Design construction and axial load testing of 48 inch diameter cast-in-steel-sheel piles

CASE STUDY: Design, Construction, and Axial Load

Testing of 48” Diameter Cast-in-Steel-Shell Piles for

Support of a Highway Bridge

GDCU OCTOBER

18, 2013

Project DescriptionImprovements were proposed for the SR-22 / I-405 interchange to improve capacity, including a new 6-span High Occupancy Vehicle (HOV) direct connector bridge and replacement of the existing SB I-405 to EB SR-22 connector bridge.

Geotechnical Investigation

Group Delta’s scope included subsurface investigation and recommendations for bridge foundation support.

Data Review:Poorly consolidated alluvial soilsShallow groundwaterExisting structures on piles

New bridges would be supported on pile foundations Key issues include pile design, approach fill

settlement, and liquefaction potential


Subsurface Investigation (minimum one boring per support):4 Mud Rotary Borings 51.5 feet to 137 feet bgs 5 Cone Penetration Tests (CPTs) 105.5 feet to 150.3 feet bgs.

Geotechnical Investigation(Mud Rotary Borings)

Geotechnical Investigation (CPT)




Laboratory Testing:

Subsurface Conditions

Subsurface Conditions

100 ft x 48” CISS PilesBents 3 & 4

75 ft x 48”CISS PilesBents 2 & 5

14” PS Conc Piles at Abuts

DEVELOP DESIGN PROFILE: DIVIDE INTO LAYERS OF COHESIONLESS SOILS (SPT “N”) and COHESIVE SOILS (“Su”)

LOCATE DESIGN WATER TABLE

Groundwater

BENT FOUNDATION DESIGN(Type Selection)

DEEP FOUNDATIONSHALLOW FOUNDATION

P

VM

T =

qmax

qmin

Soil/Rock Bearing Resistance

Passive Soil/Rock Resistance

Sliding FrictionResistance

Shallow Competent Soil/Rock

and/or

Light Loads

P

VM

Heavy Loads, Uplift Loads,

and/or

Weak or Compressibleor Scourable

Soil

DeeperCompeten

t Soil/Rock

Passive Resistance

compression

tension

Lateral PileResistance

End Bearing

Skin Friction

48” CISS PILES SELECTED FOR BENTS

FOUNDATION DESIGN (Loads)Load and Resistance Factor Design (LRFD)

( * Qi ) < * Rn

“The sum of the factored loads must be less than the sum of the factored resistances.”

Limit States•Service: (settlement, slope stability, lateral capacity, etc.)

• All load factors and resistance factors = 1.0•Strength:

• Load factors > 1.0, Resistance Factors < 1.0•Extreme Event:

• All load factors and resistance factors = 1.0

FOUNDATION DESIGN(Design for Axial Capacity =

Determination of Pile Tip Elevation)

Estimation of Nominal (Ultimate) Axial ResistanceBasic Definition of Nominal Resistance-Skin Friction and End Bearing:

Qu

Qe

qe

Layer 1

Layer 2

Layer 3

Layer 4

fs4

fs3

fs2

fs1

B

D

d1

d2

d3

d4

QS

Qu = Qs + Qe

Qu = (Asi*fsi) + qe*Ae

where

Qu = nominal resistance in compression

Qs = ultimate side friction (all layers)

Qe = ultimate end bearing at tip

fsi = average ultimate unit skin friction in layer i

Asi = side area in contact with soil in layer i

= Pi * di

Pi * = pile perimeter within layer i

qe = unit ultimate end bearing at tip

Ae = pile end area

FOUNDATION DESIGN(Skin Friction and End Bearing)

American Petroleum Institute Recommended Practice 2A , July 1, 1993

(API RP 2A)



(API RP 2A)

PLUGGING OF PIPE PILES:•Plugs if Qsi > Qep end bearing on full area and friction on outside only•Unplugged if Qsi < Qep end bearing on annulus only, friction inside and outside

QseQsi

Qep

Qea



(API RP 2A)

FOUNDATION DESIGN (Skin Friction and End Bearing)American Petroleum Institute (API RP 2A)

FOUNDATION DESIGN(Design and Specified Tip Elevation)

2 Design Piles: L = 75 feet for 1150 kip nominal resistanceL = 100 feet for 1800 kip nominal resistance

FOUNDATION DESIGN(Pile Layout)

FOUNDATION DESIGN(Pile Layout and Load Test Pile Locations)

100’ TestPile

Reaction Piles

FOUNDATION CONSTRUCTION(Pile Driving)

Caltrans policy requires axial load test for all driven piles larger than 3 feet in diameter

First Piles Driven are Load Test Piles (to be used as production piles)

• 100 ft piles:• 1 test pile and 4 reaction piles• 1800 kip nominal resistance required

• 75 ft piles:• 1 test pile and 4 reaction piles• 1150 kip nominal resistance required

• Delmag D62 Diesel Hammer• Pile Driving Analyzer (PDA) Measurement


100 ft long48” diameter pipe pilesWith ¾” wall thicknessPP 48 x 0.75


Piles “Stabbed”With Vibratory HammerPrior to Driving

Large Crane required special FAA clearance


Helmet

Delmag D62-22

Leads

Hammer

Delmag D62-22 Single Acting Diesel HammerRated Energy = 162 ft-k / blowRam Weight = 13.66 kipsMax. Stroke = 11.82 ft





FOUNDATION CONSTRUCTION(Dynamic Testing Pile Driving Analyzer [PDA])


Blowcounts versus depth on initial drive

FOUNDATION CONSTRUCTION(PDA Acceptance Curves Considering Setup)

FOUNDATION CONSTRUCTION(PDA Time-Setup Relationship)

PILE LOAD TEST(PLT)

4000 kip Capacity Load Test Frame

FULL-SCALE PILE LOAD TEST(PLT)


Calibrated Hydraulic Jacks


Jobsite Artwork


Test in Progress


Deflection Measurements

PLT RESULTS

LOAD (KIPS)

PLT RESULTS

LOAD (KIPS)

PDA & PLT RESULTSUMMARY

Pile No.

Pile Length

RequiredCapacity

PDA ResultEnd of Initial Drive (EOID)

PDARESTRIKE

Load Test

CapacityPDA

SetupFactor

BlowCount Stroke

Est.EOID

Capacity

BOR BlowCount

EOR BlowCount

9 75’ 1150kips

39 9.4’ 885kips

210 90 1700kips

1.92 @ 23 days

10 100’ 1800kips

53 10.3’ 1300 kips

630 230 2600kips

2.0@ 34 days

Based on the results of the load test, Group Delta recommended reducing the pile length of 100 ft piles to 85 feet and 75 ft piles to 68 feet.

Due to a problem in recent revisions to the Caltrans Standard Specifications, the savings could not be realized and piles were driven to the design tip elevations.. Acceptance criteria (blowcount vs. stroke) were developed and used to confirm the capacity of the remaining production piles.

POURING THE FOOTING

POURING THE FOOTING

POURING THE FOOTING

POURING THE FOOTING

THE END

Education

Design construction and axial load testing of 48 inch diameter cast-in-steel-sheel piles