1. Horizontal Loading Tests on Model Foundations Retrofitted by Micropiles Masahiro NISHITANI Jiro FUKUI Takeshi UMEBARA IAI, PWRI Structures Research Group Foundation Engineering Team

2. Retrofitting of Existing Foundation by Micropiles Limited Headroom Widening of Footing Existing Pile Micropile Bearing Layer

3. Presentation Outline Outline of horizontal loading tests on group piles Results of horizontal loading tests Results of simulation analyses for the loading tests Summaries

4. Presentation Outline Outline of horizontal loading tests on group piles Results of horizontal loading tests Results of simulation analyses for the loading tests Summaries

5. To Clarify the Effects of Group Piles…. → Horizontal Loading Tests on Model Foundations Plane of Existing Foundation with Micropiles Micropile Existing Pile Existing Footing

6. Cases of Horizontal Loading Tests

7. Case 1Case 2

8. Case 3

9. Cases of Horizontal Loading Tests

10. Models of Case 4 to Case 7 Existing Pile Micropile Loading Direction Front Rear

11. Case 4Case 5

12. Case 6 Case 7

13. Specifications of Model Piles

14. Loading Test for Case 3 Footing Steel Bar Jack

15. Presentation Outline Outline of horizontal loading tests on group piles Results of horizontal loading tests Results of simulation analyses for the loading tests Summaries

16. Curve of Load and Displacement

17. Bending Moment on Existing Piles in Case 3 and Case 4

18. Bending Moment on Existing Piles in Case 4 and Case 6

19. Bending Moment on Micropiles in Case 4 and Case 6

20. Shearing Force on Existing Piles in Case 3 and Case 4

21. Shearing Force on Existing Piles in Case 4 and Case 6

22. Axial Force on Existing Piles in Case 3, Case 4 and Case 6

23. Axial Force on Existing Piles in Case 4 and Case 6

24. 1.52.01.00.50.0 1.01.50.50.0 Curve of Horizontal Ground Reaction and Displacement

25. Presentation Outline Outline of horizontal loading tests on group piles Results of horizontal loading tests Results of simulation analyses for the loading tests Summaries

26. To Study the Design Method of Group Piles with Different Diameter Piles…. → Simulation Analyses for Loading Tests by Ductility Design Method Non-Linear Model ・ Ground Properties ・ Flexural Rigidity of Piles

27. Model of Transverse Resistance of Pile Upper Limit of Ground Reaction Displacement Ground Reaction ０ Ｐ HU Ｔ an －１ ｋ HE (m) (N/m 2 )

28. k HE = a ｋ b ｋ k H p HU = a ｐ b ｐ p U a ｋ, a ｐ : Correction Factors of a Single Pile b ｋ, b ｐ : Correction Factors of Group Piles To consider the group effects… a ｋ b ｋ = 1 a ｐ (Cray Ground) = 1.0 a ｐ b ｐ (Sandy Ground) = S/D ( ≦ 3) To consider the group effects of trailing piles… Transverse Resistance Characteristics of Pile

29. Loading Direction Trailing Piles Front Rear Front Pile p HU ½ : 1

30. 1) Study new correction factors for a single pile, fitting with Case 1 test results 2) Study new correction factors for group piles, fitting with Case 3 test results 3) Analyze Case 4 to Case 6, using new correction factors Simulation Procedure

31. New Correction Factors on Analyses

32. Model of Flexural Rigidity of Steel Pile Curvature Bending Moment ０ Mp My Y Y: Yield State (Nm) (1/m) φy Fully Plastic Moment

33. 1201401008060200 40 12010080 60200 40 100806020040 Curve of Load and Displacement

34. Bending Moment on Existing Piles in Case 3 and Case 4 Case 3 Case 4

35. Bending Moment on Micropiles in Case 4

36. Curve of Horizontal Ground Reaction and Displacement Case 3

37. Curve of Horizontal Ground Reaction and Displacement Case 4

38. Summaries Results of horizontal loading tests → Existing foundations with micropiles have a large retrofitting effects. → Spacing has little effect on retrofitting. → Retrofitting effects are counted by installing micropiles incliningly. Results of simulation analyses → It is possible to use the ductility design method to perform retrofitting design.