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Camera rig setups (a) Model U1-U3 (b) Model U4-H3, camera locations indicated by yellow circles, coordinate system definition shown on (b) with red arrows and axis labels (c) shows DSLR image of a GCP cube (d) shows video frame of the same GCP cube.
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Dam failures are examples of man-made disasters that have stimulated investigation into the processes related to the failure of different dam types. Embankment dam breaching during an overtopping event is one of the major modes of failure for this dam type, comprising both earthfill and rockfill dams. This paper presents the results of a series of...
Citations
... Previous research works investigated overtopped models (Dezert et al. 2022) from laboratory experiments conducted at the Hydraulic Laboratory (Norwegian University of Science and Technology, Trondheim) with different designs of rockfill dams, and recently Kiplesund et al. (2023) focused on breach progression for unprotected rockfill dams from laboratory experiments, using Structure from Motion techniques with Agisoft Metashape software. These photogrammetric techniques enable building 3D models of a structure from multiple 2D pictures. ...
The primary cause of embankment dam failure is the overtopping of the crest, making dam safety a crucial consideration due to the potential for catastrophic consequences. Dam safety regulations and guidelines are increasingly demanding the enhancement of rockfill dams' resistance to overtopping and leakages. Assessing the breaching of embankments is essential for conducting risk evaluations and hazard studies. Typically, this assessment is carried out using parametric breach models, which are statistically derived equations based on historical dam failure cases. However, these models often overlook important parameters such as material properties, leading to uncertainties in the results. This research focuses on quantifying the accuracy of breach parameters (breach width, failure time, peak outflow) predicted by various parametric breach models found in the literature. Three prototype embankment dams (homogeneous earthfill dam, homogeneous rockfill dam, and zoned rockfill dam), along with five historical failure cases, are considered to evaluate the predictive capability of the parametric breach models. The study compares the measured and estimated breaching parameter values, aiming to identify the most suitable parametric breach model based on the dam design. The results indicate that the performance of the different equations in estimating breach parameters significantly depends on the characteristics of the dam and reservoir. Additionally, a simplified physical model (DLBreach) is employed to estimate breach parameters for the three prototype dams, and a comparison with results from parametric breach models is presented. In conclusion, accurately predicting breach parameters is vital for improving dam safety. This research highlights the influence of dam and reservoir characteristics on the performance of different parametric breach models. By identifying the most suitable breach models for specific dam designs, this study contributes to the understanding and management of embankment dam failures.
... In this article, we are not going deep into the description of the structure from motion technique but just highlight the main steps. Detailed information can be found in Agisoft User manual (Agisoft LLC 2021) and in Kiplesund et al. (2023), where the structure from motion technique is used to model an experimental rockfill dam under overtopping conditions from video recording. The detailed algorithms used by Agisoft software have not been published. ...
Improving the knowledge of the failure mechanism of riprap exposed to overtopping is valuable to enhance the construction and reinforcement techniques of rockfill dam defense systems. In this research, four experimental overtopping tests were carried out on 1∶10 rockfill dam models with placed riprap protection layers supported at the toe. Axial reaction loads were measured and 3D models were built using the structure from motion technique to study the displacement of riprap stones exposed to overtopping. The importance of throughflow in the rockfill shoulder is brought to light by comparing these results with previous data from a placed riprap model built on a ramp without throughflow. The structure from motion technique demonstrates to be very effective and highlights the existence of a buckling phenomenon, along with the compaction of the riprap. The displacement data show that the compaction mechanism is more important (both horizontally and vertically) and appears at lower overtopping discharges for less packed placed riprap layer. Finally, similar trends for vertical and horizontal riprap displacements are demonstrated between the initial position and the last position before failure. Such information suggests that the critical discharge value is not as critical as the riprap displacement to predict dam failure under overtopping conditions.
Understanding and modeling a dam breaching process is an essential investigation, because it aims to minimize the flood’s hazards, and its impact on people and structures, using suitable mitigation plans. In the current study, three-dimensional numerical modeling is carried out using the FLOW-3D HYDRO program to investigate the impact of various factors, including the dam grain size materials, crest width, inflow discharge, and tail water depth on the dam breach process, particularly the peak outflow, and the erosion rate. The results show that changing the grain size of the dam material from fine sand to medium and coarse sand leads to an increase in the peak outflow discharge by 16.0% and the maximum erosion rate by 20.0%. Furthermore, increasing the dam crest width by 40% leads to a decrease in the peak outflow by 3.0% and the maximum erosion rates by 4.50%. Moreover, increasing the inflow discharge by 25.0% increases the peak outflow by 23.0% and the maximum erosion rates by 21.0%. Finally, increasing the tail water depth by 50.0% leads to decreasing the peak outflow by 4.50% and the maximum erosion rate by 43.0%. The study findings are considered of high importance for dam design and operation control. Moreover, the results can be applied for the optimum determination of the crest width and tail water depth that leads to improving the dam stability.
