Experimental Analysis On The Change Law Of Soil Water Physical Properties During Freezing And Thawing Periods In Cold Regions

The northeast region of China belongs to seasonal frozen soil area.The seasonal freezing and thawing of water and soil system is caused by the regular change of weather,which starts from November of each year and completely melts in June of the next year.Soil freezing and melting process can lead to soil water properties and the change of pore characteristics,as a kind of water-resisting layer and permafrost or the existence of the weak permeable layer,also makes the cold and the soil moisture migration becomes more complex,with a cold and conventional seepage theory is applied to the cold effect is poorer,therefore this article mainly aims at cold and seasonal frozen soil freezing and melting process,the soil water properties and pore characteristics of analysis,to explore the change rule,on the basis of groundwater seepage problem of cold and simple discussion.This experiment for suihua keian irrigation experiment stations in heilongjiang province in the study area,back in the area of soil sample processing after indoor experiments,the determination of soil hydraulic properties(let water,moisture,water level,water)and the size of the porosity,through the experiment,the degree of soil water capacity and water level in the process of freezing and thawing cycle presents increasing trend after reducing first,hold the trend of the degree of water increases first and then;Low temperature experiment and ice-thawing experiment were conducted to select 45% concentration of ethylene glycol solution as the inert liquid with low freezing point.The inert liquid was used to conduct the permeability experiment.The permeability coefficient was calculated to show that the permeability coefficient of frozen soil was smaller than that of non-frozen soil.The rule of porosity change in freezing-thawing cycle is that porosity decreases first and then increases.Using portable soil profile moisture measuring device in the process of soil freezing and thawing is not frozen water content are measured,it is concluded that the closer the distance from the surface of the soil,not frozen water content changes are greatly influenced by temperature,and analyzes the not frozen water in addition to greatly influenced by temperature,also affected by the soil itself,initial soil moisture content,soil salinity.The permafrost monitoring system was used for real-time monitoring of the thickness of the permafrost and the temperature of the soil layers at different depths in the study area,which deepened the microscopic concept of the formation and extinction of the permafrost,and confirmed the remarkable characteristics of the permafrost: "single freezing,double melting".Analyzed the cold soil moisture migration mechanism and the basic theory on dynamics of frozen water,simply expounds the membrane theory and moisture conductivity,starting from the principle of the soil moisture content was discussed,the coefficient of permeability and capillary pressure head to the cold and the influence of groundwater recharge,finally,in the experiment results and related on the basis of consulting literature materials,in the perspective of seepage velocity and energy conservation,the cold and the mathematical model of groundwater flow in the process of soil freezing and thawing cycle for simple discussion and assumptions.