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Research On The Influences Of Frozen Soil Water Retention Properties On Soil Moisture Conservation In Cold Regions

Posted on:2015-01-15Degree:MasterType:Thesis
Country:ChinaCandidate:L Y ChangFull Text:PDF
GTID:2250330431456497Subject:Water Resources and Hydropower Engineering
Abstract/Summary:PDF Full Text Request
Frozen layer makes the hydrological processes difference between cold area andnon cold area, the freezing and thawing cycle, water heat salt migration, freezingthawing soil infiltration have become the research target to many scholars. Lowpermeability, water conservation, thermal insulation and infiltration reduction effect offrozen layer conducts the higher soil moisture at spring. Quantitative study levels of theinfluences of frozen soil on soil moisture conservation with experiment is not very deep.Therefore, based on this topic and expand this reserch.Reserch relying on the National Science Foundation: Research on HydraulicCharacteristics of Frozen Soil and its Influencing Mechanism on Snowmelt Infiltrationin Cold Region (41202171) and the fund of State Key Laboratory of Frozen SoilEngineering: Study on Effects of Frozen Soil Characteristics on PermeabilityCoefficient (SKLFSE201310). Base on the comparison of frozen soil and non frozen soilmoisture monitoring, select the100cm below the surface soil as the research objects. Setfreezing and non-freezing experiments filed in Hulan district of Heilongjiang University,monitor the soil structural characteristics, soil water content, temperature andenvironmental parameters at the same time period, same frequency and samedepths(per20cm soil). Through the comparative analysis of different depth anddifferent stage of freeze-thaw water thermal parameters, further study and analyze thefrozen soil water retention properties effect on frozen soil moisture conservation.Selection of key parameters: particle size distribution, dry density, soil moisture,soil temperature, temperature and frost depth. Monitoring technique of parameters:particle size distribution, ring knife method, drying method/moisture-drought automatedsystems, needle type thermometer, danilin frozen depth device. To safeguard theauthenticity and validity of the comparison test first control two test boundaryconditions, monitoring the parameters based on without suffer from the effect of waterheat exchanger. Test results show that: soil water redistribution under freezing conditions, in therole of potential soil water migrate from non-freezing area to freezing area. Earlyfreezing period maximum content at0cm, freezing period the maximum moisturecontent of soil migration held in20,40,60cm, stable freeze period reaches its maximumat the80cm. Maximum moisture content general10-20cm above the freezing frontoffice, so better maintain soil moisture. Both analysis of in terms of space (differentdepth) or time (different stages of freeze-thaw) frozen soil moisture content is greaterthan the non-frozen soils. Moisture content difference increased varies with depth andfreeze-thaw phase,80cm frozen deep in stabilizing freezing period reaches its maximumin stability, maximum margin up6.4%-7.8%. Based on the monitoring data and results,combination process of frozen soil retention moisture actually occur, analysis from soilporosity, infiltration and shallow groundwater recharge three areas to reveal themechanism of effects of frozen soil cotent moisture. Base on mechanism to explain"spring floods".
Keywords/Search Tags:frozen layer, soil moisture content, water retention properties, frozen soilmoisture conservation, cold region, Hulan experiment sites HLJU, Harbin
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