The Installation and Load Testing of Drilled Shafts

Transcription

1 Presentation to the North American Chinese Geotechnical Engineers Association The Installation and Load Testing of Drilled Shafts at Clarksville, Virginia by James M. Sheahan, P.E. HDR Engineering, Inc.

2 Topics Covered Site Location and Project Setting Drilled Shaft Design Installation of Technique Shafts Load Testing of Technique Shafts Production Shafts Quality Control Testing Detection and Treatment of Defects

3 RT 58 - The Clarksville Bypass Project Location Project Location

4 Rt 58 - The Clarksville Bypass Mecklenburg County, Virginia Occoneechee Hbr B640 WB B646 EB B616 Kerr Reservoir B641 Distillery Branch

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6 Rt 58 - The Clarksville Bypass Bridges with Drilled Shaft Foundations Bridge Piers Drilled Shafts Rt 58 over Kerr Reservoir Rt 58 over Distillery Branch 3 9 Rt 58 WB over Occoneechee Hbr 2 4 Rt 58 EB over Occoneechee Hbr 2 4

7 Rt 28 - The Clarksville Bypass Project Geologic Setting Paleozoic to Late Proterozoic Aged Rocks Periphery of Clarksville Batholith (Intrusive Igneous) Volcanics Cooked by Batholith then Overturned Local Structure is Overturned Anticline (Overturned to SE) Local Strike NE-SW; Dip 70º-90º NW Andisite, Metadioroite, Metagranite, Basalt

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15 Drilled Shaft Design

16 Rt 58 - The Clarksville Bypass Rock Quality Data (Average Recovery and RQD in % by Run) Bridge Run 1 Rec (RQD) Run 2 Rec (RQD) Run 3 Rec (RQD) Run 4 Rec (RQD) Kerr Res 94 (58) 96 (51) 97 (74) 98 (78) Area 1 Kerr Res 66 (25) 87 (24) 87 (27) 87 (27) Area 2 Distillery 91 (66) 89 (67) 91 (66) 84 (48) Branch Occ Hbr EB/WB 74 (58) 85 (58) 100 (89) 100 (64)

17 Bridge 616 over Kerr Reservoir Rock Quality Designation Areas Kerr Reservoir Area 2 Area 1

18 Rock Core From Area 1

19 Rock Core From Area 2

20 Route 58 -The Clarksville Bypass Rock Strength Tests (Unconfined Compression and Point Load Tests) Bridge Kerr Reservoir (Area 1) Kerr Reservoir (Area 2) Distillery Branch Occonneechee Hbr EB/WB Avg Compressive Strength 15,540 psi (35 Tests) 13,113 psi (8 Tests) 11,838 psi (4 Tests) No Tests

21 Route 58 - The Clarksville Bypass Drilled Shaft Design Parameters (After AASHTO - LFD) Area Axial Loads (Allowable) 1 qeb = 60 ksf qsf = 50 psi 2 qeb = 24 ksf qsf = 50 psi Lateral Loads (Use with COM624P or LPILE) Vuggy LS (Strong Rock) cm = 585 psi Vuggy LS (Strong Rock) Hard Clay (Weak Rock) cm = 320 psi

22 Route 58 - The Clarksville Bypass Drilled Shaft Design Dimensions Bridge Kerr Reservoir Area 1 Area 2 Shaft/Socket Diameter (Feet) 6.5 / / 5.5 Socket Length (Feet) Distillery Branch 6.0 / Occoneechee Harbor 6.0 /

23 Route 58 - The Clarksville Bypass Recommendations/Specifications Technique Shafts (Areas 1 and 2) Axial Load Tests on Technique Shafts Lateral Load Tests on Technique Shafts Quality Control Tests (CSL, Borings, Cameras)

24 CSL Tube

25 Crosshole Sonic Logging (CSL) 1 Tube Pairs Six chords 1-2, 2-3, 3-4, 4-5, 5-6, 6-1 Four major diagonals 1-4, 2-5, 3-6 Minor chords, if needed 1-5, 1-3, 2-6, 2-4, etc

26 Camera Inspection of Socket Base Cleanliness Socket Wall Characteristics

27 Installation of Technique Shafts

28 Technique Shaft 1

29 Technique Shaft 2

30 Technique Shaft Construction

31 Technique Shaft Construction - Casing

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34 Shaft Construction - Double Walled Core Barrel

35 Shaft Construction Crane-Mounted Caldwell CH 155H

36 Drilled Shaft Cleanout with Airlift

37 Shaft Bottom Inspection With Camera (5-Point System) Cleanliness Requirements <10mm (0.5-inch) Over 50% of Area Max 40mm (1.50 inches) Over Full Area Example: 3/5 < 10mm (0.5 ) = 60% OK 5/5 < 40mm (1.5 ) = 100% OK

38 Camera Inspection of Socket Mini-SID GPE, Inc.

39 Camera Inspection of Socket Base (DHC) Down Hole Camera GPE, Inc.

40 Contractor-Designed Camera

41 Camera Inspection of Socket (Monitor/VCR)

42 Mini-SID Monitor View of Shaft Base Note: Rock visible in right quadrant from ~ 45 to 150 Water with reflection of overhead lights Sediment depth gage with air and water nozzles on either side of depth gage

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44 Installation of Reinforcing Cage

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46 Concrete Placement in Technique Shafts

47 Load Testing of Technique Shafts

48 Construction-Phase Borings at Technique Shafts (Rock Quality) Location Socket Rec (RQD) Below Tip Rec (RQD) TS1 100 (86) 100 (90) TS2 91 (41) 77 (30)

