The problem of forest roads improvement is relevant nowadays. The issues of strength of thawed and frozen soils as the materials of forest roads require further research. The article is aimed at the problem of developing a technique for indirect determination of elastic modulus and tensile stresses in frozen soil. It is based on the results of tests on three-point bending of a beam with a developing crack. The authors used methods of experimental and theoretical studies of mechanical systems. Testing was performed with samples in the form of beams with a cross section in the form of a rectangle 55 mm wide and 39 mm high. The span of the beam was 280 mm. The beam material was sandy soil at a temperature of minus 4.6 °C. Three-point bending tests were performed using of test-machine. Based on the analysis of tests a mathematical model is developed to determine the elastic modulus of the beam material and to estimate the tensile stresses in the section with a crack. Tests and results of mathematical modeling confirmed that the destruction of the beam from sandy soil with an evolving crack corresponds to the downward branch of the diagram "load-displacement". The results of the work complement the current understanding of frozen sandy soil functioning and can be used in assessing the status and substantiating recommendations for improving forest road construction technologies.
Cracks, including low-temperature cracks, reduce to the greatest extent road surfaces quality, increase the cost their repair. This problem is most relevant in the regions with seasonal soil freezing. The purpose of this study is to develop a model of interaction between the asphalt concrete layer and the underlying layer by means of friction and adhesion forces at a negative temperature, also the analyze the conditions low-temperature cracks formation of in the asphalt concrete layer, in order to reduce the risk of cracking. Methods: as a research tool used numerical methods of structural mechanics. Results: the study found that the distribution of tensile forces in the segment of an asphalt-concrete layer is approximated by a polynomial of the second order with a maximum in the middle of the length of the segment. Shear forces are unevenly distributed along the length of the segment; the intensity of the shear forces is equal to zero in the middle of the length of the segment. The greatest shear strains and stresses are localized near the transverse boundaries of the segment of the layer. A shear deformation can lead to an increase in the crack width. The validity of the numerical simulation results is confirmed by their consistency with the known analytical solution of the same problem.
Низкотемпературные (морозобойные) трещины образуются в верхних слоях автомобильных дорог при их промерзании. Предложена механико-математическая модель условий образования таких трещин. Установлено, что распределение растягивающих сил в сегменте асфальтобетонного слоя описывается полиномом второго порядка с максимумом в середине длины сегмента. По условию прочности на растяжение определена наибольшая длина сегмента без трещин.
The article is devoted to the actual problem of the low efficiency of the process of grinding meat and fish raw materials. The main drawbacks of the equipment used for grinding meat and fish raw materials are given. Structural and technological solutions were proposed to improve the process of grinding meat and fish raw materials, which formed the basis for a new hardware complex for grinding meat and fish raw materials. The design and functional scheme of the hardware complex for grinding meat and fish raw materials has been developed. The hardware complex provides a significant reduction in friction in the cutting-transport mechanism, the combination of operations transporting and chopping meat and fish raw materials, its progressive and multistage grinding, continuous feeding into the grinder, constant monitoring and regulation of the parameters of the process of loading and processing meat and fish raw materials. All this allows increasing the resource and energy efficiency, reliability and degree of automation of the process of grinding meat and fish raw materials.
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