Discussing the calculation of erosion rates in the design of filtering structures in cohesive soils

Objective: To develop a method for calculating erosion rates in the place of contact of ltering structures with cohesive soils. Methods: Previously at the VNIIG n. a. B. E. Vedeneev, hydrodynamic and strength criteria of contact suffusion were established concerning hydraulic structures. However, there were no calculated dependencies for determining the critical Reynolds number and, accordingly, the critical velocity for coarse-grained materials. Through special processing of experimental data on ltration in non-cavity drain llers of various grades, it was possible to integrate numerous curves into a single one, making it possible to isolate the transient regime boundaries and obtain a formula for the critical Reynolds number. This made it possible to calculate the critical rate. As a result, a formula was obtained for calculating the erosion rate. Results: The calculated dependencies made it possible to determine the critical rate for the ller material and the erosion rate at the contact boundary between the ltering structure and the soil, based on the initial data of the coarse-grained material from which the ltering structures are made, and the characteristics of the soils in which they are built. Practical importance: The proposed calculation method made it possible to: 1) establish whether the manifestations of erosion by the ltration ow are possible in the place of contact of the ltering structure with the soil; 2) develop measures to eliminate erosion. Geotextile material can be laid along the border of the contact of the ltering structure with the soil, or a ner material can be used as a ller in the ltering structure, the actual ltration ow rates in which will be less than the erosional rates. In this case, the erosion rates in the place of contact with the ner material will increase.