Extreme long reach drives in India 08 May 2013
Robbins Video News Release
- Progress continues in India on the world's longest tunnel without intermediate access, with best excavation rates hitting 500m/month.
Alimineti Madhava Reddy (AMR) tunnel progress
- Robbins field service team is working alongside Indian contractor Jaiprakash Associates to complete the 43.5km excavation using two 10m o.d. double-shield gripper TBMs and a continuous conveyor system for muck removal from both ends of the alignment.
- Jim Clark, Projects Manager India for Robbins, said: "The geology of the tunnel consists of about 60% quartzite and 40% granite. We had expected the quartzite to be more abrasive than the granite but we found this was not the case. We have bored through several fault zones where the geology has been blocky, and large pieces of rock were causing problems with the conveyor system through the various transfer sections. We solved this by putting deflection plates in the transfer points to reduce the fall of rock."
Robbins site assembly team
- In January 2009 TunnelTalk Editor Shani Wallis visited the work site at a time when average advance rates were well below those needed to achieve the project's stiff 50-month delivery target.
- Power failures, a once-in-a-century flooding event, bedding in of training for the Jaiprakash workers, the presence of multiple fault zones, and conveyor issues, have all contributed to slowing average progress on the extremely challenging project.
- But as the relationship between the local contractor's workforce and the Robbins field service team showed signs of developing, a positive progress pattern was already emerging at the time of the TunnelTalk site visit.
- Read the site report
- Indian main contractor Jaiprakash has extensive drill+blast tunneling experience, but until now no TBM experience.
- The US$400 million Alimineti Madhava Reddy (AMR) project features at its centre a straight tunnel under a maximum cover of 500m, which is needed to avoid any pumping in the gravity feed system. It is designed to deliver water to over 120,000 hectares of agricultural land and 500 villages in the drought-prone region of Andhra Pradesh.
Serious flood setback for TBM project in India - TunnelTalk, October 2009
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