The presentation illustrates a technique for ground improvement, Grouting. In India, grouting is still not being used very much. In this presentation, I have demonstrated the basic types of grouting, goals of ground improvement and two case studies of grouting.
3. GOALS OF GROUND IMPROVEMENT
To increase the bearing capacity
To provide lateral stability
To increase resistance to liquefaction
Modify soil properties
To increase the stiffness
Low permeability
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5. WHAT IS GROUTING?
Improvement of soil or rock through injection of grout, cement or chemical grout.
Grouting may be divided into following :-
1. Intrusion grouting
2. Compaction grouting
3. Permeation grouting
4. Jet grouting
5. Compensation grouting
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6. INTRUSION GROUTING
The joints or fractures in soil or rock are filled with injection
of grout
Pipes are first inserted into the soil from surface and than the
grout is added with pump
Advantage is, it decreases the permeability of rocks
Generally cement grout is used
Water retaining structures like dams, it is used to reduce
seepage
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Fig 1. Intrusion Grouting
7. COMPACTION GROUTING
(DISPLACEMENT GROUTING)
Grout is inserted with pump at high pressure to form a
series of intrusions in deposit
25 mm thick slump doesn’t penetrate deep in soil and
compact the adjacent soil
Resulting increase in strength
Generally used in loose soil as well as unsaturated fine-soil
When to restore the structure having excessive settlement,
compaction grouting is used to reduce the settlement
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Fig 2. Compaction Grouting
8. PERMEATION GROUTING
Thin grouting is inserted into soil that permeates into
voids of soil
The grout cures after a time and turns the soil into solid
mass
Generally used in fine-grained soil
Makes the soil less compressible, strong and impermeable
Applied to the projects of tunneling and stabilizing soil
before excavation
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Fig 3. Permeation Grouting
9. JET GROUTING
Pipe fitted with horizontal jets inserted into soil at require
depth and with pressure grout is inserted
Pipe is gradually raised and rotated while grouting still
being injected
Column is formed in the soil that makes the soil
impermeable and strong
Applied to water-logged area as well as in stabilization of
soil before excavation and tunneling operations
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Fig 4. Jet Grouting
10. COMPENSATION GROUTING
Compensation Grouting is a process used to control or
reverse the settlement of structures
It consists of the injection of material into the soil
between the foundation to be controlled and the process
causing the settlement
The material injected is forced into fractures thereby
causing an expansion to take place counteracting the
settlement that occurs or producing a controlled heave
of the foundation
Because the process requires that the soil is fractured
and not permeated, Compensation Grouting may be
used in most soil types ranging from gravels to clays or
weak soils
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Fig 5. Compensation Grouting
11. CASE STUDY 1
LONDON VICTORIA STATION UPGRADE BY JET
GROUTING
Keller carried out the UK‘s largest ever Jet Grouting
project as part of a £700m scheme to upgrade one of
London‘s busiest rail interchanges.
The scheme involved the construction of a new ticket
hall and underground walkway to the mainline
station. Much of these new structures are to be
constructed at the level of the interface between
the London Clay and water-bearing Terrace
Gravels.
Additionally, the site was surrounded by numerous
fragile listed buildings and one of London's
important theatres.
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FIG 6. VICTORIA STATION UNDER
CONSTRUCTION
12. CONT…
Keller initially carried out a trial at the site in 2008 to prove the performance of Jet Grouting. Work on
the project itself began in October 2011 and lasted until 2014. The primary aim of the scheme was to
provide a 2m thick annulus around all of the proposed tunnels and so allow safe excavation through solid
ground. This was done by installing overlapping columns ranging in diameter from 1.4m to 1.8m to
depths up to 14m. The grout columns were installed to achieve a target strength of between 1N/mm2 and
10N/mm2.
One of the most complex parts of the project was the careful measurement of the orientation of the drill
string using GPS sensors at the top and bottom of the masts in order to achieve the required 50mm
tolerance. Additionally, column diameter was monitored by thermal degradation, a technique used by
Keller in Austria and Germany. All of this information can be entered into the BIM Model to ensure
quality control.
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13. CONT…
Excavation of the early shafts was successful and allowed for the installation of 2500 Jet Grout columns.
System: Jet Grouting
Client: Transport For London
Contractor : Taylor Woodrow BAM Nuttall
Engineer: Mott McDonald
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14. CASE STUDY 2
Cross-rail C300/C410 Compensation Grouting
Cross-rail is the largest and most ambitious projects in Europe.
Works started n May 2009 and required over 10,000 people working across over 40 construction
sites.
The compensation grouting scheme on the Cross-rail contract for the Western Running Tunnel
and Caverns (C300/C410) required the installation of over 45000m of 75mm diameter steel tube
pipes.
The TaM pipes cover an approximate area of 50000 m2 in the Bond Street and Tottenham Court
Road stations.
It involves the construction of 42km of twin underground railway tunnels and 10 new stations.
The line commences in Maidenhead and the existing station, runs beneath London from
Paddington to East London When it opens in 2018, it will transform rail transport in London,
increasing capacity by 10% and cutting journey times across the city.
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15. CONT…
Keller carried out the Compensation grouting works as mitigation to the large diameter platform
tunnel and cross passage excavations underneath densely populated areas of high value and with
critical assets.
System: Compensation Grouting
Client: Cross-rail
Contractor: Bam Ferrovial Kier JV
Year of Execution: 2013/14
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16. REFERENCES
1. SOIL MECHANICS AND ENGINEERING, K.R.ARORA
2. KELLER INDIA/WWW.KELLER.COM
3. KELLER UK/WWW.KELKER.CO.UK
4. Ground Improvement and Ground Control including Waste Containment with Geosynthetics ,
DR. J.N.JHA
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