Practical Application of GI Technique Rev 0 HAKI pdf
1. Bauer Design & Construction Systems
PRACTICAL APPLICATIONS OF
GROUND IMPROVEMENT TECHNIQUES
Gavin Chung
Regional Manager Senior Manager
Bauer South East Asia Pacific Region Bauer (M) Singapore
Ground Improvement Division
Indonesian Society of Civil and Structural Engineers (HAKI)
14th December 2013
2. 2
Indonesian Society of Civil and Structural Engineers (HAKI)
14th December 2013
CONTENTS
Principles of Ground Improvement
Ground Improvement Techniques
Selection of Techniques
Type of Applications
Liquefaction
Bauer-Betterground Range of Techniques
3. 3
PRINCIPLES OF GROUND IMPROVEMENT
Consolidation
Techniques that drains and reduction of voids
Inclusion / Reinforcement
Techniques that introduce foreign elements to improve in situ soil
Compaction
Techniques that densify soil by compaction
4. Ground improvement methods are used to improve unsuitable subsurface soils and/or to
improve the performance of structures or embankments. These methods are used when
replacement of the in-situ soils is impractical because of physical limitations, environmental
concerns, or other conventional methods are costly.
Functions:
Increase bearing capacity, shear, or frictional strength,
Increase density,
Control deformations,
Increase or provide lateral stability,
Form seepage cutoffs or fill voids,
Transfer embankment loads to more competent layers, and
Increase resistance to liquefaction.
4
PRINCIPLES OF GROUND IMPROVEMENT
5. 5
GROUND IMPROVEMENT TECHNIQUES
Ground
Improvement
Consolidation
PVD + Surcharge
Vacuum
Consolidation
Stone Column +
Surcharge with
or w/o PVD
Reinforcement
Vibro – Stone
Column,
Concrete Column
Soil-Cement mix
– SCC, CSM, FDC
Grouting
Compaction
Vibro
Compaction
Dynamic
Compaction
6. 6
GROUND IMPROVEMENT TECHNIQUES
Category Function Methods
Consolidation
Accelerate consolidation , increase
shear strength and increase
density with time
a. Prefabricated Vertical Drain
b. Vacuum Consolidation
Reinforcement
In soft foundation soils, increases
shear strength, density, improves
resistance to liquefaction and
reduce settlements
a. Vibro Stone Columns
b. Vibro Concrete Columns
c. Dynamic Replacement
Physio-chemical alteration of
foundation soils to increase their
tensile, compressive, and shear
strength; reduce settlement; and
to provide lateral stability
confinement
a. Soil Cement Mix
- Soil Cement Column
- Cutter Soil Mix
- Full Displacement Column
To form fill voids, increase density,
increase tensile and compressive
strength
a. Grouting
- Permeation, Compaction,
Jetting & Compensation
Compaction
Increase instantaneous density,
bearing capacity, and frictional
strength of granular soils. Reduce
settlement and increase resistance
to liquefaction
a. Vibro Compaction
b. Dynamic Compaction
8. 8
SELECTION OF TECHNIQUES
Step Selection Process
1 Suitability of technique (soil and technique compatible)
2 Technical/Performance compliance
3 Possible damage to adjacent structures
4 Construction time available for ground improvement
5 Cost – (check material availability & compare techniques)
6 Environmental issues influencing the technique
9. 9
SELECTION OF TECHNIQUES
Soil Description Densification Reinforcement
Gravel and sand <10%
silt, no clay
Excellent Very good
Sand - 10% to 20% silt
and <2% clay
Very good Very good
Sand - >20% silt and
non-plastic silt
Marginal (with large
displacement)
Excellent
Clays Not applicable Excellent
Example of selection with Stone Column
Treatment depth of vibro stone
column can be up to 30m
Example of selection with Vibro Compaction
Soil Description Densification
Well graded sand <5% silt, no clay Excellent
Uniform fine to medium sand with
<5% silt and no clay
Good
Silty sand with 5% to 10% silt and no
clay
Moderate
Silty sand > 10% and >2% clay Not applicable
Clays Not applicable
Treatment depth of vibro
compaction column have been
done up to 70m (Lausitz,
Germany 1999 by Degen family
inventor of vibroflot)
Limited improvement in silts
can be achieved with stone
backfill. Densification base on
70% relative density
11. 11
Information Required For Design Selection
Geotechnical report (consist of soil investigation report with location of SI shown with
footprint of structures), laboratory test such as soil classification, plastic index, undrained
shear strength Cu values or friction angles, consolidation test ie Oedometer, SPT, CPT,
Vane Shear, boreholes, ground water table etc.
