The Expansion of Abu Dhabi International Airport

THE EXPANSION OF ABU DHABI
INTERNATIONAL AIRPORT
Middle East Concrete & PMV Live ExhibitionNov. 2014

Site Location

Middle East Concrete & PMV Live Exhibition
Project Organization
PROJECT MANAGER:
PARSONS
CONSULTING ENGINEER:
-OVE ARUP
-KPF
PILING CONTRACTOR:
NSCC INTERNATIONAL LTD.
RESIDENT ENGINEER:
JACOBS GIBBS CLIENT:
SCADIA
Nov. 2014

Impact of Cavities
Technical considerations
Stability of heavy machines.
Concrete Over-consumption.
Tight Schedule.

Subsurface Conditions
Nov. 2014

-35
-30
-25
-20
-15
-10
-5
0
5
10
0 10 20 30 40 50 60 70 80 90 100
RQD (%)
NADD

Fill and native sand.
Sandstone + Siltstone
Mudstone + Crystalline Gypsum
CAVITIES
Nov. 2014

Groundwater Condition

GYPSUM DISSOLUTION
Gypsum is a highly soluble rock and under suitable groundwater flow
conditions it can dissolve forming caves and karstic features
including collapse.

In General
Cavities Were
Found above
‐10 NADD
SHALLOW CAVITIESDEEP CAVITIES

How the cavities were formed?
Ground Water + Carbon Dioxide = Weak Carbonic Acid Solution
The acid solution dissolves the crystalline gypsum in the flowing groundwater
through rock joints, fractures or bedding planes and forming voids or even
continuous channels.
Geophysical and
Geotechnical Findings of
the Site

Seismic effects included in working loads (UBC 1997).
Potential cavity collapse and
corresponding down drag forces
accounted for.
Design Aspects
No skin friction considered above
-10.0 m NADD.
Reduced lateral soil resistance above
-10.0 m NADD.
Friction piles, end bearing component
neglected.
Existing Ground Level
(-10.00)
Weak Rock
With
Potential
Cavities
Competent
Rock

Design Procedure
Column
loads as given by the consultant
Load
Combinations
(70 SLS& 60 ULS)
Max. Column Loads
Design Loads of piles for
SLS and ULS
GeotechnicalDesign
Structural
Design
Soil Pile friction
Effect of Cavities
Check of Wedge Failure
Settlement of a single pile
Settlement of PileGroup
PileGroup Effect
Lateral Analysis
Check of Buckling
Crack Width Control
Check of tensile stress
Main Reinforcement
Shear Reinforcement
Nov. 2014

Column Load Combinations
BS EN1991-1_2002 Eurocode 1
For UltimateLoad combinations
UBC
For Working Load Combinations
 
 4.1/)3.03.0(75.00.1
4.1/)3.03.0(75.00.1
0.10.13
0.10.10.12
0.10.11
MyEyMxExQkGkSeismicY
MyEyMxExQkGkSeismicX
WGkSLS
WQkGkSLS
QkGkSLS





MyEyMxExQkGkSeismicY
MyEyMxExQkGkSeismicX
WGkULS
WGkULS
WQkGkULS
QkGkULS






3.03.06.00.1
3.03.06.00.1
Dead)l(Beneficia4.10.14
Dead)(Adverse4.14.13
2.12.12.12
6.14.11
Resulted in 70Load CombinationsResulted in 60Load Combinations
AnalysesforEach Pile
Cap
+
Load Combinations (SLS & ULS)
Nov. 2014

Pile Working & Ultimate Loads

 22
y
yM
x
xM
n
Q
P xy
p
Mx, My: Moment about x and y axes
x, y: Distance from y and x axes to any pile
x2, y2: Group moment of inertia
n: Number of piles
Ultimate load combinations  4 critical cases considered for structural design:
• Maximum Compression + corresponding moment and lateral load.
• Maximum Tension + corresponding moment and lateral load.
• Maximum moment + corresponding axial and lateral load.
• Maximum lateral load + corresponding axial and bending moment.
• Transformation of Loading Orientation:
Global  Pile Cap Local
• Calculation of Pile Loads
Nov. 2014

Geotechnical Design
Ultimate pile-rock unit skin adhesion (R.G. Horvath, 1978).usu qf .15.0.27
Working friction capacity of pile, Fs = 2.0
susocketsf
s
sf
a
fLDQ
F
Q
Q
...

