Dam security is an important issue. During extreme weather events, the maximal conception level of the reservoir can be exceeded. If the water level overtops the core of a dam and if the materials in contact at the crest have incompatible grain size distributions, internal erosion can occur. The objective of this Master’s thesis is to study the evolution in time of internal erosion following core overtopping with consideration for seepage force and unsaturated seepage conditions. The main hypothesis is that internal erosion will occur where seepage forces are larger in presence of granular materials with incompatible grain size distributions.
To verify this hypothesis, numerical modelling and two tests in a tank were conducted. For each test, a trapezoidal core was put in place and surrounded by a permeable filter. Water levels and suctions were measured in the core with piezometers. The tests were filmed and sediments were collected in a sedimentation column. Water samples for the determination of the total solid content were taken when erosion occurred. Subsequently, the finite element code COMSOL was used to model transient groundwater seepage considering unsaturated conditions.
The relationship between groundwater levels, hydraulic gradients, seepage velocities, erosion rate, and the evolution of the core geometry in time was studied by combining the analysis of video sequences with numerical modelling. The initiation mechanisms of internal erosion, in this case contact erosion and regressive erosion, were evaluated. It is recommended to refine the analysis of image sequences combined with numerical modelling.
| Date | 10 Jan 2020 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | François Duhaime (Supervisor) & Yannic A. Éthier (Co-supervisor) |
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Beaudoin, A. (Author),
Duhaime (Supervisor) &
Éthier (Co-supervisor),
10 Jan 2020Student thesis: Master's thesis › Master in Engineering: Construction Engineering