Temperature Evolution and Deformation Response of Frozen Construction Structure in Coastal Water-Rich Area

The stratum in coastal area is weak and rich in water with low bearing capacity. During the engineering construction by frozen method, the deformation and temperature fields of the structure and soil respond violently, which can easily lead to large-scale construction disturbances. Temperature effect parameters of soil and groundwater are obtained through field and indoor tests, a 3D thermo-mechanical coupled numerical analysis model for the whole process of freezing excavation thawing is established, the development and diffusion laws of the frozen curtain ring during the construction process is explored, the deformation and temperature evolution characteristics of soil and support structures are revealed, and the research results are finally applied and verified through engineering practice. The results show that: During the channel excavation, the soil within a range of 2.75~7.16 m from the channel center is compressed and compacted, and there are sharp temperature fluctuations. Within 15~25 days of heating and thawing, grouting reinforcement can be carried out on the soil within a depth range of 15.8 m below the ground surface. Especially within a range of 3.99 m from the channel center, the soil temperature rise faster than other regions. During the soil freezing process, the soil on the inner side of the freezing tube freezes faster than the outer side, and the soil on both sides of the channel freezes faster than the upper and lower sides. During the heating and thawing process, the upper and lower soil in the channel thaw faster than the two sides, and the thawing of the upper and lower soil in the channel mainly occurs during the continuous heating stage. During the thawing process, the deformation of the upper and lower parts of the primary support and secondary lining is significantly greater than that of the two sides, and there will be significant stress concentration at the corners of the steel rib bottom and the top and lower parts of the reinforcement mesh. Pre-embedded grouting pipes can be used to inject grout into the upper and lower soil 20 to 40 days after thawing begins, in order to slow down the development of structural displacement and stress concentration.