W
F
fLD
Q
s
susocket
uplifta 
...
)(
 Working uplift capacity, Fs = 3.0
Soil Pile Friction, working capacity

Geotechnical Design
Factor of safety against wedge failure:
t
cohesion
F
FW
SF
cos.
..


W: Total weight of the wedge (pile Wp, pile cap Wr, and soil/rock Ws)
FCohesion is the rock cohesion resistance over the wedge surface.
A minimum safety factor of 1.1 against probable wedge failure is ensured.
Check of Wedge Failure - Uplift

Wp
Wr
Ws

(a) (b)
tF tF

Geotechnical Design
Settlement & Pile Group Effects

Structural Design
Rotational Stiffness k:
Spansofnumberx
L
IE
k crc
4
Lateral Analysis using ALP
Lateral pile-soil interaction
Bending moments
Shear forces

Structural Design
Structural Capacity
Check
Crack width
assessment
Nov. 2014

Pile Tests and Design Validation
Sonic Logging almost 1800 piles
75 Working Pile Load Tests
13 Instrumented Non-Working Pile
Load Tests (conventional +
bidirectional O-cell)
(250% of the working loads)
Caliper logging tests
LONGITUDINAL SECTION
BHT-36

Testing of Piles
Analysis and Interpretation of Tests Results
391.00
37.00
416.00
391.0098.00
98.00
416.00
37.00
-22
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
6
-300 200 700 1200
Depth
58
922
740
822
922
58 822
-22
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
6
-300 200 700 1200
873
645
901
873
598
598
901
645
-22
-20
-18
-16
-14
-12
-10
-8
-6
-4
-2
0
2
4
6
-300 200 700 1200
1.0 m dia
(Sector 5)
1.2 m dia
(Sector 5)
1.5 m dia, O-Cell
(Sector 5)
(a) (b) (c)

Classification of Cavities
Existing Ground Level varies from +7.00 to +16.50 NADD
(-10.00 NADD)
Shallow Cavities
(Within 8m from Ground)
Cavities above -10.0 NADD
-Permanent Casing
-Lean Mix
Cavities below -10.0 NADD
-Concrete Overbreak
90% of suspected cavities
are situated above
-10.0 NADD

Probing

Probing Logs
Analysis of Probing Records
Spreadsheets GIS Model

Cavity (500 psi) Soft Zone
(or cavity filled with loose materials 250 psi)
2D and 3D distribution of cavities using ArcGIS
Analysis of Probing Records

Probing Conclusion
Based on the results of probing, recommendations were issued by our technical engineers to tackle:
1. For shallow cavities - either to fill or detour around it.
2. For cavities above El -10.00 NADD - use permanent
casing in pile construction, fill the cavity with lean mix
prior to pile construction, or allow for concrete over
consumption.
3. Deep cavities below El -10.00 NADD - we elected to
use self compacting concrete in order to insure that all
cavities are properly filled.

Shallow Cavities Safety Measures

Treatment of Cavities – Permanent Casing

Treatment of Cavities – Lean Mix Filling
Nov. 2014

Overall Piles Layout
TOTAL 7423
PILES
COMPLETED!!
Nov. 2014

Pile s Construction
Nov. 2014

Piles construction
Nov. 2014

Diaphragm wall construction

Diaphragm wall construction
Nov. 2014

Mass Excavation
Nov. 2014

Mass Excavation

PROJECT HIGHTLIGHTS
Total drilled Length of Piles: 220 km
Total linear meter drilled for probing :293 km
Total piles Concrete Volume: 339,416 m3 + 38,541 m3 for diaphragm
wall
Total Volume of Lean Mix : 31,043 m3
Total weight of steel used :52,500 ton
Total length of P. casings :4040 l.m.
Total length of diaphragm wall :2,100 l.m.
Total excavation volume : 1,500,000 m3
Total Number of deep wells: 102 nos. covering and controlling water
levels at area of 129,630 m2

ACHIEVEMENTS
-Complete piling construction on time with maximum production rate of 46 piles/
day consuming about 2000m3/day.
-Cost Saving for the client by proposing Lean Mix Concrete for plugging
suspected cavities instead of using permanent casings.
Estimated Cost of all permanent casings: 109 million Dirham
Estimated Cost of Combination of Lean mix + Permanent Casings: 34 million
Dirham
Saving of approximately 65 million Dirham
- The numbers of deep wells required for dewatering are reduced to 45 nos. after
conducting various stages of de-watering optimization trials .

The Final Product
Nov. 2014

THANK YOU
Nov. 2014

The Expansion of Abu Dhabi International Airport

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