Browsing by Author "Dumlu, Emre"

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Experimental and Numerical Investigation of the Evolution of Piping and Resulting Breach in Earth-Fill Dams
(01. Izmir Institute of Technology, 2022-12) Dumlu, Emre; Tayfur, Gökmen; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Earth-fill dams have been constructed for decades by compacting natural soil materials near the dam site. Piping is of the most important causes of their failure. In the scope of this thesis, 2 m in length homogenous earth-fill dams were constructed in a rectangular flume in the laboratory of the Izmir University of Economics. The experimental and numerical investigations on a breach by generating piping were realized with different weak zone scenarios. Three experiments were performed by placing a weak layer cross-section 5x5 cm2 at the dam bottom center. One scenario was performed by locating a weak layer of 2x2 cm2, 28 cm above the bottom. Temporal breach areas and the breach-wetted areas are evaluated on scaled screenshots by using Gauss’s area formulation. The Temporal breach discharges were calculated from the continuity equation. Furthermore, finite element analyses on the breaching of homogenous earth-fill dams in different scenarios were performed by comparing the hydraulic gradient with the critical value. In addition to the bottom and middle scenarios, two upper scenarios were also modeled. The water depths were used for each scenario to represent the experimental conditions, and some approaches were made for the weak zones. To simulate the breach mechanism with different loops, a python algorithm was integrated with the Jupyter console. As a result of the simulations, it has been observed that the findings obtained by simulations were in accord with the experimental studies, and the dams were exposed to backward piping starting from downstream towards upstream.
Experimental Study of Evolution of Breach Resulting From Piping at Upper Part of Earth-Fill Dam
(Turkish Chamber Civil Engineers, 2025) Guney, Mehmet Sukru; Tayfur, Gokmen; Bor, Asli; Okan, Merve; Dumlu, Emre; Aklık, Pelin; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Piping and overtopping are the most important causes of earth-fill dam failure. Such dams may erode under seepage, causing a reduction in the structural strength. The aim of this study was to investigate the temporal evolution of the breach and flow rate from the breach resulting from the piping in earth-fill dams. The experiments were carried out at Hydraulics Laboratory of Civil Engineering Department of İzmir University of Economics. The dam was constructed by using a mixture consisting of 85 % sand and 15 % fine (low plasticity clay). In the first scenario a circular tunnel with a diameter of 2 cm was created along the centreline at 6 cm below the dam crest whereas in the second one it was located at the upper edge. Six cameras at different locations recorded the evolution of the progress of the breach formation. The pump flow rate was measured by magnetic flow meter, and the continuity equation was used to calculate the flow rate values from the breach. The time-varied values of the total breach areas were determined using the Gauss Area formula. The image processing method was also applied in the determination of the breach areas. The time-dependent changes of water depth in the channel were also recorded. The obtained experimental findings are presented and commented, together with the universal dimensionless curves. The failure of the dams occurred mainly because of the head cut erosion developed from downstream to upstream. When breaching started, the orifice flow was converted to open channel flow where breach bottom behaved like a broad crested weir. In the second scenario, the rigid lateral side considerably influenced the flow rate and the development of the breach. The peak flow rate corresponding to the first scenario was found approximately 2.3 times greater than that of the second one. The maximum values of all the breach parameters were reached earlier in the case of the seepage along the centerline. The ratios between the values corresponding to the first and the second scenarios were found as 3.25 and 1.75 for maximum breach areas at downstream and at upstream sides, respectively. These ratios were 2.44 and 1.37 for the average breach widths at downstream and upstream sides, respectively. A very good agreement was found between the area values obtained from Gauss area method and image processing technique, in both scenarios. This fact demonstrated that either of these two approaches can be used to determine the time-dependent breach areas. These experimental findings provide the opportunities for the calibration and validation of the numerical models used in the relevant numerical investigations. This study also offers guidance for the strategies concerning emergency action plans related to the failure of homogeneous earth-fill dams when the piping starts at upper part of the homogeneous earth-fill dams.
