2010 VT Pavement Evaluation 1

Guangming Wang, Ph.D., EIT; Dennis Morian, P.E.Quality Engineering Solutions, IncReynaldo (Rey) Roque, Ph.D., P.E.

Department of Civil and Coastal EngineeringUniversity of Florida

Effects of Rutted Surface on Near-Surface Pavement Response

2010 VT Pavement Evaluation 2

Outline

� Background

� Develop 2-D Axle-Tire-pavementContact Model

� Investigate Rutted Surface on Near-Surface Pavement Response

� Conclusions & Recommendation

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Background

� Rutted Surface Affects Tire-Pavement Interaction

� Non-Uniform Contact Stress � Top-Down Cracking and Instability

Rutting

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Develop 2-D Axle-Tire-pavement Contact Model

� Modeling of Tire

Components of a unisteel radial tire (Goodyear after 2004)Tire to be modeled-Goodyear 425/65R22.5

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2D-Tire Mesh

Developed 2-D finite element tire model

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Modeling of 2-D Axle-Tire-Pavement Interaction

Unstable Structure Stable Structure

� Why need an axle?

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Developed 2-D Axle-Tire-Pavement Model

Flat Surface

Rutted Surface

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Model Verification

-200

-150

-100

-50

0

50

-8 -6 -4 -2 0 2 4 6 8

Tire Lateral Distance (in.)

Ve

rtic

al C

on

tac

t S

tre

ss

(p

si)

-50

-40

-30

-20

-10

0

10

20

30

40

50

-8 -6 -4 -2 0 2 4 6 8

Tire Lateral Distance (in.)

Tra

ns

ve

rse

Co

nta

ct

Str

es

s (

ps

i)

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Effects of Rutted Surface on Near-Surface Response

-350

-300

-250

-200

-150

-100

-50

0

50

-8 -6 -4 -2 0 2 4 6 8

Tire Lateral Location (in)

Vert

ical C

on

tact

Str

ess (

psi)

Flat

Rut

-80

-60

-40

-20

0

20

40

60

-8 -6 -4 -2 0 2 4 6 8

Tire Lateral Distance (in.)

Tra

ns

ve

rse

Co

nta

ct

Str

ess

(p

si)

Flat

Rut

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Effects of Rutted Surface on Near-Surface Response (Cont.)

1

m

-350

-300

-250

-200

-150

-100

-50

0

50

100

-8 -6 -4 -2 0 2 4 6 8

Tire Lateral Distance (in.)

Ve

rtic

al C

on

tac

t S

tre

ss

(p

si)

1% Slope

2% Slope

3% Slope

4% Slope

-80

-60

-40

-20

0

20

40

60

-8 -6 -4 -2 0 2 4 6 8

Tire Lateral Distance (in.)

Tra

ns

ve

rse

Co

nta

ct S

tres

s (

ps

i)

1% Slope

2% Slope

3% Slope

4% Slope

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Statistical Summary

Table 1. Statistic results of the comparison of peak contact stresses

Items

Degree of Rutting Severity

0% 1% 2% 3% 4%

Peak Vertical Contact Stress (psi) -165 -191 -226 -243 -303

Increasing Percentage

(Relative to Flat Surface)0% 16% 37% 47% 83%

Peak Transverse Contact Stress

(psi)45 47 56 61 66

Increasing Percentage

(Relative to Flat Surface)0% 4% 24% 36% 47%

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Effects of Rutted Surface on TDC and Instability Rutting

αα ≈= sinW

Fx

Forces acting on a tire on a side of a rut

For one degree of inclination angle, a lateral force of 0.0174 lb/lb is produced in the “downhill” direction by the gravitational component. For radial tire, this lateral force might be responsible for creating rut or increasing severity of rut in asphalt pavement surface (Gillespie, TD. et al. 1993).

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Critical Locations for TDC and Instability Rutting

Transverse Bending stress Vs. Principal Tensile Stress

-100

-80

-60

-40

-20

0

20

40

60

-100 -80 -60 -40 -20 0 20 40 60 80 100

Transverse distance to tire edge (in)

Str

ess_yy/S

IGM

A-1

(p

si)

Stress_yy SIGMA-1Principal Tensile Stress SIGMA-1

-1.20

-1.00

-0.80

-0.60

-0.40

-0.20

0.00

-150 -100 -50 0 50 100

Dep

th (

in)

0.45 in to Tire Edge 0.62 in to Tire Edge

0.75 in to Tire Edge 0.90 in to Tire Edge

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Effects of Rutted Surface on TDC

-60

-40

-20

0

20

40

60

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Distance to Tire Edge (in.)

SIG

MA

-1 (p

si)

Flat

Rut

-60

-40

-20

0

20

40

60

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

Distance to Tire Edge (in.)

SIG

MA

-1 (

ps

i)

1% Slope

2% Slope

3% Slope

4% Slope

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Effects of Rutted Surface on Instability Rutting

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

0 20 40 60 80 100 120

Maximum Shear Stress (psi)-425/65R22.5

Dep

th t

o A

C s

urf

ace(i

n)

Flat

Rut

0.0

0.5

1.0

1.5

2.0

2.5

0 20 40 60 80 100 120

Maximum Shear Stress (psi)

Dis

tan

ce

to

Su

rfac

e (

in.)

1% Slope

2% Slope

3% Slope

4% Slope

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Statistical Summary

Items

Degree of Rutting Severity

0% 1% 2% 3% 4%

Peak Maximum Shear Stress (psi) 80 92 101 106 110

Increasing Percentage

(Relative to Flat Surface)0% 15% 26% 33% 38%

Peak Principal Tensile Stress (psi) 20 26 32 42 50

Increasing Percentage

(Relative to Flat Surface)0% 30% 60% 110% 150%

Table 2. Summary of Peak Principal Tensile Stress and Maximum Shear Stress

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Conclusions

� The developed 2-D axle-tire-pavement finite element contact model can successfully capture patterns of both vertical contact stress and horizontal shear contact stress distributions

� Comparing with flat AC surface, contact stresses induced on the rutted surface are more concentrated on the tire shoulder and decrease along the “downhill” direction. The more severity the rut, the higher the localized contact stress on the tire shoulder.

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Conclusions (Cont.)

� Comparing with flat surface, both peak SIGMA-1 and maximum shear stress due to rutted surface are increased significantly. The more severity the rut, the greater propensity for TDC and the more severity for instability rutting

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Future Research Recommendation

� Need to develop 3-D tire-pavement interaction model to further investigate the effects of rutted surface on the near-surface pavement response

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Thank You