TY - CONF A1 - Niederleithinger, Ernst T1 - Levee inspection - geophysics between science, standards, reliability and budgets N2 - Numerous case histories show evidence that geophysical methods are valuable tools for levee inspection and monitoring. National and international standards and recommendations recommend the use of geophysics for a variety of tasks. However, in some cases reported have been flaws missed or false indications given. Due to the larger variety in type, size and construction of levees and the even larger variety of potential tasks and targets the success of geophysical surveys still pretty much depends on the available budget and the experience and capabilities of the clients and contractors involved. It is strongly recommended that all relevant parties agree on the detailed objectives of the survey, required accuracy and reliability of the results and any follow up measures. For the most common tasks more research and practical work using techniques as POD (probability of detection), which are well established in other fields of non-destructive testing, would be of benefit. T2 - SAGEEP 2016 CY - Denver, CO, USA DA - 20.03.2016 KW - Levee KW - Geophysics KW - Inspection PY - 2016 SP - paper levees 07, 1 EP - 4 AN - OPUS4-35705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Innovative seismic and resistivity tools for determining the diameter of jet grouting columns N2 - Jet grouting is used for soil improvement, foundation support and groundwater low control all over the world. It is well accepted and subject of standardization in many countries. However, some issues with the method remain. As the grout columns are produced in the subsurface without visual control in an often inhomogeneous soil, the prediction of the column’s diameter is still a challenge. All methods applied so far have their limitations. The approach presented in this study is twofold. At Colorado School of Mines a resistivity probe has been developed, which is pushed into the fresh grout directly after production. ERT sections are measured and inverted. Given some background information is available, the diameter of the columns can be evaluated. At BAM the focus has been on post-production investigations using seismic borehole methods. After hardening of the concrete seismic waves are sent through the column downhole (sensors placed in a casing in the column’s axis, source on top) and crosshole (source and sensor in boreholes on opposite sides of the column). We have developed a scheme to evaluate the diameter of the column based on travel time measurements without calibration. As this method is eventually more time and cost intensive we assume its application mainly for test columns. These are casted and dug out for visual inspection to determine appropriate grouting parameters. Our method would replace the often very cost intensive visual inspection. Both approaches have been tested at three test columns produced at BAM’s test site at Horstwalde, Germany and on an actual constructions site. Both methods have been in good agreement with the diameters predicted by the jet grouting contractors, which were confirmed in one case by mechanical measurements. T2 - SAGEEP 2016 CY - Denver, CO, USA DA - 20.03.2016 KW - Jet grouting KW - Diameter KW - Quality assurance KW - Seismic PY - 2016 AN - OPUS4-35708 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Galindo Guerreros, Julio Cesar A1 - Mackens, S. A1 - Niederleithinger, Ernst A1 - Fechner, T. ED - Manzanal, D. ED - Sfriso, A. O. T1 - Numerical simulations of crosshole and downhole seismic measurements as quality control tool for jet grout columns N2 - Sealing and strengthening of the subsoil by injection is a major issue in the field of geotechnical engineering. This involves also jet grouting, which allows creating columns of grouted soil by eroding and mixing the in-situ soil with a thin cement suspension. A general difficulty of this method is to predict the column diameter and its material strength. Here, we present two-dimensional finite-difference numerical simulation results of a promising non-destructive quality assurance testing tool to evaluate the diameter of jet grout columns. This