Citation - Scopus: 1
Experimental Study of the Evolution of the Breach and the Discharge Through the Breach Resulting From Piping Due To Seepage at the Earth-Fill Dam Bottom
(Avestia Publishing, 2022) Güney, Mehmet Şükrü; Dumlu, Emre; Okan, Merve; Bor, Aslı; Aklık, Pelin; Tayfur, Gökmen; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
Piping is one of the main causes of the earth-fill dam failures. Most of the researchers realizing numerical analyses make some simplified assumptions concerning the shape of the breach and the discharge of water flowing through the breach. The aim of this study is to realize experiments to provide data needed to perform numerical analyses by making more realistic assumptions. The dam having a height of 0.6 m, a bottom width of 2 m and a crest width of 0.20 m is built in a channel 1 m wide, 0.81 m high and 6.14 m long. The evolution of the breach and the discharge through the breach resulting from piping due to seepage at the earth-fill dam bottom was investigated experimentally. The evolution of the dam failure is recorded by six cameras located at different locations. The time-varied of the breach areas at upstream and downstream sides are determined by applying the Gauss Area functions. The discharge of water through the breach and average outflow velocity are determined by using the continuity equation.
Citation - WoS: 2
Citation - Scopus: 2
Experimental Study of the Evolution of the Breach and the Discharge Through the Breach Resulting From Piping Due To Seepage at the Earth-Fill Dam Top
(Iahr-int Assoc Hydro-environment Engineering Research, 2022) Guney, Mehmet Sukru; Okan, Merve; Dumlu, Emre; Bor, Asli; Aklik, Pelin; Tayfu, Gokmen; 01. Izmir Institute of Technology
Internal erosion, also known as piping, is one of the most important causes of earth-fill dam breaks. Many researchers dealing with numerical analyses in this area make some simplified assumptions about the shape of the breach and the discharge of water flowing through the breach. This study was conducted in the scope of the project supported financially by the Scientific and Technological Research Council of Turkey and it consists of experimental study which aims to provide data needed to perform numerical analyses with more realistic approaches. A dam with a height of 0.6 m, a bottom width of 2 m and a crest width of 0.20 m was built in a flume 1 m wide, 0.81 m high and 6.14 m long. Before the construction of the dam, some common soil mechanics tests were carried out. The dam was constructed by using a mixture consisting of 85 % sand and 15 % clay. A circular tunnel with a diameter of 2 cm was created along the centerline at 6 cm below the dam crest. In the closed system, water was pumped from the lower reservoir to the upper channel. Six cameras located at different locations recorded the evolution of the dam failure. Gauss Area formula was applied to determine the time-varied of the breach areas at upstream and downstream sides. The discharge of water through the breach and average flow velocity were determined by using the continuity equation. The changes in water depth in the channel were also recorded.
Numerical Study of Breaching at Upper Parts of Homogenous Earthen Dams
(Springer Heidelberg, 2025) Dumlu, Emre; Guney, Mehmet Sukru; Okan, Merve; Ozden, Guerkan; Tayfur, Gokmen; 03.03. Department of Civil Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
In this study, time-dependent finite element analyses of the breaching process in two homogenous earth-fill dams were performed using the finite element method. Breaching was initiated at the middle and corner sections of the upper part of the dam bodies. The numerical results were compared with the findings of the experiments realized on dams 60 cm high, 2 m wide at bottom, 20 cm wide at crest with 1 V:1.5H side slopes at upstream and downstream faces. This numerical study combines time-dependent hydraulic gradient distributions and groundwater flows to assess breach areas, velocities, and flow rates. A Python algorithm was integrated with the Jupyter console, allowing the simulation of the breach mechanism in multiple runs to determine breach parameters. Both numerical and experimental analyses revealed that the dams were exposed to backward erosion, starting at the downstream side of the dam and progressing inward. The compatibility between experimental and numerical results was sought by means of the parameters RMSE, MAE and the statistical performance of the numerical approach was evaluated by using RSR, NSE, and PBIAS. A fairly good agreement was obtained between the experimental and numerical results.