Study On Freezing Technology Of Terminal Well In Hangzhou Metro Line 3

When the shield machine is used to drive the tunnel door,it is very easy to cause instability and collapse of the soil.It is very important to reinforce the soil of the shield,which ensures the safety of the construction personnel and the progress of the project.Artificial freezing technology played a good role in the formation reinforcement.This paper first studies the composition of permafrost,the formation process of permafrost and the influence of those factors in the process of permafrost formation.Then through the simplification of the temperature field,the mathematical model of the temperature field is established.The temperature distribution law of the temperature field of the frozen soil and how to find the average temperature and temperature in the cooling zone are studied theoretically,and the thermo physical properties of the frozen soil are studied.Mechanical properties.Then combined with the construction example of the frozen reinforcement project of the end well of the shield tunnel of the Fuxing Road station to the South Star Bridge Station of Hangzhou metro line three,the temperature field is simulated by the large finite element software ANSYS,and the development law of the construction temperature field and the freezing wall is studied in detail,including the freezing curtain in the freezing time and the freezing effect.The average temperature of the fruit and the frozen curtain.Through the analysis of the data of temperature measurement points of each temperature measurement hole,it was found that the temperature of the soil decreased rapidly in the early freezing period.When the freezing time reached 14 days,the freezing curtain finished the circle,and the freezing curtain temperature was getting lower and lower as the time went on.After the active freezing period,the thickness of the frozen curtain had reached 3.2m,the average temperature was lower than-15 Centigrade.Drawing on the successful experience of the construction of the previous freezing method,the drilling construction,the freezing construction,the extraction technology of the frozen pipe and the shield wall and the hole are systematically studied.These key technologies play a very good guiding role in the actual construction,and can effectively prevent the occurrence of the engineering accidents.During the frozen construction process,the soil body will appear frost heave and thawing phenomenon,the overall trend of the ground surface can be summed up after sinking first and then sinking,but the settlement of the whole freezing period hasbeen effectively controlled,and its change amount is small and basically stable.In the end,the simulation results of No.1 and No.3 temperature measurement holes are compared with the field measured results.It is found that the difference between the simulated results and the measured results is small.It shows that the results obtained by the numerical simulation can reflect the actual situation of the project more truly,and have some reference value for similar engineering research.