Assessment of groundwater ingress to a partially pressurized water-conveyance tunnel using a conduit-flow process model: a case study in Iran

Gholizadeh, Hossein; Behrouj Peely, Ahmad; Karney, Bryan W.; Malekpour, Ahmad

Assessment of groundwater ingress to a partially pressurized water-conveyance tunnel using a conduit-flow process model: a case study in Iran | Evaluation de la pénétration des eaux souterraines dans un tunnel transportant de l’eau en partie sous pression, d’après un modèle du processus d’écoulement en conduite: une étude de cas en Iran Evaluación de la afluencia de aguas subterráneas a un túnel de conducción de agua parcialmente presurizado mediante un modelo de flujo por conducto: un estudio de caso en Irán 使用管流模型评估地下水进入部分加压输水隧道的入口:以伊朗某案例为例 Avaliação do ingresso de águas subterrâneas em um túnel de transporte de água parcialmente pressurizado utilizando um método de processo de fluxo-conduíte: um estudo de caso no Irã

2020

Gholizadeh, Hossein | Behrouj Peely, Ahmad | Karney, Bryan W. | Malekpour, Ahmad

Construction of a conveyance tunnel through rock often induces the ingress of groundwater into the tunnel, a flow that changes both the hydrogeological regime of the tunnel and its environment. To explore this key interaction, a novel modeling approach using the conduit flow process (CFP) is developed that considers both the hydraulic head and the ingress of water from the rock matrix during excavation. The resulting flow values are predicted through an adapted MODFLOW numerical model into which the tunnel is introduced with the aid of the new CFP approach. The CFP approach can simulate both laminar and turbulent flow in the tunnel whether the flow is free surface or pressurized. Several simulations, including one for which the permeability of the tunnel perimeter is assumed to be identical to the hydraulic conductivity of the surrounding rock matrix, are then used to explore the sensitivity of the predicted head and flow conditions to the permeability of the tunnel perimeter. Comparisons of the numerical results with field data from the Kerman Water Conveyance Tunnel in Iran show that the proposed approach accurately predicts the spatial variation of both groundwater ingress and hydraulic head.

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