vibrodisplacement to install stone columns and

• Vibrocompaction also known as vibrofl otation

with the result that the void ratio of the matrix decreases.

coarse grained backfi ll material (stone aggregates).

Matrix(loose material)

Matrix(dense material)

Flotation

Vibro Compaction

Vibrocompaction

Vibrodisplacement

0.001 0.01 0.1 1 10 100

BAUER Soil Improvement6

Why Soil Improvement?recommends possible types of foun-dation. Normally, the subsoil provides adequate bearing capacity without special foundation measures being required. If the geotechnical specia-list comes to the conclusion that the

During the planning stage of a construction project, a soil investigation is usually carried

out at the proposed site by a geo-technical specialist who assesses the bearing capacity of the subsoil and

In many cases, soil improvement offers an economical and fast method for improving the engineering characteristics of the prevailing subsoil.

Different subsoil conditions and possible foundation solutions

subsoil does not have suffi cient bea-ring capacity, various solutions are available, such as soil improvement or deep foundations.

• No excavation material, there-fore no cost impact resulting from transportation and no dealing with contaminated soils.

• Simple foundation conditions, similar to natural subsoils with an adequate bearing capacity. The technique is highly adaptable.

Advantages of Soil Improvement• In general, no groundwater low-

ering required during installation phase. Therefore no requirements for permits and no risk to adjacent buildings.

• Environmentally compatible by using only natural materials.

By providing high level technical supervision and workmanship throughout the project execution and understanding the interaction between subsoil and structure, it is possible to fulfi ll the design require-ments like increasing the bearing capacity and mitigating liquefac-tion.

Subsoil with

an adequate

bearing capacity

Improved subsoil

(by vibrocompaction

or vibroreplacement)

Subsoil with an

adequate bearing

capacity

Pile

7BAUER Soil Improvement

Techniques

process, the soil is „fl oated“ by a wa-ter or air fl ush, the vibrator sinks and a settlement depression is formed at surface level. This is fi lled with additional material. By extracting the vibrator in stages, a compacted zone 2-4 m diameter is created.

the surrounding soil. This creates a crushed rock or gravel column which improves the surrounding soil due to the higher rigidity of the additional installed material. The selection of

Granular or weakly cohesive sedi-ments (fi nes less than a maximum of 10 %) such as gravel or sand often have very uneven layer densities in their natural state. With vibrocom-paction the relative density can be increased up to around 80 %. In the

Using vibroreplacement technique, the added material is transported directly to the vibrator tip (bottom feed method), compacted by multiple displacement stages and pressed into

The upper meters of subsoil cannot be compacted effectively by the vibro-compaction technique only. These areas must be compacted by surface compaction techniques like rollers or similar.

the most suitable technique depends primarily on the ground conditions, the loads to be carried and the boundary conditions.

Vibrocompaction

Vibroreplacement

BAUER Soil Improvement8

Designimproved layers by using the theory of Priebe, which is common prac-tice all over the world. The following diagram (Priebe, 1995) gives you an impression of how to assess the so-

Regarding vibrocompaction we investigate the “improved” soil by fi eld tests such as CPTu or

SPT. In case of vibroreplacement we estimate the soil conditions of the

called improvement factor by a given friction angle of the stone column (φs), the area ratio and an assumed Poisson’s ratio of the soil (μB).

As an alternative for the assessment of the settlement it might be reason-able to use FE-Applications. The results can give you a better impres-sion of the behaviour of the stone column in different layers. Through FE-Calculations you can also assess the bulking effect in soft layers.

