Jet grouting method

1. APPLICATIONS OF BIG DIAMETER
JET (BDJ) COLUMNS FOR GROUND
IMPROVEMENT
Hanoi, 2023

2. 1. INTRODUCTION OF BDJ METHOD
CONTENT
2. TYPICAL PROJECTS
3. STRENGTH CHARACTERISTICS OF
CORED SAMPLES
4. CONCLUDING REMARKS

3. Concept of one-phase, two-phased and three-
phased jetting technologies
Upper jetting portion
Ultra-high pressure water
(40Mpa, 50L/min)
Lower jetting portion:
Ultra-high pressure grout
and air (40 Mpa, 300
L/min)
Three-phase jetting rod
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1. INTRODUCTION
Concept of BDJ method
In principle, BDJ method is a jet grouting method
that applies three-phase technology and high
pressure to produce soil-cement columns.

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Material Jetting pressure Jetting rate
Water 40 MPa 50 Liter/min
Grout 40 MPa 300 Liter/mine
Air 1.05 MPa 20 m3/min
1. INTRODUCTION
Equipment and typical specifications
Typical specifications of BDJ method
The specifications given in the table above are for typical column
diameters from 3.0 to 3.5 m in sandy soil with SPT N  50 and in
clayey soil with SPT  5. In practice, jetting pressure and rate can
be adjusted according to geological conditions.

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1. INTRODUCTION
Main construction steps

6.  Big diameter: High to ultra-high jet pressure can create
columns from 3.0 to 3.5 m.
 Speedy progress: Construction time is shortened significantly
compared with traditional jetting methods.
 High quality: The three-phase technology at high pressure
breaks the soil structure and mixes grout will soil at high
uniformity.
 Cost saving: Because of big diameter, a project would require
significantly less number of columns, thus reduce construction
time and therefore construction cost.
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1. INTRODUCTION
Advantages of BDJ method

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2. TYPICAL PROJECTS
No. Project name
(Location)
Key specs Constructio
n Year
Project type Key applications
1 Metro Line No.1
(HCMC, VN)
D3500, D3000,
D2500, D1400,
L= 3,500 m
2015-2016 Urban tunnel Ground improvement at break-in break-out
of Opera House and Ba Son stations;
Protection of the Opera House
2 Duyen Hai 3
Extension TPP
(Tra Vinh, VN)
D3000 / L= 1,550 m 2017 Industrial plant Ground improvement under existing water
pipes without dismantling the pipes (other
method cannot be applied)
3 Hội An SD
(Hoi An City, VN)
D2500 / L=8,499 m 2018 Resort Ground improvement for a soft soil layer
under a stiff soil layer (jetted depth from 25
m to 50 m).
4 Hoa Phat Dung
Quat Steel Plant
(Quang Ngai, VN)
D2000 / L=3,100 m 2018 Industrial plant Construction of a secant wall of columns to
support deep excavations and to prevent
water leakage in to the excavations.
5 Metro Line No. 3 -
(Hanoi, VN)
D2700/ V= 20,266
m
2019-2022 Urban tunnel Ground improvement at break-in break-out
of four underground; construction of bottom
plugs at the evacuation shaft and at Station
No. 12.
6 Vinh Tan port
(Đồng Nai, VN)
D2500/L= 8,788 m 2020-2021 River port Ground improvement along the wharf.
Recent projects

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2. TYPICAL PROJECTS – DUYEN HAI 3 TPP EXTENSION, TRA VINH
Project in brief
 Constructor: FECON-RAITO; Construction period: 05/2017
 Scope of work: Ground improvement under existing water pipe of D3800
 Total grouted length: 1,550 m (D3000, D2500, D1400), Grouted depths:  25 m

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2. TYPICAL PROJECTS – METRO LINE NO.1, HOCHIMINH CTY
Project in brief
 Constructor: FECON-RAITO; Construction period: 05/2015-03/2016
 CP1b Package: Break-in and Break-out of Opera House and Ba Son stations, Protection of Opera House.
 CP1a Package: Plug and entrance of Ben Thanh station
 Total grouted length: 3,500 m (D3500, D3000, D2500, D1400), Grouted depths: 2 – 38.0 m

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2. TYPICAL PROJECTS – METRO LINE NO.1, HOCHIMINH CTY
Improvement work at break-out - Opera House

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 Opera House protection: construction of a dome of BDJ columns to cover the subway lines
 BDJ column diameters: 3.0 to 3.5 m
2. TYPICAL PROJECTS – METRO LINE NO.1, HOCHIMINH CTY
The Opera House and plan view of improved area

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Plan views and a cross-sectional view of BDJ work near the Opera House
2. TYPICAL PROJECTS – METRO LINE NO.1, HOCHIMINH CTY
The Opera House and plan view of improved area
Vertical BDJ
columns
(D3000 – 3500)

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Example pictures of grouting work near the Opera House
2. TYPICAL PROJECTS – METRO LINE NO.1, HOCHIMINH CTY
Illustrated pictures

