Pile Testing and Evaluation for the Sand Creek Byway, Sandpoint, Idaho

Pile Testing and Evaluation for the Sand Creek Byway, Sandpoint, Idaho

Presented by

Dean E. Harris, P.E., CH2M HILL

Project DescriptionProject Description• Current alignment is

through the City

• Realignment will provide a non-stop route for through traffic

• WGI is completing roadway and structural design

• CH2M HILL is responsible for geotechnical and structural design

Sand Creek BywaySand Creek Byway

Project FeaturesProject Features

• Project features include two interchanges, a smaller bridge crossing a city street, and numerous MSE walls

• Community is sensitive to appearance and function

• Community supports the project

Sand Creek CrossingSand Creek Crossing

Geotechnical ExplorationsGeotechnical Explorations

• Piezocone (CPTu) was the primary method of subsurface exploration

• Maximum depth of CPTu soundings of 80 m

• Soil borings were advanced adjacent to many soundings to collect samples.

• Other testing included vane shear testing and shear wave velocity tests

Cone rig and barge in Sand Creek

Typical Soil ProfileTypical Soil Profile

• Upper 10 m: Medium stiff sandy silt to clay, N = 9 to 15 blows per 0.3 m

• 10 to 39 m: Very soft to soft clay with thin layers of loose to medium dense sandy silt,

N = 0 to 5 blows per 0.3 m

• 39 to 67 m: Alternating soft to mediumsilt and clay, N = 7 to 13 blows per 0.3 m

555

565

575

585

595

605

615

625

635

0 5 10 15

QT (MPa)E

leva

tio

n (

m)

0 100 200 300 400

FS (kPa)

Corrected TipResistanceFriction Resistance

Pore Pressure (kPa)

0 1000 2000

Hydrostatic

Excess PWP

0 20 40 60

Water Content (%)

Natural Water Content

LL - PL Range

Pile Loading TestPile Loading Test

• Axial compression loading test on a 0.41 m (16 in) steel pipe pile, driven to a depth of 45 m, with PDA and CAPWAP analysis

• Pile was instrumented at 8 levels, with vibrating wire gauges on sister bars, and 2 telltales; concrete-filled

• Osterberg Cell (O-Cell) used at the head of the pile, with steel reaction frame

Pile driving with APE D36-32

Piezometer Response During and After Pile Driving

0.0

10.0

20.0

30.0

40.0

50.0

0 1 10 100

Elapsed Time (Days)

Ex

ce

ss

He

ad

(m

)

Depth = 30 m

Loading System

Loading test

0

500

1000

1500

2000

2500

0 10 20 30 40 50

Movem ent (m m )

Lo

ad (

KN

)

Head O-Cell

Toe Mvmnt

Load-Movement Curves from Loading TestLoad-Movement Curves from Loading Test

Findings from Loading TestFindings from Loading Test

• Plunging failure occurred at movement of 11 mm

• Analysis considered pile residual load

• For clay layer, = 0.1, Nt = 6

Condition Capacity (kN)

End of Initial Driving 260

Restrike (after 24 hours setup)

980

Static Loading Test (50 days after driving)

1900

0

5

10

15

20

25

30

35

40

45

50

0 500 1000 1500 2000

Load (kN)

Dep

th (m

)

Residual Load

Interpreted Load

Probable Distribution of TrueLoad

Strain Gauge PlacementStrain Gauge Placement

Neutral Plane AnalysisNeutral Plane Analysis

Interpretation of Gauge LoadInterpretation of Gauge Load

0

5

10

15

20

25

30

35

40

45

50

0 500 1000 1500 2000

Load (kN)

Dep

th (m

)

Residual Load

Interpreted Load

Probable Distribution of TrueLoad

Summary and ConclusionsSummary and Conclusions

• Pile Setup is a major factor affecting construction and estimated capacity

• Instrumentation is necessary to extrapolate the pile testing data to other pile lengths

• Residual load effects are significant in interpreting capcity