Customer

Holcim (Switzerland) AG

Geological Office

BTG Büro für Technische Geologie AG

Services Provided

• Seismic mapping to assess the degree of fragmentation of a part of the quarry.
• Monthly calculation of the resonance frequency and seismic amplification for monitoring purposes at three permanently installed seismometer stations.
• Site-specific determination of the maximum vibration values depending on the blasting load and continuous blast monitoring as part of an optimized mining concept.

Project Description

In order to ensure the safety of the Haselboden quarry during blasting, Spektrum Geophysik AG was commissioned with passive seismic mapping to assess the stability of a section of the quarry and subsequent continuous seismic monitoring of the blasting.

As part of the seismic mapping, portable seismometers were installed in order to map the degree of rock fragmentation on the basis of the seismic amplification values and to identify structurally dynamic compartments using modal analysis. Our results, together with a geological report, subsequently led to extensive remediation measures for the identified compartments and an optimized mining concept.

To determine the vibrational threshold values, vibration data from dozens of blasts was collected, which was combined with numerical modeling by our project partners. Since then, three permanently installed seismometer stations have been continuously monitoring the blasts in the quarry and automatically alerting the operator to any anomalies. The combination of passive seismic mapping, specific rock remediation measures and an effective monitoring system contributes to the continuous guarantee of long-term safety in the Haselboden quarry.