49 Osterberg Cell Axial Load Test (LOADTEST, Inc.)

50 O-cell Axial Test Technique Shaft 1 Instrumentation

51 O-cell Axial Test - Technique Shaft 1 Load vs Movement Max Qs MN ( mm (0.30-inch) Max Qeb MN ( mm (0.30-inch) Max qeb MPa (141 ksf) Ref: LOADTEST,Inc. Report

52 O-cell Axial Test - Technique Shaft 1 Unit Side Shear Max 7.5 mm (0.30-inch) Zone kpa (196 psi) Zone kpa (68 psi) Ref: LOADTEST, Inc. Report

53 O-cell Axial Test - Technique Shaft 1 Equivalent Top Loading Curve Pmax 13.9 MN ( mm (0.04-inch) settlement Ref: LOADTEST, Inc. Report

54 O-cell Axial Test Technique Shaft 2 Instrumentation

55 O-cell Axial Test - Technique Shaft 2 Load vs Movement Max Qs 7.90 MN ( mm (0.14-inch) Max Qeb 7.42 MN ( mm (0.06-inch) Max qeb 4060 kpa (84.4 ksf) Ref: LOADTEST, Inc. Report

56 O-cell Axial Test - Technique Shaft 2 Unit Side Shear Max 3.5 mm (0.14-inch) Zone kpa (76 psi) Zone kpa (33 psi) Zone kpa (25 psi) Ref: LOADTEST, Inc. Report

57 O-cell Axial Test - Technique Shaft 2 Equivalent Top Loading Curve Pmax 6.5 MN (1460 ~2 mm (0.08-inch) settlement Ref: LOADTEST, Inc. Report

58 Statnamic Lateral Test Technique Shaft 1 Instrumentation

59 Statnamic Lateral Load Test (Applied Foundation Testing, Inc.)

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61 Statnamic Lateral Load Test- TS1 (Downhole Accelerometer Data) Load 2 Ref: AFT, Inc. Report

62 Statnamic Lateral Load Test - TS1 (Strain Data) Load 2 Ref: AFT, Inc. Report

63 Statnamic Lateral Test -Technique Shaft 1 Peak Displacement 78.7 ~ Rock Surface Ref: AFT, Inc. Report

64 Statnamic Lateral Test -Technique Shaft 1 P vs y Ref: AFT, Inc. Report

65 Statnamic Lateral Test -Technique Shaft 1 LPILE Model ~ Rock Surface Ref: AFT, Inc. Report

66 Statnamic Lateral Test Technique Shaft 2 Instrumentation

67 Statnamic Lateral Test -Technique Shaft 2 Peak Displacement 78.3 ~ Rock Surface Ref: AFT, Inc. Report

68 Statnamic Lateral Test - Technique Shaft 2 LPILE Model 78.3 ~ Rock Surface Ref: AFT, Inc. Report

69 Route 58 The Clarksville Bypass Load Test Program For Drilled Shafts at Clarksville Significant end bearing was obtained before reaching 10 mm (0.4-inch) of socket movement. If end bearing is used for design, verification of cleanliness is important and methods using cameras are effective. If socket sidewall inspection is necessary, definition of clean water conditions must be included in specifications.

70 Route 58 The Clarksville Bypass Load Test Program For Drilled Shafts at Clarksville The design for lateral loading of shafts with long unsupported lengths, may be controlled by the shaft s structural characteristics, rather than the rock response. More investigation is necessary to examine minimum embedment lengths of rock sockets.

71 Production Shafts Quality Control Testing Detection and Treatment of Defects

72 CSL Test Bridge 616 Pier 1 DS1 Tube Pair 1-2 Socket Good

73 CSL Test Bridge 616 Pier 1 DS1 Tube Pair 1-4 Socket Good

74 CSL Test Bridge 640 Pier 1 DS1 Tube Pair 1-4 Socket Before Repairs

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76 Coring of Shaft and Use of Downhole Miniature Camera

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79 Hydro Blaster Concrete Demolition

80 Video Camera After Use of Water Blaster and Flushing of Defective Area

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83 CSL Test Bridge 640 Pier 1 DS1 Tube Pair 1-4 Socket After Repairs

84 CSL Test Bridge 616 Pier 1 DS3 Tube Pair 1-4 Before Repairs Socket

85 CSL Test Bridge 616 Pier 1 DS3 Tube Pair 1-4 After Repairs Socket

86 Load Testing Bridge 616 Pier 1 DS 3

87 Bridge 616, Pier 1, DS 3 Map of Defect Section View (Before Repair)

88 Bridge 616, Pier 1, DS 3 Map of Defect - Plan View (Before Repair)

89 Bridge 616, Pier 1, DS 3 Map of Defect Section View (After Repair)

90 Test Load/Predicted Deflection 0.85 M n = 8880 K-Ft. (0.85 Ultimate w/o axial load no failure) Deflection = 1.39 (At top of shaft w/lateral load producing 8880 k-ft moment at top of rock)

91 Pier/Drilled Shaft Layout

92 Test Criteria for Passing (Or further review) 100% of Test Load w/o Failure (Progressive movement w/o additional load) Reasonable Correlation w/ Pred. Deflection (+/- 20%) Linear Response w/ Load Consistent Results - Both Axes of Loading

93 Transverse Load (+)

94 Longitudinal Load (+)

95 Transverse Load (-)

96 Test Results Transv (+): 100 % Load Longititudinal (+): 25% Load % Load % Load (> 120% of allowed) >75% Load --- Progressive Movement

97 Revised DS Cap New Drilled Shaft DS 3

98 Construction of Bridge 616

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116 Questions???