Rock Mechanics.pdf - Mining and Blasting

ANSWERS TO PROBLEMS
2 (a) 0.087 – 0.100 m; 0.083 – 0.104 m.
(b) 26 m.
3 48 ◦ .
4 038/20.
5 71 ◦ measured in the plane normal to the line of intersection.
6 275/50.
7 312/17.
8 RMR = 69.
Chapter 4
1 Et = 14.3GPa, = 0.23.
2 1 = 133.3MPa;1 = 85 MPa.
3 (a) 1 = 133 + 3.03 MPa.
3
0.75
4 1
= 1.0 + 4.75 is one of several possible solutions.
100 100
5 s = 15.0 + n tan 27.5◦ MPa.
7 (a) b = 30◦ , i = 15◦ .
(b) Peak strength envelope bilinear with c = 0, = 45◦ for 0 < n < 1MPa,
and c = 0.5 MPa, = 26.5◦ for 1 < n < 5 MPa. Residual strength
envelope bilinear with cr = 0, r = 30◦ for 0 < n < 1MPa,
and cr = 0.1 MPa,r = 26◦ for 1 < n < 5MPa.
8 u = 1.247 MPa; u = 0.642 MPa.
9 ′ 1 = 0.346 + 3.0′ 3 MPa.
Chapter 5
1 (b) i xx = 1.35 MPa, i zz = 1.35 MPa, i zx = 0.86 MPa.
(c) xx = 3.51 MPa, zz = 4.59 MPa, zx = 0.86 MPa.
1 = 5.07 MPa, 2 = 3.03 Mpa, 1 = 61.1 ◦
2 pzz = 20.80 MPa, fissure water pressure u = 6.86 MPa.
13.69 < pxx < 43.29 MPa.
3 (a) Plane principal stresses are vertical and horizontal.
(b) 1 = 20.0 MPa (vertical), 2 = 15.0 MPa (horizontal),
3 = 12.0 MPa (parallel to tunnel axis).
4 All stresses are in MPa.
(b) pll = 10.22, pmm = 17.09, pnn = 10.68, plm =−1.30, pmn =−4.86,
pnl = 1.12.
(c) pxx = 15.59, pyy = 11.06, pzz = 11.35, pxy = 3.05, pyz = 3.12,
pzx = 3.99.
586