influence of tie support condition on ballast behavior
TRANSCRIPT
PowerPoint PresentationInfluence of Tie Support Condition on
Ballast Behavior under Static and Dynamic Loading
Wenting Hou Bin Feng Erol Tutumluer University of Illinois at Urbana-Champaign
2018 International Crosstie and Fastening System Symposium
RailTEC at Illinois | 2
RailTEC at Illinois | 3
Introduction
In U.S., most railway corridors are constructed as ballasted track. Ballast layer undergoes deformation over time, which leads to track geometry deterioration.
Developing non-uniform support condition
RailTEC at Illinois | 4
Support Conditions in Track
Amtrak Concrete Tie and Track Structure
Improvement Study at UIUC
Amtrak NEC NB MP 75.12, Edgewood, MD Track speed 125 mph
RailTEC at Illinois | 5
Influence of Support Conditions
Reference: Kaewnruen & Remennikov (2009)
Influence of ballast conditions on ballast particle behavior and performance?
RailTEC at Illinois | 6
Static Loading
Tie-ballast interaction
Ballast particle
Amtrak Concrete Tie and Track Structure Improvement Study at UIUC
RailTEC at Illinois | 7
Research Approach
Discrete Element Method (DEM) is proven effective to study granular materials such as ballast – BLOKS3D
DEM can be calibrated with previous Laboratory testing results
Reference: Cesar Bastos et al. 2017Reference: Tutumluer et al. 2013
RailTEC at Illinois | 8
Different Support Conditions Studied
RailTEC at Illinois | 9
Total of ~11,000 ballast particles
RailTEC at Illinois | 10
Ballast grain size distribution:
Other important parameters: • Shear contact stiffness 10MN/m • Normal contact stiffness 20MN/m • Global damping ratio nil • Contact damping ratio 0.40 • Aggregate surface friction angle 31°
Sieve Size Percent Passing (%)
2 ½’’ 63.5 mm 100 2’’ 50.8 mm 95
1 ½’’ 38.1 mm 65 1’’ 25.4 mm 10 ½’’ 12.7 mm 0
Shape properties:
0
20
40
60
80
100
*Imaging Based 3D Ballast Particle Shape Properties Quantified by E-UIAIA
RailTEC at Illinois | 11
Fo rc
e Pe
rc en
0%
20%
40%
60%
Fo rc
e Pe
rc en
Fo rc
e Pe
rc en
0%
20%
40%
60%
Fo rc
e Pe
rc en
rc e
Pe rc
en t
RailTEC at Illinois | 13
Ballast Particle Contact Forces
(Wang et al. 2017)
RailTEC at Illinois | 14
RailTEC at Illinois | 16
Full support 28 70 85
Lack of rail seat support 47 97 120
Lack of center support 30 102 115
High center binding 27 77 108
Severe center binding 40 114 154 *Unit (psi) *Exceeding the AREMA allowable pressure
RailTEC at Illinois | 17
Ballast-Subgrade Contact Pressure
Ballast + subballast depth equals 14 inches Each static rail seat load is 20 kips Comparison with AREMA design procedure:
Support Conditions DEM Model AREMA 2012
Lack of rail seat support 18 psi
23 psi
High center binding 21 psi
Severe center binding 29 psi
RailTEC at Illinois | 18
Findings related to Static Loading
Only a portion of ballast particles participated in load distribution when external forces were applied
Particles on the shoulder and particles in the area with poor support condition often experience none or very low stresses under external loading
The severe center binding scenario seems to be the most critical support condition in terms of high tie-ballast contact force – exceeding AREMA allowable 85 psi contact force by over 30%
Top of subgrade pressure also calculated from the DEM simulation results. Maximum top of subgrade pressure under all support conditions except severe center binding were below the calculated pressure from empirical design manual.
RailTEC at Illinois | 19
Dynamic Loading
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0
5
10
15
20
25
30
Time(sec)
Loading magnitude calculated from train-track model developed at UIUC
RailTEC at Illinois | 20
Force Control in DEM
With PID Function Controller
RailTEC at Illinois | 21
Full Support
RailTEC at Illinois | 22
RailTEC at Illinois | 23
RailTEC at Illinois | 24
RailTEC at Illinois | 25
RailTEC at Illinois | 26
Permanent Deformation
Simulate the ballast layer performance due to dynamic loading - different ballast support conditions
Ideal case of full support is the lowest!
RailTEC at Illinois | 27
Findings related to Dynamic Loading
Ballast particle velocities were captured. Lack of center support condition and lack of rail seat support condition show the trend of moving toward one side of the track
The force chain network formation during a dynamic loading cycle can be visualized
Among the four studied support conditions lack of center support condition is found to be the most critical scenario due to higher permanent deformation with repeated loading
RailTEC at Illinois | 28
Ricardo Quiros Orozco and RailTEC at UIUC
Amtrak Concrete Tie and Track Structure Improvement Study
Huseyin Boler, graduate student
Dr. Yu Qian, Assistant Professor, University of South Carolina
Influence of Tie Support Condition on Ballast Behavior under Static and Dynamic Loading
Outline
Introduction
Model Calibration
Dynamic Loading
Contact Force Chain – Lack of Center
Contact Force Chain – High Center
Contact Force Chain – Lack of Rail Seat
Permanent Deformation
Acknowledgements
Wenting Hou Bin Feng Erol Tutumluer University of Illinois at Urbana-Champaign
2018 International Crosstie and Fastening System Symposium
RailTEC at Illinois | 2
RailTEC at Illinois | 3
Introduction
In U.S., most railway corridors are constructed as ballasted track. Ballast layer undergoes deformation over time, which leads to track geometry deterioration.
