ROCK MECHANICS AND GROUND CONTROL

ASSIGNMENT 2 DUE: 28/02/2012

1) Explain the following terms.

i. Stress [2]

ii. Strain [2]

iii. Elasticity [2]

iv. Plasticity [2]

v. Strain hardening [2]

2) Find the magnitude and direction of the normal and shear stresses (n

and ) for the state of stress given below;

x=2.5kPa y= -12.5kPa xy=13.0 kPa

[6]

3) (a) State the 5 parameters commonly used in rock mass classification

[5]

(b) A tunnel is driven through phyllite, which has a uniaxial

compressive strength of 180MPa and an RQD of 82%. The average joint

spacing is 0.5m and joints are rough. The area is completely dry and

the tunnel is driven parallel to the joints which dip at 60 degrees.

Calculate the RMR score for the rock mass, ascertaining the class of the

rock. [7]

4) Explain the importance of instrumentation and monitoring in rock

mechanics;

i. During the exploration stage [4]

ii. During production [4]

iii. During post closure [4]

33[Total: 40 MARKS]