Lizzi Lecture 2006 Performance of Seismic Retrofits with High - PowerPoint PPT Presentation

Lizzi Lecture 2006 Performance of Seismic Retrofits with High Capacity Micropiles Jiro Fukui Public Works Research Institute, Japan 1

Topics 1. Introduction (Background of Research) 2. Joint Research A) Model test 1(horizontal loading tests of group piles) B) Static analysis for group piles (simulation analyses for the horizontal loading tests) C) Model test 2 (shaking table test of group piles) 3. Construction examples in Japan 4. Development in the future 5. Conclusion 2

Topics 1. Introduction (Background of Research) 2. Joint Research A) Model test 1(horizontal loading tests of group piles) B) Static analysis for group piles (simulation analyses for the horizontal loading tests) C) Model test 2 (shaking table test of group piles) 3. Construction examples in Japan 4. Development in the future 5. Conclusion 3

Application example past in Japan Slope Stabilization Tunnel leg reinforcement 4

Capping Beam Concrete Micropiles Slope stabilization 5

Slope stabilization 6

Foundation of Observatory Shield Tunnel Micropile Underpinning of existing foundations 7

Hyogoken-nanbu EQ, 1995.1.17 8

Cracks on the cast-in-place concrete pile 9

Fall down of superstructure (Nishinomiya Br.) 10

Additional Pile Existing Pile Additional pile method 11

Construction procedure of additional pile method 12

Existing girder 13

Topics 1. Introduction (Background of Research) 2. Joint Research A) Model test 1(horizontal loading tests of group piles) B) Static analysis for group piles (simulation analyses for the horizontal loading tests) C) Model test 2 (shaking table test of group piles) 3. Construction examples in Japan 4. Development in the future 5. Conclusion 14

Joint Research on the Development of Seismic Retrofit Method for the Existing Bridge Foundation Purpose : • Develop ment of new seismic retrofit method • Establishment of design & construction manual Research Period : 1999-2001 15

Utilization of micropile for seismic retrofit of foundation (USA) 16

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Retrofit method for existing bridge foundation by using micropiles Execution at Original Footing narrow Working Enlarged Footing Area Original Pile Small Enlargement Micropile of Footing & Small Excavation 18

Content of Joint research • Loading test of High Capacity Micropile (vertical, horizontal) • Horizontal loading test of group piles(existing piles & micropiles) • Shaking table test of group piles • Centrifuge loading test of group piles • Analysis for group piles (simulation for the horizontal loading tests) • Loading test of a connection part of pile head and footing • Examination of design method for group piles • Numerical analysis considering finite deformation of piles • Examination of quality control & quality assurance by integrity test Design and Construction Manual 19

Content of Joint research • Loading test of High Capacity Micropile (vertical, horizontal) • Horizontal loading test of group piles(existing piles & micropiles) • Shaking table test of group piles • Centrifuge loading test of group piles • Analysis for group piles (simulation for the horizontal loading tests) • Loading test of a connection part of pile head and footing • Examination of design method for group piles • Numerical analysis considering finite deformation of piles • Examination of quality control & quality assurance by integrity test Design and Construction Manual 20

Topics 1. Introduction (Background of Research) 2. Joint Research A) Model test 1(horizontal loading tests of group piles) B) Static analysis for group piles (simulation analyses for the horizontal loading tests) C) Model test 2 (shaking table test of group piles) 3. Construction examples in Japan 4. Development in the future 5. Conclusion 21

max. φ 300mm max. φ 300mm max. φ 300mm Soft Stratum Steel Casing Pipe Deformed Bar Steel Pipe Deformed Bar Bearing Stratum Grout Grout Grout (a)Example of Deformed (b)Example of Steel Pipe (c)High capacity Micro Pile Bar Reinforcement Reinforcement General form of Micropiles 22

Cases of Horizontal Loading Tests Spacing between Existing Inclination Angle of Piles Center and Case Number of Piles Micropiles （ ° ） Micropiles Center （ mm ） 1 Single Existing Pile － － 2 Single Micropile － － 3 4 Existing Piles － － 4 4 Existing Piles and 6 Micropiles 200 0 5 4 Existing Piles and 6 Micropiles 400 0 6 4 Existing Piles and 6 Micropiles 200 10 7 4 Existing Piles and 6 Micropiles 200 20 23

Case 1 Case 2 24

Case 3 25

Cases of Horizontal Loading Tests Spacing between Existing Inclination Angle of Piles Center and Case Number of Piles Micropiles （ ° ） Micropiles Center （ mm ） 1 Single Existing Pile － － 2 Single Micropile － － 3 4 Existing Piles － － 4 4 Existing Piles and 6 Micropiles 200 0 5 4 Existing Piles and 6 Micropiles 400 0 6 4 Existing Piles and 6 Micropiles 200 10 7 4 Existing Piles and 6 Micropiles 200 20 26

