The Soilfrac® Process - Smet-Keller

Brochure 61- 02 E
The Soilfrac ®
Process

CONTENTS
Soilfrac®-today . . . . . . . . . . . . . . . . 2
Soilfrac-Process Description . . . . . . . . 4
Soilfrac-Foundation Restoration . . . . . 6
Soilfrac-Lifting of Structures . . . . . . . 8
Soilfrac-Protection of Structures . . . . 10

Development
Originally the Soilfracturing process was used in the oil industry to
frac sub soils to create paths for the oil to flow toward the oil wells.
In the sixties, Keller engineers adapted this process and developed
several solutions to problems in the geotechnical field. Soilfrac® is a
registered Trademark of the process used by Keller.
Position in the market
Where classical grouting techniques for voidfilling for foundations
or restoration of structures is not suitable or the lifting of structures
is required, the Soilfrac-process fills the gap within the circle of
different grouting techniques.
Together with the newly developed measuring and control techniques
as well as special observation devices it is possible to lift structures
by several decimeters.
Soilfrac ® today
3

The Soilfrac® Process
In using this process fractures in the soil are created which are then
filled with grout. Each soil formation may be improved by multiple
grouting treatments and controlled lifting may be induced.
Process
Application limits for the grouting processes
Process
Clay Silt
Sand Gravel Cobbles
100
Soilfrac®
Soilcrete-Jet Grouting®
80
Compaction Grouting
Synthetic Solutions
60
Sodium Silicate Solutions (lv)
Silicate Gel (hv)
40
Ultrafine Cement
Cement suspension
20
Mortar
0
lv = low viscous
0,002 0,006 0,02 0,06 0,2 0,6 2,0 6,0 20 60
hv = high viscous Partical size (mm)
Passing-Weight (%)
uneconomical
favourable
Installation point
basement
Installation point shaft
Installation point ground
surface
4

Construction site
installation
Water
Cement-Filler
Stone dust
Accelerator
and Additives
Mixer and
pump
Measuring
and control
▲ Mixing- and grout
station placed into a
Soilfrac®-container
allowing short installation
period.
Installation point
1 2 3
1 Sleeve pipe
installation
Sleeve pipes are installed
into the soil formation
to be treated and the
annular space between
the borehole wall and
sleeve pipe sealed with
a stiff cement-bentonite
mixture.
2 Soil fracturing
To allow the injection of
the Soilfrac® suspension
a grout hose equipped
with a double packer at
the tip is inserted into
the sleeve pipe. The
double packer seals the
sleeve pipe on either
side of the sleeve, thus
allowing the grouting of
each single sleeve along
the section to be
treated.
3 Multiple grouting
The sleeves along the
grout pipe may be
grouted once – or
several times- according
to the technical
requirements. The grout
quantity, the max. grout
pressure – and in case
of repeated grouting –
the setting times are
maintained according to
instructions. Sleeve pipes
may remain reusable
for long periods.
2
4
3
1
1 Sleeve pipe
2 Sealing mix
3 Rubber sleeve
4 Grout
5 Packer
5
Primary grouting
Multiple grouting
5

1 Restoration of the
steeple as well as cement
stabilisation of the nave in
soil formation consisting of
silt and peat.
2 Foundation rehabilitation
of a customs hut
founded on top of fill
material in a moat.
3 Modern software is
used for simulation and
control of the Soilfrac® –
works.
Foundation Restoration
Individual footings and subsoils are components of the foundation of a
structure. In the course of time both may fail due to a number of
reasons. This occurs quite often in the case of historical buildings.
In the event of excessive settlements – Soilfrac® is a suitable process
to restore the link between the base of the structure and
competent soil formation.
For the treatment of natural stone foundations, which have either
moved or cracked or the mortar has decomposed or been removed,
the classical grouting technique may be applied by adapting the type
of grout mix. Lifting of structures in a poor condition is seldom
required – but also possible.
Specific working parameters
are illustrated separately
A Grid
B Deformation foundation level
C Grout pressure
D Grout quantity
E Foundation
F Sleeve pipe fan
Restoration
1 2
A
B
3
C
D
E
F
The Soilfrac®-process is used for foundation restoration where settlements
have to be stopped such as, where natural and artificial soil distortion occurs,
mining activities create problems, non-load bearing soil exists, or partial
sections must be lifted.
6

Restoration of the
steeple by means of
the Soilfrac®-process
and cement stabilisation
of the nave.
7

