The Reduction of Surface Settlement by Employing Umbrella Arch Systems

J. Oke, N. Vlachopoulos, M.S. Diederichs

In the proceedings of: GeoMontréal 2013: 66th Canadian Geotechnical Conference; 11th joint with IAH-CNC

Session: Engineering Geology I

ABSTRACT: The umbrella arch (UA) is a tunnel pre-support system that reinforces through the interaction of support and rock mass and is installed during excavation above and around the crown of the tunnel face. This paper illustrates the effect on surface settlement when UA support is installed during tunnel excavation, and addresses two major issues with regard to the UA. The first issue concerns how to accurately numerically model such a support element within a 3D analysis; the second issue relates to the reduction of subsidence when the support element is employed. The former issue is addressed using a parametric analysis involving sequentially installed UA support in order to calibrate the numerical model to published monitoring results. The latter point is demonstrated through a reduction of surface settlement of up to 60% when an UA support was additionally installed within the case study.

RÉSUMÉ: Le fiUmbrella Archfl (UA) est un système de support utilisé lors de la construction de tunnels. Ce support sert à renforcir la structure du tunnel grâce à l'interaction entre le support et la masse rocheuse. Ce système est installé pendant l'excavation au dessus et autour de la couronne du tunnel. Cet article illustre l'effet du tassement à la surface lorsque le UA est installé pendant l'excavation du tunnel et aborde deux problèmes majeurs. Le premier problème concerne la méthode de modélisation numérique pour une analyse en 3D d'un tel type de support. Le deuxième problème touche la réduction du tassement lorsque le support est utilisé. Ce dernier problème est traité en utilisant une analyse paramétrique impliquant l'installation séquentielle du UA de façon à calibrer le modèle numérique avec des résultats publiés. La calibration est démontrée en utilisant une étude de cas impliquant une réduction de 60% du tassement de la surface une fois que le support en arc a été installé.

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Cite this article:
J. Oke; N. Vlachopoulos; M.S. Diederichs (2013) The Reduction of Surface Settlement by Employing Umbrella Arch Systems in GEO2013. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoMon2013Paper443,author = J. Oke; N. Vlachopoulos; M.S. Diederichs,title = The Reduction of Surface Settlement by Employing Umbrella Arch Systems,year = 2013}