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Example pictures of grouting work near the Ben Thanh Station
2. TYPICAL PROJECTS – METRO LINE NO.1, HOCHIMINH CTY
Illustrated pictures

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Station9
Station10
Station11
Station12
Soil improvement
by Jet grouting
 Per. period: 05/2019-05/2023
 Scope of work: Waterproofing
walls and station base
improvement
 Contract amount: 132.0 Bn VND
 Key specs: 20,260 m (D2700)
 Key features: Jetted at large
depths; Jetted in dense sandy and
granular soil.
2. TYPICAL PROJECTS – METRO LINE NO.3, HANOI
Project in brief

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2. TYPICAL PROJECTS – METRO LINE NO. 3, HANOI
BREAK-OUT
BREAK-IN
EXISTING
BUILDINGS
Vertical and inclined jetting

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2. TYPICAL PROJECTS – METRO LINE NO. 3, HANOI
Vertical and inclined jetting
BREAK-IN
Vertical Jetting
Method D2.7- 3.0m
Inclined Jetting
Method
D1600 – 2700 mm

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Vertical Jet
Method BDJ
D2700 mm
Plan and cross-sectional views of jet grouting work at Station No. 12
2. TYPICAL PROJECTS – METRO LINE NO. 3, HANOI
Construction of bottom plugs

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2. TYPICAL PROJECTS – METRO LINE NO. 3, HANOI
Illustrated pictures
Example pictures of jet grouting work at Station No. 12 (Hanoi Station)

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2. TYPICAL PROJECTS – VINH TAN PORT
A 3D design model of Vinh Tan Port (Long Tan Commune, Nhon Trach District, Dong Nai Province)
Project overview

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2. TYPICAL PROJECTS – VINH TAN PORT
Equipment for CDM method (Sungwon auger 132 kW)
Selection of ground improvement method
Equipment for Jet grouting method
Total weight  140 tonnes Total weight  10 tonnes

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2. TYPICAL PROJECTS – VINH TAN PORT
Plan view of the improved area (half left)
A total of 323 BDJ columns (D = 2.5m, L = 24 – 38 m) was constructed
Improved area ratio: a = ABDJ/At = 0.40 ( 2020 CDM columns of D1000)
Key points of improvement work

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2. TYPICAL PROJECTS – VINH TAN PORT
Cross-sectional view of the improved area (halt left)
SPT N value
0 10 20 30 40 50
Depth
(m)
0
5
10
15
20
25
30
35
40
HK7
HK8
Very soft clay
Sandly clay
Silty clay
Stiff clay
Key points of improvement work

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2. TYPICAL PROJECTS – VINH TAN PORT
Construction activities at the site
Illustrated pictures

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2. TYPICAL PROJECTS – VINH TAN PORT
Verification of column head diameter at the site
Illustrated pictures
A celebration moment for project accomplishment

26. Number of test columns: 6
Column diameter: D = 3500 mm.
Cement content: ~215 kg/m3
Water cement ratio W/C= 1
Depths of cored samples
Layout plan of Jet-grouting Core Drilling Positon
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3. STRENGTH CHARACTERISTICS OF CORED SAMPLES
Core sampling at Metro Line No.1

27. Number of test columns: 3
Column diameter: D = 2500 mm.
Cement content: ~212 kg/m3
Water cement ratio W/C= 0.8
Location of test columns Core Drilling Positon
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3. STRENGTH CHARACTERISTICS OF CORED SAMPLES
Core sampling at Vinh Tan Port
Depths of cored samples

28. Number of test columns: 3
Column diameter: D = 800 mm
Cement content: ~220 kg/m3
Water cement ratio W/C= 0.8
Layout of the improved zone (S1)
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3. STRENGTH CHARACTERISTICS OF CORED SAMPLES
Core sampling at Araki project (CDM method)
Core Drilling Positon Depths of cored samples

29. Vinh Tan Project
Akari Project
Metro line 1 Project
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3. STRENGTH CHARACTERISTICS OF CORED SAMPLES
Correlation of stiffness
Noted: Test results shown
in the figures are from UCS
test on cored samples of
28 days old.

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3. STRENGTH CHARACTERISTICS OF CORED SAMPLES
Correlation of stiffness
 At similar cement content and water/cement
ratio, the BDJ method produces mixed soil
columns having similar of higher
compressive strength compared with that of
CDM columns.
 The correlation of Es = kqu with typical k =
200 to 1000 can be obtained from BDJ
method with common cement content and
water/cement ratio.

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4. CONCLUDING REMARKS
1) BDJ method, in many cases, is a unique solution to improve difficult grounds
at difficult conditions (deep bottom plugs, under existing structures...)
2) The method can be effectively applied to many project types, and is specially
suitable to soft ground conditions where the traditional CDM method is not
optimal.
3) At similar cement content and water/cement ratio, the BDJ method produces
mixed soil columns having similar of higher compressive strength compared
with that of CDM columns.
Some concluding remarks for the method

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