approach incorporates crosshole and downhole seismic measurements. Preliminary tests showed that this tool is applicable under real site conditions. T2 - 15th Pan-American Conference on Soil Mechanics and Geotechnical Engineering CY - Buenos Aires, Argentina DA - 15.11.2015 KW - Jet grout KW - Diameter KW - Seismic KW - Crosshole KW - Downhole KW - FD KW - Quality control tool PY - 2015 SN - 978-1-61499-603-3 SN - 978-1-61499-602-6 DO - https://doi.org/10.3233/978-1-61499-603-3-985 SP - Part 1, 985 EP - 992 PB - IOS Press AN - OPUS4-37706 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Coda wave interferometry used for monitoring of concrete constructions N2 - Ultrasonic transmission measurements on concrete; embedded transducers; coda wave interferometry to check for subtle chnages in velocity as indicator for various loads or deterioration. T2 - 76. Jahrestagung der Deutschen Geophysikalischen Gesellschaft CY - Münster, Germany DA - 14.03.2016 KW - Ultrasound KW - Transmission KW - Coda wave interferometry KW - Concrete KW - Load PY - 2016 AN - OPUS4-37721 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst A1 - Ertel, Jens-Peter A1 - Sochor, M. A1 - Unseld, H. T1 - Nachbestimmung von Pfahllängen am Beispiel von Masten N2 - Im Rahmen der Lebensdauerverlängerung oder der Umnutzung von Bauwerken (z. B. Brücken, Bürogebäude oder Maste) müssen diese zum Teil neu bewertet werden. Dafür ist eine Nachrechnung für statische und dynamische Lastfälle erforderlich. Dies betrifft zum einen die Struktur selbst, die gegebenenfalls verstärkt werden muss. Aber auch die Gründung (oft Pfähle verschiedenster Typen) muss neu beurteilt werden. Nach mehreren Jahrzehnten sind jedoch für einige Bauwerke keine zuverlässigen Bestandsunterlagen verfügbar. Eine vollständige Freilegung der Pfähle verbietet sich aus Kostengründen sowie Verlust an Widerstand gegen Zug. Lediglich der Pfahlanschluss kann visuell begutachtet werden, um Pfahlzahl, -typ und Durchmesser zu bestimmen. Für die Bestimmung der Pfahllänge müssen zerstörungsfreie Verfahren eingesetzt werden. In einer Machbarkeitsstudie wurden von den Autoren teils im Blindversuch drei Verfahren evaluiert: die klassische Pfahlintegritätsprüfung nach der Hammerschlagmethode, eine mehrkanalige Variante hierzu und das Parallel-Seismik-Verfahren. Die ersten beiden Methoden lieferten an den untersuchten Pfählen nur in Einzelfällen verwertbare Ergebnisse. Die Parallel-Seismik-Methode lieferte auch im Blindversuch an Fundamenten, bei denen die Pfahllänge dem Eigentümer bekannt war, Ergebnisse mit einer Abweichung von max. 0,5 m. Diese Toleranz lässt sich bei der Standfestigkeitsbeurteilung berücksichtigen. Die Mehrkosten des Verfahrens (anders als bei den anderen Verfahren wird ein verrohrtes Bohrloch im Boden nahe dem Pfahl benötigt) halten sich in Grenzen, wenn man es in die geotechnische Untersuchung integriert. Daher wurde es inzwischen auch in der Praxis eingesetzt. Auch liegen die Gesamtkosten für die Untersuchung deutlich unter denen für eventuell notwendigen Ersatz – oder Verstärkungsmaßnahmen, die notwendig werden, wenn keine Daten zur Pfahllänge verfügbar sind. Der Vortrag erläutert die Ergebnisse der Machbarkeitsstudie, zeigt erste Praxisfälle und weist auf Möglichkeiten hin, das Parallel-Seismik Verfahren in Zukunft noch genauer und effizienter einzusetzen. T2 - 34. Baugrundtagung CY - Bielefeld, Germany DA - 15.09.2016 KW - Mast KW - Pfahl KW - Länge KW - Parallel-Seismik KW - Integritätsprüfung PY - 2016 SN - 9783946039013 SP - 31 EP - 36 PB - DGGT CY - Essen AN - OPUS4-37648 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - GEN A1 - Niederleithinger, Ernst T1 - State-of-the-art of Ultrasonic Monitoring of Concrete N2 - Ultrasonic methods are well established in various aspects of concrete testing. They are used for imaging the interior geometry of constructions, estimation of concrete strength or monitoring lab investigations. However, so far the detection of distributed damages, especially in an early stage, has been almost impossible. The arrival of new technologies as deep penetration ultrasonic echo devices, new imaging techniques, embedded transducers for permanent monitoring and sensitive