Session 40 Ebrahim Parhamifar

461 views

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
461
On SlideShare
0
From Embeds
0
Number of Embeds
10
Actions
Shares
0
Downloads
1
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Session 40 Ebrahim Parhamifar

  1. 1. <ul><li>Development of permanent deformations in </li></ul><ul><li>unbound base course materials </li></ul><ul><li>- Analysis and modeling </li></ul><ul><li>Ebrahim Parhamifar, LTH </li></ul><ul><li>Sigurdur Erlingsson, VTI </li></ul>Transportforum 2010
  2. 2. Objectives <ul><li>The aim of the work is to introduce a new test method to </li></ul><ul><li>study response and permanent deformation of unbound </li></ul><ul><li>materials. </li></ul><ul><li>The test results are compared with some established </li></ul><ul><li>models. </li></ul><ul><li>The comparison is used to build up a data base for material </li></ul><ul><li>parameters. </li></ul>
  3. 3. Testing box <ul><li>800*800*800 mm testing box </li></ul><ul><li>Deformation gauges at 10 points and two levels </li></ul>A B A: 80 or 150 mm crushed 0-40 mm base material B: 200 mm of natural 0-100 mm sub-base material
  4. 4. Testing Box Instrumentation of the specimen
  5. 5. A pavement structure Testing box Triaxial Applied stresses on body of a specimen
  6. 6. Experiments in the testing box <ul><li>Six 0-40 mm unbound granular materials were used in experiments </li></ul><ul><li>Variation in vertical applied stresses to simulate different traffic loadings on real roads and under pavement construction </li></ul><ul><li>Two series of measurements </li></ul><ul><li>- Short series to study material response </li></ul><ul><li>- Long series to study permanent deformations </li></ul><ul><li>Different frequencies to simulate different vehicle speeds </li></ul>
  7. 7. Typical loading cycle in the testing box Load (kN) Time of loading One loading cycle Load (kN)
  8. 8. Two typical crushed unbound granular materials used in experiments
  9. 9. Materials used for measurements in the testing box Material / Properties d1 d2 d3 d4 d5 d6 Dry density (g/cm 3 ) 2.08 2.22 2.20 2.29 2.30 2.25 Optimum moisture content ( % weight) 7.7 5.3 7.0 6.2 5.7 6.0 Particle density> (g/cm 3 ) 2.73 2.60 2.73 2.78 2.73 2.57 Flakiness ratio 1.51 1.58 1.52 1.56 1.55 1.37 Aggregate impact value 52 62 57 56 57 55 Nordic Ball Mill Value 23.5 25.8 20.6 15.3 15.7 25.1 % natural aggregate 0 0 0 0 0 39 /20*
  10. 10. Simulated distribution of the vertical stress in the texting box Symmetry lines
  11. 11. Response measurements. Elastic strain with different vertical stresses
  12. 12. Material characterization K -  model
  13. 13. Comparison between measurements and calculations in the middle of the base course 40 mm depth
  14. 14. Comparison between measurements and calculations at layers boundaries p = 477 kPa 80 mm depth
  15. 15. Permanent deformation models Leena K. T. 2009 Gidel et. al 2001 Tseng & Lytton 1989
  16. 16. Comparison between measurements and calculations in the middle of the base course P=396 kPa P=566 kPa P=1431kPa P=955 kPa
  17. 17. Comparison between measurements and calculations at layers boundaries P= 396 kPa P= 566 kPa P=955 kPa p=1431 kPa
  18. 18. Material parameters
  19. 19. Conclusions <ul><li>The texting box used to study material properties of the unbound materials show some interesting results compared to established methods </li></ul><ul><li>The response behaviour observed in the testing box shows very similar results to numerical calculations (KenPave) using the K -  model (stress dependent). </li></ul><ul><li>The observed development of accumulated permanent deformation in the testing box is very similar to observed deformations in pavements. </li></ul><ul><li>All models used to predict the permanent deformation show acceptable agreements with the measured values. Leena's model show the best correlation with measured values at both low and high stress levels </li></ul>

×