In the event of the destruction or explosion of tanks with oil products, basic schemes for the distribution of pollutants have been developed in the area of a technical stop of a train at a distance of up to 1000 meters in all directions, taking into account all structures located in the study area. On the basis of an analytical assessment of the consequences of an emergency, it was shown that in the event of the destruction or explosion of railway tanks with oil products, from 90 to 95 % of economic and public facilities will be located in the zone of exceeding the MPC by 2-300 times. The limits for exceeding the permissible concentrations of polluting components in the parking area and flushing of tanks intended for the transit of oil and oil products have been established. The greatest excess will be at a distance of 300 meters from the tank car parking, where, for all priority polluting components, it is possible to exceed the MPC by 300 times. For a distance from the source of emissions more than 1000 meters in each direction of light, the calculation of the maximum permissible concentration of polluting components was performed.
Computer simulation of the thermal stress state of a concrete foundation slab of a building is considered. To simulate the thermal stress state, the specialized Midas Fea software package is used. The actual tensile stresses in concrete are compared with the maximum allowable values taking into account the equivalent age. It was established that the likelihood of cracking due to sudden changes in temperature is high, which entails the likelihood of destructive processes in concrete. Using the software package, calculations were made and graphs of the temperature changes in time at the control points were plotted, as well as the isofields of temperature distribution and crack formation coefficients over the volume of the considered array were graphically depicted and investigated. Based on the calculations and modeling of temperature processes in concrete, it is proposed to use surface thermal insulation or to reduce the initial temperature of the concrete mixture in order to reduce the heat transfer rate of the concrete surface.
The paper presents the process of assessing the technical condition of reinforced concrete supports of existing technological overpasses, gives their characteristics, shows the defects found in the process of assessing the technical condition. The article describes the monitoring of concrete strength by the non-destructive method of elastic rebound using the Digi Shmidt 2000 device and the determination of the thickness of the concrete cover and the location of reinforcement by the magnetic method using the Profometer-5S device. We determined the layout of the working reinforcement in the reinforced concrete supports of the overpasses’ sections. We present the results of verification calculations of the structures of the technological overpasses, taking into account the revealed defects and damages, the strength of materials and the specified actual loads. We give recommendations for improving the performance of the concrete of the reinforced concrete supports of the overpasses.
The paper considers the main processes that affect the quality of concrete road surfaces. The quality of concrete pavement depends on the quality of the preparation of the base, the concrete components quality, and the quality of the coating technology. The processes of concrete components quality control, the process of its manufacture, as well as the control of road surfaces that have fully gained strength and are ready for use are studied. Examples of the defects formation on concrete surfaces are given. The factors influencing the occurrence of deformations in road surfaces are considered. In fact, concrete is a mixture of a binder, coarse and fine aggregate, various additives and water. The process of its production is a set of mandatory measures, without which it will not be possible to obtain high-quality durable material. The measures that exclude the defects formation on concrete road surfaces are proposed. The purpose of the paper is to analyze the processes of concrete road surfaces construction with the identification of the main measures to improve their quality.
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