Numerical solutions to unsteady filtration problems in hydraulic engineering

Introduction. The authors consider a solution to the unsteady filtration problem, arising in the clay core of a high earth-and-rockfill dam. Towards this end, the authors use the case of the dam at Nurek hydroelectric power plant. The authors provide a review of studies and calculation methods applied to unsteady filtration problems. Plaxis 2D software is used to develop a numerical solution to the filtration problem arising in the clay core of an earth-and-rockfill dam. The authors have solved the problem of its saturation with water in the process of the reservoir filling and operation. A 30-year operation period was considered. Materials and methods. The finite element method (FEM) and Plaxis 2D software package were applied to study the unsteady filtration mode using the case of the clay core of Nurek, a high earth-and-rockfill dam. Nowadays, a qualitatively higher level of solutions to such problems is attained by using numerical methods, and, most importantly, the finite element method. The application of software programmes and packages to filtration problem is reduced to solving the main differential equation of the filtration theory, if boundary and initial conditions are available. Results. A numerical solution to the filtration problem of the dam’s clay core that consists in its saturation with water in the process of the reservoir filling and operation was obtained. The 30-year period of operation was studied. Only the bottom part of the core was completely saturated with water during this period. Conclusions. The authors validated earlier conclusions, made using other methods, about the long-term establishment of the quasi-static filtration mode at similar structures. The discrepancy between the results is explained by earlier assumptions and a better filtration model, developed using Plaxis 2D software package. The model used there allows taking into account a change in the water permeability of soil depending on its water saturation rate.