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PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Helmut F. SchweigerFranz TschuchniggComputational Geotechnics GroupInstitute for Soil Mechanics and Foundation EngineeringGraz University of Technology
3D FINITE ELEMENT ANALYSIS OF DEEP FOUNDATIONS - PRACTICAL APPLICATIONS
Finite Element Analysis of Deep Foundations
2PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
THREE CASE HISTORIES
� DEEP FOUNDATION OF TWO ADJACENT HIGHRISE BUILDINGS (Vienna)
� DEEP FOUNDATION OF TOWER FOR SHOPPING MALL (Bucharest)
� JET GROUT FOUNDATION FOR RAILWAY STATION (Vienna)
OUTLINE OF PRESENTATIONDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
3PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
DEEP FOUNDATION OF TWO ADJACENT HIGHRISE BUILDINGS (Vienna)
� Project overview
� Soil conditions and its numerical modelling
� Finite element models
� Optimisation of the foundation concept
� Results
� Conclusion
DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
4PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Concept for foundation: deep foundation with diaphragm wall panels
~220m~168m
TWIN TOWERSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
5PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
TOWER ITOWER II
64.1 m
56.3 m58.9 m
24 m
TOWER I: 220 m high (around 60 stories) > constructed first TOWER II: 165 m highFoundation system: diaphragm wall panels
Undergroundcar parks
PROJECT OVERVIEW - TWIN TOWERSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
6PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
m
ref3ref
5050 p'cot'c'cot'cEE ��
�
����
��
��� Slab
Barrette length 30m
Constitutive model
Hardening Soil Model (HS):
m
ref3ref
urur p'cot'c'cot'cEE ��
�
����
��
���
m
ref1ref
oedoed pcotccotcEE ��
�
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Hardening Soil Small Model (HSS):m
ref3ref
00 p'cot'c'cot'cGG ��
�
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SOIL CONDITIONS AND ITS NUMERICAL MODELLING DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
7PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
G0
�0.7
Parameter Gravel Sandy silt Fine sand E50
ref (kPa) 40 000 20 000 25 000 Eoed
ref (kPa) 40 000 20 000 25 000 Eur
ref (kPa) 120 000 50 000 62 500 pref (kPa) 100 100 100 m (-) 0.00 0.80 0.65 G0 (kPa) 150 000 62 500 78 125 �0.7 (-) 0.0001 0.0002 0.0002
Defintion of additional parameters for the HSS model:
G0: Correlation between small strain stiffness and stiffness at larger strains after Alpan (1970)
> Young's modulus interpreted as Eur
�0.7: Stiffness reduction curves after Vucetic and Dobrey (1991)
HS model
HSS model
SOIL CONDITIONS AND ITS NUMERICAL MODELLING DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
8PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
SOIL CONDITIONS AND ITS NUMERICAL MODELLING DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
9PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
> Both towers are modelled> Models consist of around 50 000 15-noded wedge elements
FINITE ELEMENT MODELS - OVERVIEWDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
10PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Detailed model for Tower I
Barrettes with unit dimensions of 3.6 m x 0.6 m
Detailed model for Tower II
FINITE ELEMENT MODELS - DETAILED MODELSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
11PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Detailed model Tower I:• Barrette length 25 m• uy,max of 80 mm• Interaction of towers • Differential settlements
> Optimisation of foundation system
Eccentric loads lead to large differential settlements
FINITE ELEMENT MODELS - FIRST RESULTS TOWER IIDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
12PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Final design of deep foundation system
Arrangement of diaphragm wall panels for Tower I
Arrangement of diaphragm wall panels for Tower II
OPTIMISATION OF FOUNDATION CONCEPTDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
13PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
RESULTSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
14PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
• Barrette lengths between 20 m and 30 m • Maximum vertical displacements of both towers ~80 mm• Differential settlements reduced to acceptable value
RESULTSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
15PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Model details:
• No geometrical simplifications
• ~ 140 000 15-noded wedge elements
• Mesh refinement
• 300 diaphragm wall panels are modelled explicitly
Expectations:
• Validate first approach
• Detailed information about settlement trough between towers
_________________________________________________________Model Nr. El. Nr.Nodes Nr.El in 2D plane _________________________________________________________ 32 bit model 49 096 131 993 2 888 64 bit model 136 710 361 243 6 510 _________________________________________________________
RESULTS WITH 64 BIT CALCULATION KERNELDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
16PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
� 317 diaphragm wall panels
RESULTS WITH 64 BIT CALCULATION KERNELDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
17PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
• Results are similar to first approach• Maximum vertical displacements ~80 mm• More accurate with respect to interaction and settlement trough between towers
RESULTS WITH 64 BIT CALCULATION KERNELDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
18PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Layout 1:� 75 Piles � Diameter 1.5m� Spacing 6*D� Pile lengths are based on executed
deep foundation with panels (20 - 30m)� Piles are modelled as continuum (VP)
with interfaces:
� Also modelled with Embedded Piles (EP)
Alternative foundation concept: Piled raft foundation
Soilinter cRci SoilSoilinter � tantanRtan i
Soilinter � ��� � ii otherwise,0.1Rfor0
COMPARISON OF DIFFERENT FOUNDATION SYSTEMSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
19PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
An embedded pile is a pile which consists of:
� Beam elements� Properties: E, �, d� d determines the elastic zone in the soil around the beam
� Special interface elements� Properties: skin resistance, base resistance
ts Shear stress in axial direction
tn /tt Normal stress in n/t – direction
Ks Elastic shear stiffness
Kn/Kt Elastic normal stiffness in n/t - direction
up Displacements of the pile
us Displacements of the soil
COMPARISON OF DIFFERENT FOUNDATION SYSTEMSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
20PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Alternative foundation concept: Piled raft foundation
