This document discusses pile integrity testing (PIT) methods for monitoring pile construction quality. PIT uses low-strain integrity methods like cross-hole sonic logging and pile top measurements to locate defects in piles. It is an inexpensive way to test many piles for quality assurance purposes. The document provides examples of PIT use on construction projects in India, describing defects identified. It also outlines PIT testing standards, limitations, and goals of achieving quality in pile construction.

1. 1
Sanjay Gupta Ravi Sundaram
Sorabh Gupta
CENGRS GEOTECHNICA PVT. LTD.
Pile Integrity Testing for
Monitoring Pile Construction

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What makes a “good pile”?
To perform successfully, a pileTo perform successfully, a pile
must:must:
•• Have adequate soilHave adequate soil
resistanceresistance
•• Be structurally soundBe structurally sound
These are two separate requirements
Both must be satisfied

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Low Strain Integrity Methods
PILE INTEGRITY TESTING (PIT)PILE INTEGRITY TESTING (PIT)
Measure Pile Top Motion, Reflections from Defects
CROSS-HOLE SONIC LOGGING (CSL)
Determines Concrete Quality Between Tubes in Shaft
For larger augercast piles
SINGLE-HOLE SONIC LOGGING (SSL)
For smaller augercast piles
PARALLEL SEISMIC (PS)
Hit Pile, Measure Hydrophone in Parallel Tube
Determines only Pile Length

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QA/QC:
Unplanned Inspection
In response to something gone wrong
Unplanned costs - project delays
Planned Inspection (PreferredPreferred)
Included in project specifications
Planned costs - normal pay item

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Why Do Pile Integrity Testing?
• prime function is to locate major defects (to evaluate
questionable shafts)
• inexpensive, can test many piles (good for quality
assurance)
• no advance selection required (good for forensic purposes)

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Defective Piles

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PIT Equipment
Accelerometers
Non-Instrumented
Hammer
Instrumented
Hammer

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PIT looks for defects
Small Hammer
Impact Device Accelerometer
Measures
Response
Defect
One Person Operated

9. FF
∆∆∆∆∆∆∆∆LL
Compressed Zone, races
along pile at wave speed c
cc is the wave speed of the pile materialis the wave speed of the pile material
In a timeIn a time ““∆∆∆∆∆∆∆∆tt”” the wave travels a distancethe wave travels a distance ∆∆∆∆∆∆∆∆L = cL = c ∆∆∆∆∆∆∆∆tt
Wave Propagation

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Good PileGood Pile
800 mm drilled shafts
L = 25 m (L/D = 31)
Bad PileBad Pile
Normal test (pile top “free”)
PIT - Basic Interpretations

12. 12Any of these piles could have a defect..
How many piles should I test?

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Grinding top surface to make flat spot
Pile top preparation is key to good data
which is the key to best interpretation.
Shortcuts cause questionable data.
Preparation..

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Remove loose
contaminated or fractured
concrete from core; cut
rebar to min lengths

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Case Study 1: Noida Mall
Ongoing Project
800 mm dia BCIS piles in
sand
Initial Cyclic Pile Load Test:
Qult = 270 MT
Qsafe = 135 MT
14 PIT were performed on
initial and routine piles
0
10
20
30
40
50
60
70
80
90
0 50 100 150 200 250 300 350
Load (MT)
Field Data
Extrapolated Values
(Hyperbolic Model)
Qsafe (MT) = 135.0
270 MT

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Case Study 1: Noida Mall
7 m
Original Ground Level
Excavated Level, Pile COL
Pile Toe Level
27 m

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Case Study 1: Noida Mall
Variations in Pile Cross-sectionMajor defect at 16~18 m depth (or short pile)

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Case Study 2: ROB in Malout, Punjab
Good Pile (14 m length)Weak Toe Response

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PIT - Low Strain Integrity Testing
Standards
ASTM D5882 (1996)
Deep Foundations Institute “Inspector’s Guide to Augered Cast-in-Place
Piles” 1994
Australian Standard AS 2159 (1995)
Eurocode 7, Section 7, Pile Foundations
Specification for Piling - Institution of Civil Engineers (1988) - England
CIRIA Document CP/28 (1995) - England
Norme Francaise NF P94-160-2 (1993) - France
DGGT Com.2.1 for Pile Integrity Testing (draft Sept 1997) - Germany
Slovenia Highway Code
Spain Driven Pile Foundations Art.670 (draft 1996)
Bangladesh National Building Code (1993)
CED 43 (4917) for concrete piles in IS-2911 (draft 1998) - India
Other documents…...
(Draft standards may have been further updated and made official)

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PIT Limitations
As per published literature, piles with L/D ratio upto 30 give reasonably
good results
Highly non-uniform piles may be difficult to interpret
Cracks or mechanical joints block waves
Small defects or short length hard to find
Not always applicable: pile type, walls, in structure
No direct correlation to pile capacity; but can help to identify which
piles to load-test

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Let us strive to achieve.. quality in pile
construction
THANK YOU…
Cengrs Geotechnica Pvt. Ltd