Abstract. The article describes the general problem of safe operation of buildings and structures with the dynamics of permafrost in Russia and other countries. The global warming on Earth will lead to global disasters such as failures of buildings and structures. The main reason of these failures will be a reduction of bearing capacity and the reliability of foundations. It is necessary to organize the observations (monitoring) for the process of reducing the bearing capacity of foundations to prevent such accidents and reduce negative consequences, to development of preventive measures and operational methods for the piles reliability analysis. The main loadbearing elements of the foundation are reinforced concrete piles and frozen ground. Reinforced concrete piles have a tendency to decrease the bearing capacity and reliability of the upper (aerial) part and the part in the soil. The article discusses the problem of reliability analysis of existing reinforced concrete piles in upper part in permafrost regions by the reason of pile degradation in the contact zone of seasonal thawing and freezing soil. The evaluation of the probability of failure is important in itself, but also it important for the reliability of foundation: consisting of piles and frozen soil. Authors offers the methods for reliability analysis of upper part of reinforced concrete piles in the contact zone with seasonally thawed soil under different number of random variables (fuzzy variables) in the design mathematical model of a limit state by the strength criterion.Keywords: permafrost; foundation; reinforced concrete piles; compression; theory of possibility; evidence theory; buildings; construction РАСЧЕТ НАДЕЖНОСТИ ЖЕЛЕЗОБЕТОННЫХ СВАЙ НА СТАДИИ ЭКСПЛУАТАЦИИ В УСЛОВИЯХ ВЕЧНОЙ МЕРЗЛОТЫ В.С. Уткин, Л.А. СушевВологодский государственный университет, г. Вологда, РОССИЯ Аннотация. Рассматривается общая проблема безопасности эксплуатации зданий и сооружений в усло-виях динамики вечной мерзлоты применительно к Российской Федерации и другим странам. Глобальное потепление на Земле приведет к глобальным катастрофам в виде разрушений зданий и сооружений. Ос-новной причиной разрушений будет снижение несущей способности и соответственно надежности осно-ваний фундаментов. Для предупреждения таких аварий и снижения негативных последствий необходима организация наблюдений (мониторинг) за процессом снижения несущей способности оснований фунда-ментов, разработка предупредительных мероприятий и оперативная оценка надежности (безопасности) свайных оснований. Основными несущими элементами основания являются железобетонные сваи и мерз-лый грунт. Сваи имеют тенденцию к снижению несущей способности и надежности верхней (надземной) части и части находящейся в грунте. В работе рассматривается проблема расчета надежности верхней ча-сти железобетонных свай на стадии эксплуатации зданий и сооружений в условиях вечной мерзлоты в связи с их снижением несущей способности в зоне контакта сезонного оттаивания и замерзания грунта. Оценка их вероятности безотказной работы ...

The increase in the rate of global warming directly affects the safety of buildings and structures on permafrost. The research presents the problem of reliability analysis for piles on permafrost soils by the stability criterion under the action of tangential forces of frost heaving. The two groups of piles reliability analysis methods are developed: for complete and limited statistical data about random variables in the models of limit states. Approximations of the dependences of the design resistances of permafrost soils to the shear along the freezing surface on the temperature are proposed. It can be used to estimate the freezing force that keeps the pile from buckling. The method for reliability monitoring and durability forecasting has been developed for piles on permafrost soils. The proposed method makes it possible to reasonably reduce the cost of reliability analysis in the initial periods, which can increase the number of buildings and structures being inspected by the similar costs.

Introduction. The paper describes a new approach for pile foundations design. The system of mechanical impacts is described in a new way for the pile foundation design based on the foundation settlement taking into account the distribution of elastic deformation of the pile material in a soil base. Materials and methods. In contrast to the existing approaches to determining the pile settlement due to elastic deformations of the pile material, all impacts in the form of load from the pile cap, friction forces on the pile lateral surface and the actual reaction at the pile tip are taken into account differentially according to the principle of forces independence. The new design equation is proposed to describe the distribution of friction forces on the lateral surface of the pile. The friction forces in a homogeneous soil of the base are represented as a parabolic distribution function, and not as a linearly increasing one, as established in the standards. Results. As a result, the equation is obtained for a pile settlement design due to the elastic strain of pile material. An example of calculating the pile settlement according to the proposed method and comparing the results with existing methods is given. Negative friction forces from the reaction of the soil under the lower end of the pile increase the value of the elastic deformation of the pile shaft. Conclusions. The refined equation for calculating the elastic component of the pile settlement makes it possible to obtain a lower value of the settlement in comparison with the standard approach by taking into account the influence of friction forces of the soil along the pile lateral surface. The proposed method for pile foundations design based on the settlement can serve as a justification for the reserve of the load-bearing capacity of the pile foundation according to the settlement criterion which will allows obtaining a certain economic effect.