Lateral Load Testing for Pile Design. Kyle Rollins Brigham Young University

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1 Lateral Load Testing for Pile Design Kyle Rollins Brigham Young University

2 Wind and Waves in Hurricanes Seismic Forces Ship Impact Landslides and lateral spreading in Earthquakes

3 Lateral Testing Useful where lateral loads may control design Main Objective: measure soil resistance of critical strata Zone of most influence Approx top 5 D

4 Objectives Evaluate Soil Resistance Confirm Design Assumptions Improve Reliability Reduce Foundation Cost

5 Stratigraphy & the big picture Must have good geotech investigation at the test site and elsewhere Consider site variability when interpreting results & applying to design; site specific correlations w/ in-situ testing? Scourable materials?

6 Field Test Setup & Loading Calibrated Jack, Load Cell w/ rot l bearing Long travel jack, displacement transducers Strain gages and inclinometers in piles Test appropriate stratigraphy!

7 Single Pile Load Tests 324 mm OD Steel Pipe Pile 600 mm OD Steel Pipe Pile

8 Measurements - Purpose Back-fit model to observations Evaluate model for general soil conditions across site Develop model for design (using judgment) Note: boundary conditions will differ between test setup & design

9 Instrumentation & Measurements At pile top: Load cell & jack Displacement Rotation (use pair of LVDT s)

10 I-15 Lateral Load Test Schematic Reaction Beam Reaction Piles Swivel-Head End-Platens LVDT attached to reference frame Inclinometer Pipe Test Pile 300 kip Load Cell 300 kip Hydraulic Jack Spacer box

11 Load (kn) Load-Deflection Curve (12.75 Pipe Pile) Continuous 15th Cycle Curves 1st Cycle 15th Cycle Deflection (mm)

12 Instrumentation & Measurements Below Grade: Slope & Displacement Inclinometer probe EL-Sensor (downhole inclinometer array) Shape Array Sensors Strains

13 Depth Below Top of Pile (ft) Depth Below Top of Pile (ft) Deflection vs. Depth Moment vs. Depth 0 Displacement (in) Moment (kips-ft) kips kips 20 kips 20 kips kips 50 kips kips 50 kips 75 kips 75 kips kips 95 kips kips 95 kips 30 30

14 Shape Accelerometer Array

15 Shape Accelerometer Array Shape Array Inclinometer Pipe

16 Depth From Top of Cap (in) Depth From Top of Cap (in) Shape Sensor Array Displacement (in) Displacement (in) South Array 350 South Inclinometer 350 North Array North Inclinometer

17 Strain Gauges Photos courtesy Applied Foundation Testing

18 Interpretation of Instrumentation M = ε(ei/c) What is effective I (cracked section)? What is concrete modulus? What is precision of strain measurement?

19 Depth Below Ground Surface (m) Bending Moment vs Depth 0 Bending Moment (kn-m) Deflection 4mm 6mm 13mm 19mm 25mm 38mm 51mm 64mm 76mm 89mm 12

20 Analysis of Lateral Load Test Data

21 Lateral Load Analysis H p p p y y Interval y 2 y 1 Nonlinear springs p p y y y 4 3 y y 5 After Coduto

22 Develop Design Soil Model P-y criteria should reasonably match geotechnical profile Backfit to test results using LPILE or FLPIER Match load vs displacement response Match general displacement vs depth and moment vs depth response Nonlinear bending response of the pile can be important Evaluate possible soil variations across site Recommend soil parameters for design model

23 Depth below excavated surface (m) Undrained Strength, s u (kpa) m 1.07 m STIFF CLAY Water Table s u = 70 kpa 50 = k= 136 N/cm m SAND = 36 O k =61 N/cm 3 STIFF CLAY s u = 105 kpa 50 = k= 271 N/cm m 3.48 m SAND = 36 O k=61 N/cm m STIFF CLAY s u = 105 kpa 50 = k= N/cm 3 SILTY SAND = 38 O k=61.07 N/cm m Vane Shear Tests Unconfined Comp. Tests Avg CPT strength SOFT CLAY s u = 35 kpa 50 = 0.01 k= 27 N/cm Strength Used in Analysis

24 Load (kn) 450 Measured & Computed Load vs Deflection Measured Computed - LPILE Deflection (mm)

25 Moment (kn-m) Computed & Measured Moment vs. Load Computed with LPILE Measured Load (kn)

26 Depth Below Excavated Ground (m) Computed & Measured Moment vs Depth Bending Moment (kn-m) kn 240 kn 300 kn 414 kn

27 Use of Model for Design Adjust for differing pile top boundary conditions Allow for scour or other changes Allow for site variability Adjust for cyclic loading, group effects, any other parameters which may not be reflected in the load test data (liquefaction?)