Rear Front Micropile Existing Pile Loading Direction Arrangement of piles (Case 4 - 7) 27

Case 4 Case 5 28

Case 7 Case 6 29

Dimensions of Piles Sectional Area Moment of Inertia Thickness Diameter 2 ) 4 ） （ mm ） （ mm ） (cm （ cm Existing Pile 114.3 3.5 12.18 187.0 Micropile 34.0 2.3 2.291 2.89 30

Jack Steel Bar Footing Loading Test for Case 3 31

210 180 150 Load （kN） 120 Case1 90 Case2 Case3 60 Case4 Case5 30 Case6 Case7 0 0 20 40 60 80 100 Deflection （mm） 32

Bending Moment (KN-m) Bending Moment (KN-m) -1 -0.5 0 0.5 -20 -10 0 10 20 0 0 -50 -100 -150 Depth (cm) -200 Existing pile Micropile -250 -300 Case 3 Front Pile Case 4 Front Pile Case 3 Rear Pile Case 4 Rear Pile Case 4 Front Pile -350 Case 4 Rear Pile -400 33

-45 Front Case 4 -40 Analysis Existing Pile -35 Shear Force (ｋN) -30 Rear -25 -20 -15 Analysis -10 Front Micropile -5 Rear 0 0 20 40 60 80 100 120 Load (kN) Distribution of Shear Force 34

Horizontal Ground Reaction (KN/ 2 ) 400 C ase3 ( G . L. -0. 27m ) C ase3 ( G . L. -0. 57m ) C ase3 ( G . L. -0. 87m ) C ase4 ( G . L. -0. 27m ) 300 C ase4 ( G . L. -0. 57m ) C ase4 ( G . L. -0. 87m ) 200 100 0 0. 0 0. 5 1. 0 1. 5 2. 0 2. 5 0.0 0.5 1.0 1.5 2.0 0.0 0.5 1.0 1.5 D i spl acem ent of Pi l e ( cm ) Horizontal ground reaction - Displacement Curve 35

Topics 1. Introduction (Background of Research) 2. Joint Research A) Model test 1(horizontal loading tests of group piles) B) Static analysis for group piles (simulation analyses for the horizontal loading tests) C) Model test 2 (shaking table test of group piles) 3. Construction examples in Japan 4. Development in the future 5. Conclusion 36

To Study the Design Method of Group Piles with Different Diameter Piles…. → Simulation Analyses for Loading Tests by Ductility Design Method Ｐ 100 200 300 200 400 300 200 200 200 200 200 200 200 Non-Linear Model 200 200 200 200 200 4,400 200 3,900 ・ Ground Properties 200 200 200 200 200 200 ・ Flexural Rigidity of Piles 200 200 200 200 200 200 200 200 200 200 350 500 250 37

Model of Transverse Resistance of Ground (N/m 2 ) Upper Limit of Ground Reaction Ground Reaction p HU tan -1 k HE ０ Displacement (m) 38

Transverse Resistance Characteristics of Ground 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… 39

210 180 150 Load （kN） C ase3 Test 120 C ase3 Anal ysi s C ase4 Test 90 C ase4 Anal ysi s C ase5 Test 60 C ase5 Anal ysi s C ase6 Test 30 C ase6 Anal ysi s 0 0 20 40 60 80 100 120 140 160 40 0 20 60 80 100 120 140 40 0 20 60 80 100 120 0 20 40 60 80 100 Di spl acem ent of Foot i ng （ m m ） Load – Displacement Curve 40

Bending Moment of Existing Piles in Case 3 and Case 4 B endi ng M om ent （ kN ･m ） B endi ng M om ent （ kN ･m ） -15 -10 -5 0 5 10 -15 -10 -5 0 5 10 30 30 -30 -30 -90 -90 Ground Level (cm Ground Level (cm Case 3 Case 4 -150 -150 -210 -210 Test Resul t on Front Pi l e -270 -270 Test Resul t Test Resul t on Rear Pi l e on Fr ont Pi l e Anal ysi s Resul t Test Resul t on Front Pi l e -330 -330 on Rear Pi l e Anal ysi s Resul t Anal ysi s on Rear Pi l e Resul t -390 -390 41

Bending Moment on Micropiles in Case 4 B endi ng M om ent （ kN ･m ） -1. 0 -0. 5 0. 0 0. 5 30 -30 -90 Ground Level (cm -150 -210 Test Resul t on Fr ont Pi l e -270 Test Resul t on Rear Pi l e Anal ysi s Resul t -330 on Fr ont Pi l e Anal ysi s Resul t on Rear Pi l e -390 42