Surface mining ground falls

Surface mines have relatively few serious falls of ground, with six fatalities in the period from 1996 to... 

This chapter has presented an overview of the most significant ground control hazards facing todays mineworkers. Underground miners, particularly in coal mines, are at the greatest risk from ground falls. The six highwall and slope fatalities that occurred in the first half of 1999 show that surface miners are at risk as well. 

Figures 7.64 and 7.65 provide a view of the fracture surface of a bolt recovered following a fall of ground from a hardrock mine. This is at magnification x 10. A close-up of dimpled areas is presented in Figure 7.66, at a magnification x 1500. The dimples are shallow and inclined characteristic of ductile fracture. No sign of cleavage or quasicleavage, is observed (absence of river pattern that would be associated with brittle fracture). In the upper right part of the photo dimpled areas are masked by oxidation.

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