Page 478 - Rock Mechanics For Underground Mining

LONGWALL AND CAVING MINING METHODS

Figure 15.26 Geometry of a sub-
level caving layout in the plane of the
wall of a slice.

overlapping draw ellipsoids. For the case shown in Figures 15.23 and 15.24 where
the ellipsoid has a circular cross section, the volume of material drawn is
" 2 2 #
h − a N
h − a N
1 h
h
V d = a N b 2 N 1 − √ 2 − √ − 2 − 1 +
3 a N d 2 a N a N
and the corresponding volume of waste is
2
1 + h − a N − V/ sin
2 − h − a N − V/ sin
V W = a N b 2 N √ √
3 d d
where
b 2
2 N
d = a +
N
2
tan
460