On the use of the Hardening Soil modelg

Rafal OBRZUDRafal OBRZUD

GeoMod Ing. SA, Lausanne

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Content

IntroductionIntroduction

Example 1 – Berlin Sand - excavation problem

Example 2 – Montreux – 3D excavation problemExample 2 Montreux 3D excavation problem

Example 3 – London Clay - tunnel excavation

Example 4 – Almere - trial embankment problem

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Why do we need advanced constitutive models?

GEOENGINEERING COMPUTINGS

LIMIT STATE ANALYSIS DEFORMATION ANALYSIS

Bearing capacity Pile, retaining wall deflection

Slope, wall stability Supported deep excavations

Tunnel excavationsTunnel excavations

Consolidation

Basic models e.g. Mohr-Coulomb Advanced soil models

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Basic differences between implemented soil models

Mohr-Coulomb

qi ld

K0-line

yieldsurface q

p’

Linearelasticdomain

K0-p’

q p’

K0unloading

E Eur

ε1

E=Eur

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Basic differences between implemented soil models

Volumetric cap Mohr-Coulomb

Volumetric cap models

qi ld

q isotropich d i

K0-line

yieldsurface

hardeningmechanism

q

p’ p’

σ1’ constant

Linearelasticdomain

Linearelasticdomain

p’ p’

q q Stiffnessdegradation

p’

E Eur EurE

ε1 ε1

E=Eur E < Eur

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Basic differences between implemented soil models

Volumetric cap Hardening Soil Mohr-Coulomb

Volumetric cap models

Hardening Soil models

qi ld

q qisotropich d i

K0-line

yieldsurface

hardeningmechanism + shear

hardeningmechanism

p’

Linearelasticdomain

p’ p’

Linearelasticdomain

p’ p’ p’

q q qStiffnessdegradation

Stiffnessdegradation

NON-LINEAR elastic domain

E EurEurEur

E0

E E

ε1 ε1 ε1

E=Eur E<EurEur E0

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Basic differences between implemented soil models

1 Mohr‐Coulomb

Small strain stiffness in geotechnical practice

0.8

1

nessG/G

0[‐]

o Cou o b

Modified Cam Clay

Cap model

HS‐Standard

HS‐Small

Non‐linear elasticityat very small strains

0.4

0.6

lized

soilstiffn

Linear elasticity at

Linearelasticityat smallstrains

0

0.2

1E‐06 1E‐05 0.0001 0.001 0.01 0.1

Norma

Axial Strain ε [‐]

Linear elasticity atvery small strains

1E 06 1E 05 0.0001 0.001 0.01 0.1Axial  Strain ε 1 [‐]

e.g. Atkinson, Jardine and many others

Shear strain [‐]

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Content

IntroductionIntroduction

Example 1 – Berlin Sand - excavation problem

Example 2 – Montreux – 3D excavation problemExample 2 Montreux 3D excavation problem

Example 3 – London Clay - tunnel excavation

Example 4 – Almere - trial embankment problem

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 1: Berlin Sand - excavation problem (Schweiger, 2002)

Engineering draft FE mesh

Sand

Sand

Anchors

Diaphragm wall

Impermeablebarrier

Truty (2008)

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Truty (2008)

Example 1: Berlin Sand - excavation problem

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Content

IntroductionIntroduction

Example 1 – Berlin Sand - excavation problem

Example 2 – Montreux – 3D excavation problemExample 2 Montreux 3D excavation problem

Example 3 – London Clay - tunnel excavation

Example 4 – Almere - trial embankment problem

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 2: – Montreux – 3D excavation problem

No continuum elems: 41’108No continuum elems: 41 108

Existing building

Av. des Alpes

15 20m diaphragm15-20m diaphragmwall excavation

No shell elems: 3’412No truss elems: 930

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

No truss elems: 930

Example 2: – Montreux – 3D excavation problem

Section A‐A

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 2: – Montreux – 3D excavation problem

Mohr-Coulomb HS-SmallStrain

Lifting of retaining wall Settlements behind the retaining wall

UY 1 5

E = 60MPa

UY = ‐0.5cmUY = +1.5cm

Eur = 132MPa

E0 = 264MPa

UY = +5.3cm

E50 = 44MPa

at 15mE = 360MPa

Section A‐A Section A‐A

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Content

IntroductionIntroduction

Example 1 – Berlin Sand - excavation problem

Example 2 – Montreux – 3D excavation problemExample 2 Montreux 3D excavation problem

