TY - JOUR

T1 - Hinterfüllkontrolle für Erdwärmesonden 

T2 - Beurteilung einer magnetischen Methode

AU - Ukelis, Olaf

AU - Link, Julian

AU - Zorn, Roman

AU - Steger, Hagen

AU - Zelinski, Viktor

N1 - Funding Information: Diese Arbeit basiert auf Ergebnissen des Forschungsprojekts „EWS-tech II: Entwicklung überprüfbarer Qualitätskriterien für Erdwärmesondenverfüllungen unter realitätsnahen Randbedingungen“. Wir bedanken uns für die Förderung durch das Ministerium für Umwelt, Klima und Energiewirtschaft Baden-Württemberg (Förderkennzeichen L75 16008-16011). Dank gilt auch den Verfüllbaustoffherstellern und der Fa. Santherr Geothermietechnik für die Unterstützung im Verlauf des Projekts. M. Sc. Sebastian Mergenthaler und Chloé Pereira danken wir für die tatkräftige Unterstützung im Labor. Dr. Petra Huttenloch und Dipl.-Geol. Stefan Gutekunst danken wir für die wertvollen Anmerkungen und Diskussionen zu dieser Arbeit. Auch bei den Gutachtern dieses Artikels möchten wir uns für die sehr konstruktiven Kommentare bedanken.

PY - 2021/6

Y1 - 2021/6

N2 - When installing borehole heat exchangers, it is essential to use proper backfilling to avoid hydrogeological failure. In this study, a magnetic susceptibility system for backfilling control was investigated at the laboratory scale. The sensor penetration depth, its sensitivity and the unknown values were assessed by using magnetite-containing backfilling material samples. In addition, the capability to detect slurry levels and cavities was investigated, as well as measurement disturbances. Measured values correspond to volume susceptibilities in the SI system multiplied by a factor of 350 for translation into clear integers in the range from 0 to 11 [–]. This approach was evaluated by comparative measurements using a second susceptibility sensor. The reason for the translation is to provide an easier system for handling at construction sites. The 20–35 mm penetration depth and a sensitivity of only 10% for penetration depths > 20 mm is sufficient for slurry level detection; however, it is not sufficient for detecting all critical cavities. Differentiation between susceptibility weakening as caused by tubes, spacers and cavities is difficult; in addition, specific types of rocks can create disturbances. Optimization of penetration depth, measurement procedure as well as material susceptibility can improve quality control to avoid failure events and possibly ease future installation approval in currently forbidden hydrogeological areas.

AB - When installing borehole heat exchangers, it is essential to use proper backfilling to avoid hydrogeological failure. In this study, a magnetic susceptibility system for backfilling control was investigated at the laboratory scale. The sensor penetration depth, its sensitivity and the unknown values were assessed by using magnetite-containing backfilling material samples. In addition, the capability to detect slurry levels and cavities was investigated, as well as measurement disturbances. Measured values correspond to volume susceptibilities in the SI system multiplied by a factor of 350 for translation into clear integers in the range from 0 to 11 [–]. This approach was evaluated by comparative measurements using a second susceptibility sensor. The reason for the translation is to provide an easier system for handling at construction sites. The 20–35 mm penetration depth and a sensitivity of only 10% for penetration depths > 20 mm is sufficient for slurry level detection; however, it is not sufficient for detecting all critical cavities. Differentiation between susceptibility weakening as caused by tubes, spacers and cavities is difficult; in addition, specific types of rocks can create disturbances. Optimization of penetration depth, measurement procedure as well as material susceptibility can improve quality control to avoid failure events and possibly ease future installation approval in currently forbidden hydrogeological areas.

KW - Backfilling control

KW - Borehole heat exchanger

KW - Leaky borehole sealing

KW - Magnetic logging

UR - http://www.scopus.com/inward/record.url?scp=85099932006&partnerID=8YFLogxK

U2 - 10.1007/s00767-021-00476-0

DO - 10.1007/s00767-021-00476-0

M3 - Artikel

AN - SCOPUS:85099932006

VL - 26

SP - 135

EP - 153

JO - GRUNDWASSER

JF - GRUNDWASSER

SN - 1430-483X

IS - 2

ER -