Imp

rove

me

nt

Fa

cto

r n

6

5

4

3

2

1

Area Ratio A/Ac

1 2 3 4 5 6 7 8 9 10

μB = 1/3

φs = 45,0°

φs = 42,5°

φs = 40,0°

φs = 37,5°

φs = 35,0°

9BAUER Soil Improvement

Testinginvestigate the success of soil im-provement, especially for vibrocompac-tion. The resulting graphs display for

of a soil improvement by vibrore-placement, a zone load test can be executed. In this case for example, a concrete plate will be manufactured, set in place to cover a number of stone columns and loaded in stages (dead

The execution of the so-called Cone Penetration Tests (CPT)is the most common practice to

The graphs of a CPT can be used to evaluate for example the soil type and the Young’s modulus. In addition, it is possible to assess the liquefac-tion mitigation due to soil improve-ment works. To prove the success

example the cone resistance against depth and friction ratio.

load test) or as an alternative you can use a kentledge test. The settlement during the different load stages will be recorded, so you receive the load settlement behaviour of the improved soil.

Load cellHydraulic jack

Reference beamDial gauge extensometers

Load dispatcher (e.g. timber mat)

Concrete block (kentledge)

Beam

Kentledge support

De

pth

[m

]

Cone Resistance qc [MPa]

0

5

10

15

20

25

0 5 10 15 20 25 30 35 40 45 50

Reinforced concrete test base

BAUER Soil Improvement10

TR 17

TR 75/TR 85

Head piece

with 2“ fl ushing

connection

Follower pipe

Joint

(Isolator)

Poker with wear

shield and fl ush

holes

R90

155

170

580Ø320

696

5850

5850

3000

945

2232

[115

]

Ø300

1885

0

700

7000

7000

1000

012

0030

01

900

Ø406

2907

0

Qualityproduction data for documentation purposes is also carried out by the B-Tronic system.By deploying our professional employ-ees on all our projects, Bauer guaran-tees the quality of the soil improvement works. Documentation and quality management happens in accordance to the rules of DIN EN ISO 9001.

Based on extensive experience Bauer uses methods, equipment and techniques which allow safe

execution of soil improvement pro-jects. All process-specifi c production data are monitored and displayed on the B-Tronic monitor inside the ope-rator cabin for quality purposes. Elec-tronic data acquisition of all relevant

The horizontal centrifugal forces of the deep vibrator are generated by a hydraulic motor and an oscillator inside the vibrator section. When de-ploying deep vibrators in conjunction

Equipment

with customized Bauer base ma-chines, the required hydraulic power can be provided by the base machine itself (BG, BF or MC) or by a separate hydraulic power pack, for example

the HD 460. Bauer uses two different vibrator types, the TR 17 and the TR 75/TR 85. The TR 17 can reach a penetration depth of up to 25 m and the TR 75/TR 85 up to 45 m.

11BAUER Soil Improvement

Projects Worldwide

For the „Palm“ the Emirate of Dubai builts a 7,000,000 m² artifi cial island off Jumeirah Beach to house hotels and luxury villas. Most of the area was compacted by 17 Bauer deep vibrators.

In the port of Balboa on the pacifi c coast of Pa-nama, Bauer Fundaciones Panama compacted some 15 hectare of newly reclaimed land down to a depth of 22 m. The improved ground is being utilized to extend the second largest container terminal in Latin America and will in future be ca-pable of withstanding all kinds of loads that such use demands.

In Abu Dhabi, on Al Sowah Island, the 90,000 m² Cleveland Clinic is under construction. Bauer deployed as many as ten TR 85 deep vibrators when carrying out vibrofl otation densifi cation to provide ground improvement of the 10 m thick alluvial sand layer.

In Schindellegi, Highend I to III, a housing estate at the hillside was constructed. For the necessary ground improvement 12,800 lin.m vibroreplace-ment (stone columns) were installed, comprising of 1,117 columns with a length of up to 12 m.

Palm Jumeirah, Dubai, UAE

Port of Balboa, Panama

Cleveland Clinic, Abu Dhabi, UAE

Highend I to III, Schindellegi, Switzerland

BAUER Spezialtiefbau GmbHBAUER - Strasse 186529 Schrobenhausen, GermanyTel.: + 49 8252 97- 0Fax: + 49 8252 97-1496BST@bauer.dewww.bauer.de

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