Folie 1 Institute of Geotechnical Engineering and Construction Management Torben Pichler

High-Performance Abaqus Simulations in Soil Mechanics

Reloaded -

Chances and Frontiers

Folie 2 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Content

1. Soil as a multi-phase material

2. Installation of screwed piles

3. Deep penetration process of spudcan foundation

4. Ship collision with gravity based offshore structure

5. First application of Smoothed Particle Hydrodynamics in soil

mechanics

6. Conclusions

Folie 3 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Multi-phase material

Content

1. Soil as a multi-phase material

2. Installation of screwed piles

3. Deep penetration process of spudcan foundation

4. Ship collision with gravity based offshore structure

5. First application of Smoothed Particle Hydrodynamics in soil

mechanics

6. Conclusions

Folie 4 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Multi-phase material Multi-phase material in geomechanics: soil is a multi-phase porous material

load-bearing behavior is significantly dependent on pore water

concept of effective stress is used

multi-phase material only available in Abaqus/Standard

Folie 5 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Multi-phase material VUMAT for two-phase material: Simulation of fully saturated soil in Abaqus/Explicit

Solid skeleton is described as isotropic and linear elastic

behavior of pore water is modeled by a mass balance equation

relative velocity of pore water is obtained by Darcys law

For each strain increment Abaqus/Explicit calculates, the user subroutine computes a new effective stress state and pore water pressure and returns a new total stress state.

Main limitation of this approach is the determination of the gradient of the pore water pressure, because Abaqus provides no build-in function to obtain the gradient of a SDV.

Folie 6 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Multi-phase material Validation of user subroutine: axisymmetric oedometric test under static loading is simulated with user subroutine in Abaqus/Explicit

results are compared to a coupled pore fluid diffusion and stress analysis carried out with Abaqus/Standard

Folie 7 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Multi-phase material Validation of user subroutine: axisymmetric oedometric test under static loading is simulated with user subroutine in Abaqus/Explicit

results are compared to a coupled pore fluid diffusion and stress analysis carried out with Abaqus/Standard

Folie 8 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Multi-phase material Validation of user subroutine: axisymmetric oedometric test under static loading is simulated with user subroutine in Abaqus/Explicit

results are compared to a coupled pore fluid diffusion and stress analysis carried out with Abaqus/Standard

Folie 9 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Screwed piles

Content

1. Soil as a multi-phase material

2. Installation of screwed piles

3. Deep penetration process of spudcan foundation

4. Ship collision with gravity based offshore structure

5. First application of Smoothed Particle Hydrodynamics in soil

mechanics

6. Conclusions

Folie 10 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Full displacement pile: effects during installation are difficult to predict

bearing capacity of FD-piles is difficult to predict

rate of penetration and rotation is chosen only by operating experience

soil behavior is very complex and difficult to investigate by field measurements

Screwed piles

Folie 11 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Pile installation: Previous method:

Screwed piles

zipper technique

rigid pile pushed over rigid tube

tube allows separation of soil continuum and boundaries

no modeling of screwed piles possible

Folie 12 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Pile installation: Previous method: Simulation with CEL:

Screwed piles

Folie 13 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Pile installation: Detail: Simulation with CEL:

Screwed piles

Folie 14 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Pile installation: deformation (video): stress (video):

Screwed piles

Folie 15 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Influence of construction parameters:

Screwed piles

Folie 16 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Influence on surrounding soil:

Screwed piles

Folie 17 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan

Content

1. Soil as a multi-phase material

2. Installation of screwed piles

3. Deep penetration process of spudcan foundation

4. Ship collision with gravity based offshore structure

5. First application of Smoothed Particle Hydrodynamics in soil

mechanics

6. Conclusions

Folie 18 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan Spudcans: Footing of jack-up rigs

Disembarked on seabed

Used to transfer all loads safely

into the seabed

Jack-up rig Odin (http://www.beluga-hochtief-offshore.de/)

