Session Start Date

6-1-1988

Abstract

A double tunnel of 6.3 m height has been driven in loess underground of low friction and relatively large capillary cohesion. To attain a tunnel climate corresponding to natural underground conditions, earth windows were provided along the side walls of the tunnel. The portal was supported by steel profiles, anchors and a shotcrete layer. The stability of the retaining construction was ensured by two independent methods. A preexcavation of the tunnel was found to be necessary. The works were performed simultaneously with excavation of the hillside facing the portal. The tunnel lining consists of reinforced shotcrete. The bearing behaviour of the lining was investigated through different finite element analyses assuming both a single tunnel and the double tunnel. For the latter case, a simultaneous excavation as well as successive individual excavations were studied. The support system of the final tunnel faces is presented. A comparison of both measured and calculated convergences is given. During excavation of the hillside facing the portal a crack occurred in the supported ground. Good agreement was obtained between the observed crack course and the one presumed in the stability analyses.

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

Construction of a Double Tunnel with Ground Windows

A double tunnel of 6.3 m height has been driven in loess underground of low friction and relatively large capillary cohesion. To attain a tunnel climate corresponding to natural underground conditions, earth windows were provided along the side walls of the tunnel. The portal was supported by steel profiles, anchors and a shotcrete layer. The stability of the retaining construction was ensured by two independent methods. A preexcavation of the tunnel was found to be necessary. The works were performed simultaneously with excavation of the hillside facing the portal. The tunnel lining consists of reinforced shotcrete. The bearing behaviour of the lining was investigated through different finite element analyses assuming both a single tunnel and the double tunnel. For the latter case, a simultaneous excavation as well as successive individual excavations were studied. The support system of the final tunnel faces is presented. A comparison of both measured and calculated convergences is given. During excavation of the hillside facing the portal a crack occurred in the supported ground. Good agreement was obtained between the observed crack course and the one presumed in the stability analyses.