Numerical simulations have been widely used to predict groundwater inflow into tunnels during excavations. An appropriate geometric size of a numerical model is crucial for reducing the simulation time and ensuring the accuracy of numerical results. However, to the best of our knowledge, no information concerning the scale effect of the model extent on the seepage characteristics of tunnels under drained conditions has been published. This study evaluates how the model extent affects the tunnel inflow, drawdown, and water pressure via the Signorini type variational inequality formulation. A series of two-dimensional finite element models are conducted with various combinations of tunnel parameters, including tunnel radius, initial groundwater level, lining thickness, and relative permeability. Subsequently, a comprehensive function to yield the optimum model extent within an allowable error is proposed. Interestingly, the optimum model extent for both tunnel inflow and water pressure decreases with an increase in the relative permeability, whereas that of the drawdown exhibits the opposite pattern. A model extent of no less than 200 times the tunnel radius is recommended to acquire accurate model results and is verified with existing analytical methods. This study therefore not only highlights the drainage effect of the tunnel but also provides universal suggestions for engineering practice.
Scale Effect of the Model Extent on Seepage Analysis of Circular Tunnels under Drained Conditions
KSCE J Civ Eng
KSCE Journal of Civil Engineering ; 26 , 12 ; 5358-5371
2022-12-01
14 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
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