cfa piling rms

8/18/2019 CFA Piling RMS

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SEMINAR

Introduction to Continuous Flight

Auger (CFA) pilingThursday 21/8/2013

Facili tator: Martin Larisch


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Brief History of Piling Contractors, its capabilities and market

Introduction to CFA piling

2

Introduction to ContinuousFlight Auger (CFA) pil ing


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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


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GLOBAL SCALE LOCAL FOCUS

The Keller Group


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The Keller Group


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2007 2008 2009 2010 2011 2012 2013

Incidence rate (L.T.I. Per 100 employees)

Frequency rate (L.T.I. Per 1million Man Hours)

Severity rate (Avg. Workdays Lost Per Occurrences)

Safety Improvements


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Safety Improvements


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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


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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


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Technical Activities, Representative Memberships and Industry Engagement

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

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

R&D / Technical Papers

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

Technical Capabil ity


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National Coverage


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Non displacement piles - Continuous Flight Auger (CFA) piles

Introduction to Continuous

Flight Auger (CFA) pil ing


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Non displacement piles - Continuous Flight Auger (CFA) piles




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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




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




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




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




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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)




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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)




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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)




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Soldier pile wall

Contiguous pile wall

Secant pile wall





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Retaining structures (e.g. secant pile wall)




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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





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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)




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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)




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Load transfer through CFA piles

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




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Non displacement piles - Continuous Flight Auger piles (Risks)



Stationary augers used to transport loose granular material and water


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CFA augers are soil conveyors!

Signs of severe side loading can include:

Surface coning/depressions

Difficulty extracting augersUnexpectedly high torque demand on machine


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Risk of over-excavation in loose sand layers




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Piles drilled too close can result in concrete blow through



1 2

SandlayerConcrete


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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."




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Operator controls operations via computer data

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




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Computer monitoring systems are common for some systems to monitor:

Depth, penetration rate & extraction rate

Torque

Pull down forces

Rotation

Concrete Volume





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Pile record sheet

Non displacement piles

Continuous Flight Auger piles

(Quality control)




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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)




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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 forcesDifferent 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




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





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Computer monitoring systems:

PDA & CAPWAP

Pile-top Force Comparison

Load-settlement response





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Low strain integrity tests (PIT)





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

outside the Australian Standards or code of practice

Any further questions?




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Feedback & Discussion:

Did the presentation meet your expectations?

What do take home?

Any further questions?




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SEMINAR

Introduction to Continuous Flight

Auger (CFA) piling

Thursday 21/8/2014

Facili tators: Martin Larisch

Thanks for your active

participation and attention

cfa piling rms

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