i Single-hole sonic logging A study of possibilities and limitations of detecting flaws in piles MARTIN PALM Master of Science Thesis Stockholm, Sweden 2012 Single-hole sonic logging A study of possibilities and limitations of detecting flaws in piles Martin Palm July 2012 TRITA-BKN. Master Thesis 362, 2012 ISSN 1103-4297 ISRN KTH/BKN/EX-362-SE ©Martin Palm, 2012 Royal Institute of Technology (KTH) Department of Civil and Architectural Engineering Stockholm, Sweden, 2012 Preface This master thesis deals with pile integrity testing in general and single-hole sonic logging of bored piles in particular. It was initiated by Deltares in Delft, the Netherlands. It was carried out during a period of six months in the office of Deltares which is an independent research institute in the field of water, subsurface and infrastructure. This report is the written record of a master thesis project at the KTH Department of Civil and Architectural Engineering as a part of the fulfillment of the requirements for a Master degree in Civil Engineering. I would like to thank my supervisor at Deltares Paul Holscher for his support and guidance and Rodriaan Spruit, PhD candidate, TU Delft and Gemeentewerken Rotterdam for kindly giving me laboratory measurement data. I also want to express my gratitude to all the coworkers at Deltares who contributed to this thesis by answering my questions. I would also like to thank my supervisor at KTH, Raid Karoumi, for his kindly advices and for handling a lot of my paper work when I was stuck in the Netherlands. Paul Holscher (Deltares) and Raid Karoumi (Kungliga Tekniska högskolan, KTH) were supervisors. Paul Holscher (Deltares), Michael Hicks (Deltares) and Raid Karoumi (KTH) were examiners. Delft, The Netherlands. July 2012 Martin Palm ii iii Abstract As a part of the Dutch development program Geo-impulse, which aims to half the occurrence of geotechnical failures in civil engineering projects inside the Netherlands by 2015, this master thesis is investigating how to trace imperfections in bored piles at an early stage. The objective is to carry out literature study on suitable methods and then focus the research on one particular method. The basis of the research is the single-hole sonic logging method. Field and laboratory measurements are carried out with the aim to investigate the detection range of the method as well as try to apply more advanced post-processing techniques. Results from the measurements are discussed and also a comparison between single- hole sonic logging and the better standardized test cross-hole sonic logging is made. The results indicate that single-hole sonic logging has a small detection range inside a bored pile, especially compared to cross-hole sonic logging. Also more advanced post- processing techniques fails or make the test to advance to use on a daily basis. Finally the recommendation is to carry on research with other techniques which in scientific papers have showed some promising results. Keywords: Pile integrity, Single-hole sonic logging, Cross-hole sonic logging, Bored piles, Nondestructive testing iv v Contents Preface ................................................................................................................ ii Abstract ............................................................................................................. iv 1 Introduction.................................................................................................. 1 1.1 Background ................................................................................................. 1 1.2 Objective ..................................................................................................... 1 1.3 Delimitations ............................................................................................... 2 1.4 Methodology ............................................................................................... 2 2 Literature study ............................................................................................ 4 2.1 On bored piles ............................................................................................. 4 2.1.1 General ............................................................................................ 4 2.1.2 Problems during construction .......................................................... 5 2.2 Pile integrity investigation methods ............................................................ 7 2.2.1 General ............................................................................................ 7 2.2.2 Direct tests ...................................................................................... 7 2.2.3 Indirect tests.................................................................................... 8 2.2.4 Single-hole sonic logging .................................................................. 9 2.2.5 Sonic echo ...................................................................................... 11 2.2.6 Parallel seismic .............................................................................. 13 2.3 Case studies for pile integrity .................................................................... 15 2.4 Theory of wave propagation and ray-tracing ............................................. 17 2.4.1 Elastic wave theory ....................................................................... 17 2.4.2 Waves............................................................................................ 18 2.4.3 Wave fronts ................................................................................... 19 2.4.4 Attenuation ................................................................................... 20 2.4.5 Waves in media with interfaces or inclusions (heterogeneous media) 21 2.4.6 Ray-tracing theory ........................................................................ 24 3 Water test and the CHUM-equipment ............................................................ 27 3.1 Introduction .............................................................................................. 27 3.2 Methodology ............................................................................................. 27 vi 3.3 Results ...................................................................................................... 28 3.4 Discussion ................................................................................................. 30 4 The Horstwald test site ................................................................................. 31 4.1 Introduction .............................................................................................. 31 4.2 Methods .................................................................................................... 31 4.2.1 General .......................................................................................... 31 4.2.2 Theoretical ray-path fitting to the measurement data.................... 33 4.2.3 FAT-picking analyses .................................................................... 36 4.3 Results ...................................................................................................... 37 4.3.1 Theoretical ray-path fitting to the measurement data.................... 37 4.3.2 FAT picking analyses .................................................................... 41 4.4 Discussion ................................................................................................. 42 4.4.1 Theoretical ray-path fitting to the measurement data.................... 42 4.4.2 FAT picking analyses .................................................................... 43 5 Laboratory experiment in Delft ..................................................................... 45 5.1 Introduction .............................................................................................. 45 5.2 Methods .................................................................................................... 45 5.2.1 General .......................................................................................... 45 5.2.2 Cross-hole sonic logging ................................................................. 46 5.2.3 Single-hole sonic logging ................................................................ 46 5.3 Results ...................................................................................................... 47 5.3.1 Cross-hole sonic logging ................................................................. 47 5.3.2 Single-hole sonic logging ................................................................ 51 5.4 Results ...................................................................................................... 54 5.4.1 Cross-hole sonic logging ................................................................. 54 5.4.2 Single-hole sonic logging ................................................................ 54 5.4.3 Comparison between single-hole and cross-hole sonic logging......... 55 6 Conclusions and further studies ..................................................................... 56 Bibliography ....................................................................................................... 59 A Seismograms from BAM test site in Horstwald ................................................ 63 B Plots of Zoeppritz equations .......................................................................... 69 C Cross-correlations ........................................................................................