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Rock Mechanics.pdf - Mining and Blasting

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Figure A.6 Axisymmetric tunnel<br />

problem showing the development of<br />

a plastic zone around the tunnel.<br />

APPENDIX C ROCK–SUPPORT INTERACTION ANALYSIS<br />

Calculation sequence<br />

(1) M = 1<br />

2<br />

(2) G =<br />

m<br />

4<br />

2<br />

E<br />

2(1 + )<br />

+ mp<br />

c<br />

1/2 + s − m<br />

8<br />

(3) For pi p − Mc, deformation around the tunnel is elastic,<br />

i<br />

ri<br />

= (p − pi)<br />

2G<br />

(4) For pi < p − Mc, plastic deformation occurs around the tunnel<br />

ue<br />

re<br />

= Mc<br />

2G<br />

(5)<br />

<br />

p − Mc<br />

N = 2<br />

+<br />

mr c<br />

sr<br />

m2 1/2 r<br />

(6)<br />

<br />

re<br />

pi<br />

= exp N − 2 +<br />

ri<br />

mr c<br />

sr<br />

m2 <br />

1/2<br />

r<br />

(7)<br />

576<br />

i<br />

ri<br />

= Mc<br />

G( f + 1)<br />

<br />

( f − 1)<br />

+<br />

2<br />

re<br />

ri<br />

f +1

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