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1. Piping failure processes resulted in a breach, a) initiation, b) continuation, c) progression, d) the collapsing of the dam roof, e) final breach formation (Okeke et al, 2012)
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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...
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Citations
... Insight of the study, it was observed that the breach at upstream was found greater than that at downstream. Dumlu (2022) performed several piping experiments by creating a weak layer at different positions within the homogenous earth-fill dam to initiate piping. He concluded that the erosion started at downstream, developed and continued inward toward upstream. ...
One of the most prominent failure reasons for earth-fill dams is internal erosion resulting from piping. This failure mode may cause irreversible weakened structural integrity, loss of properties, and even loss of lives. Therefore, it is important to understand the breaching process due to piping by providing reliable data for the decision-makers in case of emergency. This study was supported by the Scientific and Technological Research Council of Turkey with project number 119M609 and involves experimental investigation on piping under three different weak zone scenarios to examine the breach process and provide the data for more realistic numerical evaluations. The experiments were conducted in the hydraulic laboratory of Izmir University of Economics and Dokuz Eylul University. The initiation of piping was triggered from seepage in weak layers at the bottom, middle, and upper parts, along the centerline of homogenous earth-fill dams in a rectangular flume. As a result of the experiments, the magnitude of the peak discharges and their durations as well as the eroded breach areas were found to be affected by the locations of the seepage and initial water heads acting on the weak zones. Also, in the experiments, at the beginning of the breaching, initial cascading surface flow resulted in sheet and rill erosion.
... In Mehmet Sukru . In addition to these submitted papers, two master theses were also prepared and submitted (Dumlu, 2022;Okan, 2022). ...
One of the most significant reasons for earth-fill dam failures is internal erosion resulting from piping. This research was carried out as a part of a project supported financially by the Scientific and Technological Research Council of Turkey (TÜBİTAK). This paper involves the comparison of the experimental findings related to two different scenarios to look into the breach process and to provide the data allowing the realization of more realistic numerical analyses. A circular tunnel of 2 cm diameter located 6 cm below the dam crest was created to induce the seepage. The experiments were conducted at Hydraulics Laboratory of Civil Engineering Department within İzmir University of Economics. The homogeneous earth-fill dams having a height of 0.60 m and a bottom width of 2 m were built in a flume 1.00 m wide, 0.81 m high and 5.44 m long. Some common soil mechanics tests were carried out before the dam was built. The dam bodies were constructed by using a mixture of 15 % clay and 85 % medium sand. High-precision cameras were used to record the temporal development of the breach resulting from the piping. The pump flow rate was measured by a magnetic flowmeter and the flow rate values outgoing from the breach were determined from the continuity equation. Gauss area formula was used to obtain the time-varied values of the breach areas. The temporal changes of water depth in the channel were also recorded. The so obtained experimental findings are presented and commented.
... In addition to these submitted papers, two master theses were also prepared and submitted (Dumlu, 2022;Okan, 2022). This paper involves experimental results concerning the evolution of dam failure due to the seepage at the upper part of an earthfill dam with clay core. ...
One of the most significant reasons for earth-fill dam failures is internal erosion, often known as piping. This research was carried out as part of a project funded by the Scientific and Technological Research Council of Turkey (TÜBİTAK) and it involves an experimental investigation to look into the breach process and provide the data for more realistic numerical evaluations. The experiments were conducted at Hydraulics Laboratory of Civil Engineering Department within İzmir University of Economics. The earthen dam with clay core 0.65 m high, a bottom width of 2 m and a crest width of 0.05 m was built in a flume 1.00 m wide, 0.81 m high and 5.44 m long. Some common soil mechanics tests were also carried out before the dam was built. The dam body was constructed by using a mixture of 15 % clay and 85 % sand. The clay core width was 15 cm at bottom and 1 cm at crest. The weak layer of a cross section of 5x5 cm2 was created by no-compacted soil mixture, and it was placed at 60 cm level from the bottom, along the centerline of the dam. High-precision cameras were used to record the temporal development of the breach resulting from the piping. The pump flow rate was measured by magnetic flowmeter and the flow rate values through the breach were determined from the continuity equation. Gauss Area formula was used to obtain the time-varied values of the total and wetted breach areas. The velocity values were calculated by dividing the flow rates through the breach to the corresponding wetted areas. The temporal changes of water depth in the channel were also recorded. The so obtained experimental findings are presented and commented.
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.
Toprak dolgu baraj yıkılmalarının çoğu üstten aşma ve borulanmadan kaynaklanmakta ve ciddi can ve mal kayıplarıyla sonuçlanabilmektedir. Bu sebeple, baraj yıkılmasıyla oluşan taşkının ilerleyişinin incelenmesi ve riskli alanların tespiti, mansap bölgesinde oluşabilecek zararların önceden belirlenmesi ve önlenmesi açısından önem arz etmektedir. Bu çalışmada, homojen toprak dolgu barajların üstten aşma ve borulanma sebebiyle yıkılması sonucu oluşan taşkının ilerlemesi ve baraj gövdesinden taşınacak sedimentin taşkın dalgası ile mansaptaki hareketi deneysel olarak incelenmiştir. Baraj gövdesi, medyan tane çapı 0,441 mm olan sediment kullanılarak 30 cm yüksekliğinde, 2 m genişliğinde inşa edilmiştir. Baraj gövdesi, standart bir teknikle sıkıştırılmış her biri 10 cm yüksekliğe sahip üç kattan meydana gelmektedir. Deneyler 2 farklı noktadaki kamera ile kayıt altına alınmıştır. Deney sonunda limnimetre ile ölçülen sediment kalınlıkları verileri kullanılarak batimetri grafikleri elde edilmiştir. Borulanma nedeniyle barajın yıkılması, baraj rezervuarındaki suyun baraj gövdesindeki sedimenti mansap bölgesine taşıması ve kret genişliğinin zamanla azalmasından sonra başladığı için suyun üstten aşması durumundakine göre daha uzun sürmüştür. Taşkın dalgası, üstten aşma deneyinde baraj gövdesinin orta kısmını mansap bölgesine taşımıştır. Borulanma deneyinde ise baraj mansap bölgesindeki erozyonun zamanla genişlemesi ile rezervuardaki suyun sağ sahile 60 cm mesafedeki en zayıf kesitten barajı yıkmaya başlaması, baraj gövdesinin sağ sahile daha yakın bölgesinin mansap bölgesine taşınmasıyla sonuçlanmıştır. Deney sonuçları taşkın dalgası ekseninde yayılan sedimentin kalınlığının daha az olduğunu göstermiştir. Borulanma deneyinde sızma-erozyon boyunca baraj gövdesinden taşınan sediment, taşkın dalgasının etkisini ve yayılımını azaltmıştır. Bu azalma, borulanma deneyinde baraj mansabına yayılan sedimentin kalınlığını arttırmış, üstten aşma deneyinde daha uzun ve daha geniş sediment yayılımıyla sonuçlanmıştır.
