كاربرد رابطه مانينگ در تجزيه و تحليل جريان درون مصالح سنگريز

APPLICATION OF MANNING FORMULAE FOR ANALYSIS OF FLOW IN ROCKFILL

In analysis of flow through rockfill media, due to high velocity and Reynolds number, the flow is transformed to non-Darcy state. In a Darcian flow, due to the linear relationship between velocity and hydraulic gradient, analysis is made more easily. However, by increasing the flow velocity, the regime is diverted from Darcy law and becomes turbulent where its analysis is more complicated. At the present stage, there are no exact criteria to distinguish between Darcy and non-Darcy flow. Since the Manning equation has a wide application in open channel flow, in the present paper the concept of Darcyʹs friction factor has been combined with Manningʹs equation and a new form of equation has been obtained for analysis of flow through a rockfill media. In the process of investigation, two sets of laboratory data from the tests conducted on flow through unconfined and confined rockfill media were obtained and the analytical relationships were calibrated accordingly. Based on the analytical solution and laboratory data, for determination of Manningʹs roughness coefficient (n), new relationships were developed. For this purpose, more than 150 laboratory data from flow through confined and unconfined flumes filled with rockfill materials were used. The results of the investigation have proved the validity of application of the Manning equation in a fully rough flow.