Kanpur: Under the 23 km long Corridor-1 of Kanpur Metro Rail Project (IIT to Naubasta), the construction work of about four km long tunnel for underground section between Chunniganj to Nayaganj will commence from Monday. The tunneling of this section is to be done with the help of two Tunnel Boring Machines (TBM). Both TBM machines have already been lowered inside rectangular launching shaft which has a length of about 21 meters, width of 24 meters and a depth of about 17.5 meters. From Monday, construction of down-line tunnel from Bada Chauraha to Nayaganj with the help of first TBM will begin and after about 15 days, construction of up-line tunnel will be started with the second TBM.
The Uttar Pradesh Metro Rail Corporation (UPMRC) has named the TBM machines as ‘Nana’ and ‘Tatya’ (named after Tantya Tope and Nana Rao Peshwa). These TBM machines will be used in the construction of Chunniganj-Nayaganj underground section. From Monday, excavation of down line tunnel in this section by TBM named ‘Nana’ will start. The total length of Tunnel Boring Machines used in this underground section of Kanpur Metro is about 80 meters and their weight is about 450 tonnes. With the help of these machines, tunnel of 5.8 meter diameter will be constructed.
Tunnel boring machines are the most efficient and safest instruments for tunnel construction. These machines work under the ‘Earth Pressure Balance’ system and are capable of constructing underground tunnels in the heart of the city with complete safety without affecting the traffic on the roads. World class and state-of-the-art tunnel boring machines are being used for the construction of underground sections in Kanpur Metro. The front part of the TBM is the cutterhead, with the help of which excavation is done under the ground. Thrust jack cylinders in TBM work to continuously push the front shield or front part of the machine forward. In addition to boring through the cutter head, the machine also releases a mixture of polymers and foams continuously, which further facilitates the boring or digging process.
The soil after excavation is conveyed to the conveyor belt at the rear of the machine through the machine screw conveyor and with the help of this belt the soil is taken out of the tunnel. The TBM also erects tunnel ring segments during excavation. The ring erector keeps erecting circular rings by inserting loaded ring segments in the machine. Along with this it also keeps filling a mixture of water, cement and special chemicals in the empty space to avoid water leakage and this process is called grouting.
The TBM machine itself has a backup system unit. It can also be called as the control room of TBM and from here all the processes of TBM are controlled. The machine operates 24 hours a day and the system is handled by engineers in different shifts. This control room also has the facility of rest room and toilet. The state-of-the-art computerized tunnel guidance system will ensure that the tunneling is as per the prescribed alignment. Keeping in view the safety aspect, a team of experts will also be deployed for real time monitoring during the TBM operation.
Constructing a tunnel of about 940 meters long from Bada Chauraha towards Nayaganj, the TBM will reach at the starting point of Nayaganj Metro station, where the machine will be retrieved from the retrieval shaft. Thereafter, both the machines will be re-launched from the launching shaft to be built at Chunniganj and tunnel will be constructed till the starting point of Bada Chauraha Metro Station via Naveen Market.