Aisle Freezing Construction Numerical Simulation Analysis

Artificial freezing method is widely used in mine construction projects, in recentyears, with the development of underground engineering, artificial freezing methodhas been commonly used in the construction of connecting passage of the subwaytunnel. In the past artificial frozen wall design is mainly based on the construction ofthe mine, but there is a big difference between the urban underground engineering andmines in depth, construction method and construction stress, so the related designcalculation method is also different. So far research on the temperature field anddisplacement field of frozen soil freezing and thawing in the construction of thesubway connecting passage by the artificial freezing method is rare. In addition, thenumerical simulation of connecting passage construction by the artificial freezingmethod rarely takes the phase change process of soil into consideration. However, theprocess of soil freezing is a thermodynamic coupling process, considering theinteraction of temperature field and displacement method is an inevitable requirementof further development.Aiming to solve the above problems, this paper establishes a numerical model ofa connecting passage in tianjin subway construction. In the process of artificial frozen,coupling effect of the temperature field and displacement field is simulated, and thefreezing temperature field distribution and development are also studied. Method todetermine the average temperature of the frozen wall with a certain thickness range isproposed, also method to determine the freezing time that is used to attain thetemperature is proposed; Based on the research of the displacement field in theprocess of freezing, the impact on the surrounding environment of the artificialfreezing method construction is evaluated.The main research contents and conclusions are as following:1. Based on the thermodynamics, thermal elastic mechanics theory and theassumption of the temperature change of soil, the thermal coupling equationconsidering phase change process and its finite element solution are put into forward,thus the temperature field and displacement field of artificial freezing methodconstruction are acquired. 2. The distribution of displacement field and temperature field of the subwayconnecting passage by the artificial freezing construction method is researched. Theresults show that the distribution of temperature field decides the distribution ofdisplacement field.3. The influences of soil parameters on the temperature field distribution areresearched. The results show that soil density, specific heat, and coefficient of thermalconductivity have a great influence on the temperature field distribution; Land surfacetemperature, phase change latent heat, phase change of soil temperature andtemperature conductivity have a little influence on the temperature field distribution.4. Influences of different construction conditions on the temperature field arestudied. The results show that the subway tunnel lining insulation measures have agreat influence on the temperature field distribution; the layout and refrigeranttemperature of frozen pipe have a great influence on the temperature field.