Abstract

PINA, Adriana; CORTES, Diego; DONADO, Leonardo David  and  BLESSENT, Daniela. Embedded Discrete Fracture Networks to Analyze Groundwater Inflows during Tunnel Drilling. Ing. Investig. [online]. 2022, vol.42, n.1, e105.  Epub Oct 29, 2021. ISSN 0120-5609.  https://doi.org/10.15446/ing.investig.v42n1.89889.

Tunnels commonly go through fracture zones, which are analyzed as an equivalent porous medium with homogeneous permeability. However, this is a rough simplification that overlooks the connection triggered by underground works in fractured massifs. This study introduces the use of synthetic discrete fracture networks (DFN) to analyze groundwater inflows through tunnel excavation in a fractured zone while considering the daily advance of the drilling front. First, a hypothetical case with six different settings, varying fracture length and density, as well as aperture distribution, was analyzed. Each setting had about 100 realizations. DFN hydraulic properties were estimated and compared with previous DFN studies, displaying the same behavior even though the magnitude of the estimated parameters differed. As an application example, structural measurements of the Alaska fault zone in the La Línea massif (Colombia) were used to obtain the statistical parameters of fracture length and aperture distributions to generate the DFN. Five settings were built, obtaining measured and simulated groundwater inflows of the same order of magnitude. These results highlight the potential of synthetic discrete fracture networks to analyze the effects of tunnel construction on groundwater flow.

Keywords : discrete fracture networks; groundwater inflows; numerical modeling; tunnel.

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