A comparison of the calculation results of the foundation pit enclosure made of flexible retaining walls is presented. Calculations were performed by the method of numerical modeling using Plaxis PC software, which is based on the finite element method. This task was implemented in three-dimensional (3D) and flat (2D) formulations of the problem, which provides more opportunities for a comprehensive assessment of the stress-strain state (SSS) of the elements of the "soil massif - anti-landslide structures" system when using complex configurations retaining walls. Calculations were performed within three calculation sections for different stages of construction: 1st stage – the initial faze (formation of the soil massif in its natural state), 2nd stage – excavation of the first layer of the pit, 3rd stage – excavation of the second layer of the pit. Based on the results of the calculations, the SSS analysis of the elements of the "soil massif - anti-landslide structures" system was carried out and the reinforcement of the retaining walls was selected. An assessment of the slope stability was also performed at the stage of full excavation of the foundation pit. It is shown that the advantage of using a plane FEM to assess the stress-strain state in the anti-slide structures is a much smaller amount of time spent on calculations and ease of understanding, but the disadvantage of this method is the lack of the possibility of taking into account the spatial stiffness of structures. It has been demonstrated that the use of spatial FEM allows taking into account the spatial stiffness of structures, which in the future makes it possible to more effectively design the retaining walls structures, however, modeling using this method is quite labor-intensive and requires significant resources of computer equipment for making calculations. According to the results of the calculations, the displacements obtained in the calculation using 2D modeling are on 6-43% more than using 3D modeling, the bending moments are on 12-33% more.

Comparison of the results of assessment of the of slope stability to determine the feasibility of construction of retaining structures is presented in this paper The construction of a grain terminal on a landslide slope in the Odessa region was selected as the object of researching. The building area belongs to the Black Sea basin region and is located on the southwestern slope of the Ukrainian Crystal Shield. The uneven stepped surface of the crystalline basement consists of blocks. Despite the significant irregularities of the crystalline basement, they are reflected in the relief through the sedimentary cover. To ensure of the slope stability, it is planned to install a cascade of retaining structures. There are pile retaining walls. The calculations are based on the analysis of the stress-strain state of the slope and anti-landslide structures using two fundamentally different methods. These methods of calculation using modern software: - analytical method for assessing the slope stability (limit equilibrium method); - assessment of the slope stability by the method of numerical modeling of the stress-strain state of the elements of the system "soil mass - anti-landslide structures". Calculations were made for two calculated cross-sections and for different stages of construction. There are stages native state, during construction and exploitation. 1st stage is assessment of the slope stability in its natural state, before building beginning. 2nd stage is assessment of the slope stability during the construction of the 1st retaining wall and excavations of the first level of the pit; stage 3 - assessment of slope stability after construction of anti-landslide structures and excavations of the pit. Stage 4 - assessment of the slope stability at the stage of grain terminal exploitation, it is meaning the construction of foundation structures. According to the results of calculations, the slope stability safety factors were determined, the analysis of SSS elements of the system "soil mass - landslide structures" was carried out and the reinforcement of retaining walls was selected.