Which one of the following methods of tunnelling does not require the use of time bearing?

Which one of the following methods is generally adopted for tunnelling in firm ground

A

Full face method

B

Top heading and benching method

C

Drift method

D

All the above

The frictional torque transmitted in a flat pivot bearing, considering uniform wear, is (where μ = Coefficient of friction, W = Load over the bearing and R = Radius of bearing surface)

A

$$\frac{1}{2}$$μWR

B

$$\frac{2}{3}$$μWR

C

$$\frac{3}{4}$$μWR

D

μWR

When the bearing is subjected to large fluctuations of load and heavy impacts, the bearing characteristic number should be _________ the bearing modulus.

A

10 times

B

5 times

C

15 times

D

20 times

If p = bearing pressure on projected bearing area, Z = absolute viscosity of lubricant and N = speed of journal, then the bearing characteristic number is given by

A

$$\frac{{{\text{ZN}}}}{{\text{p}}}$$

B

$$\frac{{\text{p}}}{{{\text{ZN}}}}$$

C

$$\frac{{\text{Z}}}{{{\text{pN}}}}$$

D

$$\frac{{\text{N}}}{{{\text{Zp}}}}$$

Which one of the following statements is not correct for heading and benching method of tunnelling?

A

Drilling and mucking can be done simultaneously

B

Benching provides a platform for working on heading

C

Removal of muck from the heading is very easy

D

None of these

Which one of the following statements is not correct with regard to heading and henching method of tunnelling?

A

Driving of tunnel is done in two portions of its section

B

Driving the top portion is done in advance of the bottom portion

C

The holes in head and bench are loaded together with explosive for blasting

D

Firing of head holes is done just before the bench holes are fired

Pick up the explosive used for tunnelling in soft rocks from the following:

A

Blasting gelatine

B

Special gelatine

C

Ammonia dynamite

D

Semi-gelatine

The most suitable soil for compressed air tunnelling is

A

Silt

B

Sand

C

Clay

D

Gravel

In compressed air tunnelling, the volume of free air provided is

A

6 m³ per second per m² of face area

B

6 m³ per minute per m² of face area

C

20 m³ per minute per m² of face area

D

6 m³ per hour per m² of face area

The length of the needle beam used in needle beam method of tunnelling is usually

A

2 m to 4 m

B

2.5 m to 6 m

C

4 m to 7 m

D

5 m to 6 m

Which one of the following methods of tunnelling does not require the use of time bearing?

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