Layout 2:� Piles modelled with Embedded
Piles concept (EP) � Diameter 1.5 m� Pile spacing is reduced in high
loaded regions� Pile lengths are based on
executed deep foundation with panels (20 - 30 m)
COMPARISON OF DIFFERENT FOUNDATION SYSTEMSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
21PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Alternative foundation concept: Piled raft foundation
Layout 2:� Piles modelled with Embedded
Piles concept (EP) � Diameter 1.5 m� Pile spacing is reduced in high
loaded regions� Pile lengths are based on
executed deep foundation with panels (20 - 30 m)
Maximum vertical displacements:� Tower I: ~ 90 mm� Tower II: ~ 90 mm
COMPARISON OF DIFFERENT FOUNDATION SYSTEMSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
22PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Maximum settlements:• Barrettes: 7.6cm• Layout 1 (VP): 12.0 cm• Layout 1 (EP): 12.0 cm• Layout 2 (EP): 8.7 cm
• Shallow foundation: 18.7cm
Barrettes
Shallow foundation
COMPARISON OF DIFFERENT FOUNDATION SYSTEMSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
23PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Comparison of different foundation systems
� Maximum settlements
� �KPP:
Layout 1: 0.42Layout 2: 0.80
tot
PileKpp R
R �
~ 50 %
DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
24PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Settlements / differential settlements
> Road - up to 40 mm tolerable
> Highway - Point A 14 mm
Inclination 1/900
> Train - Point B 18 mm
Most critical area
Inclination 1/600
> Measurements during construction are necessary
A
B
RESULTSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
25PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
� Same length of deep foundation elements > high differential settlements.
� Final foundation concept with lengths between 20 - 30 m improves the settlement behaviour of the towers.
� In most calculations the geometry is simplified in that way that only one tower is modelled in detail and the foundation of the second tower is modelled with a homogenized block.
� The computed maximum vertical displacements are about 80 mm. The settlements of the highway and the railway lines are in the order of 15-20 mm.
� With a 64 bit calculation kernel both towers are modelled in detail. The settlements are similar to the simplified models but the settlement trough between the towers is more accurate.
CONCLUSION FOR THIS PROJECTDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
26PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
DEEP FOUNDATION OF TOWER FOR SHOPPING MALL (Bucharest)
� Project overview
� Soil conditions
� Finite element models
� Optimisation of the foundation concept
� Results
� Validation of numerical model
� Conclusion
DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
27PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Sky Tower
SHOPPING MALL WITH SKY TOWER DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
28PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
SHOPPING MALL WITH SKY TOWER DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
29PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Results of interest:
1. Maximum differential settlements (of 2.6 m thick slab)
2. Arrangement of diaphragm wall elements
• Dimensions 93.4 x 61.7 m
• Height more than 130 m
• Excavation depth 20.4 m
• Slab thickness 2.6 / 1.5 m
• Point loads up to 14 900 kN
PROJECT OVERVIEW - SKY TOWER DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
30PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Silty Clay
Constitutive models:
• Diaphragm wall panels > Mohr-Coulomb
• Floors > Linear elastic
• Soil layers > Hardening Soil Model
Sand
~20.5 m
~25.0 m
60.0 m
Soil profile:
• Core drillings down to -60 m
• Altering layers of sands and silty clays
• Drained conditions are assumed
Assumption: Alternate layers continue
SOIL CONDITIONS DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
31PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
All models consist of about 52 000 15-noded wedge elements
Core walls Floors (Top-down method)
FINITE ELEMENT MODELSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
32PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
~ 94 m
~ 62 m
Cross section
2D "Plane strain" model
Layout 1 Top view Deep foundation elements in 3D
FE model
FINITE ELEMENT MODELSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
33PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
uy,max~ 95 mm
uy,diff.max ~ 50 mm
uy,max~ 165 mm
uy,diff.max ~ 100 mm
• 2D (plane strain) model overestimates differential settlements by approx. 100%
• 2D representation of geometry / load situations not possible
• 2D representation of deep foundation elements not possible
> For optimisation of foundation concept full 3D modelling is required
FINITE ELEMENT MODELSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
34PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
• Maximum settlements between 85 - 100 mm
• Differential settlements between 42 - 60 mm
• Full connection of barrettes difficult to achieve in practice
Circle of panels beneath concentrated loads
Discontinuous barrettes Different lengths of barrettes
OPTIMISATION OF FOUNDATION CONCEPTDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
35PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Final foundation concept
Top view
25 m
15 m
FE discretization of panels
OPTIMISATION OF FOUNDATION CONCEPTDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
36PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
• Maximum vertical displacements of about 105 mm
• Maximum differential settlements of about 65 mm
• Between point A and C (2.6 m thick slab) differential settlements of about 47 mm
Final foundation concept
Contour lines of settlements Vertical displacements of slab
OPTIMISATION OF FOUNDATION CONCEPTDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
37PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
• FE analysis predicts slightly higher settlements > conservative estimate of parameters• Effect of small strain stiffness is not taken into account
FE model Measurements vs calculation
VALIDATION OF NUMERICAL MODEL (IN SITU LOAD TEST)DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
38PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
SHOPPING MALL WITH SKY TOWER Step 3:Excavation to -15.00 mConstruction of slab at -5.0 m
DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
39PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Step 4:Construction of base slab
DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
40PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
� Due to the geometrical layout 2D analysis proved to be too conservative.