data processing techniques adopted from seismology have opened new fields of work. Recent research has been focused to detect changes in concrete elements induced by stress, temperature, moisture or chemical attacks. KW - Ultrasound KW - Concrete KW - Monitoring KW - Imaging PY - 2016 IS - 10 SP - 15 EP - 18 AN - OPUS4-38728 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - State-of-the-art ultrasonic monitoring of concrete N2 - Ultrasonic methods are well established in various aspects of concrete testing. They are used for imaging the interior geometry of constructions, estimation of concrete strength or monitoring lab investigations. However, so far the detection of distributed damages, especially in an early stage, has been almost impossible. The arrival of new technologies as embedded transducers and sensitive data processing techniques adopted from seismology has opened new field of work. Recent research has been focused to detect changes in concrete elements induced by stress, temperature, moisture or chemical attacks by permanent monitoring. Techniques as Coda Wave Interferometry can resolve changes in ultrasonic velocity in the order of 1*10-5. In addition, many researchers believe that the investigation of nonlinear effects can be used to characterize damages. The presentation will give a wrap up of ultrasonic techniques currently used in practice. This will include echo based methods as multi-channel/multi-offset imaging of structural elements using commercial and prototype devices. Imaging methods as SAFT and RTM will be shortly discussed. The focus will be on the emerging techniques used for monitoring. New types of sensors will be presented as well as the devices used in laboratory and field applications. Insight will be given on the various influence factors on ultrasonic signals and various ways of feature extraction and data processing. The results of lab experiments will be shown to demonstrate the detection of various kind of damages from mechanical load, ASR, corrosion to fatigue. The experiences with or first installations in real constructions (bridges, tunnel) will also be presented. T2 - CBIR Research Seminar, University of Technology Sydney CY - Sydney, Australia DA - 05.12.2016 KW - Ultrasound KW - Concrete KW - Monitoring KW - Imaging PY - 2016 AN - OPUS4-38730 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Progress in non-destructive testing and monitoring of concrete N2 - The presentation will give an overview on non-destructive testing techniques being developed at the Federal Institute for Materials Research and Testing, Germany (BAM). This includes ultrasonic methods, ground penetration radar, Laser-Induced Breakdown Spectroscopy (LIBS), infrared thermography, pile testing, sensor technology and building scanner. A focus of the talk will be ultrasonic methods, which are well established in various aspects of concrete testing. They are used for imaging the interior geometry of constructions, estimation of concrete strength or monitoring lab investigations. However, so far the detection of distributed damages, especially in an early stage, has been almost impossible. The arrival of new technologies as embedded transducers and sensitive data processing techniques adopted from seismology has opened new field of work. Recent research has been focused to detect changes in concrete elements induced by stress, temperature, moisture or chemical attacks by permanent monitoring. Techniques as Coda Wave Interferometry can resolve changes in ultrasonic velocity in the order of 1*10-5. In addition, many researchers believe that the investigation of nonlinear effects can be used to characterize damages. The presentation will give a wrap up of ultrasonic techniques currently used in practice. This will include echo based methods as multi-channel/multi-offset imaging of structural elements using commercial and prototype devices. Imaging methods as SAFT and RTM will be shortly discussed. The focus will be on the emerging techniques used for monitoring. New types of sensors will be presented as well as the devices used in laboratory and field applications. Insight will be given on the various influence factors on