نوع مقاله : پژوهشی
نویسندگان
1 دانشجوی دکتری سازههای آبی، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه لرستان، خرمآباد، ایران
2 دانشیار گروه سازههای آبی، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه لرستان، خرمآباد، ایران
3 استاد گروه سازههای آبی، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه لرستان، خرمآباد، ایران
4 استاد گروه مهندسی عمران، دانشکده فنی و مهندسی، دانشگاه مراغه، مراغه، ایران
5 استادیار گروه سازههای آبی، گروه مهندسی آب، دانشکده کشاورزی، دانشگاه لرستان، خرمآباد، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Goal
The gabion vertical drop structure, as one of the modern hydraulic structures, is widely used in watershed management projects and structural operations. The structure is a combination of permeable rock mesh units that dissipate fluid kinetic energy by creating a water level difference between upstream and downstream. The passage of flow through the porous pores of the structure reduces the intensity of bed shear stresses and moderates the peak instantaneous discharges, thereby reducing the rate of channel erosion. Due to the limitations of previous research in comparing the performance of gabion and rigid structures, this researcch investigated the flow behavior and energy dissipation amount using a laboratory approach, and analyzed their functional differences in flood management and local erosion control. The importance of these structures in unstable riverbeds and vulnerable supercritical flow environments is twofold in promoting the hydrological and environmental sustainability of systems.
Materials and Methods
This research was conducted in the Hydraulic Laboratory of Lorestan University, in 2024-2025, using a flume with a length of 11 m, a width of 0.6 m, and a height of 0.5 m. To comprehensively analyze the hydraulic behavior, a total of 60 experiments were designed and conducted on two types of vertical drop structures: rigid and gabion. In these experiments, three structural thicknesses (Xg) of 20, 30, and 40 cm were investigated in combination with five flow rates of 18, 21, 24, 27, and 30 L.s-1 for the control sample. For the gabion samples, three effective porosity levels of 30, 35, and 40 percent were employed, using three categories of gravel materials—fine, moderate, and coarse—with average diameters (D50) of 21, 30.5, and 42 mm, respectively. Also, in all models, the structure height was kept constant at 32 cm to ensure comparision of conditions.
Results and Discussion
Analysis of the obtained data showed that in all models, the relationship between the flow energy dissipation parameter and the relative critical depth was inverse; so that with increasing energy dissipation efficiency, the relative critical depth decreases, and this trend was observed in all experimental scenarios.The findings showed that the combining of the drop structure with a gabion bed significantly increased the energy dissipation of the flow, such that the use of gabions improved energy dissipation efficiency by approximately 60% compared to the rigid drop. The flow passing through the gabion models was divided into two modes: overpass and throughpass, ın the throughpass state, the quasi-non-Darcy and nonlinear flow passed through the porous moderate, and the main contribution of energy dissipation was related to this state. Furthermore, increasing the size of the gabion core particles and the effective width of the structure enhanced the energy dissipation process. Finally, the overpass and throughpass discharge values were calculated for all scenarios, and these data can be used as a valuable template for hydraulic modeling and improving the design of similar structures.
Conclusion and Suggestions
In this study, the interaction of water flow and energy dissipation in two types of vertical drop structures: rigid and gabion, were investigated experimentally. The results showed that by using a gabions type and creating a porous and permeable environment, the flow energy can be reduced, thus reducing the need for additional structures such as stilling basins or mesh plates. Furthermore, the effect of parameters such as aggregate particle size, gabion porosity, and structure thickness on energy dissipation efficiency and the share of inflow and overflow was significant. The findings indicate that the use of vertical gabion drops in water transfer projects in steep and mountainous areas is more efficient and sustainable than the rigid model from a technical and economic perspective. In addition, the results of this research can be used to improve the design of vertical gabion drops in watershed management plans.
کلیدواژهها [English]
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