The stability analysis of large-span tailrace bifurcation tunnels with complex 3D geometries and the associated challenges are presented in this paper. A new nonlinear reinforcement analysis method is firstly proposed for the design of reinforcement systems, i.e. steel-reinforced concrete lining and rock bolts, for large-span tailrace tunnel bifurcations with complex 3D geometries. The proposed method is then implemented into FLAC3D using the FISH language to calculate the reinforcement parameters and the resultant nonlinear stress distributions. After that, it is validated by comparing the concrete lining stresses and reinforcement obtained by the proposed method with the analytical solutions for the ideal case of a circular tunnel in an infinite elastic body. Finally, the new method is applied to calculate the distribution of deformations, stresses, plastic zones and design the reinforcement system for the large-span tailrace tunnel bifurcation in the Guandi Hydropower Station during the construction, operating and maintenance periods, respectively. The calculated reinforcement parameters successfully guided the construction of the tunnel. The proposed nonlinear reinforcement analysis method may also be beneficial to the design and construction of other large-span tunnel bifurcations with complicated irregular cross sections in similar hydropower projects currently ongoing in southwest China.

Item Type:	Refereed Article
Keywords:	large-span tunnel stability, nonlinear reinforcement analysis and design, bifurcated tunnel, Guandi Hydropower Station
Research Division:	Engineering
Research Group:	Resources engineering and extractive metallurgy
Research Field:	Geomechanics and resources geotechnical engineering
Objective Division:	Construction
Objective Group:	Construction processes
Objective Field:	Civil construction processes
UTAS Author:	Liu, H (Dr Hong Liu)
ID Code:	86677
Year Published:	2013
Web of Science® Times Cited:	38
Deposited By:	Engineering
Deposited On:	2013-10-09
Last Modified:	2017-11-06
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