Technical Papers

Caving in the Fabian Orebody —from Mining Stope to Cave Crater in Malmberget

The Fabian orebody is a non-daylighting iron orebody in the LKAB Malmberget Mine in northern Sweden. The orebody was mined using slot caving and sublevel stoping during the 1970s and 1980s, resulting in a large open stope under a 250 m thick crown pillar. The orebody has since been mined using sublevel caving beneath the open stope, which has caused progressive caving and a corresponding continuous reduction of the crown pillar thickness toward the ground surface.

During 2010, a prognosis of the cave development in the Fabian area was developed, based on compilation and analysis of all available material. At this time, the crown pillar had a minimum thickness of 77 m. The prognosis was presented at the end of 2010, and predicted a slow, progressive caving of the crown pillar and the formation of a cave crater on the ground surface within the previously fenced-off area, and with minor disturbance to the surrounding municipality.

The cave development was followed up continuously through laser scanning, visual observations and seismic monitoring. In March 2012, a new cave crater formed on the ground surface above the Fabian orebody, similar to what was predicted. The crater developed in the morning of March 20, with no disturbances to nearby residents or municipal functions.

The prognosis is compared with observations of the caving and the differences and implications quantified. A program for continued monitoring of mining-induced deformation in Malmberget is also described and a criterion for allowable mining-induced surface deformations is proposed.

PRESENTATION

Download the conference presentation.

TECHNICAL PAPER

Sjöberg, J., & Savilahti, T. (2014, January 1). Caving in the Fabian Orebody - from Mining Stope to Cave Crater in Malmberget. International Society for Rock Mechanics and Rock Engineering.

Latest News
  • Introducing FLAC2D Itasca is very pleased to announce FLAC2D as the next generation of our foundational software,...
    Read More
  • Itasca Partners with Rescale for FLAC3D Cloud Computing With the advent of web licenses, Itasca software can be run in the cloud via...
    Read More
  • Software Forum Now Open Itasca has launched a new software forum to provide a platform for users to ask...
    Read More

Upcoming Events
23 May
71st Highway Geology Symposium
Better highways through applied geology.... Read More
20 Jun
URTeC 2022
The Unconventional Resources Technology Conference (URTeC) is an event focused on the latest science and technology applied to explorat... Read More
20 Jun
IAEA International Conference on the Safety and Security of Radioactive Sources
The IAEA is organizing the International Conference on the Safety and Security of Radioactive Sources - Accomplishments and Future Ende... Read More