26 - 28 september 2017 hannover, germany v international ... fileauthors: joaquín irazábal,...
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![Page 1: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/1.jpg)
Authors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate
Shape characterization of railway ballast stones for discrete element
calculations
PARTICLES 2017
26 - 28 September 2017 Hannover, Germany
V International Conference on Particle-Based Methods
![Page 2: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/2.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
1. Motivation
2. Ballast layer
3. Discrete Element Method (DEM)
4. Geometric representation of railway ballast
5. Railway ballast modelling within the DEM
6. Conclusions
Outline
![Page 3: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/3.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Increasing interest all over the world in high-speed trains
Sometimes under unfavorable conditions
BALAMED (Jan. 2013 – Dec. 2015)
MONICAB (Jan. 2016 – Dec. 2018)
Motivation
![Page 4: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/4.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Layer of granular material placed under the sleepers whose
roles are: resisting to vertical and horizontal loads and
facing climate action
Ballast layer
![Page 5: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/5.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Force balance Torque balance
Discrete Element Method (DEM)
![Page 6: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/6.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Spheres Clusters of spheres
Spheropolyhedra Potential particles
Polyhedra Superquadrics
Geometric representation
![Page 7: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/7.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
• Low computational cost
• Efficient neighbour search and force evaluation
• Geometrical variety
• Allow concave particles
Geometric representation requirements
![Page 8: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/8.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Spheres
with RF
Sphere
clusters
Squad. Polyhed. Sphero-
Polyhed.
Potential
Particles
Low comput. cost
Efficient
Geometrical variety
Concave particles * *
Geometric representation comparison
Irazábal, J., Salazar, F., & Oñate, E. (2017) Numerical modelling of granular materials with spherical discrete
particles and the bounded rolling friction model. Application to railway ballast. Comput Geotech, 85 220–229
![Page 9: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/9.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Spheres Clusters of spheres
Geometric representation
![Page 10: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/10.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
• Density
• Sample size distribution
• The inter-particle friction
• Particle-wall friction
• The initial void ratio
• Coefficient of restitution
• Particle shape
• Particle stiffness
Normally well-known
Some considerations
to be taken into
account
Ballast properties
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Spherical Particles
Rolling Friction
Clusters of spheres
Accuracy
Particle shape
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Real contact geometry Numerical contact geometry
Hertzian contact model: contact stiffness depends on
the contact volume
Particle stiffness
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Repose angle test with spheres
Irazábal, J., Salazar, F., & Oñate, E. (2017) Numerical modelling of granular materials with spherical discrete
particles and the bounded rolling friction model. Application to railway ballast. Comput Geotech, 85 220–229
![Page 14: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/14.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Repose angle test with spheres
Irazábal, J., Salazar, F., & Oñate, E. (2017) Numerical modelling of granular materials with spherical discrete
particles and the bounded rolling friction model. Application to railway ballast. Comput Geotech, 85 220–229
![Page 15: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/15.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Rolling friction = 0.20
Rolling friction = 0.05 Rolling friction = 0.10
Rolling friction = 0.15
Rolling friction = 0.25
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Zand and Moraal (1997) Roads and Railways Research Laboratory Technical University of Delft
Lateral resistance force test
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Lateral resistance force test
Irazábal, J., Salazar, F., & Oñate, E. (2017) Numerical modelling of granular materials with spherical discrete
particles and the bounded rolling friction model. Application to railway ballast. Comput Geotech, 85 220–229
![Page 18: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/18.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Lateral resistance force test
Irazábal, J., Salazar, F., & Oñate, E. (2017) Numerical modelling of granular materials with spherical discrete
particles and the bounded rolling friction model. Application to railway ballast. Comput Geotech, 85 220–229
![Page 19: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/19.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Irazábal, J., Salazar, F., & Oñate, E. (2017) Numerical modelling of granular materials with spherical discrete
particles and the bounded rolling friction model. Application to railway ballast. Comput Geotech, 85 220–229
![Page 20: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/20.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Repose angle test with clusters
Clusters with different number of spheres
![Page 21: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/21.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Clusters with more spheres Clusters with less spheres
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
High dependence in distribution of contacts → Clusters
Large-scale direct shear test
Indraratna, B., Ngo, N. T., & Rujikiatkamjorn, C. (2011) Behavior of geogrid-reinforced ballast under various
levels of fouling, Geotextiles and Geomembranes, 29(3) 313–322.
![Page 23: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/23.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Large-scale direct shear test
![Page 24: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/24.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
![Page 25: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/25.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Large-scale direct shear test
![Page 26: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/26.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Geometric friction
Clusters of spheresReal Particles
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Alternatives:
• Decrease the inter-particle friction coefficient globally
+ Simple
- One value for each compression stress
Geometric friction
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Alternatives:
• Decrease the inter-particle friction coefficient globally
+ Simple
- One value for each compression stress
• Make the inter-particle friction coefficient dependent on
the contact stress
+ Non-dimensional
+ Works for different compression stresses
- Needs two new parameters to be defined
Harkness, J., Zervos, A., Pen, L. L., Aingaran, S., & Powrie, W. (2016) Discrete element simulation of railway
ballast: modelling cell pressure effects in triaxial tests. Granular Matter, 18 (3) 65.
Geometric friction
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
New parameters: critical maximum stress (σcmax) and
adimensional parameter γ
Stress-dependent friction contact model
![Page 30: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/30.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
New parameters: critical maximum stress (σcmax) and
adimensional parameter γ
Stress in a Hertzian contact:
Stress-dependent friction contact model
![Page 31: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/31.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
New parameters: critical maximum stress (σcmax) and
adimensional parameter γ
Stress in a Hertzian contact:
Critial contact force:
Stress-dependent friction contact model
![Page 32: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/32.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
New parameters: critical maximum stress (σcmax) and
adimensional parameter γ
Stress in a Hertzian contact:
Critial contact force:
Condition:
Stress-dependent friction contact model
![Page 33: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/33.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Large-scale direct shear test
![Page 34: 26 - 28 September 2017 Hannover, Germany V International ... fileAuthors: Joaquín Irazábal, Fernando Salazar and Eugenio Oñate Shape characterization of railway ballast stones for](https://reader033.vdocuments.us/reader033/viewer/2022041418/5e1d08be18b5435b324995a3/html5/thumbnails/34.jpg)
Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Large-scale direct shear test: γ = -0.05
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Large-scale direct shear test: γ = -0.10
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
Large-scale direct shear test: γ = -0.15
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Shape characterization of railway ballast stones for discrete element calculations
1. Motivation | 2. Railway tracks | 3. DEM | 4. Geometric representation | 5. Ballast modelling |
6. Conclusions
• The angle of repose test allows us to characterize the
shape of the particles
• To characterize the contact mechanism, stresses and
deformations should be measured
• For tests with a big amount of material the calculations
using spheres with rolling friction provides good results
at a low computational cost
• Clusters of spheres should be used in calculations where
the contacts distribution is important
• There is uncertainty in the assignment of properties
even if the geometry of the DE is accurate
Conclusions
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Thank you for your attention
PARTICLES 2017
26 - 28 September 2017 Hannover, Germany
V International Conference on Particle-Based Methods
http://www.cimne.com/dem/