Example 3 – London Clay - tunnel excavation

Example 4 – Almere - trial embankment problem

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 3: – London Clay - tunnel excavation (Addenbrooke et al., 1997)

Problem statement FE meshProblem statement FE mesh

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 3: – London Clay - tunnel excavation (Addenbrooke et al., 1997)

50

800

1000

1200

[‐]

CIUE test

CAUE test

CIUE HS‐Small

CIUE MC 30

35

40

45 CIUE test

HS‐Small ‐ q

J4 ‐ q

MC ‐ q

200

400

600

E sud/ p' [

10

15

20

25

q [kPa]

0

1E‐05 0.0001 0.001 0.01 0.1 1

Axial strain [%]

0

5

10

‐2.08E‐17 0.002 0.004 0.006 0.008 0.01600Axial strain [%]

400

500

CIUE test

HS‐Small ‐ q

J4 ‐ q

MC ‐ q

100

200

300q [kPa]

0

100

0 0.1 0.2 0.3 0.4

A i l t i [%]Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Axial strain [%]

Example 3: – London Clay - tunnel excavation

Mohr-CoulombTunnel level:E = 183 MPa

max uabs= 16.8 mm

HS-SmallStrainTunnel level:E0 = 500 MPaEur = 90 MpaE 40 MPE50 = 40 MPa

max uabs= 61.3 mm

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 3: – London Clay - tunnel excavation

i f b d l0

]Excavation of Westbound Tunnel

‐10

‐5

nts  [m

m]

‐15

ettlem

en

Field data

‐20

urface se Field data

M‐C (Ko=1.0, E=6000z kPa)

HS‐Std (Ko=1.0)

‐30

‐25Su HS‐Small (Ko=1.0)

Model ‐ J4 (Ko=1.5)1st tunnel30

‐10 0 10 20 30 40 50 60

Offset from the westbound tunnel [m]

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Content

IntroductionIntroduction

Example 1 – Berlin Sand - excavation problem

Example 2 – Montreux – 3D excavation problemExample 2 Montreux 3D excavation problem

Example 3 – London Clay - tunnel excavation

Example 4 – Almere - trial embankment problem

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 4: – Almere - trial embankment problem (Bringreve & Vermeer (1992)Rowe, Soderma (1985) )

Sand fill Retaining bank

2m

Sand layer

Organic Clay OCR =2

Stages:1. Excavation2. Embankment + Fillba e3. Consolidation

Clay layer modeled with: Mohr-Coulomb and Hardening Soil-SmallStrain

EMC = 13 750 kPa Eur = 2 EMC

E50 = EMC /2

E0 = 2 Eur

E E

σref = 30kPa

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Eoed = E50

Example 4: – Almere - trial embankment problem

Pt - A

Pt - B

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

Example 4: – Almere - trial embankment problem

Pt APt A Pt B

Pt B ‐ Embankment basePt A ‐ Embankment  top

2

‐1

0

mm]

‐10

‐5

0

mm]

‐4

‐3

‐2

acem

ent [m

‐20

‐15

10

cemen

t [m

‐6

‐5

‐4

Y‐displa

Mohr ‐ Coulomb35

‐30

‐25

Y‐displa

‐7

0 5 10 15 20 25X‐displacements [mm]

HS‐SmallStrain‐40

‐35

‐4 ‐2 0 2 4 6 8X‐displacements [mm]

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model

X displacements [mm]X displacements [mm]

Summary

Hardening Soil-SmallStrain model:Hardening Soil-SmallStrain model:

correctly reproduces strong reduction of soil stiffness with correctly reproduces strong reduction of soil stiffness with increasing shear strain amplitudes

is recommended for Serviceability Limit State analyses as it generally closer predicts soil behavior and field measurements than generally closer predicts soil behavior and field measurements than basic linear-elasticity models

is applicable to most soils as it accounts for pre-failure nonlinearities for both sand and clay type materials regardless of nonlinearities for both sand and clay type materials regardless of overconsolidation state

Rafal Obrzud25 years of Z_Soil30.08.2010, Lausanne

On the use of the Hardening Soil model