Abstract:

Regulating conduits through embankment dams are used to convey water from reservoirs to discharge points downstream. The conduits can increase the potential for internal erosion in the embankment dam body or foundation due to poor design and construction. A conduit can develop defects due to deterioration, differential settlement or conduit joint separation. The shear stress from leaking water flow caused by defects can initiate internal erosion at the conduit interface and its surrounding filter or embankment materials. Internal erosion may trigger serious damage to or failure of embankment dams.

This paper first reviews the best practice available for the geotechnical and structural design of a conduit through an earthen dam. It also studies a simple hypothetical case for possible seepage and internal erosion around the conduit. The finite element code COMSOL will be used to model the water flow in the embankment and the conduit based on water conservation equations at the continuum scale. The simple empirical and semi-empirical methods are applied to evaluate the erosion process using the hydraulic gradients and water velocity calculated from the COMSOL model and the filter material properties. Finally, the paper recommends more robust methodology to evaluate internal erosion around the conduits.

Biography of the presenter: Dr. Vahid Marefat is a professional engineer with more than 12 years’ experience in the domain of geotechnical and geoenvironmental engineering. He has worked on numerous geotechnical projects including tailings and earth-fill dam design, foundation design, 3D and 2D slope stability and seepage analysis, instrumentation, geotechnical investigation, as well as projects management. Dr. Marefat’s research and expertise centered on foundation design, geotechnical design of tailings/earth-fill dams and waste rock piles. His expertise has also extended to the geotechnical engineering and hydrogeology of the Champlain Clay. In addition, Dr. Marefat has led and supervised several complex research projects on geotechnical instrumentation, geotechnical field and laboratory tests, grouting and climate impact on the foundation engineering in the laboratory of Geotechnical and Geoenvironmental Engineering and in the laboratory for Hydrogeology and Mining Engineering in Montréal, Québec, Canada. Dr. Marefat has demonstrated great leadership in construction project management in both the public and private sectors, with strong performance in budget and schedule control.

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Dr. Vahid Marefat