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  • Features of construction of foundations in permafrost soils

    The article analyzes the natural conditions of the Northern latitudes of Russia, where the main reserves of fossil hydrocarbons and metals are concentrated. It is shown that mining requires the development of the road network and artificial structures on the roads. It is noted that the most difficult stage in the construction of bridge structures is the construction of foundations. The types used in the Northern latitudes of foundations are considered, and their positive and negative qualities, such as weight, method of construction and volume of earthworks, are noted. The paper emphasizes the relevance of the problem of maintaining the stability of permafrost soils in seasonal thawing and loss of their bearing capacity. Methods of maintaining the soil in a solid state can be natural and artificial. The methods of thermal stabilization of soils, as well as machinery and equipment used in these conditions.

    Keywords: permafrost, road network, bridge, polystyrene, superstructure, pile support, Foundation, thermal insulation screen, heat stabilizer

  • Destruction of bridges as a result of flood disaster

    The article deals with the problem of the functional state of the bridge park in Russia. The statistics of the number of bridges, newly built bridges. Attention is focused on the inconsistency of old bridges with modern regulatory requirements for safety, carrying capacity, and carrying capacity. Noted on the relevance of flood impact on bridges and roads. The causes of occurrence are described. The problem of flood forecasting is highlighted. Examples of accidents of bridge structures from the effects of water flow are given: sediment, roll of supports and abutments, erosion of the embankment approach. Based on the situation in the city of Chita, the statistics of the frequency of flooding in different years are given, the critical levels of these disasters are indicated, and statistics on the consequences of the impact of the flood is given. The impact of the normative water flow is considered, and it is proposed to analyze the effect of the excess flow arising from the maximum level of bottling. Presents the results of calculations for which comparisons are made of various approaches to determine the depth of erosion of the channel.

    Keywords: bridges, flood impact, safety, bridge destruction, regulatory documents, erosion depth, water flow

  • Astrakhanskiy bridge in Volgograd: symbol and problems

    This article is dedicated to one of the symbols of Volgograd city, which is the Astrakhanskiy Bridge. We described the history of creation and the technical specifications of the bridge over the Tsaritsa river. After conducting an investigation, some defects in the bridge construction were uncovered. The framework arcs have longitudinal cracks, the protective layer of concrete is destroyed; the longitudinal main reinforcement is exposed and corroded. The protective layer of concrete was removed and the longitudinal main reinforcement was corroded on the longitudinal beams. During operation of the bridge, the defects that decrease load capacity and durability appeared: destruction of the protective layer of concrete on a plate of about 2 square meters. This led to the beginning of corrosion of the lower reinforcement net. Steel brackets, holding the walkway slabs, are heavily corroded; the protective paint coating on them is destroyed over significant lengths. The analysis of detected damage allowed to evaluate their impact on the durability and load capacity of the construction and determine those, who are responsible for its occurrence. It is noted that postponing of repair operations has a negative impact on the state of the bridge.

    Keywords: bridge, city symbol, superstructure, roadway plate, defects, arch, bridge system, bearing structures, durability, load capacity

  • Deformable flat supporting parts of bridges

    In this article we consider correspondence problem of the supporting parts containing deformable polymers used in the beam bridges (used in bridge constructing - лишнее, мне кажется). According to the shear diagram, supporting parts shall provide free angular and linear displacements of the beams' end faces sections. Otherwise gradual destruction of the nearby areas is possible. We study a rubber supporting part (RSP). Factors contributing to the deformation of the supporting part and their calculation with different algorithms, including the differential equation of the curved axis and Mohr method are given. The values of angular and linear deformations for the concrete reinforced bridge beam are calculated.

    Keywords: bearing, adjustable bearing, deformation, bridges, bridge beam, shear strains, angular displacement, linear displacement, crumple.