Author: Bobomurodov, Furkat Farkhod ugli; Khazratov, Alisher Rahmatillo ugli; Sodikov, Jasur Bakhtiyor ugli

Annotation: The paper presents the results of a theoretical investigation of erosion processes in cohesive soils forming the beds of open channels under the influence of wind-generated waves. The relevance of the study is associated with the need to ensure the stability and reliability of channels composed of cohesive soils under the combined effects of hydraulic flow and wind-induced wave action. The stability conditions of cohesive soils are considered, and the forces acting on an individual soil aggregate within the near-bed flow region are analyzed, taking into account the additional hydrodynamic effects generated by wind waves. In the proposed calculation model, cohesive soil is represented as a system of interconnected aggregates whose stability is governed by the cohesive forces between the aggregates and the channel bed, the submerged weight of the aggregate, and the hydrodynamic forces associated with wind-generated waves. Using the limit-state approach, the critical condition of a cohesive-soil aggregate subjected to combined hydraulic and wind-wave action is established. The analysis considers the frontal and lifting components of the hydraulic forces, the additional effects of wind-generated waves, the geometric characteristics of the soil aggregate, its resistance to tensile and bending effects, and the roughness characteristics of the channel bed. Theoretical relationships are derived for determining the erosive, non-erosive, and bottom non-erosive velocities of water flow in channels composed of cohesive soils under wind-wave action. In determining the near-bed flow velocity, the logarithmic law of velocity distribution in the vicinity of the channel bed is taken into account together with the adopted value of absolute bed roughness. The influence of wind-generated waves on the near-bed hydrodynamic conditions and the resulting shear and lifting forces acting on cohesive-soil aggregates is also considered. The proposed calculation approach is based on the principles of reliability theory and probabilistic assessment of the limit state of a soil aggregate. The resulting relationships make it possible to evaluate the stability of cohesive soils and determine the permissible hydraulic flow parameters under the combined influence of water flow and wind-generated waves, at which detachment and progressive erosion of soil aggregates from the channel bed do not occur. The obtained results can be applied to the hydraulic analysis and design of unlined channels, as well as to the assessment of the stability of channel beds composed of cohesive soils exposed to wind-wave action. However, the influence of the lateral slope of the channel and the detailed spatial characteristics of wind-generated waves are not considered in the derived relationships, although these factors may significantly affect the hydraulic characteristics of the flow and erosion intensity. Therefore, further research should focus on establishing the influence of the geometric parameters of trapezoidal channels, side slopes, and wind-wave characteristics on the non-erosive velocity of water flow and the stability of cohesive-soil channel beds..

Keywords: cohesive soil, channel erosion, open channel, wind-generated waves, wind-wave action, non-erosive velocity, erosive velocity, limit state, hydrodynamic force, near-bed velocity, channel roughness, soil stability, wave-induced hydrodynamic forces.

Pages in journal: 247 - 257