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Tunnel cave-in, - Convergence confinement and 2D analysis

Tunnel cave-in, - Convergence confinement and 2D analysis

Category
Academic lecture
Abstract
A serious cave-in failure in a headrace tunnel in Buon Kuop, Vietnam is analysed using convergence confinement (CC-method) and 2D numerical modelling (Phase 2). Results from convergence confinement method show that the method is an excellent tool for parameter study to obtain the reasonable rock mass properties and the appropriate failure criterion. The results from the analyses indicate that the properties obtained by observing and classifying the material in the weakness zone may replace expensive in-situ tests during the pre-investigation. The results also indicate that non-linear failure criteria, such as the Hoek-Brown failure criterion, are most suitable for analysing the problem. Subsequently, the obtained rock mass properties and the recommended failure criterion are used for 2D numerical analyses, in which the cave-in is well indicated. Excavation and support measures are also modelled. Even though, the methods produce results that match relatively good with what happens in reality, there are some limitations concerning groundwater and the support properties that one needs to be aware of. These limitations are discussed.
Language
English
Author(s)
  • Nghia Quoc Trinh
  • Einar Broch
Affiliation
  • SINTEF
  • Norwegian University of Science and Technology
Presented at
SHIRMS 2008 - 1st Southern Hemisphere International Rock Mechanics Symposium
Place
Perth
Date
16.09.2008 - 19.09.2008
Organizer
Australian Centre for Geomechanics
Year