28 Lateral Statnamic Load Testing 0 to 400 kips in 0.2 seconds Large Displacement, High Velocity

29 Lateral Statnamic Testing Have Safely Generated Loads >1000 tons 2000 ton Potential Load Pulse Can Last Up To 200 ms Rate of Loading Similar To Initial Pulse of Earthquakes, Transient Wind Loads, Impact

30 Schematic of Statnamic Test Test Foundation Load Piston Combustion Chamber Statnamic Sled

31 Statnamic Test Firing Videos

32 Downhole Motion Sensors & Strain Gauges

33 Equation of Motion F = F a + F v + F u = ma + cv + ku where, F = applied force (statnamic load cell) m = mass of the foundation a = acceleration in g s c = damping coefficient v = velocity k = static stiffness u = displacement

34 Load (kn) Comparison of Dynamic Forces Fstn Fa Fv Fu Time (sec)

35 Damping force (kn) Load (kn) Damping is Calculated static load Measured static load Statnamic load the Difference Deflection (mm) Damping ratios between 0.3 and Deflection (mm)

36 Computation of Equivalent Static Force Lumped Mass Model of Drilled Shaft F s = F stn - ΣM i a i - ΣC i v i

37 Elevation View of Test Site 3x3 Pile Group High-Speed Hydraulic Ram 1 m Drilled Shaft Liquefied Sand 5 m 8 m Non-Liquefied Sand

38 Treasure Island Naval Station Test Site

39 Blast Charge Pattern Pile Group Drilled Shaft Blast Holes

40 Ru Pore Pressure Dissipation Data m E a st o f A 5.5 m E a st o f A 4.3 m E a st o f A P o int A 3.2 m W e st o f A 6.4 m W e st o f A T im e [s e c ]

41 Single Pile Test

42 Load (kn) Load vs Deflection Curves for Single Pipe Pile Non-Liquefied Liquefied Displacement (mm)

43 Load (kn) Ru (%) Time (sec) Time (sec)

44 Blast Liquefaction Video (4 Pile Group and Shaft)

45 Depth Below Excavated Ground (m) Moment Before & After Liquefaction -2 Moment (kn-m) Before Liquefaction 10 After Liquefaction 12

46 Development of p-y Curves Strain Curvature Integrate Slope Integrate Deflection, Y EI P-Y curve Moment Differentiate Shear Differentiate Distributed load or pressure, P

47 Gerber p-y Analysis Routine

48 Generalized p-y Curves

49 Computed vs Measured Response

50 Cooper River Bridge Charleston, South Carolina Longest Cable-stayed bridge in North and South America New Bridge-Completed July 2005

51 Charleston Statnamic Testing

52 Good Group Behavior

53 Poor Group Behavior Angry Mob Congress Group IQ = Lowest IQ of anyone in the group

54 Pile Group Interaction Leading Row Piles Row 1 Row 2 Trailing Row Piles Row 3 Direction of Loading

55 Horizontal Force/Length, P P-Multiplier Concept (Brown et al, 1988) Single Pile Curve P SP Group Pile Curve P GP = P MULT P SP Horizontal Displacement, y

56 P-multipliers from Full-Scale Tests (Situation in 1998) Soil Type (Reference) Clean Sand (Brown et al. 1988) Stiff Clay (Brown et al. 1987) Soft Silty Clay (Meimon et al. 1986) Front Row 2 nd Row 3 rd Row BYU has conducted 11 Full-scale tests over the past 10 years

57 P-Multiplier P-multiplier vs. Spacing Curves Reese et al (1996) Reese & Van Impe (2001) WSDOT (2000) AASHTO (2000) US Army (1993) Pile Spacing (c-c)/pile Diam.

58 I-15 Pile Group Testing 9 Pile Group (324 mm) at 5.6 D Spacing 12 Pile Group (324 mm) at 4.5 D Spacing 15 Pile Group (324 mm) at 3.3 D Spacing 9 Pile Group (600 mm) at 3 D Spacing

59 15 Pile Group at 3.3 D Spacing

60 9 Pile Group at 5.6 D Spacing Pinned Connection LVDT Tie-Rod Load Cell

61 Avg. Pile Load (kn) 9 Pile Group at 5.6 D Spacing Single Row 1 Row 2 Row Avg. Group Deflection (mm)

62 Avg. Pile Load (kn) 12 Pile Group at 4.5 D Spacing Avg. Group Deflection (mm) Single Row 1 Row 2 Row 3 Row 4

63 Avg. Pile Load (kn) 15 Pile Group at 3.3 D Spacing Single Row 1 Row 2 Row 3 Row 4 Row Avg. Group Deflection (mm)

64 Avg. Pile Load (kn) 9 Pile Group at 3 D Spacing Single Row 1 Row 2 Row Avg. Group Deflection (mm)

65 P-Multiplier P-Multiplier P-multiplier vs Spacing for Stiff Clay (a) Leading Row P-Multipliers (b) Trailing Row P-Multipliers Reese et al (1996) Reese et al (1996) ft Pile Brown et al (1997) AASHTO (1998) Stiff Clay-Rollins et al (2003) ft Pile 2 ft Pile Brown et al (1997) AASHTO (1998) Row 2-Stiff Clay Rollins et al (2003) Rows 3-5-Stiff Clay-Rollins et al (2003) Pile Spacing (c-c)/pile Diam Pile Spacing (c-c)/pile Diam. Rollins et al. Oct 2006, ASCE JGGE

66 P-multiplier Curves vs. Spacing Rollins et al. Oct 2006, ASCE JGGE 1.2 P-Multiplier, P m st Row Piles 2nd Row Piles 3rd or Higher Row Piles AASHTO Pile Spacing (c-c)/pile Diam.

