DRILLED DISPLACMENT PILE PERFORMANCE

IN COASTAL PLAIN AND RESIDUAL SOILS

Presented by:

W. Morgan NeSmith, P.E.

Berkel & Company Contractors Inc.770.941.5100

mnesmith@berkelapg.com

SC Engineering Conference

Myrtle Beach SC11 June 2015

San Francisco

Kansas CityCorporate Office

Houston

Orlando

Baltimore / Washington D.C.

Atlanta

Louisville

Berkel & Company Contractors, Inc

Founded by Mr. Charles J. Berkel in 1959

• Scope of Presentation (Case- History)

Project Details

What are Drilled-Displacement Pile?

Local Geology

Test Piles

Supplementary CPTs

Modifications to Displacement Tool

Conclusions

Project Location – Aiken SC

Project Details - Aiken SC :

Industrial Facility with 19 separate structures

Total number of piles ~ 1000

Area A

~ 120 pile

~ Cut-Off elevations: 0 to -3

Area B

~ 700 pile

~ Cut-Off elevations:

-22 to -39

Area C

~ 120 pile

~ Cut-Off elevations: 0 to -5

Project Details- Aiken SC:

Loads:Compressive Loads: 200 to 350 tons

Tension Loads: 0 to 50 tons

Lateral Loads: 0 to 19 tons

• 24-inch diameter Partial Displacement

Piles (APG-PD) – Specified

• Berkel was responsible for pile length

• Effective Length Ranging from 40’ to 65’

Cast-in-place piles installed by

single-pass, rotary drilling processes

Terminology for Piles

Continuous Flight Auger European Screw Piles

ACIP

aka Augercast

(APG) European CFA

Intermediate (Partial) Displacement

Displacement Pile (APG-D)

Gaspar Coelius granted patent for

cast-in-place screw pile in 1960

Analogous to augered… .. And to displacement

From De Cock and Imbo, Transportation Research Record 1447

Example of Augercast Pile and Displacement Piles

Fixed-Mast Platform Crane-Mounted Platform

4’-0” +/-

30’-0” +/-

Fixed Mast Platforms

Overview ofDrilling

Platformand Sensors

PLATFORM FEATURES

• 150,00 to 200,000 ft-lb torque

• 40,000 to 80,000 lb crowd

• 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

Primary Drilling Parameters

(Recorded at 1 Reading per Second)• Time: Recorded by an internal counter and referenced to

the initial date and time input by the operator at the beginning of the project.

• Depth: From proximity switch that measures rotation of the main winch supporting the drilling turntable and drilling tools.

• Hydraulic Fluid Pressure driving turntable (i.e. KDK Pressure): From in-line pressure transducer.

• Rotations (of drilling tools): From proximity switch on turntable.

CONVENTIONAL ACIP TOOL DRILLED DISPLACEMENT TOOLINTERMEDIATE (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

Berkel Displacement Pile Tool

Figure 1. Berkel Displacement Tool

Stem becomes

progressively larger,

terminating in the

displacing element

+- 3 feet, regular flighting,

12” to 18” diameter

Reverse flighting Displacing element. Same

diameter as the flighting

below

Stem, smaller than flighting

DD PILE 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.

DD PILE GROUTING• 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.

DD Pile Design

Nesmith, W.M. (2002). “Static Capacity Analysis of Augered, Pressure-Injected Displacement Piles”.

