Application of Refraction Tomography to Map the Extent of Blast- induced Fracturing.
Cumerlato-CL; Stachura-VJ; Tweeton-DR
Proc Symp on Applic of Geophysics to Eng & Envir Problems 1989 :456-466
The U.S. Bureau of Mines has conducted high-resolution refraction surveys at a limestone quarry both before and after standard production blasts where variations in the blast design were made. The data collected were processed using a tomographic inversion algorithm to produce maps (tomograms) of the seismic velocity field of a shallow refracting layer in the rock left standing. Overlapping of surveys, velocity measurements from shotholes (preblast), and measurements of predominant joint sets were used to verify results. Resulting tomograms show sublinear low-velocity zones whose orientations correspond to those of measured joint sets. Low-velocity zones near pitwalls are interpreted as the extent of intense fracturing caused by blasting. These results demonstrate that refraction tomography can be a powerful and economical tool for locating predominant jointing and areas of preexisting or blast- induced fracturing, and thus an important aid to operators during premine planning and blast designing.
Proc. Symp. on Applic. of Geophysics to Eng. & Envir. Problems. 1989, PP. 456-466