Nondestructive Testing involves the use of methods such as wave propagation, electromagnetism, electrical conductivity, and thermal conductivity to test structural integrity and thereby allow nondestructive assessment of structures and the possibility of structural failures before they occur.
Nondestructive Testing of Deep Foundations covers different techniques designed to provide information about the integrity and quality of the material that makes up a deep foundation.
Nondestructive Testing methods are used at all stages of a structure's life - from new construction quality control to residual lifetime prediction, and even during the monitoring of demolition. In addition, Nondestructive Testing is being increasingly specified in deep foundation projects, though often without a good understanding of its limitations and with the result that methods are often misused. In order to be able to specify an appropriate method, or to recognize an inappropriate specification, it is necessary for the engineer, specifier and/or contractor to understand the capabilities and limitations of each of the methods currently in use.
Nondestructive Testing of Deep Foundations:
- Describes the most commonly used deep foundation construction techniques, including typical use of material
- Provides a brief history of the development of commercially available nondestructive methods
- Summarises each method's capabilities and limitations
- Acts as a one stop reference drawing together resources only previously available in conference proceedings and journal papers
This manual will prove to be a welcome addition to the bookshelf of all practitioners in civil/structural and geotechnical engineering and architecture. It will also provide a valuable insight into this highly technical field for university researchers, lecturers and postgraduate students in civil/structural and geotechnical engineering.
Table of Contents:
FOREWORD xi
PREFACE xiii
ABOUT THE AUTHORS xv
ACKNOWLEDGEMENTS xvii
PHOTOGRAPHY AND ILLUSTRATION CREDITS xix
1 INTRODUCTION AND BRIEF HISTORY 1
1.1 Introduction 1
1.2 A Brief History of Deep Foundations and the Advent of NDT 3
1.3 Deep Foundation Failures and NDT 10
1.4 Deficiencies in Existing Foundations 16
2 DEEP FOUNDATION CONSTRUCTION METHODS 19
2.1 Driven Piles – Timber, Steel and Concrete 20
2.2 Caissons and Drilled Shafts 28
2.3 Diaphragm Walls, Cut-off Walls and Barrettes 32
2.4 Augered, Cast-in-Place Piles 33
2.5 Micropiles or Minipiles 35
2.6 Stone Columns and other Soil Improvement Techniques 40
3 HOW SOILS AFFECT THE CHOICE OF FOUNDATION 43
4 TRADITIONAL, VISUAL AND NEW INSPECTION METHODS FOR DEEP FOUNDATION CONSTRUCTION 47
4.1 Driven Piles 47
4.2 Augered, Cast-in-Place Piles 48
4.3 Drilled Shafts 50
4.4 The Inspector's Role 55
5 A REVIEW OF FULL-SCALE LOAD-TESTING TECHNIQUES 59
5.1 Static Load-Test Techniques – Axial Compression 61
5.2 Static Load-Test Techniques – Axial Tension 68
5.3 Static Load-Test Techniques – Lateral 68
6 HIGH-STRAIN TESTING FOR CAPACITY AND/OR INTEGRITY 71
6.1 High-Strain Dynamic (Drop-Weight) Testing of Driven Piles 71
6.2 High-Strain Testing of Drilled Shafts and Augered, Cast-in-Place Piles 79
6.3 Modification of Shaft Head for High-Strain Tests 84
6.4 Practical Considerations for Drop-Weight Techniques 87
6.5 HSDT Alternatives 89
6.6 Limitations of High-Strain Dynamic Testing 98
7 LOW-STRAIN SURFACE TESTS – SONIC ECHO 101
7.1 Sonic Echo (Impulse ECHO) 102
8 SONIC MOBILITY (IMPULSE RESPONSE) 115
8.1 Principles of Impulse–Response Curve Interpretation 122
8.2 Practical Considerations 124
8.3 Classification of Signal Responses 127
8.4 Pile Simulation Techniques 132
8.5 Time Domain–Velocity Reflectors 135
9 THE IMPEDANCE-LOG ANALYSIS 137
10 LOW-STRAIN DOWN-HOLE TESTS 143
10.1 Introduction 143
10.2 Cross-Hole Sonic Logging 143
10.3 Cross-Hole Tomography 148
10.4 Single-Hole Sonic Logging 152
10.5 Gamma–Gamma Logging 155
10.6 Parallel Seismic Testing 162
11 FIELD MOCK-UPS OF DEEP FOUNDTIONS: CLASS-A PREDICTIONS 167
12 THE RELIABILITY OF PILE SHAFT INTEGRITY TESTING 175
12.1 Statistical NDT Sampling Schemes 176
12.2 Methodology Reliability 178
13 CURRENT RESEARCH 189
13.1 Developments in Measurement and Analysis 190
13.2 Electrical Methods 190
13.3 Optical Techniques 198
13.4 Guided Wave Analysis 201
13.5 Statistical Analysis 202
13.6 Self-Consolidating Concrete 203
13.7 Acceptable Vibration Levels 206
13.8 Automated Monitoring Systems 206
13.9 Wireless Acquisition Systems 207
13.10 'SMART' Structures 208
14 THE PLACE OF NONDESTRUCTIVE TESTING AT THE BEGINNING OF THE 21ST CENTURY 211
14.1 Nondestructive testing and load and resistance factor design 214
14.2 Setting up an Effective Quality Management Program 215
14.3 Who's Testing the Tester? 216
14.4 Acceptance Criteria 220
14.5 Evaluating Defects 221
APPENDIX I STRESS-WAVE PROPAGATION IN CYLINDRICAL STRUCTURES 223
1. General Theory 223
2. Determination of Damping 228
3. Determination of Harmonic Response – Mechanical Impedance 229
4. Resonant frequency of an infinitely long pile 232
5. Impedance input for a finite length pile with unknown mechanical impedance at its base 233
