Peculiarities of using small-diameter bored piles for effective solving of geotechnical problems

Abstract. The peculiarities of the use of small-diameter drill piles in modern construction considered, with an emphasis on their advantages and areas of application in specific conditions. Two main types of piles distinguished: cast-in-place, which characterized by continuous reinforcement and filling with concrete or cement mortar, and composite, where the load transfers to reinforcing elements. Main advantages of small-diameter bored piles noted, including the possibility of performing work in confined spaces, reducing the level of noise and vibrations, a variety of drilling technologies, the possibility of application in geological conditions of varying complexity, etc. Particular attention paid to the areas of application of small-diameter bored piles, including the installation of new foundations, underpinning of existing structures, soil improvement and land-slide protection. The main groups of factors that can influence the choice of small-diameter bored piles as the main design decision for various fields of application considered, including: - physical factors (restricted access, remoteness of the area, distance of piles to existing structures); - subsoil factors (difficult geological conditions, soil liquefaction tendency); - environmental factors (sensitivity to vibration/noise, hazardous or contaminated soils); - necessity of adaptation to existing structures; - load/settlement requirements; - economic factors. Limitations for the use of small-diameter drill piles from the point of view of their efficiency described. An example of the effective practical use of small-diameter bored piles in the confined conditions of dense urban development in close proximity of metro tunnels with increased requirements regarding the level of vibrations and noise considered. The task of minimizing subsidence of the designed residential and office complex and the impact on surrounding buildings and structures solved. The compliance of the adopted design decisions confirmed by means of field tests, as well as using the results of settlements monitoring. Attention focused on the need for further improvement of design approaches and technological solutions to optimize the efficiency of small-diameter bored piles for solving geotechnical problems.