Lifting of Structures
Settlement of structures can be rectified by the Soilfrac®-process.
Depending to the condition of the building and the soil the lifting speed
is adjusted accordingly.
Precise partial lifting within a millimeter is combined and added to
a total lifting in the decimeter range without damaging the structure.
Lifting of structures is normally performed without restricting
their use.
1 Insertion of the grout
hose into the sleeve pipe.
2 Partial repositioning and
rehabilitation of the river
pier of a highway – bridge.
3 Lifting of the discharge
ramp of a refuse
incineration plant.
Lifting
1 2
3
Restoring leaning structures to a vertical position is a spectacular event such
as the efforts in connection with the leaning tower of Pisa. In some cases
only a partial restoration is sufficient to achieve a satisfactory technical result
as well as improving the esthetic view of the structure.
8

High rise building
restored to the vertical
position
Preparatory works for
an extension caused the
leaning of a high rise
building.
After installation of an
extensive control point
system to measure the
vertical movements a
sleeve pipe fan was
installed in accordance
with the lifting
requirements. Within
5 month a total lifting of
60 mm was achieved.
9

1 Installation of sleeve
pipes from a temporary
shaft.
2 Sectional excavation of
a tunnel to minimise
settlements.
3 Representation of
prelifting in mirror image
form of the estimated
settlement trough within
structural limits as well as
the permanent uplift to
secure the structure above
the tunnel line.
Protection of Structures
To protect structures against predictable settlements during tunnel
construction horizontal sleeve pipe fans between tunnel roof and the
building foundation will be installed from temporarily shafts. The
building to be protected will be equipped with an electronic measuring
system for registration of vertical movements.
Primary grouting - up to appearance of lifting tendencies-consolidate
the soil mass, followed by a predetermined lifting operation reflecting
the size and form of the expected settlement trough due to tunnel
driving.
According to the local situation the tunnel will be excavated in one
operation or in a number of segments. The settlement occuring during
the tunneling works will be adjusted – either partially or to the full
amount. The quick reaction in respect of the developing deformations
reduces larger differential tensions within the structures, an advantage
of the Soilfrac® process compared with other technical solutions.
A Settlement prediction
B Pre – Lifting
C Interim settlement
D Interim Lifting
E Final position
Protection
1 2 3
A
B
C
D
E
The protection of structures against settlements from tunnel and mining
activities is an important application of the Soilfrac® - process. This technique
was used for the first time by Keller for a subway
project in the Ruhr area of Germany in 1985.
10

Structure protection during
subway construction in a
large European city.
Installation of horizontally
located sleeve pipes from
shafts to protect the old
town.
11

Keller Grundbau GmbH
International Geotechnical Contractors
www.KellerGrundbau.com · www.Keller-Asia.com
Germany
Head Office and Overseas Division
P.O. Box 10 06 64
63006 Offenbach
Tel. +49 69 8051-0 · Fax +49 69 8051-270
E-mail: Overseas@KellerGrundbau.com
Bahrain
Keller Grundbau GmbH
Flat 205, Bldg. 63
P.O. Box 5452
Manama 332
Tel. +973 17741677 · Fax +973 17741688
E-mail: Keller@batelco.com.bh
U.A.E.
Keller Grundbau GmbH
Office No. 407
H. H. Shaikh Ahmed Bin Saeed Al Maktoum Tower
Shaikh Zayed Road · P.O. Box 11 13 23
Dubai
Tel. +971 4 329-8089 · Fax +971 4 329-8099
E-mail: info@kellergrundbau.ae
Saudi Arabia
Keller Turki Co. Ltd.
P.O. Box 718
Dammam 31421
Tel. +966 3 8333997 · Fax +966 3 8335325
E-mail: Keller-turki@atco.com.sa
Egypt
GENCO · Geotechnical Engineering Contractor Ltd.
462, Horreya Avenue, Roushdy
Alexandria
Tel. +20 3 5458443 · Fax +20 3 5427372
E-mail: Genco-alx@link.net
Malaysia
Keller (M) Sdn. Bhd.
B-5-10 Plaza Dwitasik
Bandar Sri Permaisuri
56000 Cheras, Kuala Lumpur
Tel. +60 3 91733198 · Fax +60 3 91733196
E-mail: info@keller.com.my
Singapore
Keller Foundations (S E Asia) Pte Ltd.
18 Boon Lay Way
#04-104 Tradehub 21
Singapore 609966
Tel. +65 6316-8500 · Fax +65 6316-8652
E-mail: Keller@singnet.com.sg
India
Keller Ground Engineering India Pvt. Ltd.
S-15, Economist House
First Cross Road, Guindy Industrial Estate
Chennai – 600032
Tel. +91 44 2250185-0 /-1 · Fax +91 44 22501852
E-mail: info@kellerindia.com
A company of Keller Group plc