Numerical Simulation of Earthworks and Retaining System for an Excavation

F. Geiser and S. Commend

GeoMod ing. conseils SA

Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Introduction

• Offices and commercial building • Lausanne region • 120 x 35(max) x 9.3 m Numerical modelling: 3D numerical simulation (Z_Soil) 30’000 continuum elements Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Geometry:

structural elements Slurry wall Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

3.5 m

Hydrogeotechnical conditions

Remblai Glacio-sableux Glacio-argileux mou Fluvio-glaciaire Glacio-argileux Moraine Molasse imperméable 412.7 msm = 0.0

9.3 m 8.0 m Puits de décharge Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

Piles T = 0. Etat initial Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Piles realisation

Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Slurry wall realisation

Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

T = 1. Excavation globale jusqu’à -3.0 m Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

zone A T = 2. Excavation zone A à -7.0 m, puis étayage à -2.5 m Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

T = 3. Excavation du reste à -7.0 m Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

T = 3.2. Excavation zone A jusqu’à -9.3 m (f.f.) Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

T = 3.4. Excavation de la moitié du reste jusqu’à -9.3 m Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

T = 3.6. Sous-radier à -9.3 m sur la moitié de la surface Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Excavation stages

T = 5 T = 4. Excavation du reste à -9.3 m, puis fin du sous-radier T = 5. Application des charges de service du bâtiment Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Results:

final horizontal displacements A B uz Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Results:

horizontal displacements evolution 0.05

0.04

0.03

0.02

0.01

0 -0.01

0 1 2

Etape

Point A 3 Point B 4 5 Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Results:

final horizontal displacements Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Results:

final vertical displacements Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Results:

forces in the bracing Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Results:

moments in the slurry wall Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Results:

moments in the slurry wall Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Water :

particular study

17.2 m 15 m

Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Water :

simplified 3D model 3.5 m Remblai K = 10 -5 m/s épaisseur = 3.5 à 7.5 m Glacio-sableux K = 10 -5 m/s épaisseur = 4 m Glacio-argileux mou K = 10 -10 m/s épaisseur = 7.6 m Fluvio-glaciaire K = 10 -3 m/s épaisseur = 3.7 m Glacio-argileux K = 10 -8 m/s épaisseur = 4 m Moraine K = 10 -9 m/s épaisseur = 6 m Molasse imperméable 412.7 msm = 0.0

Well (model with/without) K = 10 -3 m/s e= 15 m 9.3 m 8.0 m Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Water :

simplified 3D model with well -100.0

-75.0

-50.0

-25.0

Tranche 3D avec puits, esp. = 15 m Coupe 2D avec tranchées drainantes 0.0

3.207e+00 EXTR-VX 5.131e+00 -9.283e-01 EXTR-VY 4.483e+00 -2.413e+00 MAX-VEL.

5.157e+00 UNIT [m/day] A = 15 * 17.2 = 258 m Title : Zsoil example 2 Author : ZACE Date : 2007-02-15 09:46:01 File : C:\Mandats\GeoMod\M686_Orange\Technique\14fev\2D\orange_coupeCFF_2x2_paroiBeam_puits_Eunl_OK Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Water :

simplified 3D model Clay – low permeability e Model Simple 1 Simple 2 Simple 3 Thickness of the « impermeable » layer 5.30 m 5.30 m 1.35 m Well Yes No No Z_Soil Day 2007 Lausanne, 27th August 2007 Flow in the excavated area ( 258 m 2 ) 65.7 m 3 /d 2.4e-3 m 3 /d 9.7e-3 m 3 /d

Flow for the entire excavation (3200 m 2 ) 815 m 3 /d 30 litres/d 120 litres/d

Commend, Mellal, Geiser – 08.2007

Low permeability

Water :

3D model Z_Soil Day 2007 Lausanne, 27th August 2007 High permeability Commend, Mellal, Geiser – 08.2007

Water :

3D model Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Water :

3D model

1625 m 3 / jour

Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Water :

3D model Impermeable wall

0.04 m 3 / jour

Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Impermeable wall Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Temperature effect on bracing :

2D model general considerations for D T = 30 ° Free truss: Fixed conditions Imposed displacement D l = a D T L/2 = 5 mm D F = 1000 kN D F = 165 kN -7.5

0.0

7.5

15.0

2.771e-03 D D ux imposé = - 5 mm ux = - 4.2 mm EXTR-U 4.022e-04 -5.849e-03 9.101e-04 -9.855e-04 MAX-DISP 5.896e-03 UNIT [m] Z_Soil Day 2007 Lausanne, 27th August 2007 DEFORMED MESH t-ref.= 4.0 [day] t = 5.0 [day] Z_SOIL.PC 2003 v.6.26 Expert License No: -------- Company : ZACE Author : ZACE Date : 2007-03-08 08:29:12 File : C:\Mandats\GeoMod\M686_Orange\Technique\14fev\2D\orange_coupeCFF_2x2_paroiBeam_puits_Eunl_OK_deltaU5mm Title : Zsoil example Commend, Mellal, Geiser – 08.2007

Temperature effect on bracing :

2D model imposing D T on bracing (Q4) -5.0

T = 10 °C = cte 0.0

5.0

10.0

T : from 10 °C to 40 °C => D T = 30 °C 15.0

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 1.000e+01 1.150e+01 1.300e+01 1.450e+01 1.600e+01 1.750e+01 1.900e+01 2.050e+01 2.200e+01 2.350e+01 2.500e+01 2.650e+01 2.800e+01 2.950e+01 3.100e+01 3.250e+01 3.400e+01 3.550e+01 3.700e+01 3.850e+01 4.000e+01 TEMPERATURE t = 2.0 [day] Z_SOIL.PC 2003 v.6.26 Expert License No: -------- Company : ZACE Author : ZACE Date : 2007-03-08 09:14:18 File : C:\Mandats\GeoMod\M686_Orange\Technique\Simple_heat\orange_coupeCFF_heat2 Title : Zsoil example UNIT [C] Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Temperature effect on bracing :

2D model imposing D T on bracing -15.0

-7.5

0.0

7.5

15.0

1.885e-03 D N=230 kN D ux = 0 (imposed) EXTR-U 4.055e-04 -6.979e-03 EXTR-V 7.084e-03 -1.010e-03 MAX-DISP 7.084e-03 UNIT [m] DEFORMED MESH t-ref.= 1.0 [day] t = 2.0 [day] Z_SOIL.PC 2003 v.6.26 Expert License No: -------- Company : ZACE Author : ZACE Date : 2007-03-08 10:39:04 File : C:\Mandats\GeoMod\M686_Orange\Technique\Simple_heat\orange_coupeCFF_heat+mech2 Title : Zsoil example Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007

Conclusions

Currently under construction •Predictions in the range of deformations and forces •Horizontal displacements slightly > measurements •Linked mainly to: - « conservative » evaluation of f - real water behaviour and c Z_Soil Day 2007 Lausanne, 27th August 2007 Commend, Mellal, Geiser – 08.2007