Plan view & cross section of the project
Specification for geotechnical solutions
Design loads – infrastructure and adjacent buildings
Load bearings of structures and drawings of the dimension of structures
Engineering performance/design criteria and seismic design requirement, if any
Standards and codes expected to follow
Design reports for foundation and ground improvement
Construction time frame and expected commencement for the ground engineering
works. The time allowance is critical in determining a cost effective proposal.
For projects involving mitigation of earthquake induced settlements and lateral
spreading: Mw, Moment Magnitude and PGA, Peak Ground Acceleration datas required.
The above information is crucial to check the 3 main elements for any ground improvement
design:
a. Settlement
b. Stability
c. Liquefaction
18. 18
Prediction of Earthquakes?
Globally a Magnitude 6 earthquake happens once a week, Magnitude 5 ≈
10 times , 4 ≈ 100 times, 3 ≈ 1000 times.
These quakes happen often in uninhabited locations and then generate
little or no damage.
The main damage by earthquakes originates from large quakes of a size
that only happens a few times in a century.
Per today we are not able to predict location, time, and magnitude of
future earthquake events.
This has to do with the fact that in contrast to weather phenomena, the
phenomena generating earthquakes occur mainly underground , hidden
from direct observation.
The best insight is gained from recording annual movements on the fault
lines and from recording the small-earthquake activity.
22. 22
LIQUEFACTION MITIGATION
Increase strength ( CRR)
Ground improvement (densification or
grouting)
Decrease exertion stress ( CSR)
Shear reinforcement with ‘stiffer’ elements
within soil mass
Decrease excess pore pressure quickly
Reduce drainage path distance with tightly
spaced drains
“What to do?”
23. 23
Stone Columns act as
vertical drains, thus
reducing the excess pore
pressures that lead to
liquefaction.
The earthquake induced
shear stress τ is distributed
onto soil and column in a ratio
proportional to the stiffness ratio
between both materials.
LIQUEFACTION MITIGATION
Liquefaction prevention by Stone Columns
24. 24
BAUER-BETTERGROUND TECHNIQUES
Improvement by Consolidation
Improvement by Inclusion/Reinforcement
Improvement By Compaction
Prefabricated Vertical Drain
Vibro Stone Column Cutter Soil Mix
Soil Cement Column
Vibro Concrete Column
Full Displacement Column
Grouting
Vibro Compaction Dynamic Compaction
Dynamic Replacement
47. 47
CSM Sequence of Work
Cutter Soil Mix (CSM)
CSM Site Configuration
P 1
S 2
P 3
S 4
P 5
S 6
P 7
S 8
P 9
S 10
P 11
S 12
P 13
S 14
dia 8,5 m
Ø
8,5m
Joint Operation
52. 52
Permeation Grouting
Permeation grouting – is a process of injection of grout into granular, fissured
or fractured ground to produce a solidified mass to support increased load
and/or to fill voids and fissures.
Joint Operation
53. 53
Compaction Grouting
Drilling to final depth
Start grouting from lowest level
Gradually lifting the rod
Grouting in steps
Compaction grouting – injected to
loose soils, homogenous grout
bulbs are formed and displace,
densify and strengthen the
surrounding soil
Joint Operation
55. 55
Compensation Grouting
Compensation grouting – process used to control or reverse the settlement of
structures, to induce fractures in the soil thereby causing an expansion to take
place counteracting settlement and producing controlled heave.
Joint Operation
56. 56
Dynamic Replacement (DR)
Ground reinforcement technique which inclusion such as stone or sand
is compacted into the ground
Typical design of 2.5m diameter column with spacing between 4.5m to
6m with depth up to 4m-5m
Increase bearing capacity, stability, drainage path and reduce settlement
Joint Operation
58. 58
Vibro Compaction
Vibro compaction applications are use in conditions where existing
cohesionless or slightly cohesive soils can be improve by vibration.
The basic principles is that the cohesionless soils can be rearranged by
means of vibration, which requires a combination of high frequency
vibration and movement induced by the flushing action of injected water
resulting in initial replacement and compression of the surrounding soils.
Densification of granular soils by VC results in:
a. Increased bearing capacity of soil
b. Reduced foundation settlement
c. Increased resistance to liquefaction
d. Increased resistance to shear movement
Joint Operation
61. 61Joint Operation
• compaction by surface impact,
• Typical drop height: 20 - 30 m,
• Typical weight:10 to 30 tons,
• Economic depth reach: 12 m to 15 m.
(depending on material)
Dynamic Compaction
63. 63
For more info: www.bauer.de/en
Special thanks to Dr. Dradjat Hoedajanto, President of HAKI for giving us
the opportunity to make this presentation, the support of Mr. Thomas
Domanski, Bauer’s Regional Director and our partner Betterground,
Dr. Wilhelm Degen.
