ROCK MECHANICS AND TUNNELING REPORT

ON

PIR PANJAL RAILWAY TUNNEL: CASE STUDY

SUBMITTED BY:

Akshay Kumar

Devyani Tewatia

Kavita Verma

Prateek Roshan

School of Engineering

Gautam Buddha University

IntroductionA tunnel is an underground or underwater passageway, dug through the surrounding soil/earth/rock and enclosed except for entrance and exit, commonly at each end.

A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal.

Tunnels are dug in types of materials varying from soft clay to hard rock. The method of tunnel construction depends on such factors as the ground conditions, the ground water conditions, the length and diameter of the tunnel drive, the depth of the tunnel, the logistics of supporting the tunnel excavation, the final use and shape of the tunnel and appropriate risk management.

There are three basic types of tunnel construction in common use:

Cut-and-cover tunnels, constructed in a shallow trench and then covered over.

Bored tunnels, constructed in situ, without removing the ground above. They are usually of circular or horseshoe cross-section.

Immersed tube tunnels, sunk into a body of water and sit on, or are buried just under, its bed.

Indian Railway has constructed a rail link project from Udhampur-Srinagar-Baramulla which is the lifeline for the people of Jammu and Kashmir in India. The alignment is passing through the mountains of the Himalayas and crossing high current flowing rivers. Hindustan Construction Company Ltd. is executing the India’s longest Railway Tunnel which connects Bichlari Valley at the South side with Kashmir Valley at the North side, is named as PIR PANJAL TUNNEL.

The Pir Panjal Tunnel is a work of Pioneering nature being the longest transport tunnel in India and may become a benchmark for more ambitious and longer transport tunnels in future. The quantum of work involves one million cum of underground excavation. 11 Km long tunnel is completely straight in almost N_S direction. Maximum overburden is approx.. 1100m. Tunnel is at 440m lower level than road tunnel and will be much less vulnerable to snow.

The single track tube has been adopted with side road for repair/ emergency rescue. The clear 3m wide passage exists in the cross-section all along extends outside the portals. Rising grade of 1% from south to the high point at Km. 159.134 followed by a falling gradient of 0.5% towards north end (for better constructability). Tunnel will be provided with properly conceived ventilation, fire fighting and monitoring systems.

The whole tunnel is being constructed by utilising New Austrian Tunnelling Method in composition of rock formations from soft to medium strength. Laser-guided alignment control system is also provided to facilitate correct excavation.

Highlights of constructionThe underground tunnel excavation by Roadheader is carried out in Rock Class III, IV and V, having Unconfined Compressive Strength from 40MPa to 60MPa.(Photo 2) Underground excavation is excavated by Roadheader in a heading section only.

Underground Tunnel Excavation by Roadheader

In operation of underground tunnel excavation, the telescopic boom is moved horizontally as well as vertically to excavate the rock from central crown portion to side walls with the help of cutterhead. Excavated material is collected by loading apron and sent to the conveyor belt. The dedusting unit must function properly during tunnel excavation by Roadheader. According to behaviour of rock mass, operator has changed driving frequency from zero to 200Hz in assistance of Variable Frequency Drive Unit. Operator has to protect his body and eyes by wearing PPE.