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Investigating the Influence of the Geometry of Rigid Barriers on the Dynamics of Simplified Debris Flows by Developing A 2d Flume Physical Model

Aghagoli, Anahita | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57529 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Sadeghi, Hamed
  7. Abstract:
  8. Debris flows are mass flows of soil, rock and water that typically occur on steep slopes in mountainous regions due to intense rainfall. These flows travel long distances and, due to their significant volume and speed, cause significant causalities downstream. In order to dissipate the energy of debris flows, slit barriers are installed along the flow path to prevent rocks and coarse particles from moving further downhill, thereby reducing the speed and destructive power of the debris flow. Given that the interaction between debris flows and barriers plays a crucial role in energy dissipation, and the geometry of slit barriers is one of the most important factors influencing the interaction process, the aim of this study is to examine the impact of three types of barriers—cubic, curved, and stepped—on reducing the velocity and energy of debris flows. To evaluate the interaction of the flow mixture with each type of barrier, a two-dimensional physical flume model featuring adjustable slope angles was designed and constructed. Analysis of images captured during the interaction process showed that the overflow angle of the flow from cubic barriers towards the downstream changes in parallel with the static zone formed upstream of these barriers. In contrast, in stepped barriers, this angle remains constant and parallel to the inclined surface of the barriers throughout the interaction, leading to the direction and projection of a significant volume of flow downstream. Curved barriers, unlike cubic and stepped barriers, reflect the debris flow upstream, which not only results in more effective energy dissipation but also reduces the flow volume downstream. This type of interaction causes the flow at the end of the flume to experience a reduction in kinetic energy by 70%, 83%, and 98% for stepped, cubic, and curved barriers, respectively, compared to when no barrier is present. Additionally, the results showed that increasing the bed slope causes the discharge of debris flow through the slits to increase, and the overflow angle changes in a way that projects the flow jet downstream of the second row of barriers. The simultaneous effect of these two factors leads to a decrease in the efficiency of slit barriers in dissipating the kinetic energy of debris flows
  9. Keywords:
  10. Debris Flow ; Physical Model ; Energy Dissipation ; Rigid Barrier ; Slit Barrier ; Two-Dimensional Flume

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