PROBABILISTIC RELIABILITY ASSESSMENT OF GRAVITY ABUTMENTS ON ROCK AND NON-ROCK FOUNDATIONS BY THE CRITERIA OF STABILITY AGAINST DISPLACEMENT OF THE GRAVITY ABUTMENTS ON THE EXAMPLE OF HYDRO SCHEMES OF THE DNIEPER CASCADE

Abstract

When calculating and designing modern hydraulic structures, it becomes necessary to assess their reliability and safety based on probabilistic methods. This work further develops the method for assessing reliability of gravity abutments by the criteria of stability loss against displacement. The work considers the random nature of the external loads and impacts, which the gravity abutments bear during operation, as well as correlations between them. It also considers the random nature of mechanical properties of the foundation soils and correlations between them. For solving this problem, the method of statistical tests (Monte Carlo method) was applied, which is widely used for assessing probabilistic reliability of complex technical systems. In applying the method of statistical tests to assess the reliability of a complex technical system, it is necessary to perform a significant number of statistical tests. This implies determination of internal parameters of the system during each statistical test. A numerical probabilistic assessment of the risk when the gravity abutments on rock and non-rock foundations at hydro schemes of the Dnieper Cascade reach the boundary conditions has been performed. Confidence limits of the probability of losing stability of the gravity abutments against displacement are determined; a number of statistical tests required to achieve confident accuracy is determined. Correctness of the obtained results is confirmed by their correspondence with the reliability assessment of the gravity abutments of the Dnieper cascade by deterministic analyses using the method of boundary conditions. In the future, the proposed method could be used in probabilistic reliability analyses of hydraulic structures and cascades of hydro schemes, taking into account the correlations between natural factors: wind, ice, and hydrological characteristics, as well as temperature loads and impacts.