Folie 19 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan Spudcans: Footing of jack-up rigs

Disembarked on seabed

Used to transfer all loads safely

into the seabed

Folie 20 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan

Jack-up rig Arabdrill 19 failure due to punch-through in Saudi Arabia, 2002 (Hunt, 2005)

Spudcans: Footing of jack-up rigs

Disembarked on seabed

Used to transfer all loads safely

into the seabed

punch-through is possible

Folie 21 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan Simulation: Large deformation -> CEL

Hypoplastic constitutive model

Comparison to centrifuge tests

Folie 22 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan

Hypoplasticity:

Different stiffness for loading and

unloading

Dilatancy

Contractancy

Stiffness is dependent on pressure

and void ratio

Folie 23 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan

Folie 24 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Spudcan Comparison of numerical simulation to laboratory tests:

Folie 25 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Ship collision

Content

1. Soil as a multi-phase material

2. Installation of screwed piles

3. Deep penetration process of spudcan foundation

4. Ship collision with gravity based offshore structure

5. First application of Smoothed Particle Hydrodynamics in soil

mechanics

6. Conclusions

Folie 26 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Ship collision North sea Offshore wind parks:

Folie 27 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Foundations for offshore wind energy turbines:

source: http://www.fino3.de

Ship collision

Sketch of monopile, tripile, tripod, jacket and gravity based foundation for offshore wind energy turbines

Folie 28 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Model of gravity based foundation:

Ship collision

Folie 29 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Ship model:

Ship collision

Folie 30 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Numerical model:

Ship collision

Folie 31 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Simulated scenarios:

Ship collision

Folie 32 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Scenario 1:

Ship collision

Folie 33 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Contact forces:

Ship collision

Folie 34 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Damage to ship:

Ship collision

Folie 35 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Content

1. Soil as a multi-phase material

2. Installation of screwed piles

3. Deep penetration process of spudcan foundation

4. Ship collision with gravity based offshore structure

5. First application of Smoothed Particle Hydrodynamics in soil

mechanics

6. Conclusions

SPH in soil mechanics

Folie 36 Institute of Geotechnical Engineering and Construction Management Torben Pichler

SPH in soil mechanics Strip-footing benchmark: Rigid footing pressed into soil

Analytical solution by Hill (1950)

p = (2 + )c

Benchmark modeled with FEM and CEL for comparison

Folie 37 Institute of Geotechnical Engineering and Construction Management Torben Pichler

SPH in soil mechanics Strip-footing benchmark: SPH- and CEL-results have

similar quality

SPH-method seems suitable for complex geomechanical boundary value problems

Folie 38 Institute of Geotechnical Engineering and Construction Management Torben Pichler

SPH in soil mechanics Pile installation: Rigid pile pressed into soil

Folie 39 Institute of Geotechnical Engineering and Construction Management Torben Pichler

SPH in soil mechanics Pile installation: Reaction force of SPH-

simulation increases with decreasing mesh size

Reaction force of CEL-simulation increases with increasing mesh size

SPH-method is suitable for simulating the pile installation process

Folie 40 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Content

1. Soil as a multi-phase material

2. Installation of screwed piles

3. Deep penetration process of spudcan foundation

4. Ship collision with gravity based offshore structure

5. First application of Smoothed Particle Hydrodynamics in soil

mechanics

6. Conclusions

Conclusions

Folie 41 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Conclusions: Abaqus is a helpful tool to solve geotechnical boundary value problems

Abaqus built-in features are the basis for geotechnical problems but user-defined extensions are necessary to deal with special efforts

Future requirements for geotechnical purposes: availability of sophisticated constitutive models for soils multiphase materials in Abaqus/Explicit improved numerical stability for large deformations enhanced efficiency in parallel computing

Conclusions

Folie 42 Institute of Geotechnical Engineering and Construction Management Torben Pichler

Thank you for your attention!

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