4 Literature review and problem statementWorld practice of designing and operation of metal corrugated structures demonstrates that a decisive influence on the stressed-strained state of MCS is exerted by the degree of compaction of soil backfill [1][2][3]. Recommended compaction should reach the degree of 0.95-0.97. However, paper [1] indicated that the reduction of soil compaction even from 0.95 to 0.8 leads to the reduction of soil deformation module by 4 times, which, in turn, is the cause of significant growth of stresses and strains in the walls of the structure.Conducting a long-term monitoring of more than 900 objects from corrugated pipes, constructed from 1951 to 1965 in the state of Ohio (USA) [4,5] made it possible to draw the following conclusion: in all cases, for the designs that did not experience destruction, large deformations accounted for 22-34 %; for the structures that suffered damage, such 4

The paper deals with the estimation of the load carrying capacity of the bellow compensator DN100, made of stainless steel AISI 304, which is supposed to be used for providing the necessary level of deformability of main buried gas pipelines in the mining production areas. Experimental investigations of the compensator under cyclic loading by tension-compression with the simultaneous action of working internal pressure are carried out. According to the results of experimental research and numerical simulation, it is shown that such compensators can be used as structural elements of main buried gas pipelines in the mining production areas.Introduction. The problem of the buried pipeline failure as the result of geodynamic processes of the ground surface is very important. According to EGIG [1] 8 % of cases of lossof-piping integrity in the main buried gas pipelines (MBGP) in Europe are caused by their failure as the result of geodynamic processes in the Earth crust. Furthermore, the activity of coal mines also results in the ground surface displacement.The Coal mines influence on MBGP is an important problem on the territory of Ukraine as well since 22.1 km of MBGP [2] have been already located in the areas of their influence and this amount is constantly increasing due to the expansion of mining boundaries.The area of the ground surface where the deformation processes occur as the result of mining production forms so called "shift trough" (see Fig. 1: Нmining depth; mmining capacity; ηmmaximum ground subsidence).As the result of mining development in the shift trough the compression areas and areas of the ground surface tension are formed (see Fig. 1) transmitting their effect on pipeline. Since the axial forces are the main load factor then the horizontal substitution component (vertical is usually neglected) has sufficient effect on the pipeline stressed state.Analyzing the ground displacement kinetics during mining we determined [3] that for the worst case of lava mining (along MBGP) its most loaded areas are subjected to three consequent semicyclestensioncompression and again tension due to the relaxation processes in the ground. Depending on geological conditions, mutual location of the pipe with mining areas the MBGP section can reach the effect area of 15 minings and thus undergo 45 load semicycles.To ensure reliable operation of buried pipelines during lava mining a number of measures aimed at stress state [4 -6] reduction are used, such as:1. Carrying capacity (on the design stage) is increased by:

The current state of the main gas pipelines diagnostics is analyzed in this paper. It is noted that the gas extraction and gas transportation complex now plays an important role in the structure of the Ukrainian economy and is considered to be an industry which should ensure the implementation of important projects aimed to reduce the energy crisis in the country. Some aspects of implementation of the main gas pipelines open and hidden areas diagnostics are considered. The methodological principles of the construction of the scientifically grounded method of formulation of the predictive estimation of the gas pipelines residual life under the conditions of long-term operation are described. The peculiarities of the implementation of such approach is that the basic calculations of the criteria are carried out within the framework of theories reflecting the main mechanisms of the bearing capacity exhaustion of the gas pipelines pipe material, in particular, according to the criterion of static strength, taking into account the corrosion and deterioration of the material, estimation of the residual life according to the criterion of low cycle fatigue allowing to predict the residual life of the pipeline, taking into account the processes of the origin of fatigue cracks near constructive stress concentrators, estimating the residual resources according to the criterion of crack resistance. On the basis of the data obtained during the diagnosis, and the results of calculations the recommendations for the repair, replacement and strengthening of dangerous parts of main gas pipelines are developed; their regular diagnostics makes it possible to determine effectively the technical condition and allows to establish the expediency of further operation and recommendations for the elimination of detected defects.

Purpose. The purpose of the work is to establish the real technical condition of transport structures made of corrugated metal structures on the basis of the analysis of scientific and technical sources.And to analyze the experience of operation of metal corrugated structures in the soil environment and to form and generalize the problems of ensuring the reliability and durability of structures made of metal corrugated structures in the conditions of operation on railways and highways of Ukraine. Methodology. To achieve this goal, a review of scientific and technical sources and regulations of different countries on the technical condition of transport facilities in Ukraine was conducted. In particular, data on the distribution of bridges and pipes made of corrugated metal structures by mode of transport are given. It is shown that the development and implementation of new technologies for the repair of existing defective pipes and small bridges, both on the railways and highways of Ukraine is a very important issue. A thorough analysis of the experience of operation of corrugated metal structures in the soil environment in different countries was conducted. Data on the main inadmissible defects of pipes and the reasons of their development are given. CMS' (corrugated metal structures) corrosion and other defects are given. A number of examples of overpass defects, collapse of bridges and structures with MCS in operation are presented. The qualitative indicators of metal corrugated structures, their advantages and disadvantages are also considered, the problems and the analysis of ensuring the reliability and durability of the structures with CMS in the conditions of operation on the railways and highways of Ukraine are formulated. Findings. An analysis of domestic and foreign scientific and technical sources on the technical condition of transport facilities in Ukraine was conducted. In particular, the experience of operation of corrugated metal structures in different countries of the world is studied and generalized. The analysis and synthesis of problems of ensuring the reliability and durability of buildings with CMS in the conditions of operation on the railways and highways of Ukraine. Originality. As a result of the analysis of the technical condition of transport facilities operated on railways and highways of Ukraine, it was found that about 15 % of transport facilities – small and medium bridges and culverts on Ukrainian railways and about 45 % of transport facilities on Ukrainian roads have unacceptable defects and require immediate repair and replacement. Also, it was established on the basis of research that there are no methods for assessing the load-bearing capacity of transport facilities with CMS in the presence in the body of the embankment of the railway or highway metal corrugated structures with a diameter greater than 6 m. It was determined that standards don't include regulations on design and monitoring of CMS on railway tracks. Practical value. On the basis of these data it was possible to offer directions of theoretical and experimental research and methods of calculation, tests of CMS and diagnostics of a technical condition of transport structures with CMS. In particular, the measurement of the impact of the environment on the bearing capacity of the CMS and the measurement of residual deformations of the corrugated metal pipe on the railway track. Execution of the analysis and synthesis of methods of calculation of transport constructions with CMS will lead to improvement of methods of calculation of CMS.

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