Installation time of ground support in many caverns excavation is mainly based on analytical and empirical method, instead of the robust numerical simulations. A novel graph method is proposed to determine the installation time of the support upon finite difference method (FDM) simulation. A three dimensional numerical model for the diversion tunnel of Guandi hydropower station is developed. The curve d-r between the convergence d and the excavation unloading rate r is built up upon one-step excavation simulation. Meanwhile, the curve d-l between d and the distance from the tunnel face l, is established via the step-by-step simulation. Using the dimensionless convergence λ instead of d in both curve d-r and curve d-l, curve λ-r and curve λ-l can be yielded to achieve the composite graph r-λ-l. When r = r0, l can be chose as l0 along the identical λ in the comprehensive graph r-λ-l, where r is the excavation unloading rate at the critical plastic state and l0 is the distance from the tunnel face to the support installation location. The proposed graph method is demonstrated to meet well with common sense upon the diversion tunnel of Guandi hydropower station and can be conveniently realized in other engineering practice.
Installation Time of Ground Support during Tunnel Excavation: A Novel Graph Methodology
KSCE J Civ Eng
KSCE Journal of Civil Engineering ; 24 , 12 ; 3866-3874
2020-12-01
9 pages
Article (Journal)
Electronic Resource
English
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