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- Parallel seismics (4)
- Pile integrity testing (4)
- Piles (4)
- Spektrale Induzierte Polarisation (4)
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Organisationseinheit der BAM
NDT investigation methods
(2006)
During the re-use process of existing concrete memebers like foundations information about geometry and location of piles or strip foundation is necessary. Ultrasonic echo with a need of only one-sided access may provide this information and help the engineer to assess foundations. Cost effectiveness by the re-use of foundations gains an increasing economic role due to decreasing average economic lifetime of buildings on urban sites. Results of systematic ultrasonic echo investigations at a slab from 75 cm to 125 cm thickness with ten different reinforcement ratios are presented. The influence of the varying reinforcement ratio and thickness on the reliability of the results is shown. Available data-processing algorithms based on reconstruction calculation and imaging of results to reveal the geometry of a slab and the location of piles or strip foundations are introduced. Practical guidance for the application of ultrasonic echo and its limits are presented to ensure reliable results.
Zusammenfassung
In der Geophysik wird seit einiger Zeit das Verfahren der "Spektralen Induzierten Polarisation (SIP)"eingesetzt, um nähere Informationen über die Art, die Struktur und den Zustand des Bodens zu erhalten. Die Methode beruht auf der Messung des komplexen spezifischen elektrischen Widerstands im Frequenzbereich zwischen 1 mHz und 10 kHz.
Die SIP kann neue Möglichkeiten beim Einsatz elektrischer Verfahren in der Bauwerksuntersuchung eröffnen. So lassen sich beispielsweise Materialunterschiede von Feuchteinhomogenitäten trennen, was mit konventioneller Widerstandsmessung nicht möglich ist. Ebenfalls denkbar ist eine Detektion kontaminierter Bereiche (z. B. bei starker Belastung durch organische Substanzen oder Salze) im Mauerwerk.
Vorgestellt werden das Verfahrensprinzip, die Messtechnik und erste Ergebnisse von Messungen an Mauerwerksziegeln.
RUFUS - Re-Use of Foundations on Urban Sites - Ein EU-Projekt zur Wiedernutzung von Fundamenten
(2003)
Pile testing as a NDT-CE (non-destructive-testing in civil engineering) method provides information about the condition of foundations. It is also used as a tool for quality control. Real size test fields with sound piles, piles with flaws and piles connected with a foundation allow calibration of measurement devices and method comparison under "real" conditions. Such a site is planned on a BAM testing area south of Berlin. The joint use facilitates the establishment of the testing site as a national or European reference site.
The reuse of existing foundations is considered in various construction Projects to save time and costs while avoiding unnecessary interference with other underground objects. Because the design and as-built drawings might not be complete and questions may arise regarding the condition of the foundations, a detailed investigation is a prerequisite for the planning process in most cases. Nondestructive testing (NDT) techniques are a core part of this endeavor.
The processes and procedure for foundation reuse planning are not yet standardized, and the possibilities and limitations of NDT methods are not known to many planners and stakeholders. The German research Project REFUND (2014–2016) has developed charts for the planning and Investigation process that consider available standards and the current state of the art in NDT.
These charts are separately available for single and strip, slab, and pile foundations. Available NDT methods have been compiled and evaluated for specific tasks at these foundation types, including their respective limitations.
The procedures have been successfully tested in two real-world projects. The results from these projects enable planners to improve the reliability of the process while potentially saving significant resources. This paper discusses the procedures for pile foundations and demonstrates the use of various NDT methods in a project on the reuse of electrical tower foundations.
Improperly built or managed tailing dams pose major risks to human lives and the environment. Research for risk reduction by new technologies including slurry handlings, stochastic modelling, development of a parameter framework as well as work on legislation and authorisation procedures will be done in the EC-funded project TAILSAFE. Focus of this paper is on geophysial techniques for structure investigation and monitoring.