Recent Trends in Pile Foundations Auger Cast Piles for

Low Noise / Low Vibration

Presenter: Nick Briffa, PE Group Delta Consultants

Presented to: ASCE Orange County Geo-Institute

Driven Piles

Auger Cast – Continuous Flight Auger (CFA)

• Continuous Hollow Screw Auger

• Genrates spoils • Designed like CIDH • No displacement • Not common in Calif

Need for Auger Cast Piles

• Soft Clay Site • High Groundwater • Surcharge improvement not always possible • Sound restrictions for driven piles • Environmental restrictions for drilled piles • Contaminated Groundwater/soil (no cuttings)

Auger Displacement Pile (ADP)

• Solid lead with Displacement Tip

• Generates little spoils • Designed like Driven

Pile • Displacement • Most common in Calif • Morris-Shea, Condon-

Johnson, Malcolm, Berkel

Auger Cast Pile Overview

Goal of Previous Test Programs by Group Delta

• Test Program for Agency Acceptance • Replacement for Driven 14” Concrete Piles • 180-200 Kip Design Loads • 70-100 Kip Liquefaction Down-drag loads • 500-600 Kip Ultimate Capacity • Over 50 Load Tests to date

Project Location Largest Urban In-fill in US

$6 Billion development

Former Hughes Aircraft / Runway Facility

Playa Vista Geotechnical

AUGER CAST PRESSURE GROUTED (closed system, continuous grout pressure)

QC - Installation Record

• Improvement from standard record

• Real-Time plots of torque, grout pressure and grout take with depth (not time)

• Field Verification of embedment depth into target layer

• Torque in absolute Kip-ft

DeWaal Pile

• Open System • Concrete

Gravity • Conc Feed

Pressure by tremmie head

QA/QC - Installation Record

• “Open System” – top open to gravity

• DeWaal Pile, Fundex Inspector’s IPad Screen

Torque as a Target Indicator

• Absolute torque analogous to driving energy

• Dense Sand/Gravel indicated by 60 Ft-Kips

• Good correlation with CPT Qc

• Useful for Installation / End Bearing Verification

Torque vs. Qc

Typical Compression Test Result

Typical Tension Test Result

Load Test – Creep Plot • Modified ASTM Procedure • Held at Design load until less than 0.005 inch/hr. (ASTM is 0.01 inch/hr)

Long Term Test – 62 days • Tested at Ultimate Load – 602 Kips.

Pile Exhumation Initial Jack-out Pile Lifting after relief holes drilled

Exhumed Pile Examination

Exhumed Pile Details Pile “Belly” – Soft Clay Response

Pile “Wart”

Exhumed Pile Details Pile “Swirl” – Sensitive Clay Response

Pile “Neck” – low grout at interval

Pile Tip – In Dense Gravel from 50 feet deep

Composite of Exhumed Pile

Pile Coring

ADP Conclusions • Local Agency Acceptance (DSA, City) • Torque good indicator of bearing (60 ft-kips) –

independent of auger type • Electronic Monitoring improved QC and installation

verification – better than Gamma or HighStrain • Monitored Grout increment should be no more than

2 feet • Long Term Testing at ultimate load – long term creep • Pile Exhumation verified monitoring and NDT

Alternate Application

Auger Cast Tangent Pile Walls

Current Pile Installs and Testing Morris Shea DeWaal Piles

• 8,000 Piles since 2013 • 50-70 Feet Long • 500-600 Kip Ult. Capacity • 200 Kip Allowable Capacity • Another 2000 for 2 projects

starts Nov 2015

Accepted Specs for Buildings

Open Systems (DeWall, Fundex)

Accepted Specs for Buildings Closed Grout Systems (APGD, Alpha)