Study On Evolution Of Temperature Field And Water Redistribution During Artificial Multi-Row Freezing

As a friendly environmental construction method,artificial freezing method can satisfy the construction requirements of the complex urban underground environment in the future.However,the frost heave and thaw settlement dominated by the transfer of water and heat is a problem that needs to be highlighted.Therefore,it is necessary to meticulously study the field distribution of temperature and water in urban underground freezing engineering.In this paper,Xuzhou silty clay with highly frost heaving sensitivity is studied.Based on the vertical freezing method of equidistant plum-blossom pipes,the evolution of temperature and water redistribution during the freezing process are systematically studied by means of physical experiment and numerical simulation.Firstly,according to the geotechnical test rules,the relevant physical parameters of the soil for testing were determined,and the freezing characteristics were obtained by the measurements of thermocouple and dielectric constant moisture sensor.Secondly,a multi-row freezing local model test system is self-organized.Threefactor and three-level orthogonal tests are designed to consider three factors,pipe spacing,initial water content and freezing temperature.The typical evolution of temperature and water redistribution in the core freezing zone are analyzed during the freezing process.The primary and secondary factors and the superior level are obtained by range analysis method according to the self-determined evaluation indexes of uniformity of temperature field and water field.Furthermore,the evolution of temperature field of equidistant plum-blossom pipelaying freezing method in saturated soil is simulated based on the prototype of physical experiments,considering the influence of pipe spacing and freezing temperature.The influence of pipe spacing and freezing temperature on the parameters of freezing wall is compared by using range analysis method.Finally,combined the results of physical experiment and numerical simulation,the suggestion for the selection of pipe spacing and freezing temperature is proposed for artificial freezing of equal spacing plum-blossom pipe laying mode,taking account into the uniformity of temperature field and water field.