Home/Volume-1/Rock Mechanics and Roof Supports Volume-1 Rock Mechanics and Roof Supports Admin02/08/20240 100 Less than a minute Report a question What's wrong with this question? You cannot submit an empty report. Please add some details. 0% Rock Mechnics and Roof Supports Rock Mechanics and Roof Supports 1 / 34 1. The max gap between two chock shield supports is..? 250mm 200mm 150mm none of the above 2 / 34 2. The number of props required to support one square meter of the roof area is? one two three prop density 3 / 34 3. The yielding props which exert resistance with continuous increase in yield are called? Early bearing supports Late bearing supports Hydraulic supports none of the above 4 / 34 4. For equal resistance to crushing and bending the prop should have dia..? 1/3 of the length 1/6 of the length 1/9 of the length 1/12 of the length 5 / 34 5. Phenomena of the rocks in immediate roof bending downwards under their own weight and tend to separate from one another is known as..? subsidence pressure arch bed separation roof bending 6 / 34 6. The immediate roof is called..? 3m above the seam 6m above the seam 6m below the seam 3m below the seam 7 / 34 7. Crushing strength of sandstone is..? 13.5 kg/sq.mm 2.25 kg/sq.mm 2.25 kg/sq.cm 13.5 kg/sq.cm 8 / 34 8. The anchorage support of resin capsule is? 6te 8te 10te 12te 9 / 34 9. The inclination of prop to the vertical when set to side support is? 10 - 14 deg 14 - 20 deg 20 - 25 deg 25 - 30 deg 10 / 34 10. In roof stitching the face should not be advanced more than ....m from the last tensioned rope? 4m 3m 2.4m 2m 11 / 34 11. A timber prop is expected to support an area of about.....all round? 1 - 2 m 0.1 - 0.3 m 0.2 - 0.4 m 0.4 - 1 m 12 / 34 12. The weight of the rocks in coal mining areas exerts a pressure nearly per metre depth from the surface is..? 1 kg/sq.cm 0.5 kg/sq.cm 0.2 kg/sq.mm 0.2 kg/sq.cm 13 / 34 13. For testing a specimen in the laboratory the length:dia ratio should be? more than 1:2 more than 2:1 less than 2:1 less than 1:2 14 / 34 14. The maximum height of the roof that can be tested by bamboo? 2.5m 3m 1.5m 3.5m 15 / 34 15. If the bedded planes are separated by more than 1.2 m apart then the rocks are said to be? Massive Bedded Flaggy Rubble 16 / 34 16. The load at which an 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 17 / 34 17. The timber prop available max height up to..? 3m 6m 9m 11m 18 / 34 18. Compressive strength of coal is..? 13.5 kg/sq.mm 2.25 kg/sq.mm 2.25 kg/sq.cm 13.5 kg/sq.cm 19 / 34 19. In hydraulic oil the % of emulsion oil is? 2 3 4 5 20 / 34 20. 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 the prop none of the above 21 / 34 21. The anchorage support of the roof stitching is ? 5 te 7 te 10 te 12 te 22 / 34 22. If the prop has to be set on loose ground it should be placed on a flat base piece having thickness not less than..? 2 cm 3 cm 4 cm 5 cm 23 / 34 23. The depression of ground surface and the structures is called? subsidence pressure arch bed separation roof bending 24 / 34 24. The load on a prop when upper member begins to slide is called? Load bearing capacity Setting load Yield load Limit load 25 / 34 25. Bulk strength of the timber prop is ...(kg/sq.cm)? 150-230 100-150 250-300 none of the above 26 / 34 26. The pressure arch in L/W workings has its apex or crest at a min height above the seam at nearly .... times the length of face? 1 2 3 4 27 / 34 27. The phenomena of lifting up of the floor if the floor is weak is called..? Heave Creep Bending none of the above 28 / 34 28. In resin capsule the mixture hardens within .... seconds and becomes solid? 20 - 30 30 - 40 40 - 50 50 - 60 29 / 34 29. Hand packing is useful up to max gradient? 35 deg 30 deg 25 deg 20 deg 30 / 34 30. Freshly exposed roof after blasting is effectively and quickly supported by..? Timber supports Roof bolts Safari supports Bars 31 / 34 31. 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 32 / 34 32. L/W faces with caving have caused difficulties in roof control at a depth of less than nearly..? 100m 200m 300m 400m 33 / 34 33. On account of the weight of the rocks the pressure arch is transmitted to abutment if the depth of coal seam is ....the length of the pressure? Equal Twice Thrice 4 times 34 / 34 34. The best method of mining for controlling the subsidence is..? Bord and pillar Longwall with stowing Longwall with caving Harmonic mining Your score is The average score is 56% LinkedIn Facebook Twitter 0% Admin02/08/20240 100 Less than a minute