APPENDIX II CONTACT ADDRESSES 235
APPENDIX III STANDARDS REFERRED TO IN THIS BOOK 239
1. Cross–Hole Sonic Logging 239
2. GAMMA–GAMMA Logging 240
3. High-Strain Testing of Piles 240
4. Impulse-echo and Impulse-Response Tests 240
5. Parallel Seismic 241
6. Static Load Testing of Deep Foundation Shafts 241
APPENDIX IV SAMPLE SPECIFICATIONS FOR NDT METHODS FOR DEEP FOUNDATIONS 243
1. Sample Specification for Low-Strain Testing by Either Impulse Echo or Impulse Response 244
2. Sample Specification for Cross-Hole Sonic Logging (CSL) 248
REFERENCES 255
INDEX 267
About the Author :
BERNARD H. HERTLEIN, M.ASCE
Bernard Hertlein started his professional career as a mechanical engineering student but soon realized that he had a natural affinity for electronics. After working professionally with automotive electronic systems and pursuing audio engineering as a hobby for several years, he migrated through audio engineering to instrumentation of civil engineering structures and finally to nondestructive testing. After joining Testconsult, the English subsidiary of the French National Center for Building and Civil Engineering Research (CEBTP), Mr Hertlein became deeply involved with the development of both the software and the hardware for several nondestructive test techniques for deep foundations that are now in common use worldwide. He worked on construction testing projects throughout Europe, HongKong, parts of North Africa and the United States, eventually settling in the United States, where he and Allen Davis introduced the Cross-hole Sonic-Logging technique, the Parallel-Seismic test and the Impulse-Response (Sonic-Mobility) test in the mid 1980s.
In 1992, Mr Hertlein joined STS Consultants, based inVernon Hills, Illinois, where he has continued to design and build test equipment and research new applications for the test techniques that he had helped to introduce to the United States. Mr Hertlein is an active member of several key professional societies. At the time of writing this book, he is a member of the American Society of Civil Engineers, Chairman of the Nondestructive and In-place Testing Committee of the American Society for Testing and Materials (ASTM C9-64), Chairman of the Testing and Evaluation Committee of the Deep Foundations Institute, and Secretary of the Nondestructive Testing Committee of the American Concrete Institute (ACI 228). He also serves as a member of ACI Committee 336: Footings, Mats and Drilled Piers, ASTM Committee C9-47:Self-Consolidating Concrete, D18-11: Deep Foundations and G9-14: Corrosion of Reinforcing Steel. Mr Hertlein has written numerous conference papers and journal articles. He is a regular member of the faculty for the International Association of Foundation Drilling(ADSC-IAFD) Drilled Shaft Inspector's School and a frequent lecturer at other educational seminars presented byACI International, ADSC regional chapters, the ASCE Geo-Institute and the Deep Foundations Institute.
ALLEN G. DAVIS, PH.D., D.SC., PE
Allen Davis qualified as a geologist and his first career was as prospector for De Beers Corporation in Central Africa. He then converted to Civil Engineering through Geotechnics, gaining his Ph.D. from Birmingham University, UK in that subject. He has had Academic, Research and Industrial experience in fairly equal proportions, including: Professor at the University of Birmingham, UK, for 10 years. Head of the Geotechnical and Highways Research Division, National Center for Building and Civil Engineering Research (CEBTP), Paris, France, for 8 years. Technical and Managing Director, Testconsult CEBTP (UK) for 8 years. He was one of the founding members of Testconsult in 1974. Principal Engineer, STS Consultants, Ltd and Manager for NDE, Madsen, Kneppers Associates, Chicago, Illinois and Salt Lake City, Utah, USA for 6 years. Senior Principal Engineer, Construction Technology Laboratories, Inc. (CTL), Skokie, Illinois, USA for the last 6 years.
At the time of writing this book he was Manager of Nondestructive Evaluation at CTL in Skokie, Illinois. His special interests included vibration problems and realtime data acquisition from dynamic testing of concrete foundations and structures, and he was a member and past Chairman of Committee 228 (Nondestructive Testing of Concrete) of the American Concrete Institute and also a member ofASTMCommittee Nondestructive and In-place Testing. He has published over 80 technical articles and publications to date in the fields of Civil Engineering and Building, Transportation and Materials Resources. Eleven Ph.D. research students (seven in France, four in England) have graduated under his supervision, and he was awarded the degree of Doctor of Science by Birmingham University in 1980. His contributions to the concrete industry and to the work of the ACI were recognized at the October 2004 meeting of the ACI in San Francisco, where it was announced that he had been elected a Fellow of the Institute. Unfortunately ill-health had prevented him from going to San Francisco, and he passed away suddenly at his home a few hours after learning of the fellowship announcement. Rest in peace, old chum.