Geotechnical Special Publication No. 116. M.W. O’Neill and F. C. Townsend (Eds.). ASCE. February. Volume

1. pp. 1088 – 1097

Recommended method in FHWA Geotechnical Engineering Circular (GEC) No. 8, “Design and

Construction of Continuous Flight Auger Piles”

Intermediate (Partial) Displacement

Pile System

CONVENTIONAL ACIP TOOL DRILLED DISPLACEMENT TOOLINTERMEDIATE (PARTIAL)

DISPLACEMENT TOOL

Intermediate Displacement Tooling

For design, use full displacement method with factor for amount of partial displacement

Partial Displacement Auger Used at

this Job Site

Conventional ACIP Auger Stem

Partial Displacement Auger Stem

LOCAL GEOLOGYElevation 0

Elevation ~ -55

Elevation ~ -85

Coastal Plain

Residual Soil

Partially Weathered Rock (PWR)

What does that mean ?Residual Soil:

Weathered in place from underlying

Bedrock – typically granite / gneiss in the

southeast with more schist in the northeast

Weathers to PWR (N > 100) to silty sand to

sandy silt to silty clay closer to ground

Coastal Plain:

Divided into the lower and upper plain.

The upper Coastal Plain is then divided into

the Aiken Plateau, the Richland Red Hills,

and the High Hills of Santee. All of which are

remains of land left by the constantly moving

sea of the Pliocene. Six steep slopes at the

edge of high ground and seven terraces

create the surfaces of the lower Coastal

Plains. These terraces represent the seven

cycles of the receding ocean of two Pliocene,

four in the Pleistocene, and one in Holocene.

Terraces are temporary oceans floors that go

from the sea level rise and fall over time.

Example

Boring

24-inch APG-PD Tooling

18 inch Dams

24 inch Flight

with 18 inch

Dams

Test Pile Program

Depth = 0

Depth ~

50 to 60 - ft

Depth ~

85 to 90 - ft

Coastal Plain

Residual Soil

Partially Weathered Rock (PWR)

Depth = 0

Depth ~

55 to 60 ft

Depth ~

85 to 90 ft

Coastal Plain

Residual Soil

Partially Weathered Rock (PWR)

Supplementary Test Pile Program

Test Pile 1

Coastal

Plain

Residual

Soil

Partially

Weathered

Rock (PWR)

Test Pile 2

Coastal

Plain

Residual Soil

Partially

Weathered

Rock (PWR)

Test Pile 3

Coastal

Plain

Residual

Soil

Partially

Weathered

Rock (PWR)

Test Pile 5

Coastal

Plain

Residual

Soil

Partially

Weathered

Rock (PWR)

Test Pile 4

Coastal

Plain

Residual

Soil

Partially

Weathered

Rock (PWR)

Analysis of Pile Behavior During Loading

TP-1: “Typical” Behavior

TP-4: Atypical Behavior

structural issues suspected from results

Test Pile 4A Results

Coastal

Plain

Residual

Soil

Partially

Weathered

Rock (PWR)

Fine-Grained material observed during installation!!!

Test Pile 4A Results

TP4A was tested 7 and 16 days after installation

Results of TP-4A & TP-5

Fine-Grained material observed during installation!!!

Example

Boring

CPT Supplementary

Increase in pore pressure

with advancement of cone

in clayey silt fine grained

Classification: very stiff

fine grained residual soils

Supplementary Site

Characterization

Very Stiff high plasticity fine-graded residual

material

Pore pressure of material due to displacement is

detrimental to grout column

Modifications to APG-PD

Tool

σ′ = σ − 𝑢

Probably not

Modified APG-PD Tool

Modified tooling by taking dams out

Test Pile 4A2

Coastal

Plain

Residual

Soil

Partially

Weathered

Rock (PWR)

www.berkelandcompany.com

• Given 24 inch pile, depth was determined by Berkel

• In Coastal Plain Soils, test piles performed as expected

• In Residual Soils, some indication that large volume of displacement

was detrimental to cast in place piles

• Supplementary CPTs indicated residual soil was more fined grained

and of higher plasticity than originally described

• Tool was modified to reduce the ratio of displacement to removal

• Depth of TP-4 was re-analyzed considering less displacement (slightly

reduce friction values)

• Test results on TP-4 A 2 showed no signs of structural problems and

demonstrated that design loads could be supported

• Final recommendations used a combination of both tools depending

on top-of-pile level and required penetration into residual soil