influence of deep foundation installation methodscfpbolivia.com/2015/nesmith/influence-of-deep...1.8...

13/05/2015

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Influence of Deep Foundation

Installation Methods Presented by:

Morgan NeSmith, PE Director or Engineering

[email protected]

http://www.berkelandcompany.com

To

2⁰ Congresso Internacional de

Fundaciones Profundas de Bolivia

Santa Cruz, Bolivia

May 2015

• Scope of Presentation

Precast Piles – steel, concrete

Cast-in-Place Foundations:

Drilled Shafts

Augered Cast-in-Place Piles / Continuous

Flight Auger Piles

Drilled Displacement Piles

Micropiles

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Factors Influencing Performance

• Installation Method

• Foundation Material (concrete, steel, wood)

Precast Piles

•Steel

•Pipe (open-end or closed-end)

•H-Pile

•Tapered

•Shell (mandrel driven)

Concrete

•Octagonal

•Square

•Cylinder

Timber

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Driven or

Vibrated

Piles

Driven Piles in Clay

http://user.engineering.uiowa.edu/~swan/courses/53139/notes/changes-in-soil-during-

pile-driving.pdf

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Driven Piles in Sand


pile-driving.pdf

Driven Piles in Sand


pile-driving.pdf

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Environmental

Effects Dynamic loading during

installation

- Vibrations: good for pile

installation, possibly very bad

for your neighbors

- Noise: not good for anything

except upsetting your

neighbors

- In saturated clay (nearly

incompressible in short term)

can heave ground and nearby

piles

Drilled Shafts

• With casing or slurry, drilled incrementally

Typically most useful for:

- ultra-high compressive loads (concrete compressive strengths up to 12,000 psi (83 MPa) or greater)

- high lateral loads

(requiring large amounts of reinforcing steel)

- geologies providing little shaft resistance where toe resistance is crucial (e.g. hard, shallow bedrock)

- where it would be beneficial to have direct connection from structure column to single foundation element

(bridges, structures where pile cap construction is not feasible)

• In last 15 years, line has blurred between when to use

single-pass augered / drilled piles and drilled piers / shafts

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Drilled Piers

Devon Energy - Oklahoma

Devon Energy WHQ

Drilled Piers

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Drilled Shaft – Example Reinforcing

Reinforcing

installed

PRIOR to

concrete

placement

Use concrete,

not grout,

typically

poured from

top or tremied

to bottom

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Shaft Typically Stabilized by

Casing or Slurry

Generally Neutral Displacement

(if constructed correctly!!!) Casing and slurry can smooth soil surface lowering the friction coefficient

between shaft and soil

Tremied concrete also has lower bond strength with soil than other cast-in-place

methods (grouted or pressure grouted)

Not many places in North America where shafts bear in soil only – mostly in

rock – however some in Chicago (hard OC clay locally called hardpan) and

Mississippi (large deposits of OC clay) where belled piers are often efficient

Many designers neglect shaft and only consider end bearing (possibly very,

very conservative)

Reinforcing is set after drilling but before concreting so is typically full length

whether the shaft needs it or not (lateral loads typically resolved in the upper

6-m to 12-m of shaft)

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Cast-in-place piles installed by

single-pass, rotary drilling processes

Terminology for Cast-in-Place Piles

Continuous Flight Auger European Screw Piles

ACIP

aka Augercast CFA

Intermediate (Partial) Displacement

Displacement Pile

Auger Pressure Grouted (APG) Pile System

• Cast-in-place piles grew out of pressure-

grouting processes at Intrusion-Prepakt,

late 1940s, early 1950s

• Patent granted to Raymond Patterson for

construction of cast-in-place piles by

pumping grout through a hollow-stem

auger.

• Licenses granted to Lee Truzillo and

Charles Berkel

“The Evolution of Cast in Place Piles”

November/December 2013 DFI Magazine

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• Gaspar Coelius granted patent for

cast-in-place “Screw” pile in 1960

Augered vs. Screwed or Displacement

Analogous to augered… .. And to displacement

From De Cock and Imbo, Transportation Research Record 1447

Excavated ACIP piles

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Stratigraphy?

