NUMERICAL MODELING OF THE STRESS-STRAIN STATE OF THE ROAD EMBANKMENT DURING CONSTRUCTION ON SOFT SOILS

Problem statement. Ensuring the bearing capacity of bases is a pressing issue in the construction of roads and artificial structures on soft soils. The method of preloading the base ensures the strengthening of soft soils. However, the calculation and design methodology for the roadbed, taking into account the specific features of its interaction with the soil base during construction, requires improvement. The purpose of the research is to improve the methodology of numerical modeling using the finite element method (FEM) for the stress-strain state (SSS) of road embankments during construction on soft soils, taking into account their precompression. Research Results. The reliability of soil models was assessed through test numerical modeling of field tests on foundations using the ideal elastic-plastic model with the Mohr-Coulomb strength criterion and the Hardening Soil model, utilizing the PLAXIS 3D software. The study considered tasks such as modeling the stress-strain state (SSS) during loading and partial unloading (precompression effect) of a soft soil layer during the construction of a road embankment, determining the time required for settlement stabilization, modeling the SSS during the compaction of soft soil with vertical sand drains and a filtration layer, and modeling the embankment on a sand cushion. Based on the numerical modeling results, the dimensions of the strengthening and plastic deformation zones in the base and the allowable pressure for soil improvement were determined. The consolidation time of the soil and settlement stabilization of the foundation were calculated based on the dissipation of excess pore pressure in the soft water-saturated soil layer. The stability of the embankment slopes was checked by calculating the “safety factors”. Conclusions. For modeling the FEM SSS of foundations under loading and partial unloading (precompression effect) of a soft soil layer during the construction of a road embankment, the use of an elastic-plastic isotropic hardening model is advisable. The application of the preload method using a filtering embankment with vertical drains will strengthen the soft soils and increase the bearing capacity of the foundation in a short period, allowing the road to be used without significant additional deformations, thus enhancing its reliability during operation. The proposed method of numerical modeling FEM SSS can be applied in the design of structures on soft soils, which involves the calculation of settlements and stresses, excess pore pressure, consolidation time, analysis of plastic deformation zones, soil strengthening and stability.