Studies On Basic Theories And Technologies For Artificial Thawing Of Artificial Frozen Soil

Based on the experiment of the artificial thawing of artificial frozen soil wall in the tunnel restoration project on Line 4 of Shanghai Metro, the characteristics of the artificial thawing are discussed in this thesis, the basic theory of artificial thawing method is studied and a model of single-pipe thawing is found according to the theory of heat transfer, and a calculation is made with it.First, the thesis introduces the construction and calculation methods of artificial thawing of frozen soil in our country and abroad and the basic principle and the system of the artificial thawing of the frozen soil formed in the freezing construction.Then, based on the theory of heat transfer, according to the persistent boundless line-heat-inflow model, the thesis founded the model of single thaw pipe. This model regards the heating process of the single thaw pipe as the thaw process of a persistent boundless line-heat outflow. In terms of the assumption, the thesis deduces afresh the calculation formula of the position of the ice-out face, and the calculation formulas of soil temperature before and after the phase change. In the way of the calculation and analysis, the thesis sums up the disciplinarian of the artificial thawing process, introduces the four periods in the artificial thawing process: the period of temperature rise slowly, the period before the phase change, the influence period of the phase change and the period after the phase change.In the thesis, based on the experiment of the artificial thawing of artificial frozen soil wall in the tunnel restoration project on Line 4 of Shanghai Metro, the monitoring content, purpose and method are introduced. Through the analysis of the experiment data, the relationships of the thaw rate with the time and the certain point temperature with time are found, and the consequence of the experiment and the model calculation are compared, which proves the definition of the model. According to the rule of the model of single thaw pipe, the thesis advances the concept and calculation formulas of the best thaw radius and the limited radius for the first time.Last, the thesis advances some uncertain problems and gives some advice to...