DBPapers
DOI: 10.5593/SGEM2014/B11/S5.074

PROFILE SEISMOLOGICAL MEASUREMENT DURING WINDING TOWER DEMOLITION

Z.Kalab, M. Lednicka
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-07-0 / ISSN 1314-2704, June 19-25, 2014, Book 1, Vol. 1, 565-572 pp

ABSTRACT
This paper describes experimental measurements of seismic effect originated during demolition of a reinforced-concrete winding tower in the area of former company “Rudné doly” in Zlaté Hory (the Czech Republic). A short mining history of the deposit in Zlaté Hory is included. The winding tower, situated above the abandoned mining pit, was demolished using blasting operations on April 15, 2011. Seismological measurement was performed by six three-component sensors in the profile of 250 m long for the purpose to obtain the information on the effect of vibration in the near zone. Recorded wave patterns caused by demolition can be divided into three phases in accordance with the visual observation – the first phase caused by blasting, the second one caused by settling of a separate part of the tower to its foundations, and gradual tilting, and the third phase caused by falling of a separate part of the tower to the ground. Vibration effect during those individual phases is analysed in this article in time and frequency domain. The analysis documents a direct demonstration of the blasting operation with recorded air pressure induced wave. A complex combination of successively emerging waves, including surface wave with a significant harmonic vibration during the second phase of demolition, is also identified. In order to get more detailed information on the source of recorded harmonic vibration, analysis of resonance frequency of soil layers along the profile was performed. Geological search study, including the description of borehole in the area, documents that rock massif represents slates covered by disintegrated rocks and shallow layer of loams. Experimental measurement of seismic noise was carried out at 11 points along the profile of the length of almost 210 m. The data were analysed and resonance frequency was determined using the HVNR method. The seismic refraction measurement was also performed in the same profile to specify local geology in order to complete the results of seismic noise measurement.

Keywords: demolition, blasting operation, vibration effect, frequency analysis, site effect