Studying On Artificial Freezing Soil's Speciality Of Frost-heaving And Thaw-settlement Experimentation

Exploring artificial freezing soil's speciality of frost-heaving and thaw-settlement is keytechnology and important basal research about popularizing artificial freezing method for municipal underground space.Owing to being lack of uniform freezing temperature and frost heaving tester at present in China, in the paper, the author has developed the freezing temperature and frost-heaving device which introduces computer to gather data. For the first time, aiming at representative soil group-silt clay, silt mealy clay and mealy sand in the region of Nanjing by the device.it uses single ingredient and orthogonal experimentation to proceed the freezing temperature, frost heaving and thaw-settlement test systematically.Educing freezing temperature's rule which adapts soil group, water content, dry-density, salinity content and water quality to change its value. The study shows that salinity content factor influencing freezing temperature remarkably, and the dry-density seldom influencing the freezing temperature.After the opening and obturation frost heaving test, the paper studies the soil's frost heaving's relationship with the freezing end temperature, water content, dry-density and upside load, the frost heaving quotiety minishs with the freezing end temperature debasing and water content reducing and the frost heaving quotiety minishs linearly with power exponential rule to upside load's augment. There is four factors influence the frost heaving quotiety: water content prominence, freezing end temperature at second place .It also obtains the frost heaving forecast statistic model of Nanjing silt clay and silt mealy clay in opening and obturation system-the plus model can denote compositive effect of every ingredient which influnces soil's frost heaving.The study indicates that the frost heaving character of the meal sand is decimus of silt clay's. And its frost heaving quotiety is seldom influenced by the different freezing end temperature and water content. Thus the surroundings influence is in the small area when the artificial freezing method is used in sand and no-stickiness soil.After the soil's thaw-settlement test, the author finds three soil group's thaw-settlement coefficient has a corresponding critical dry-density which soil's thaw-settlement coefficient is minimum. Soil's thaw-settlement coefficient increases with water content augment and it exists a water content turning point. But their variational current is different-when silt clay and silt mealy clay is less than this water content turning point, the ratio of thaw-settlement coefficient changes a little, on the contrary, the ratio will changes great and augment linearly ; if the soil is the mealy sand, its water content is less than this turning point, the ratio is great, exceeding with a small ratio and augment linearly .Finally, it discusses the application of the research production in engineering and brings forward some measure about controling frost-heaving and minishing thaw-settlement. These task has great applied importance and guide significance to the artificial freezing method'spractice in the municipal underground engineering and will reduce the endangerment to the ambience in the future.