Session Start Date

6-1-1988

Abstract

A 8.56 km long circular tunnel of 4.75 m diameter has been constructed under Maneri hydel project on the river Bhagirathi. The tunnel passes alternatively through quartzitic and metabasic rock formations of the young Himalayan terrain. Tunnel excavation was started from four faces, one at the upstream end at maneri, two from an intermediate adit at Heena, and one at the downstream end near Uttarkashi where a 80 MW surface powerhouse is located. In excavating the tunnel from different faces, the problems of tunnel face collapse with heavy ingress of water, cavity formations and large tunnel closures leading to buckling of steel ribs on account of squeezing ground conditions were encountered. In the paper the approach of these problems has been dealt in detail. The predicted values of support pressure obtained from Terzaghi, Barton et al and CMRS approaches have been compared with the observed values of support pressure. The CMRS approach shows promise for better results in both squeezing and the elastic ground conditions.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Second Conference

Publisher

University of Missouri--Rolla

Publication Date

6-1-1988

Document Version

Final Version

Rights

© 1988 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Jun 1st, 12:00 AM

Case History of Maneri-Uttarkashi Power Tunnel

A 8.56 km long circular tunnel of 4.75 m diameter has been constructed under Maneri hydel project on the river Bhagirathi. The tunnel passes alternatively through quartzitic and metabasic rock formations of the young Himalayan terrain. Tunnel excavation was started from four faces, one at the upstream end at maneri, two from an intermediate adit at Heena, and one at the downstream end near Uttarkashi where a 80 MW surface powerhouse is located. In excavating the tunnel from different faces, the problems of tunnel face collapse with heavy ingress of water, cavity formations and large tunnel closures leading to buckling of steel ribs on account of squeezing ground conditions were encountered. In the paper the approach of these problems has been dealt in detail. The predicted values of support pressure obtained from Terzaghi, Barton et al and CMRS approaches have been compared with the observed values of support pressure. The CMRS approach shows promise for better results in both squeezing and the elastic ground conditions.