The Analysis Of Thermal Parameters For Frozen Soil And Coupled Thermal-stress For The Process Of Soil Freezing

It was a huge challenge towards the subway connection passage to construct safely and economically, because it’s particular position and sophisticate execution conditions. Currently, freezing method was mostly adopted to the construction of subway connection passage. It easily resulted in excessive waste of resource or led to engineering accident that the insufficient knowledge of law of development towards temperature field. So, it is necessary to expand analysis and study towards the evolution of the temperature field in the process of soil freezing. The paper was set in the freezing engineering of the connection passage in aero track elongation of Tianjin metro line 2. A variety of means was adopted to expand the analysis of artificial freezing temperature. The research methods included the correlation theory analysis of temperature field, the thermo physical parameter of interior test, model tank test and numerical simulation etc. The primary research contents and gains as follows:(1) The new constitutive relation of frozen soil was based on the existing, considering that there was unfrozen water in frozen soil. It was established that the equation of constitutive relation, the equation of equilibrium differential and the equation of compatibility of deformation simultaneous equation, then appropriate initial and boundary conditions was selected and the heat-stress differential equation group of frozen soil was established.(2) The main influence factors of freezing temperature, thermal conductivity and specific heat were laid special stress on analyzing via indoor test. The change rules were constrasted, then it was concluded that water content was the most important factors.(3) A thermo-mechanical coupling equation of soil was derived based on Fourier heat conduction law and principle of energy conservation, considering the existing of inner-cooling source and ice-water phase transition in the freezing process of soil. The thermo-mechanical coupling model of monotone, duplex tube and multibank tube frozen were established via FLAC3 d. The new constitutive model of frozen soil was established by varying the parameters of Mohr-Coulomb in FLAC3 d using fish sentences. The developing law of freezing temperature, development speed of the freezing front and thickness of freezing curtain were obtained by the contrast of simulation results and the result of model tank freezing test.(4) A thermo-mechanical coupling model was built based on the freezing engineering of the connection passage in aero track elongation of Tianjin metro line 2. The results of model calculation were contrast to actual measurement, the rationality of model was demonstrated. At last, the developing law of freezing temperature of stalk-circular arch form and parameters relevant freezing temperature field were gained.