Mumbai University > Civil Engineering > Sem 8 > Construction Engineering

Marks: 10Marks

Describe the various types of tunnelling machines which have been developed in recent years. Describe the operation of one of these machines. Compare the use of moles with conventional tunnelling method.

Various types of tunnelling machines are:

a) Road headers

b) Reaming Machines

c) Partial face/mini tunnelling machines

d) Shield tunnelling machines.

e) Full face Tunnel Boring Machines(TBMs)

Road Headers:

A road header, also called a boom-type road header, road header machine, road header or just header machine, is a piece of excavating equipment consisting of a boom-mounted cutting head, a loading device usually involving a conveyor, and a crawler travelling track to move the entire machine forward into the rock face.

The cutting head can be a general purpose rotating drum mounted in line or perpendicular to the boom, or can be special function heads such as jack-hammer like spikes, compression fracture micro-wheel heads like those on larger tunnel boring machines, a slicer head like a gigantic chain saw for dicing up rock, or simple jaw-like buckets of traditional excavators

Types of cutting heads:

Longitudinal - rotates parallel to the cutter boom axis

Transverse - rotates perpendicular to boom axis

Uses: Road headers were initially utilized in coal mining applications, however they are now used in a broad range of applications including but not limited to tunnelling both for mining and municipal government projects, building wine caves, and building cave homes.

Comparison of the use of moles with conventional tunnelling method:

At present tunnelling in our country is being mostly done by conventional drilling and blasting methods which is very time consuming, which leads to delays in commissioning of projects. There is, therefore, a pressing need for employing TBMs (moles) for driving tunnels for speedy, economic and timely completion of large projects such as hydroelectric, underground metro rail and other projects requiring tunnelling work.

Use of moles have revolutionised tunnelling practises in many countries. The tunnels which would have been completed in years are executed in months.

Use of moles have Less danger of fallouts since adjacent rocks are undisturbed as no blasting is done

Uses of moles require less manpower.

Use of moles results in Reduction of tunnel supports requirement

Muck removal is continuous and fast while using moles.

Use of moles Produces smooth and round opening which is strongest available geometric configuration.