Methods of Tunnel Construction.

The following civil engineering aspects you shall focus upon if it is a manual tunnelling method used for road construction (smaller projects)

1.    Techniques of controlled blasting (tamrock boomer)

2.    Rock bolt anchoring (for stabilising rock excavations)

3.    Shotcreting of walls (inner side)

 

For in case of tunnelling at longer lengths (like underground metro or large rail road projects, hydro power project) tunnel boring machines (TBM) are used also its depends on alignment and shape of tunnel section. TBMs are the current trend and an effective way of building tunnels. But isn't cost effective when the lengths are short.

TBM is itself is such a huge automated equipment that simultaneously bores, transports surplus earth, places precast slabs at its required places, fixes the slabs and water proofing with pressure grouting. All these works are being done continuously while TBM is on move, with the help of few competent operators. The TBM needs an entry pit and an exit pit. Entry pit is from where the tunnel starts, as it moves forward, the exit pit is dug where the desired tunnel ends and the machine is taken out. Entry pit is point A and exit pit is point B. The machine is taken out after point B and the pit is closed or used for further activities as required.