| Artificial freezing method has been widely used in tunnel construction because of its less pollution to groundwater resources,less impact on surrounding buildings and less construction restrictions.However,in the application process of artificial freezing method in the tunnel-connecting channel,the development of frozen wall is the premise of the tunnel construction.Therefore,it is of great significance to study the temperature field of the freezing wall of the connecting passage for the construction of the tunnel-connecting channel.In this paper,taking the connecting channel between Nong Lin University Station and Hongtang Road Station of Fuzhou Metro Line 5 as the research object,the temperature field development law of the freezing wall during the active freezing period of the connecting channel is simulated by using ABAQUS simulation software,so as to judge whether the freezing design scheme is reasonable and whether the optimization measures are needed.Firstly,the thermal physical parameters of different soil layers are obtained through indoor test;secondly,two-dimensional plane model of different cross-sections of skew cross-section is established by ABAQUS finite element software,and the thickness of frozen wall,average temperature of frozen wall and temperature distribution of each temperature measurement point are compared with freezing construction scheme to verify the rationality of freezing construction scheme;finally,based on this foundation The development of the frozen wall and the variation law of the temperature field of the freezing wall are analyzed.The main conclusions are as follows:(1)The density,specific heat,uniaxial compressive strength,thermal conductivity and freezing temperature of frozen soil and unfrozen were obtained by thermal physical and mechanical properties test of artificial frozen soil samples from different soil layers,which provided parameters for subsequent ABAQUS simulation.(2)ABAQUS numerical simulation results show that the development speed of frozen wall is faster in the early stage of freezing,and the development speed of freezing wall is obviously slowed down in the later stage of freezing,but the overall development of freezing wall is good.After 45 days of active freezing,the thickness of freezing wall on each characteristic surface meets the design requirements.(3)The results show that the average temperature of the freezing wall decreases rapidly in the early stage of freezing,while the average temperature of the freezing wall decreases relatively gently in the later stage.The average temperature of freezing wall on each characteristic surface is about-20℃,reaching-13℃ of the design requirement.(4)The law of temperature change at the temperature measuring point shows that at the initial stage of active freezing,the temperature of frozen soil at the measuring point decreases at the largest rate.This is because the temperature of salt water in the freezing pipe is quite different from that of the soil in the initial freezing stage,and the two will have strong heat exchange,which makes the soil temperature drop faster;when the soil temperature at the measuring point drops to 0℃,the water in the soil will appear supercooling phenomenon When the soil temperature at the measuring point is lower than 0℃,the unfrozen water content gradually decreases and the soil temperature continues to decrease;when the soil temperature at the measuring point drops to-20 ℃,the change of soil temperature tends to be gentle.Figure 34 table 34 reference 76... |
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