21. Which one of the following shapes is suitable for the construction of tunnel in non-cohesive soils?
- Horse-shoe
- Rectangular
- Circular
- Egg-shaped
22. NATM method of tunneling is suitable for
- Subway construction.
- Abnormal geological conditions
- Soils at medium of shallow depth.
- Tunneling large sections in very difficult ground
- i and ii only
- ii and iv only
- i, ii and iv only
- i, ii, iii and iv only
23. The tunnels that are made to shortcut minor local obstacles are called
- Spiral tunnels
- Short tunnels
- Off-spur tunnels
- Saddle tunnels
24. The amount of fresh air required to maintain ventilation for workers inside the tunnel should be
- 1 – 5 m3/minute
- 6 – 14 m3/minute
- 20 – 30 m3/minute
- 30 – 50 m3/minute
25. Which of the following is a serious health issue in case of workers involved in tunneling operations?
- Deafness
- Pneumonia
- Jaundice
- Silicosis
26. If ‘D’ is a diameter of tunnel in meters, then the thickness of lining in mm as per the empirical formula is given by
- 82 D
- 72 D
- 92 D
- 102 D
27. To attain the required shape of the tunnel we use
- Chisels
- Cut holes
- Trimmers
- Easers
28. Which one of the following tunneling methods is used for laying underground sewers?
- Needle beam method
- German method
- English method
- Army method
29. Pick up the explosive used for tunneling in soft rocks from the following
- Blasting gelatine
- Special gelatine
- Ammonia dynamite
- Semi-gelatine
30. The length of the needle beam used in the needle beam method of tunneling is usually
- 2 m to 4 m
- 1.5 m to 4.5 m
- 5 m to 6 m
- 6 m to 7 m