The development of theoretical principles and rules for calculating multi-blade screw piles under conditions of permafrost soils

Abstract

The development of areas with severe climatic conditions, which include cryolithozone, requires the improvement of construction technology, which allows reduction in construction time, and at the same time ensure the load-carrying capacity of structures. This postulate applies fully to the foundation construction on permafrost soils. Improving the methods of constructing foundations, in particular pile foundations, will significantly improve the efficiency of founding on permafrost soils. One of the promising designs is screw-pile foundations with using multilapped piles, using of which at present is not possible due to the lack of reliable studies.

In 2016 the specialists of NIIOSP named after N.M. Gersenvanov, which is structural subdivision of JSC ‘Research and Development Center of Construction’, performed research work (NIOKR) on the theme: ‘Development of a methodology for calculating multi-blade screw piles in permafrost soils’ as part of the state order compiled by Federal center of standardization (FAU «FCS»).

Within the framework of the work an analysis of the status of the question under study, as well as normative and methodological bases affecting the scientific and technical problem was done. Based on the results of the analysis, a program of laboratory studies, including tests of scaled models of metal multi-blade screw piles on a frozen clay base in a cryocamera was developed. In the course of the study several calculation schemes were considered, one of which was confirmed experimentally. Based on the confirmed design scheme a technique has been developed to determine the bearing capacity of a single multi-blade screw pile in permafrost conditions.

This article discusses the relevance of the work, describes the experimental part, and characterizes the test equipment. The adopted calculation schemes, methodology, and the calculation method are also considered. In conclusion, recommendations are given on the further use of the methodology and its improvement.