The Role of the Composition and Thickness of a Gravel-Sand Mixture in the Formation of a Stable Filter of Vertical Wells of Vertical Drainage

SANIIRI Drainage Laboratory (NIIIVP) carried out a set of laboratory and production studies to clarify the composition of the backfilling of vertical drainage wells, which were included in the “Instruction for the design of irrigation systems” (Part VIII. Drainage on irrigated lands , VSN-II-8-74). Studies on sector flumes found that in order to reduce the input velocities to the filters, it is necessary to increase the diameter of the well (packing thickness), at which the inflow to it will occur in a laminar mode with an increase in water- holding capacity and well flow rate. The author clarified the formulas of SK Abramov and IF Volodko for determining the allowable input velocities in the filters of vertical drainage wells and gave recommendations for the construction of vertical drainage wells of large diameter (1500-2000 mm and more), which will halve the content of fractions with a diameter 1-5 mm, ie reduce the requirements for gravel-sand filling.