The calculation of the capacity and stability of the channels
The calculation of the channel capacity for a given estimated flow consists in determining the dimensions (or one of them for another given) cross-section. Such a calculation is carried out by selection, for which most often they use a very laborious graph-analytical method. To solve such problems, the author has developed a less laborious technique, using which the channel parameters can be determined directly (without selection) using formulas. Based on a joint solution of the flow continuity equation, formulas for determining the area of the trapezoidal section of the channel and the relationship between its bottom width and depth, a formula is obtained for the channel depth of a hydraulically most advantageous profile. When deriving analytical dependencies, to determine the channel parameters for one given cross-sectional size, a calculation model was used, in which the living cross-section was taken as the standard, providing the highest channel capacity at a given size, with the most advantageous hydraulic radius determined by a special formula. To develop the formulas of permissible speeds, the deterministic equilibrium model in which the object of influence is the soil element in its upper layer is adopted as the calculated one. The soil resistance to erosion is expressed as an indicator of soil strength, taking into account all its basic physical and physico-mechanical characteristics. Values of permissible speeds according to the proposed formulas showed good agreement with the experimental data. Dependences are obtained for determining the particle diameter of coarse-grained bottom loading and slopes. Existing formulas for determining the transporting capacity of the flow and, accordingly, non-silting speed, give results that differ significantly from field data. These formulas do not take into account the inhomogeneity coefficient of suspended sediment and the nature of the resistance during the deposition of particles of various sizes. We have obtained formulas that take these factors into account and give a satisfactory agreement with field observations.