� A number of 3D calculations have been performed investigating different arrangements of diaphragm wall panels.
� The final concept of the deep foundation consists of two discontinuous circlesbeneath the highly loaded areas.
� The computed maximum settlements are 105 mm. The expected maximum differential displacements are about 65 mm.
� The numerical back analysis of an in situ load test shows reasonable agreement � The soil parameters have been estimated prior the test and no adjustments have
been made.
CONCLUSION FOR THIS PROJECTDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
41PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
JET GROUTING FOUNDATION FOR RAILWAY STATION (Vienna)
� Project layout
� Soil profile
� Finite element models
� Validation of numerical model
� Results
CONTENTDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
42PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
~ 500m
~ 400m
PLAN VIEW
PROJECT OVERVIEW - PLAN VIEWDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
43PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
175m
100m
PROJECT OVERVIEW - ARRANGEMENT OF JET GROUT COLUMNSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
44PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
8 m - gravel3 m - sandy silt
14 m - sand
11 m - sandy silt
2 m - sand
10 m - stiff base layer
TYPICAL CROSS SECTION - SOIL PROFILEDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
45PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
� Three different models for the sensitive zones
Zone A: => 130 embedded piles => 51376 elements
Zone B: => 615 embedded piles => 47464 elements
Zone C: => 114 embedded piles => 47022 elements
FINITE ELEMENT MODELDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
46PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Zone B: => 615 embedded piles => 47464 elements
Model without soil - top view
Model without soil - bottom view
EMBEDDED PILE MODEL FOR ZONE BDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
47PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
> 615 Piles
� Different pile lengths
� Different pile inclinations
> Rest is modelled as blocks
EMBEDDED PILE MODEL FOR ZONE BDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
48PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
inclined embedded piles
vertical displacements - uy,max = 63 mm
EMBEDDED PILE MODEL FOR ZONE B - RESULTSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
49PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
� Global settlement behaviour of construction is obtained because complete structure is modelled including areas with significant different load intensities.
� Detailed results in the zone where the embedded piles are modelled.
� Benefit of zone B (embedded piles): spacing, pile length and pile diameter can be modified with reasonable effort.
EMBEDDED PILE MODEL FOR ZONE B - RESULTSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
Finite Element Analysis of Deep Foundations
50PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
MODEL - 64 bit calculation kernel
General results:• Global settlement behaviour of construction is obtained because complete structure is modelled including
areas with significant different load intensities. Maximum vertical displacements of ~65 mm.• Detailed results in the zones where the embedded piles are modelled. • "Embedded pile zones": spacing, pile length and pile diameter can be modified with reasonable effort.
64 bit calculation kernel:• Validation of first approach. • More than 1200 jet grout columns are modelled - more accurate results with respect to interaction of
sensitive zones.
DEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
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Finite Element Analysis of Deep Foundations
51PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
� In many cases the geometry can be simplified in that way that only sensitive parts are modelled in detail > yields global settlement behaviour.
� With a 64 bit calculation kernel less simplifications are necessary. The settlements are similar to the simplified models.
� When creating embedded piles no additional geometry points are created � embedded piles do not influence the finite element discretisation.
� With embedded piles it is possible to model a high number of deep foundation elements with different spacings, inclinations and lengths.
� When using the HSS model the influence of the model boundary condition is reduced and a more realistic settlement behaviour can be obtained.
CONCLUSIONSDEEP FOUNDATION (Vienna) DEEP FOUNDATION (Bucharest) JET GROUT FOUNDATION (Vienna)
PLAXIS Hong Kong Lectures / Hong Kong, 28 November 2011
Helmut F. SchweigerFranz TschuchniggComputational Geotechnics GroupInstitute for Soil Mechanics and Foundation EngineeringGraz University of Technology
3D FINITE ELEMENT ANALYSIS OF DEEP FOUNDATIONS - PRACTICAL APPLICATIONS