Pile Testing and Evaluation for the Sand Creek Byway, Sandpoint, Idaho Presented by Dean E. Harris, P.E., CH2M HILL

Project 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 Byway

Project 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 Crossing

Geotechnical 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 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 medium silt and clay, N = 7 to 13 blows per 0.3 m

Pile 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

Loading System

Loading test

Load-Movement Curves from Loading Test

Findings from Loading Test Plunging failure occurred at movement of 11 mm Analysis considered pile residual load For clay layer,  = 0.1, N t = 6

ConditionCapacity (kN) End of Initial Driving260 Restrike (after 24 hours setup) 980 Static Loading Test (50 days after driving) 1900

Strain Gauge Placement

Neutral Plane Analysis

Interpretation of Gauge Load

Summary 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