seminar introduction to continuous flight auger · pdf file1 seminar introduction to...

1

SEMINAR

Introduction to Continuous Flight Auger (CFA) piling

Thursday 21/8/2013

Facilitator: Martin Larisch

22

Brief History of Piling Contractors, its capabilities and market

Introduction to CFA piling

2


33

History

• Piling Contractors (Qld) Pty Ltd

• Started as a one rig operation in Queensland in 1983

• We expanded into NSW in 1999 and WA in 2006

• Now work nationally

• Acquired by Keller Group plc in 2006

1995

4

GLOBAL SCALE LOCAL FOCUS

The Keller Group

55

The Keller Group

6

0.0

10.0

20.0

30.0

40.0

50.0

60.0

2007 2008 2009 2010 2011 2012 2013

Incidence rate (L.T.I. Per100 employees)Frequency rate (L.T.I. Per 1million Man Hours)Severity rate (Avg. Workdays Lost Per Occurrences)

Safety Improvements

7

Safety Improvements

88

Large diameter bored piles – up to 3m diameter 76m deep

Driven pre-stressed piles – 550mm octagonal up to 32m single length

Continuous flight auger piles – up to 1.2m diameter 32m deep

Mine Fill – in joint venture with Keller Ground Engineering

Contiguous and Secant Pile Retaining Walls

Key Techniques

99

Diaphragm and Slurry Walls

Marine piling using leaders off falsework or barges

Driven steel tubes, sheets and steel sections and ductile piles

Large diameter shafts up to 6m diameter 76m deep

Key Techniques

1010

Technical Activities, Representative Memberships and Industry Engagement

• We take a lead role in the technical activities of the Piling and Foundation Specialists Federation (PFSF) and the Concrete Institute of Australia (CIA). Many of our engineering staff are Members of the major national and international professional institutions.

• We have a Graduate Training programme approved by Engineers Australia to train new graduates and technicians in our speciality, building the future engineers and managers of our industry.

R&D / Technical Papers

• Our staff publish and present technical papers at local, regional and international seminars and conferences and we maintain a strong commitment to research and development.

Technical Capability

1111

National Coverage

121212

Non displacement piles - Continuous Flight Auger (CFA) piles


131313

Non displacement piles - Continuous Flight Auger (CFA) piles


141414

Pile types and pile systems (AS2159-2009)

Displacement piles

Driven piles

Screw auger piles

Non-displacement systems

Conventional bored piles

CFA piles

Barrettes

Hard rock drilling


151515

Non displacement piles - Continuous Flight Auger (CFA) piles(process after Brueckner Grundbau)


161616

Non displacement piles - Continuous Flight Auger (CFA) piles(process after Brueckner Grundbau)


171717

Non displacement piles - Continuous Flight Auger (CFA) piles(Schematic of the CFA auger after Slatter, 2000)


181818

Q = Pull down force applied by piling rig

M = Torque applied by piling rig

P = Soil resistance at auger tip

N = Auger weight

z = auger length / drill depth

τ = Friction between surrounding soil and soil in auger

l = auger pitch

d = Outer auger diameter

d0 = Auger stem diameter

Non displacement piles - Continuous Flight Auger (CFA) piles(Forces acting on the auger during augering after Viggiani, 1993)


191919

CFA piles were developed in the 1940’s in the USA, introduction in Europe during

early 1970’s with the invention of the first hydraulic piling rigs

The system has been available in Australia since the 1980’s

Possible diameters for CFA piles:

450mm – 1200mm

Standard diameters in Australia are 450, 600, 750, 900 and 1200mm

Depth up to 35m and more possible

Common depth up to 20m with standard equipment

Common diameters 450, 600, 750 and 900mm

Non displacement piles - Continuous Flight Auger piles (Introduction)


202020

CFA piles are commonly used as foundation piles for:

Buildings and bridges

Pile rafts

CFA piles are used for retaining structures as:

Soldier piles

Contiguous piles

Secant piles

Pile loads are usually smaller than for conventional bored piles but generally

bigger than for auger displacement piles

Non displacement piles - Continuous Flight Auger piles (Applications)


212121

Soldier pile wall

Contiguous pile wall

Secant pile wall



222222

Retaining structures (e.g. secant pile wall)