Developing non-uniform support condition
RailTEC at Illinois | 4
Support Conditions in Track
Amtrak Concrete Tie and Track Structure
Improvement Study at UIUC
Amtrak NEC NB MP 75.12, Edgewood, MD Track speed 125 mph
RailTEC at Illinois | 5
Influence of Support Conditions
Reference: Kaewnruen & Remennikov (2009)
Influence of ballast conditions on ballast particle behavior and performance?
RailTEC at Illinois | 6
Static Loading
Tie-ballast interaction
Ballast particle
Amtrak Concrete Tie and Track Structure Improvement Study at UIUC
RailTEC at Illinois | 7
Research Approach
Discrete Element Method (DEM) is proven effective to study granular materials such as ballast – BLOKS3D
DEM can be calibrated with previous Laboratory testing results
Reference: Cesar Bastos et al. 2017Reference: Tutumluer et al. 2013
RailTEC at Illinois | 8
Different Support Conditions Studied
RailTEC at Illinois | 9
Total of ~11,000 ballast particles
RailTEC at Illinois | 10
Ballast grain size distribution:
Other important parameters: • Shear contact stiffness 10MN/m • Normal contact stiffness 20MN/m • Global damping ratio nil • Contact damping ratio 0.40 • Aggregate surface friction angle 31°
Sieve Size Percent Passing (%)
2 ½’’ 63.5 mm 100 2’’ 50.8 mm 95
1 ½’’ 38.1 mm 65 1’’ 25.4 mm 10 ½’’ 12.7 mm 0
Shape properties:
0
20
40
60
80
100
*Imaging Based 3D Ballast Particle Shape Properties Quantified by E-UIAIA
RailTEC at Illinois | 11
Fo rc
e Pe
rc en
0%
20%
40%
60%
Fo rc
e Pe
rc en
Fo rc
e Pe
rc en
0%
20%
40%
60%
Fo rc
e Pe
rc en
rc e
Pe rc
en t
RailTEC at Illinois | 13
Ballast Particle Contact Forces
(Wang et al. 2017)
RailTEC at Illinois | 14
RailTEC at Illinois | 16
Full support 28 70 85
Lack of rail seat support 47 97 120
Lack of center support 30 102 115
High center binding 27 77 108
Severe center binding 40 114 154 *Unit (psi) *Exceeding the AREMA allowable pressure
RailTEC at Illinois | 17
Ballast-Subgrade Contact Pressure
Ballast + subballast depth equals 14 inches Each static rail seat load is 20 kips Comparison with AREMA design procedure:
Support Conditions DEM Model AREMA 2012
Lack of rail seat support 18 psi
23 psi
High center binding 21 psi
Severe center binding 29 psi
RailTEC at Illinois | 18
Findings related to Static Loading
Only a portion of ballast particles participated in load distribution when external forces were applied
Particles on the shoulder and particles in the area with poor support condition often experience none or very low stresses under external loading
The severe center binding scenario seems to be the most critical support condition in terms of high tie-ballast contact force – exceeding AREMA allowable 85 psi contact force by over 30%
Top of subgrade pressure also calculated from the DEM simulation results. Maximum top of subgrade pressure under all support conditions except severe center binding were below the calculated pressure from empirical design manual.
RailTEC at Illinois | 19
Dynamic Loading
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0
5
10
15
20
25
30
Time(sec)
Loading magnitude calculated from train-track model developed at UIUC
RailTEC at Illinois | 20
Force Control in DEM
With PID Function Controller
RailTEC at Illinois | 21
Full Support
RailTEC at Illinois | 22
RailTEC at Illinois | 23
RailTEC at Illinois | 24
RailTEC at Illinois | 25
RailTEC at Illinois | 26
Permanent Deformation
Simulate the ballast layer performance due to dynamic loading - different ballast support conditions
Ideal case of full support is the lowest!
RailTEC at Illinois | 27
Findings related to Dynamic Loading
Ballast particle velocities were captured. Lack of center support condition and lack of rail seat support condition show the trend of moving toward one side of the track
The force chain network formation during a dynamic loading cycle can be visualized
Among the four studied support conditions lack of center support condition is found to be the most critical scenario due to higher permanent deformation with repeated loading
RailTEC at Illinois | 28
Ricardo Quiros Orozco and RailTEC at UIUC
Amtrak Concrete Tie and Track Structure Improvement Study
Huseyin Boler, graduate student
Dr. Yu Qian, Assistant Professor, University of South Carolina
Influence of Tie Support Condition on Ballast Behavior under Static and Dynamic Loading
Outline
Introduction
Model Calibration
Dynamic Loading
Contact Force Chain – Lack of Center
Contact Force Chain – High Center
Contact Force Chain – Lack of Rail Seat
Permanent Deformation
Acknowledgements