Imaging steeply dipping near-surface mine workings using surface seismic waves

Surface subsidence and sinkhole development over abandoned and collapsing underground mine workings are major environmental and public safety hazards in some areas. Small-scale undocumented workings are particularly problematic because their presence is often unknown until infrastructure has been developed over them and there is an unexpected subsidence event, often requiring expensive site stabilization or abandonment. Surface wave imaging is a relatively new seismic technique that generates subsurface depth images without having to drill boreholes and is becoming a standard tool in non-destructive geotechnical characterization. The objective of this investigation was to evaluate the capability of surface wave seismic techniques to image narrow steeply dipping abandoned workings at the Montague Gold Mines district near Dartmouth, Nova Scotia. This district has numerous abandoned workings from historical mining activity and has actively subsiding and collapsing crown pillars. The steeply dipping geology, and narrow workings (often less than 1 m) at the Montague site were conditions not typically encountered for routine surface wave imaging. These conditions were addressed in the imaging system developed for these field trials.Two locations at the Montague district were selected for field trials following a preliminary site survey. At each site, mine records and surface subsidence patterns indicated the presence of two parallel steeply dipping workings. The seismic data recorded at both sites were processed to generate seismic velocity versus depth images and a comparative gravity survey was also conducted at one site. On the velocity-depth images, narrow vertical zones of zero velocity are prominent at the same lateral positions where vertical mine workings were expected. This is shown in the figure where both the zero velocity zones are present where workings were mapped, and where the gravity survey shows prominent negative anomalies. Overall, the results of the study indicate that surface wave imaging techniques have good potential to image shallow steeply dipping mine workings. However, there are several key areas for future work in this area, including: 1) additional field trials where ground truthing, either by drilling boreholes or excavation of the site, is conducted to rigorously evaluate the accuracy of the seismic images; 2) improvements in the waveform processing methodology to reduce the processing time and improve the depth resolution; and 3) continued work in a related research program to quantify the relationships between measured seismic attributes and mechanical rock mass quality, subsidence potential, etc.
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Summary: Following initial discovery in 1991, BHP Diamonds Inc. (now part of BHP Billiton) opened Canada’s first diamond mine, the EKATI Diamond Mine, in the Northwest Territories, on October 14, 1998. Four short years later, on November 29, 2002, saw the opening of North America’s first underground diamond mine—the Koala North mine. Nestled between the original Panda open pit and the new Koala pit, which is now in production, Koala North represents the first underground kimberlite...
Publication: CIM Bulletin
Author(s): P. Harvey
Issue: 1089
Volume: 98
Year: 2005
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Summary: Several sources of information often contribute to the comprehension of an ore deposit, for instance samples from diamond drill holes, reversed-circulation drill holes, or blast holes. Even if all the available information comes from the same drill hole type, it may have been collected through several campaigns, sampled with different protocols, or analyzed by different laboratories. In general, these sources of information do not have the same quality, therefore, they constitute different...
Publication: CIM Bulletin
Author(s): X. Emery, J.P. Bertini, J.M. Ortiz
Issue: 1089
Volume: 98
Year: 2005
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Summary: The preparation of a long-term plan requires an understanding of all the facets of a mine, among them, the access and other infrastructures; the general layout; the geology, reserves, and extraction plan of every sector; and the productivity of the workers. The planner combines all these elements, often in an intuitive way, into a number of alternative plans, trying to identify the most likely outcomes and problems. The final plan that is compiled is functional, but there is no certainty that...
Publication: CIM Bulletin
Author(s): G. McIsaac
Issue: 1089
Volume: 98
Year: 2005
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Summary: Underground coal production at the Hustas mine, west of the village of Eynez, was from the KM2 seam, which lies at an average depth of 200 m and ranges from 15 m to 25 m in thickness with an average extractable thickness of about 18 m. The underground lignite mining methods employed in Turkey are mostly non-mechanized longwall methods. At the Hustas mine, the method used is a manual double-slice longwall method. The face area is maintained at about 2 m high using hydraulic steel props...
Publication: CIM Bulletin
Author(s): C.O. Aksoy
Issue: 1089
Volume: 98
Year: 2005
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Summary: The Ambatovy Nickel Project involves the proposed recovery of nickel and cobalt from a laterite deposit in Madagascar. The project has the potential to produce 60,000 t of nickel and 5,600 t of cobalt annually. In support of the bankable feasibility study, laboratory and mini pilot plant testwork was carried out at the Dynatec laboratory in Fort Saskatchewan. This paper describes the major findings of the test program.The Ambatovy ore is primarily ferralite (limonite). Saprolite is...
Publication: CIM Bulletin
Author(s): M.J. Collins, L.A. Barta, K.R. Buban, R. Kalanchey, G. Owusu, R. Raudsepp, J. Stiksma, I.M. Masters
Issue: 1089
Volume: 98
Year: 2005
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Summary: Load-haul-dump vehicles (LHDs) are extensively used in underground mining, however, equipment design and operating conditions contribute to restricted operator sight lines. The inability to clearly see people, objects, or hazards around the machine has contributed to a number of accidents including fatal injuries. In order to identify vehicle design characteristics resulting in restricted and blocked sightlines, line-of-sight assessments are traditionally completed in the field. However,...
Publication: CIM Bulletin
Author(s): T. Eger, A. Jeffkins, P. Dunn, I. Bhattacherya, M. Djivre
Issue: 1089
Volume: 98
Year: 2005
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