Location

New York, New York

Session Start Date

4-13-2004

Session End Date

4-17-2004

Keywords and Phrases

Narmada dam, Bagh beds, intra-formational shears, settlement, sliding, shear keys, concrete plug.

Abstract

Geotechnical evaluation of the 163 m high concrete gravity Sardar Sarovar (Narmada) dam, under construction, and 1200 MW underground powerhouse (210m x 23m x 57.5m) and its ancillary structures has been done. The dam and powerhouse sites are occupied by basalt flows underlain by infra-trappean sedimentary rocks (Bagh beds) intruded by basic dykes. The area is structurally complex and seismically active. Intra-formational shears and sub-horizontal to low dipping weak layers like red bole, tuff, argillaceous sandstone having low values of shear parameters posed the problem of sliding stability of dam blocks. Concrete shear keys were provided as one of the remedial measures. Differential settlement was apprehended in the foundation of dam having varying physicoengineering properties and rock mass characteristics. Reinforced concrete mats were provided to treat the weathered and sheared rock mass and 34.5m deep reinforced concrete plug to prevent differential settlement of dam blocks located on river channel (dam base) fault. The horizontal seismic coefficient adopted for the dam is 0.125g. The construction of 1200 MW underground powerhouse located in basalt is nearing completion. During progressive excavation of the machine hall (cavern) cracks were observed in the 57.5m high shotcreted walls. Additional longer rock bolts/ cables/ tendons were provided as remedial measures. Draft tube and exit tunnels are passing through dolerite rocks dissected by chlorite-coated joints and slaked rock zones. Rib supports were introduced after observing behaviour of the rock mass and collapses in part of these tunnels.

Department(s)

Civil, Architectural and Environmental Engineering

Appears In

International Conference on Case Histories in Geotechnical Engineering

Meeting Name

Fifth Conference

Publisher

University of Missouri--Rolla

Publication Date

4-13-2004

Document Version

Final Version

Rights

© 2004 University of Missouri--Rolla, All rights reserved.

Document Type

Article - Conference proceedings

File Type

text

Language

English

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Apr 13th, 12:00 AM Apr 17th, 12:00 AM

Rock Mass Evaluation of the Sardar Sarovar (Narmada) Dam and Underground Powerhouse, India

New York, New York

Geotechnical evaluation of the 163 m high concrete gravity Sardar Sarovar (Narmada) dam, under construction, and 1200 MW underground powerhouse (210m x 23m x 57.5m) and its ancillary structures has been done. The dam and powerhouse sites are occupied by basalt flows underlain by infra-trappean sedimentary rocks (Bagh beds) intruded by basic dykes. The area is structurally complex and seismically active. Intra-formational shears and sub-horizontal to low dipping weak layers like red bole, tuff, argillaceous sandstone having low values of shear parameters posed the problem of sliding stability of dam blocks. Concrete shear keys were provided as one of the remedial measures. Differential settlement was apprehended in the foundation of dam having varying physicoengineering properties and rock mass characteristics. Reinforced concrete mats were provided to treat the weathered and sheared rock mass and 34.5m deep reinforced concrete plug to prevent differential settlement of dam blocks located on river channel (dam base) fault. The horizontal seismic coefficient adopted for the dam is 0.125g. The construction of 1200 MW underground powerhouse located in basalt is nearing completion. During progressive excavation of the machine hall (cavern) cracks were observed in the 57.5m high shotcreted walls. Additional longer rock bolts/ cables/ tendons were provided as remedial measures. Draft tube and exit tunnels are passing through dolerite rocks dissected by chlorite-coated joints and slaked rock zones. Rib supports were introduced after observing behaviour of the rock mass and collapses in part of these tunnels.