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Rock Mechanics.pdf - Mining and Blasting

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Figure 15.26 Geometry of a sublevel<br />

caving layout in the plane of the<br />

wall of a slice.<br />

LONGWALL AND CAVING MINING METHODS<br />

overlapping draw ellipsoids. For the case shown in Figures 15.23 <strong>and</strong> 15.24 where<br />

the ellipsoid has a circular cross section, the volume of material drawn is<br />

Vd = <br />

3 aNb 2 2 <br />

h − aN h − aN<br />

N 1 − √ 2 − √ −<br />

aN<br />

d<br />

1<br />

<br />

2 −<br />

2<br />

h<br />

2 <br />

1 +<br />

aN<br />

h<br />

<br />

aN<br />

<br />

<strong>and</strong> the corresponding volume of waste is<br />

where<br />

460<br />

VW = <br />

3 aNb 2 N<br />

1 + h − aN − V/ sin <br />

√ d<br />

d = a 2 N + b2 N<br />

tan 2 <br />

2 2 − h − aN − V/ sin <br />

√ d

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