1. What is the shear stress on an element experiencing the maximum principal stress?
2. Which type of rosette would you use to find the stress conditions in a coal mine? 6. What are the different types of forces?
3. Comment on the types of failure which you would observe near a fold, fault.
4. Comment on the type of failure you may expect in a tunnel.
5. What is the safe distance for excavating an extra opening from an existing opening?
6. What are cleats in coal?
7. How is shearing strain defined? Show with the help of a diagram. Show a deformed 2-D element with negative shearing stress.
8. The following data are given to you. Plot an approximate Mohr circle diagram and show the state of stress on a plane that makes an angle of -30 degress with the x-axis. Sigma xx- -300 psi, sigma yy- +1000 psi, sigma xy- -100 psi.
9. What is approximate vertical stress for mining depth of 555 feet?
10. Given Poisson’s Ratio of .35, what would the approximate horizontal stress be if the mining depth was 330 feet, assuming there are no tectonic stresses?
11. A 2-d element is subjected to sigma xx= -1000 psi. The E and poisson’s ratio values are 150000 psi, and .3 respectively. Compute strains in the x- and y- directions.
12. What are typical compressive strength and tensile strength values for shale, limestone and sandstone.
13. What do we mean by brazillian test for tensile strength? Why is this test better than direct tensile strength from mine design point of view? 18. How do we define poisson’s ratio?
14. Show with the help of a diagram typical stress-strain curve for rock?
15. With the help of diagrams, how tangent and secant moduli of elasticity for rocks. Which one is better for mine design point of view?
16. What are body forces and surface forces?
17. What are interior and exterior surfaces?
18. What are the surface forces on a freshly excavated tunnel without supports?
19. Given a tunnel in an infinite rock mass subjected to vertical stress only, where would you expect the tunnel to fail. Where would you not to expect it to fail based on stress analysis?
20. What is approximately the value of stress concentration factor at the corner of a rectangular opening? How can you minimize it?
21. How would you orient an elliptical shaft in relationship to orientation of highest compressive stress?
22. What is St. Venant Principle? 28. What is the principle of superposition?
23. How do we define a beam? Show a fixed-ended and a simply supported beam.
24. What is the neutral axis or surface in the context of beam analysis?
25. Write the equations for stress in a beam given the bending moment and geometry of the beam?
26. Under what conditions would you expect bed-separations for multiple-layered beams of different materials?