232323

CFA piles are suitable for:

Generally for all types of structures with low to medium vertical loads

Penetration and removal of underground obstructions

Piles with single length reinforcement cages up to 18m

CFA piles should be considered carefully for:

Soft soil conditions or contaminated ground

High strength rock

Piles next to existing buildings

Strata which require penetration of stiff layers

Raked piles



242424

Advantages:

Very cost effective piling system with high production rates

Installation in stiff soils / weak rock possible

Suitable for changing and non-homogenous ground conditions

Disadvantages:

Cage installation after pouring process might be difficult

Limited capacity for bending moments, lateral forces and tension forces

Might cause uncontrolled over excavation if penetration rate is not constant

Non displacement piles - Continuous Flight Auger piles (Advantages & Disadvantages)


252525

CFA piles are suitable for:

Medium to very dense sands / gravels

Stiff to hard clays

Generally all types of weak or weathered rock (exception see below)

Installation below the ground water table

CFA piles are NOT suitable for:

High strength, unfractured rock

Soft soil conditions

Changing strata

Non displacement piles - Continuous Flight Auger piles (Suitable ground conditions)


262626

Load transfer through CFA piles

Loads will be transferred through skin friction and / or base resistance


272727

Non displacement piles - Continuous Flight Auger piles (Risks)


Stationary augers used to transport loose granular material and water

282828



CFA augers are soil conveyors!

Signs of severe side loading can include:

Surface coning/depressions

Difficulty extracting augers

Unexpectedly high torque demand on machine

292929


Risk of over-excavation in loose sand layers


303030


Piles drilled too close can result in concrete blow through


1 2

SandlayerConcrete

313131

Non displacement piles - Continuous Flight Auger piles (Risks B63)

Second pass as per B63 Clause 6.2.3:

“To ensure the base of the pile socket is clean, adopt a multi-pass technique

using a minimum of two passes. After commencement of discharge of

concrete withdraw the auger 500 mm and drill back down to the toe of the pile

to pick up any contaminated concrete before re-commencing concreting of the

pile. Verify the use of the multi-pass technique from the pile monitoring

records."


323232

Operator controls operations via computer data

Non displacement piles - Continuous Flight Auger piles (Quality control)


333333

Computer monitoring systems are common for some systems to monitor:

Depth, penetration rate & extraction rate

Torque

Pull down forces

Rotation

Concrete Volume



343434

Pile record sheet

Non displacement piles Continuous Flight Auger piles (Quality control)


353535


Breakout (Clause 6.2.2)

No breakouts are to be performed – RMS needs to ask for documentation of

contractors at tender time to ensure contractors provide suitable equipment

Concrete life (Clause 6.2.3)

Concrete life should be extended to 4 hours. With current concrete technology

this can be achieved easily. 45 minutes is not realistic in some remote

locations or inner city projects

Concrete oversupply should be at least 5% (not 8%) but could be as much as

40% (function of soil conditions)


363636


Concrete pressure (Clause 6.2.3)

Concrete pressure can be zero as sensor is located at the top of the mast. If

the stem is filled with concrete the pressure sensor shows zero but concrete is

still delivered to the pile via gravitational forces

Different rig monitoring systems monitor data in different ways, it is important

to understand the particular monitoring system when analysing the installation

records

Monitoring (Clause 6.3 (f))

Monitoring mm/rev is unusual, better monitor rev/m or rev/min


373737

Concrete quality is crucial (workability, strength, pump-ability, bleeding)



383838

Computer monitoring systems:

PDA & CAPWAP

Pile-top Force Comparison

Load-settlement response



393939

Low strain integrity tests (PIT)



404040

What else:

Importance of safe working platforms (typically 400 kPa platform requirement)

Get early involvement of a piling specialist

Compare what you get for your money

Rigs and technologies are readily available, look for specialists knowledge

Keep in mind rigs are very heavy high tech machines when you specify tolerances

outside the Australian Standards or code of practice

Any further questions?


414141

Feedback & Discussion:

Did the presentation meet your expectations?

What do take home?

Any further questions?


42

SEMINAR


Thursday 21/8/2014

Facilitators: Martin Larisch

Thanks for your active

participation and attention

seminar introduction to continuous flight auger · pdf file1 seminar introduction to...

Documents