Building 3D Model of Rock Quality Designation Assisted by Co-Operative Inversion of Seismic and Borehole Data

Abstract

The rock quality designation (RQD) is an important factor for geotechnical work in mining operations. A 3D model of RQD is significant for mine design. In practice, the mine design needs information of the whole mine area, but, borehole data is localised in only a small part of the whole area. Although, surface seismic methods can provide information of the whole survey (mine) area, the resolution of such data is generally smaller than the borehole data. The combination of seismic and borehole data may provide very useful information for geotechnical features like RQD if we can exploit seismic data as a means of interpolating the borehole information to the whole model of that geotechnical feature. In this work, we build a 3D model of RQD from seismic and borehole data acquired in Kevitsa mine site, Northern Finland. We investigate the relationship between Vp and RQD from eight boreholes to build a functional conversion between theses parameters. The seismic model obtained by co-operative inversion of seismic reflection and borehole data is converted into a RQD model using this function. Our model is assessed by comparison between RQD of core measurements and estimation from Vp of borehole data and seismic inversion. The results demonstrate that our process can build a reasonable 3D RQD model for geotechnical purposes.