Rock Mechanics Mid - I, September - 2014

1.The rocks are said to be flaggy if the bedded planes are separated by.
  • more than 1.2m,
  • 1m-1.2m
  • 75mm-1m,
  • less than 75mm.
Answer: D
2.If the bedded planes are separated by more than 1.2m apart then they are said to be.
  • Massive
  • Bedded
  • Flaggy
  • rubble.
Answer: A
3.The weight of rocks in a coal mining areas exerts a pressure nearly per meters depth from the surface is.
  • 1 kg/sq.cm
  • 0.5 kg/sq.cm
  • 0.2kg/sq.cm
  • 0.2kg/sq.mm.
Answer: D
4.The immediate roof is called……..
  • 3m above the seam.
  • 6m above the seam.
  • 6m below the seam.
  • 3m below the seam.
Answer: B
5.For testing a specimen in the laboratory the length: diameter ratio should be.
  • More than 1:2.
  • More than 2:1
  • less than 2:1.
  • less than 1:2.
Answer: B
6.Compressive strength of coal is
  • 13.5 kg/sq.mm
  • 2.25 kg/sq.mm
  • 2.25 kg/sq.cm
  • 13.5kg/sq.cm.
Answer: A
7.The load on a prop when upper member is begins to slide is called.
  • Load bearing capacity
  • Setting load
  • Yield load
  • Limit load
Answer: C
8.The load at which on axially loaded prop reaches its elastic limit or at which it begins to buckle is called.
  • Load bearing capacity
  • Setting load
  • yield load
  • Limit load.
Answer: A
9.By tapering the prop at the foot or top by providing a lid on the top of the prop.....could be obtained?
  • Max strength,
  • Yield,
  • max life of prop,
  • none of the above.
Answer: B
10.The maximum height of the roof that can be tested by bamboo?
  • 2.5m.
  • 3m.
  • 3.5m.
  • 1.5m.
Answer: A
11.For equal resistance to crushing and bending the prop should have diameter________________ .
Answer: 1/12th of the length
12.Freshly exposed roof after blasting is effectively and quickly Supported by_______________.
Answer: Safari supports
13.The phenomenon of lifting up of the floor if the floor is weak is called______________.
Answer: Heave
14.On account of the weight of the rocks the pressure arch is transmitted to abutment if the depth of the coal seam is _________the length of the pressure.
Answer: Twice
15.Angle of draw for flat seams are maximum for undistributed over lying mass while it is up to _____________ for distributed rock mass.
Answer: 30-35
16.A rock because of its physical and geological characteristics is capable of sustaining openings without any structural support is called_____________.
Answer: Massive/competent rock
17.The rod which are used to reinforce the rocks are under______________.
Answer: Tension
18.Strength of rock is ________when tested dry as compared to when tested wet.
Answer: More
19.The general equation to find flexural strength of the prismatic specimen is ________________.
Answer: Supported
20.The over break of rock around underground working is excessive in Highly ________ rock.
Answer: α= (3xfxl/2xbxa2)