ultrasonic signals and various ways of feature extraction and data processing. The results of lab experiments will be shown to demonstrate the detection of various kind of damages from mechanical load, ASR, corrosion to fatigue. The experiences with our first installations in real constructions (bridges, tunnel) will also be presented. T2 - CIE Research Seminar, University of Western Sydney, New South Wales CY - Sydney, Australia DA - 15.12.2016 KW - Ultrasound KW - Concrete KW - Monitoring KW - Imaging PY - 2016 AN - OPUS4-38732 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Coelho Lima, Isabela A1 - Grohmann, Maria A1 - Niederleithinger, Ernst T1 - Alternative imaging conditions for reverse-time migration N2 - Poster on the evaluation of several imaging conditions for reverse time migration, applied to ultrasonic echo data, tested with synthetic (simulated) dat and real data from a polyamide model. T2 - Jahrestagung der Deutschen geophysikalischen Gesellschaft CY - Leoben, Austria DA - 12.2.2018 KW - Ultrasound KW - Reverse time migration KW - Imaging condition KW - Concrete KW - Polyamide PY - 2018 AN - OPUS4-44583 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Concepts from seismic interferometry transferred to sonic and ultrasonic concrete inspection and monitoring N2 - Seismic interferometry (SI) deals either with the sensible detection of changes in the subsurface or with the reconstruction of virtual signals between two receivers by crosscorrelation of signals from diffuse sources. These concepts can be applied in NDT in civil engineering for various purposes, e. g. to detect changes in bridges. Here it is demonstrated using data from a reference structure on our test site. Practical applications can be expected in the very near future. T2 - European Conference on Non-Destructive Testing (ECNDT) CY - Gothenburg, Sweden DA - 11.6.2018 KW - Ultrasound KW - Monitoring KW - Concrete KW - Interferometry KW - Coda PY - 2018 AN - OPUS4-46844 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Niederleithinger, Ernst T1 - Codawelleninterferometrie zur Detektion von Spannungszuständen in Betonbauteilen N2 - Informationen zu in Betonbauteilen stattfindenden Umlagerungsprozessen sowie Druckspannungsverteilungen können mit konventioneller Messtechnik bislang nicht zweifelsfrei beantwortet werden. Ultraschallmessungen mit eingebetteten Sensoren könnten hier eine sinnvolle Ergänzung zur konventionellen Messtechnik sein. Durch Einsatz der Codawelleninterferometrie (CWI) sind hiermit schon sehr kleine Änderungen im Material detektierbar. Um diese neue Methodik zu evaluieren, wurde das Forschungsprojekt „Querkrafttragfähigkeit von Spannbetonbrücken – Erfassung von Spannungszuständen in den Spannbetonversuchsträgern mit Ultraschallsensoren“ durch die Bundesanstalt für Straßenwesen (BASt) initiiert. In diesem Projekt wurden durch die Bundesanstalt für Materialforschung und –prüfung (BAM) Ultraschall-Transducer in mehrere Spannbetonträger des Instituts für Massivbau der RWTH Aachen eingebettet, die anschließend bis zum Bruch belastet wurden. Der Belastungsversuch an einem der Spannbetondurchlaufträger zeigte das große Potential dieser Methodik. Die im Netzwerk erfassten Änderungen der Ultraschallwellengeschwindigkeit geben die Spannungsverhältnisse im Längsschnitt des Trägers schon bei sehr niedrigen Belastungen qualitativ richtig wieder und zeigen bei hohen Belastungen eine gute Korrelation zum Rissbild. Dabei weisen räumliche Anomalien und Änderungen in der Charakteristik der Geschwindigkeitsänderungen oft schon auf Rissbildung hin, wenn diese noch nicht an der Oberfläche sichtbar ist. Dies zeigt das Potential im Hinblick auf eine Frühwarnung. Hierfür und ebenso in Bezug auf eine Quantifizierung der Effekte ist aber noch Entwicklungsarbeit notwendig. Ein Vorteil der Methodik ist, dass die Transducer nicht direkt am Ort der Änderung platziert werden müssen und einen relativ großen Bereich um die Transducer herum erfassen. T2 - DGZfP Jahrestagung CY - Leipzig, Germany DA - 07.05.2018 KW - Ultraschall KW - Monitoring KW - Codawelleninterferometrie KW - Brückenträger PY - 2018 AN - OPUS4-44863 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -