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Numerical Simulation of Channel Frozen Based on Solar Radiation Research

Author: ZuoChangCheng
Tutor: WangZhengZhong
School: Northwest University of Science and Technology
Course: Hydraulic Structure Engineering
Keywords: Frost heaving ASHRAE solar radiation model Hottel solar radiation model FRP Polystyrene insulation board
CLC: TV698.26
Type: Master's thesis
Year: 2011
Downloads: 49
Quote: 0
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Abstract

China is a shortage of water resources, agricultural water use accounts for more than half of the country's total water consumption. The concrete lining channels of effective measures to improve the efficiency of irrigation and water conservation, but the seasonal permafrost zone is widely distributed in China, severe frost heaving damage of concrete lining channels become the bottleneck of restricting water-saving projects. Frost heaving damage of concrete lining channels with different solar radiation model, the concrete lining channel boundary conditions, numerical simulation of the irrigation channel frozen process; using orthogonal experimental design theory, latitude, altitude, wind speed, concrete on solar radiation absorption rate, channel slope angles and five factors the channels sensitivity analysis of the surface absorption of solar radiation; analysis of FRP lining canals in the northern seasonal permafrost validity of impermeable anti-frost heave; polystyrene insulation plate the mechanism of the anti-frost heave, a reasonable thickness of the insulation board in different areas to give the effect of the different thickness of insulation board anti heaving law, given the method of determining the different regions of polystyrene foam insulation board thickness. The full text of the main conclusions are as follows: (1) the use of the channels to the surface of the ASHRAE solar radiation model calculations of solar radiation to overcome the shortcomings of the observations of the solar radiation intensity in most parts of China is difficult to obtain by the theoretical model to calculate the intensity of solar radiation can be generalized to other the frost heaving of the region having the advantages of versatility. And can be analyzed directly, in theory, do not need channels built through field monitoring temperature field analysis of frost heave, can be analyzed in the channel design stage frost heave anti the frost heave designed to provide reference for the channel. For the shady slope monitoring points and the sunny monitoring point 8 sinusoidal temperature variation of temperature with the measured thermal radiation, but sinusoidal temperature greater than the measured value, maximum difference of 3.5 ℃ and 2.7 ° C respectively; either case the amount of frost heave variation, consider the thermal radiation frost heave amount is less than the the measured sinusoidal temperature load resulting frost heave, the biggest difference between 0.8mm and 0.82mm; variation of the normal frost heaving force in both cases, to consider law of thermal radiation frost heave force is less than the the measured sinusoidal temperature load obtained to frost heave force, the maximum the difference 0.066Mpa and 0.047Mpa. Deviation calculation results in both cases because the negative temperature solar radiation Found sinusoidal plot number is less than the temperature, so that the resulting temperature field numerical value is greater than the measured sinusoidal temperature. (2) taking into account the impact of a variety of factors channel concrete lining absorbs solar radiation, the use of Hottel solar radiation model to calculate solar radiation values ??using the theory of orthogonal analysis, sensitivity analysis of influencing factors. Range analysis, trend analysis, analysis of variance derived factors affect the channel concrete lining to absorb solar radiation sensitivity size. Sensitivity descending order: wind speed, the concrete on the rate of absorption of solar radiation, channel slope, slope, elevation, latitude. By trend analysis of the results: As the latitude increases, the channel concrete lining to absorb the reduction in solar radiation;, channel concrete lining absorbs solar radiation increases with altitude increases; When the wind speed increases, the channel concrete lining absorbs solar radiation decreases ; channels for concrete lining absorbs solar radiation values ??increase with increasing absorption rate; absorbed in the sunny slope factor of 1:1 when solar radiation values ??of slope coefficient 1:2,1:0.5 followed. Through analysis, the the concrete solar radiation absorption rate of the concrete lining channels absorbs the sun's radiation have a greater impact, brushing a light-colored coating to the surface of the concrete lining channels can be used in practical engineering, concrete structures and try to make the surface smooth, can be reduced The concrete solar radiation absorption rate, thereby reducing the absorption of solar radiation values. (3) the displacement field of numerical analysis: FRP material protective structure, the modulus of elasticity than ordinary concrete, and the lining plate thickness is less than the concrete lining board, thus displacement larger, but the numerical point of view, does not affect the channels safe operation, and through the release of the deformation, can improve the stress state of the lining plate. Numerical results show that the stress field: to frost force goes under the big law distribution tends to be uniformly distributed in the channel bottom; along the slope of the tangential frost heave force goes to large law tends to be almost in the channel bottom zero, FRP material protective structure allows it to reduce frost heaving force by 51% to 74%, 34% to 46% smaller tangential frost heave force. (4) polystyrene insulation board used in the permafrost regions channels anti-frost heave effect significant, positive temperature Drainage substrate soil temperature reaches, not freezing. Polystyrene insulation board thickness of concrete lining channels in different regions, can be calculated by the finite element software ADINA the Drainage substrate soil temperature values ??increase with the thickness of the insulation board and elevated, but the temperature increase rate decreases with the increase in the thickness of the insulation board. Therefore, in determining the thickness of the insulation panels should be obtained by calculating the optimum value of the thickness of the economic and technical. According to the different parts of the meteorological data, the canal with the nature of the base soil, groundwater conditions, the use of finite element software ADINA its numerical simulation, channel concrete lining its base soil temperature field distribution reasonable thickness of polystyrene insulation board correct, the results obtained using the empirical formula or specification, designed to provide reference for different parts of the concrete lining channels insulation resistance to frost heave.

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CLC: > Industrial Technology > Hydraulic Engineering > Water control,hydraulic structures > Hydraulic structures management > Management and maintenance of hydraulic structures > Freezing measures and freezing of hydraulic structures
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