Stratigraphy?

Residual soils

from soft to hard

to partially

weathered rock

(PWR = 100+

blows per 30 cm)

to bedrock

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(1) Stem augers hole

(4) Hollow stem

auger retracted

while grout pumped

into hole

(2) Grout pumped

under pressure

(3) Build up grout

head prior to

withdrawing auger

APG Pile Example Installation

2007 Berkel & Company

Cast-In-Place Pile

Seminar

(4) Hollow Stem

Auger is retracted

while grout is

pumped into hole

APG Pile Installation

(2) Grout is injected

under pressure

(1) Auger drills

hole

(3) Build up grout

head prior to

withdrawing auger

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Typical APG Pile Rig

Hollow Stem Auger

• Continuous flight auger

• 75 mm inside diameter pipe

• Auger diameters:

– Historical: 300 mm to 460 mm

– Typical: up to 610 cm = no problem

– Specialty: 760 cm to 1220 cm

• Auger section lengths: ~ 1 to 6 m

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JADE SIGNATURE - SUNNY ISLES BEACH, FL

90-cm Diameter (APG) Piles – 47-m Deep

Over 300 Installed in 20 weeks

To resist ~ 1000 metric tons compression

Auger Flights attached to Hollow Stem

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Drill Bits • Basic Bit - Pengo bit

• Basic Rock Bit - fitted with carbide teeth

• Clay Flight Bit - for clay soils

Leads Torque Arm

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Gearbox

• Hydraulically operated top

head drive

• Travels up and down the

leads

• Torques range from about 20

to 120 kN/m

• Weighs 1 to 5 metric tons

• Rotational speed ranges from

30 to 60 rpm

• Hydraulically

operated, positive

displacement piston-

ball valve pump

• Pump pressures

typically around 350

psi at pump outlet

• Stroke vols. typically

range from about 0.4

to 1.0 cubic feet per

stroke (up to 1.7)

• Grout hoses typically

2 to 3 inch diameter

• Can pump grout

several hundred feet

• Grout typically

delivered by ready mix

trucks

Grout Pump

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Typical Limited Headroom (LHR) Rig

• Used where overhead clearances

are at least 2.5 to 3 m

• Track-mounted or forklift mounted

drilling equipment

• Piles are drilled with auger sections

typically 1 to 3 m length

• Installation time longer than with

crane-mounted equipment (thus,

more expensive per foot

Neutral or

Negative

Displacement • If proper equipment not

used, stress release

can occur

• Potential for release is

greater in alluvial or

marine sands than in

residual soils and stiff

clay

• Potential for release is

greater in segmental

(low-head room) than

single auger

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Neutral or

Negative

Displacement • Can “suck” adjacent

piles if drilling too close

together

Fresh completed pile

Pile to be drilled

Maybe soil wants to displace

towards new pile being drilled as

horizontal confinement lowers

Pile to be drilled

Fresh pile may collapse into new

pile. Typically don’t drill adjacent

piles (closer than 6 diameters)

within 12 hours

ANCILLARY BENEFITS

Minimal Spoils

No Vibration

Low Noise

Easy to vary pile lengths to suit site conditions

Grouted bond to soils produces larger shaft

resistance than concrete-soil bond or driven

pile friction coefficients

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Fixed Mast Platforms

Drilled Displacement Piles

(full and partial displacement)

CFA (APG-FMC) Piles

Overview of Drilling

Platform and Sensors

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INSTALLATION PLATFORM

• 200 to 270 kN/m torque

• 18 to 36 metric tons downward force

• Fixed mast for stability, inclinometer

with display in operator’s compartment

• Grout pressure, measured at top of tools,

is displayed in operator’s compartment

• Real-time display of installation

parameters (depth, KDK pressure,

Installation Effort, grout pressure)

pressure

CAST-IN-PLACE PILES INSTALLED WITH A

FIXED MAST DRILLING PLATFORM (APG-FMC)

Wilkins, B., NeSmith, W.M,

Tebbenkamp, F., and Duncan, S. (2009)

Performance of Cast-in-place Piles

Installed with a Fixed Mast Drilling

Platform in Claystone – Glenrock WY

Proceedings of the DFI 34th Annual

Conference on Deep Foundations.