67 Test Site Layout 15 Pile Group at 3.9 D Spacing 9 Pile Group at 5.6 D Spacing 1.2 m Drilled Shafts 9 Pile Group at 2.8 D Spacing SLC Airport Pile Group Tests

68 P-Multiplier P-Multiplier Group Interaction Reduction Factors (P-multipliers) (a) Leading Row P-Multipliers (b) Trailing Row P-Multipliers Reese et al (1996) Reese et al (1996) AASHTO (1998) 0.6 AASHTO (1998) Stiff Clay-Rollins et al (2003) Soft Clay-This Study Pile Spacing (c-c)/pile Diam Row 2-Stiff Clay Rollins et al (2003) Rows 3-5-Stiff Clay-Rollins et al (2003) Row 2-Soft Clay-This Study Rows 3-5-Soft Clay-This Study Pile Spacing (c-c)/pile Diam.

69 Pile Group Load Tests in Sand 3x5 Group at 3.9D Spacing 3x3 Group at 5.65D Spacing 3x3 Group at 3.3D Spacing 2x2 Group at 3.3D Spacing

70 P-Multiplier P-Multiplier P-Multiplier P-Multipliers vs Spacing (Sand) (a) 1st Row P-Multipliers, fm (b) 2nd and 3rd Row P-Multipliers , fm Reese et al (1996) Full-Scale Tests Centrifuge Tests Design Line, fm AASHTO Reese et al (1996) 0.8 Full-Scale Tests Centrifuge Tests 0.6 Design Line Pile Spacing 0.0 (c-c)/pile Diam. AASHTO Pile Spacing 0.2 (c-c)/pile Diam. 0.0 (c) 4th or higher Row P-Multipliers Reese et al (1996) Full-Scale Tests Centrifuge Tests AASHTO (2000) Pile Spacing (c-c)/pile Diam.

71 Explanation of Variability in Sand Natural variability of sand relative to clay Sand more influenced by installation procedure than clays Different installation procedures Jetting Driven, Open-ended Sand compacted around previously driven piles Drilled shafts

72 Influence of Friction Angle on Group Interaction Elevation View 45- /2 Passive failure wedge inclined at 45- /2. As increases the angle gets smaller and wedge gets longer. Longer wedge causes more group interaction.

73 Influence of Friction Angle on Group Interaction Plan View Passive failure wedge fans out at. As increases the angle gets larger and wedge gets wider. Wider wedge causes more group interaction.

74 P-Multiplier Influence of Friction Angle on P-multiplier 1.0 Less Group Interaction More Group Interaction Soft Clay Stiff Clay Looser Sand Denser Sand Drained Friction angle,

75 Average Pile Load (kn) Post-Liquefaction Pile Response Single Pile Resistance due to Pile alone Resistance due to Soil Dilation Displacement (mm) P-y curves for Liquefied Sand (ASCE JGGE, Jan 2005) Built into LPILE/GROUP

76 Average Pile Pile Load Load (kn) (kn) Post-Liquefaction Group Effects (10th 200 mm Cycle) Lead Row-Group Single Pile Middle Lead Row-Group Row-Group Trail Middle Row-Group Trail Row-Group Displacement (mm) Displacement (mm)

77 Rollins Pile Group References Rollins, K.M., Olsen, R.J., Egbert, J.J., Jensen, D.H., Olsen, K.G., and Garrett, B.H. (2006). Pile Spacing Effects on Lateral Pile Group Behavior: Load Tests. J. Geotechnical and Geoenvironmental Engrg., ASCE, Vol. 132, No. 10, October, p Rollins, K.M., Olsen, K.G., Jensen, D.H, Garrett, B.H., Olsen, R.J., and Egbert, J.J. (2006). Pile Spacing Effects on Lateral Pile Group Behavior: Analysis. J. Geotechnical and Geoenvironmental Engrg., ASCE, Vol. 132, No. 10, October, p Rollins, K.M., Lane, J.D., and Gerber, T.M. (2005). Measured and Computed Lateral Response of a Pile Group in Sand. J. Geotechnical and Geoenvironmental Engrg, ASCE, Vol. 131, No. 1 Jan., p Rollins, K.M., Gerber, T.M., Lane, J.D. and Ashford. S.A. (2005). Lateral Resistance of a Full-Scale Pile Group in Liquefied Sand. J. Geotechnical and Geoenvironmental Engrg., ASCE, Vol. 131, No. 1, p Rollins, K.M., Snyder, J.L. and Broderick, R.D. (2005). Static and Dynamic Lateral Response of a 15 Pile Group. Procs. 16th Intl. Conf. on Soil Mechanics and Geotech. Engineering, Millpress, Rotterdam, The Netherlands, Vol. 4, p

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