Liquefaction is a phenomenon in which the strength and stiffness of a soil are reduced as a result of seismic or other dynamic effects. Liquefaction was the main reason of the huge damages caused by many earthquakes around the world. The modeling of soil behavior is the main step in the process of predicting the soil liquefaction. Currently, a large number of soil models are presented. However, only some of them can simulate this process. One of these models which can be used is model UBC3D-PLM. In this paper, the possibilities of this model are considered by modeling the seismic impact on a building with its different heights on the PLAXIS software package. The real data of Upland earthquake 1990 near Los Angeles city was used. Results of the simulation showed the difference in the behavior of the soil mass under the influence of an earthquake compared with the elastic behavior, as well as the need to use the UBC3D-PLM model to estimate the seismic impact.

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Introduction. In case of brief exposure to static loads or dynamic loads, in conditions of absence of drainage, distribution of total stresses between the skeleton of soil and pore gas-containing water should be taken in account. The situation of the stress-strain state of the base is further complicated when we consider the degree of water-saturation of soil of the foundation (0.8 < Sr ≤ 1). The aim of the study is to pose and solve problem of the stress-strain state of a water-saturated soil massif, Including settlement and bearing capacity of a water-saturated base of a foundation of finite width, depending on the degree of water saturation of soils, taking into account the linear and nonlinear properties of the skeleton of soil and the compressibility of pore gas-containing water. Materials and methods. Henckyʼs system of physical equations are used as a calculation model to describe the relationship between deformation and stresses of soil, which takes into account the influence of the average stress on the deformation and strength properties of the soil. This system allows us to represent the linear deformation of the soil as the sum of the volumetric and shear components of the soil of this deformation. In addition allows us too to determine the deformation of the layer of soil, as part of the compressible thickness of the base of foundation with finite width under conditions of free deformations. Results. Depending on the linear and nonlinear deformation parameters, the settlement can be developed with a damped curve (S – p) and stabilize, and can be developed with a non-damped curve (S – p) and moved to the stage of progressive settlement. Conclusions. Solutions have been made for cases when the water-saturation of the base soils changes in the range of 0.8 to 1.0. It is shown that the settlement and bearing capacity of a water-saturated base significantly depends on the degree of water saturation of soils.

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