ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
1TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Water-Soil Interaction Simulation using
Smoothed Particle Hydrodynamics
Bozhana STEFANOVA, Karlotta SEITZ, Julian BUBEL, Jürgen GRABEHamburg University of Technology
Institute of Geotechnical Engineering and Construction Management
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
2TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Introduction
• Gravity base foundation for an offshore wind energy converter:– hollow structures
made of concrete– manufactured onshore
and transported to the construction site
– lowered into a prepared foundation pit
• Jet grouting:– used since the 1970´s– method of ground
improvement andstabilization
– high presure streams tobreak up the soil
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
3TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Introduction
• Gravity base foundation for an offshore wind energy converter:– hollow structures
made of concrete– manufactured onshore
and transported to the construction site
– lowered into a prepared foundation pit
• Jet grouting:– used since the 1970´s– method of ground
improvement andstabilization
– high presure streams tobreak up the soil
interaction betweenfluid and soil
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
4TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Lowering of a gravity base foundation (GBF)
water flow underneath thefoundation is induced:→ flow in the voids of the soil→ erosion
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
5TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Soil interaction with a fluid jet
• high velocity andpressure
• different stages ofinteraction
• reduction ofeffective stress in the soil
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
6TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Smoothed Particle Hydrodynamics (SPH)
• meshfree method • uses particles that have
the properties of the material
• originally applied in the 1970`s in the astrophysics
• nowadays used for different physical, hydrodynamic and also geotechnical calculations
• approximation for each particle using its neighbors
(fig. after Colagrossi, 2003)
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
7TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Conservation equations in SPH
mass conservation momentum conservation
equation of state
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
8TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Implementation in SPH
• soil as a viscous fluid, using Gadget H2O by C. Ulrich & T. Rung– viscosity μ as function of the angle of friction φ, cohesion c,
pressure p and deviatoric strain rate ė:
– useful approach to study the applicability and feasibility of the models
– for further geotechnical applications: more sophisticated treatment of soil needed
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
9TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Simulation of the lowering of a gravity base foundation
STRABAG Gravity Base (Weber, 2010) Model setup
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
10TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Results for lowering of a gravity base foundation
velocity magnitude [m/s]
initial configuration
5 s
15 s
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
11TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Results for jet grouting
0.015s
0.03s
velocitiesparticles
[m/s]
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
12TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Results for jet grouting
0.015s
0.03s
velocitiesparticles
[m/s]
ICSE 6 – 6th International Conference on Scour and Erosion, Paris Aug. 27-31 2012
13TUHH Water –Soil Interaction Simulation using SPH - Stefanova, Seitz, Bubel, Grabe
Conclusions & outlook
• soil-water interaction for two geotechnical problems was analyzed
• promising results• future goals
– two-phase-model in order to describe the soil-fluid-interaction
– test cases for numerical analysis & variation of parameters– calibration and validation of the simulation results