Experimental Study of Structural Strategy on Debris Brake Performance
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RESEARCH PAPER
Experimental Study of Structural Strategy on Debris Brake Performance Soroor Rezapourian1 · Mohammad Mehdi Ahmadi1 · Kourosh Qaderi1 Received: 2 July 2019 / Accepted: 21 August 2020 © Shiraz University 2020
Abstract We performed an experimental study to investigate the effects of structural strategy for improving the debris brake performance. The stony debris flow was generated by releasing water discharge from a tank that contained gravel material. The efficiency of debris brake, debris accumulation pattern and its position parameters was used to evaluate the performance of the debris brake structure. The influences of debris brake slope, opening size and nonuniformity in deck opening size parameters that have not been studied before were investigated for different debris flow conditions. The results showed that the slope of debris brake was the most important factor on debris brake performance. The suitable slope was found to be a function of the debris flow velocity, and it can increase debris brake efficiency up to 10%. The analysis of the experimental data suggests the optimum opening size ratio (i.e., the ratio of opening size to median diameter of debris) smaller than or equal to one. Experimental data indicated that the nonuniformity in opening size of the debris brake cannot improve the debris brake efficiency. Keywords Debris flow · Experiments · Flood · Hydraulic structure · River List of Symbols Wf Flume width Sf Flume slope Wdb Width of debris flow brake Ldb Length of debris flow brake Sdb Slope of debris flow brake Lo Opening size of the deck of debris flow brake Lb Blocking size of the deck of debris flow brake LT Travel length of the debris flow over the debris flow brake Vd Sediment volume stopped LH(max) Location of the longest height of sediments accumulated on the structure C Concentration Cin The net concentration reached at the beginning of structure * Soroor Rezapourian [email protected] Mohammad Mehdi Ahmadi [email protected] Kourosh Qaderi [email protected] 1
Department of Water Engineering, Faculty of Agriculture, Shahid Bahonar University of Kerman, Kerman, Iran
𝛾s Buoyancy specific weight of sediment ρ Mass density μ Dynamic viscosity h Flow depth V Flow velocity flow g Gravitational acceleration ρs Mass density of debris D50 Mean particle diameter ω Falling particle velocity Ws Buoyancy weight of the particle φs Friction angle of gravel C∗ Chezy coefficient v∗ Shear speed 𝜏0 Shear stress
1 Introduction Rivers debris flow is a moving mass of mixture of water and fragmented rock, wood, soil that travel down due to gravity (Itoh et al. 2007; Takahashi et al. 1992). Debris flow may physically damage water structure (Liu et al. 2013), destroy bridge, accumulate masses on river and bridge pier (Stancanelli et al. 2015), increase river bed scour (Park et al. 2016).
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Vol.:(0123456789)
Iranian Journal of Science and Technology, Transactions of Civil Engineering
The different techniques are used to reduce river debris effects.
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