| Water is the source of everything, and it is also vital to the survival of all creatures including humans. However, the lack and waste of water resource seriously restrict the sustainable development of economy in our country. In China, the amount of water consumption for agriculture is more than 4000 billion cubic meters, and the irrigation water use is about 350-390 billion cubic meters, which accounts for approximately 90 percent of total agricultural water use. But in China, the use efficiency of irrigation water is only 0.4-0.5, and almost the half of irrigation water is wasted. Channel anti-seepage engineering can effectively reduce the seepage loss of irrigation water during delivery and improve the utilization efficiency of irrigation water. In northern area of China, with cold climate, frost heaving damage of channel lining occurs frequently, which makes anti-seepage engineering failure and reduces the effect of seepage control, and also seriously influences the service life of channel.For the problem of channel lining, in this paper, the research mainly focus on three fields(temperature, moisture and stress fields) coupling. Firstly, considering the effects of phase transition, then with considering the moisture field, the change law of moisture during the hydrothermal coupling process is researched. After that, adding the hydrothermal coupling module into stress field, the change laws of mositure field, temperature field and stress field during the freezing and thawing process of channel soil under lining plate are analyzed, and how the interaction among three fields affects the channel lining plates is also studied. Applying the model to the sitution that HAS solidified fly ash, a kind of new lining materials, is used for channel lining and comparing with the sitution with using concrete for channel lining material, the feasibility of model is analyzed. The main contents of paper are as follows:(1)Phase transition affects frozen depth and temperature field significantly. Frozen depth and temperature field of a soil column are both analyzed with and without considering phase transition, and the difference is also analyzed. With cold climate, in northwest, northeast and north China, replacement of foundation soil is one kind of effective measures for channel to resist frost heaving. Base on specifications, with and without considering the phase transition temperature field, the channel with replacement of gravel soil which depth is 80 cm is analyzed, and the related conclusions which the temperature difference is large and freeze depth varies great, frost heave changes great when steady state is reached without considering the phase transition and the freeze depth varies little, frost heave changes little duo to releasing latent which water into ice to prevent the temperature dropped when steady state is reached with considering the phase transition are obtained.(2) By numerical simulation of water and heat coupling on the soil column above, it is concluded that water distribution in space is different before and after freezing, and water redistribution occurs. After analyzing the temperature distribution rule at different moments, it is found that, because of the inadequate frost heaving in first two hours, the temperature distribution curves along the height of soil column at different time have no obvious distribution law. After three hours, because of fully frost heaving, the change of temperature is little and the curves are almost coincided. Geometric calculation of water migration between the period from 3h to 10 h is carried out, and it is obtained that the ratio between ice content of migration and ice content frozen in situ is 1.083 which is very close to theoretical value of 1.09, and the conclusion can provide scientific basis and technical support for analyzing frost heaving of soil accurately.(3)Applying the conclusions obtained above to the reseach on channel lining, the numerial simulation of water, heat and stress coupling on HAS solidified fly ash is carried out. In numerical simulation, regarding HAS solidified fly ash, the lining material, as elastic-plastic material and using Mohr-Coulomb constitutive model included in ABAQUS simulation software, the mechanical parameter is defined and the mechanical property of HAS solidified fly ash is simulated and analyzed. At the same time, how moisture distribution affects temperature, frozen deepth and stress is researched, also the results are compared with that when concrete is used for lining material. Finally, by analyzing the strength of the most dangerous point of lining structure with the theory of maximum tensile stress and the theory of third strength, it is found that the lining structure is safe and reliable, which also shows that using HAS solidified fly ash for channel lining is feasible. |
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