SUBSTANTIATION OF CONCEPTS OF SUBGRADE’S STRENTHENING IN UKRAINE AND THE EUROPEAN UNION

Abstract

Purpose. Substantiating the concepts of subgrade’s strengthening in Ukraine and the European Union. In the work, based on the experience gained in the field of increasing the strength and stability of objects constructed from the soil, based on the ranking of parameters, the hypothesis about the greatest effectiveness of vertical strengthening elements, unlike all others, in the case of transition to a combined track (1520/1435 mm) is proven. Methodology. The options for strengthening the subgrade with geotextile or geogrid, as well as a rigid layer, are considered, as regulated by CP-0204 "Rules for the arrangement of the main subgrade site during major repair and modernization of the track". Three concepts of strengthening developed and implemented in the European Union with the help of: 1) geosynthetic materials; 2) vertical piles or micropiles; 3) combinations of geosynthetic materials with piles (Geosynthetic-Reinforced-Pile-Supported) are analyzed. Findings. The ranking of the methods of strengthening the subgrade was carried out according to positive and negative parameters that characterize the situation of placement of reinforcement elements in the soil matrix. Reinforcement parameters are divided into positive (reduction of horizontal and vertical deformations) and negative (technology parameters). It was determined that the maximum value of the positive impact on the reduction of vertical deformations is provided by options of vertical piles or micropiles created on the basis of Boring and Mixing Technology or Jet-grouting. Originality. For the first time, on the basis of the ranking formulas for positive and negative parameters, the justification of the concepts of subgrade’s strengthening in Ukraine and the European Union was performed. Practical value. Any method of strengthening can be ranked before its practical implementation. That is, its efficiency and rationality can be determined during implementation in specific situations of railway operation, with subgrade that needs strengthening.