Kansas City MO, USA. 20 – 23 October

2010.

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CFA Example

• 6 to 9-m of weak, saturated,

compressible sand, silt and

clay

• Ground water at 1 – 2.5 m

depth

• Deep foundations for all major

units assumed from the outset

• Initial budget based on 1,600 x

9000-mm dia. drilled piers 3-m

into rock with temporary

casing.

• Considered drilled piers,

driven piles and auger cast

piles

Final decision:

** 600-mm dia. CFA pile w/

fixed mast platform**

Comments on CFA and Fixed Mast

Platforms

- Slower penetration and slower rotation with

fixed mast than with crane mounted APG piling

- Less spoils removed with CFA (maybe ~ 75%)

than with APG

- Slightly higher shaft values with fixed mast than

crane mounted systems

- Very economical to replace large pile caps or

drilled shafts

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Fixed-Mast Platform Crane-Mounted Platform

4’-0” +/-

30’-0” +/-

CONVENTIONAL ACIP TOOL

DRILLED DISPLACEMENT TOOL

INTERMEDIATE (PARTIAL)

DISPLACEMENT TOOL

APG and Displacement Tooling

Displacement leads to increased horizontal stresses (and densification) for higher shaft resistance in many soils

Grout/soil interface is a more effective load transfer interface than pre-cast or steel/soil

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Berkel Displacement Pile Tool

Figure 1. Berkel Displacement Tool

Stem becomes

progressively larger,

terminating in the

displacing element

+- 1-m, regular flighting,

300-mm to 460-mm diameter

Reverse flighting Displacing element. Same

diameter as the flighting

below

Stem, smaller than flighting

INSTALLATION METHOD

• Tool advances as a screw in low

to medium consistency soils.

• In dense soils, material

transported up the auger to the

displacing element. Material in

auger flights is compressed; thus

no stress relief in the zone

adjacent to the auger.

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INSTALLATION METHOD • When the target level has been

reached, pumping of grout is

begun. Grout pressure is

monitored by the operator Lift

off and withdrawal rate are

varied to maintain pressure

where possible.

• Tool is rotated during

withdrawal and material which

falls around stem is captured

and displaced.

• Typically get grout return only

after tip is at or near ground

surface.

Soil Improvement Aspects Of Displacement Pile

Installation • When displacement piles are installed in materials that exhibit

granular behavior, there is a significant increase in density in the vicinity of the piles

• The increase is most pronounced in loose to medium dense materials

• After a certain density, as the in-situ density of the materials increases, the density percentage change goes down

• The increase in density is additive-the more piles that are installed, the greater the increase

• Pressure grouted bond to soils produces larger shaft resistance than concrete-soil bond or driven pile friction coefficients

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2.1 METERS 2.1 METERS 1.8 METERS

1.8 METERS

0.46 M

0.46 M

0.46 M

46 CM BY 7.6 M COMPRESSION TEST PILE 46 CM BY 12.2 M EXTRA PILE

46 CM BY 12.2 M EXTRA PILE

46 CM BY 12.2 M REACTION PILE

Improvement from Drilled Displacement Tool Installation

“AMBIENT” CONDITION-3D FROM PILE

0

5

10

15

20

25

30

35

0 25 50 75 100 125 150

Qc, tsf

DE

PT

H,

ft

FINE SAND, TRACE TO SOME

SILT, OCCASIONAL THIN

SILT/CLAY LAYERS. AVERAGE

Qc = 3.1 MPa (32 tsf)

3.1 METERS

7.6 METERS

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AVERAGE CONE TIP RESISTANCE

COMPARISON OF CPT VALUES, 1D, 2D, 3D FROM PILE

0

5

10

15

20

25

30

35

40

0 25 50 75 100 125 150

CONE TIP VALUE, TSFD

EP

TH

, FEET

3D OUT 2D OUT 1D OUTAVERAGE CONE TIP

RESISTANCE FROM 3.1 M TO

7.6 M (10 FEET TO 25 FEET)

3.1 MPa (32 TSF,

N = 8 BPF)

