NUMERICAL SIMULATION OF SEISMIC VIBRATIONS OF BURIED STRUCTURES IN SEMI-LIMITLESS AREAS ON QUASI-UNIFORM GRIDS

An effective method for numerical simulation of seismic vibrations of buried structures is presented, taking into account the nonlinear interaction with the ground base. The novelty of the proposed approaches lies in the application of the superimposed grid method to separate incident, transmitted and reflected waves in the ground base at the boundary of the calculated subdomain in contact with the structure, as well as the use of quasi-uniform grids with quadratic and linear viscosity to dampen radiated waves, reduce the dimension of a discrete finite element problem and reduce computational costs. The testing of the superimposed grid technique was performed in a two-dimensional formulation on the problem of radiation of a wave from a point source on a boundary of a rectangular computational domain through a layer of superimposed grids on the opposite boundary. The absolute velocity error in the calculated area after two run periods is estimated in comparison with the velocity field distribution in the enlarged calculated area. A method of spatial discretization of the attenuation region of the emitted waves is proposed, grids that are sparse in two directions – for a two-dimensional problem and three directions - for a three-dimensional one make it possible to ensure effective emission of not only compression waves, but also shear waves. The effect of the laws of change in numerical viscosity on reducing the time step for grids discharging according to quadratic, cubic, biquadratic, and hyperbolic laws is investigated. The options for setting the quadratic and linear viscosity are recommended, which make it possible to prevent a decrease in the time step. The proposed method for calculating the seismic resistance of large-sized buried structures combines the above techniques and allows you to design a variety of grids, increasing the efficiency of counting.