The influence of the round length on the stability of tunnel face and unsupported span

Young-Zoo Lee, Wulf Schubert, Chang-Yong Kim

Publikation: Beitrag in Buch/Bericht/KonferenzbandBeitrag in einem KonferenzbandBegutachtung

Abstract

A number of research projects on the face stability of tunnels have been carried out in the past.
However, the influence of the round length has not been thoroughly investigated, although it is an essential factor for the stability and excavation costs. This paper presents typical failure mechanisms of the face including the unsupported span in relation to the round length in weak rock tunnels, whose behavior is not governed by discontinuities. A series of small-scale model tests and numerical analyses by PFC-2D (Particle Flow Code, Itasca) were carried out to define failure modes at the face and unsupported span. Five failure modes according to its shape and extent are suggested for excavation planning. The influence of the lining stiffness
and overburden on the overbreak and round length has been investigated in the model tests. Failure mechanisms, their initiation and propagation have been also investigated by PFC analyses and compared to the results of the model tests. Overbreak in the unsupported span does not affect the face stability as long as the face is initially stable and the round length is small enough not to cause excessive overbreak or daylight collapse. Therefore, the decision on the round length should be made in consideration of the interaction of overbreak and support rather than the face stability itself.
Originalspracheenglisch
TitelUnderground Space Use - Analysis of the past and lessons for the future
Untertitelproceedings of the 31st ITA-AITES World Tunnel Congress, 7-12 May 2005, Istanbul, Turkey
ErscheinungsortLeiden
Herausgeber (Verlag)A.A. Balkema
Seiten211-216
Band1
ISBN (Print)04-1537-453-7
PublikationsstatusVeröffentlicht - 2005
Veranstaltung31st ITA-AITES World Tunnel Congress - Istanbul, Türkei
Dauer: 7 Mai 200512 Mai 2005

Konferenz

Konferenz31st ITA-AITES World Tunnel Congress
Land/GebietTürkei
OrtIstanbul
Zeitraum7/05/0512/05/05

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