6.5 MPa (68 TSF,

N = 17 BPF)

8.1 MPa (84 TSF,

N = 21 BPF)

FINE SAND, TRACE

TO SOME SILT,

OCCASIONAL THIN

SILT/CLAY LAYERS

3.1 METERS

7.6 METERS

CPT VALUES AT 1D, 2D, 3D FROM PILE

COMPARISON OF CPT VALUES, 3D FROM PILE AND CENTER OF GROUP

0

5

10

15

20

25

30

35

40

0 25 50 75 100 125 150

CONE TIP VALUE, TSF

DEP

TH

, FEET

3D OUT CENTER OF GROUP

3.1 MPa (32 TSF,

N = 8 BPF)

9.6 MPa (100 TSF,

N = 25 BPF)

3.1 METERS

7.6 METERS

AVERAGE CONE TIP

RESISTANCE FROM

3.1 M TO 7.6 M (10

FEET TO 25 FEET)

CPT VALUES AT 3D and CENTER OF GROUP

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ANCILLARY BENEFITS

Minimal Spoils

No Vibration

Low Noise

Easy to vary pile lengths to suit site

conditions

DOES THE BENEFIT

HOLD UP IN

RESIDUAL SOILS?

Some empirical

indications that shaft

resistance in medium

to dense sandy

residual soils are not

as high as expected

from marine, alluvial

and other younger

deposits.

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ORDER OF

INSTALLATION IN LARGE

GROUPS IS CRITICAL

DESIGN MODELS

UNDERESTIMATE GROUP

EFFECTS

Intermediate (Partial) Displacement

Pile System

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CONVENTIONAL ACIP TOOL

DRILLED DISPLACEMENT TOOL

INTERMEDIATE (PARTIAL)

DISPLACEMENT TOOL

APG and Displacement Tooling

Partial Displacement Auger Stem

Conventional ACIP Auger Stem

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Equipment/Process Summary

• Same installation platform as Drilled Displacement Piles-high torque, crowd

• Large diameter stem, small flight dia. (typically less than 2/3 ratio)

• Tooling is screwed into ground where possible (displacement), drilled in where necessary (excavation)

• Improve loose soils, limit stress relief in dense soils

• Target spoil is less than 75% of neat hole volume

• May be cast by volume (like APG piles) or by pressure (like Drilled Displacement piles)

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Efficiency Comparison to APG Pile

• Drilled displacement piles use more expensive

equipment

• Unit capacities from displacement systems can

be significantly higher than traditional APG piles

• Generally: If piles can be shorted and the

diameter can be decreased, displacement

systems can be more efficient (pending project

size)

Fixed-Mast Platform Crane-Mounted Platform

4’-0” +/-

30’-0” +/-

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Screening 1 – Insert the Screen

Screening 2 – Remove Foreign Objects

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Reinforcing Cage Placement

• In general, not as efficient as single-pass drilled or augered systems but:

– High capacity (particularly for size)

– Installation in limited access and/or low headroom

– Minimal disturbance/vibration to adjacent structures

– Capability to penetrate subsurface obstructions (very useful for rubble in urban fills and boulders in glacial till)

– Can case through voids (useful in limestone with large cavities)

Micro Piles (less than 300-mm dia)

• Refer to FHWA Micropile Design and Construction Guidelines and DFI / ADSC Micropile 2010 Seminar (also see local contractors!)

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Example Installations - Micro Piles

Copyright © 2009 PT. Geonusa Utama

• Drilling is somewhat neutral displacement. Post grouting and pressure grouting are positive displacement and the pressure grout to soil or rock bond is very high

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Hollow Bar - Micropiles

Hollow Bar - Micropiles

Net Neutral Displacement – similar unit

shaft values as ACIP piles (so far)

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THE END – QUESTIONS?

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