关键词: 人工冻结, 冻结壁, 温度场, 盾构对接, 模型试验

Abstract: The complicated construction conditions, the small volume and irregular shape of the frozen wall are the characteristics of freezing reinforcement for shield junction in soft soil stratum. According to a freezing reinforcement project of shield junction in Shanghai, the model test based on similarity theory is conducted. Some conclusions are drawn through analyzing temperature data measured in the test. Firstly, under the condition of constant temperature on the inner surface of shield shell, the average expansion speed of the frozen soil inside the freezing-pipes is about 1.5 times that of outside the freezing-pipes. And the average temperature of the inside frozen wall is about 1.9 times that of the external frozen wall after 28 hours, when the temperature at the interface of shield and soil is about ?20 °C. Secondly, with a superposition of freezing-pipes, little difference appears at the beginning, and then similar variation for the temperature occurs in main plane and interface of the frozen wall during the freezing process. Thirdly, the freezing effect of the inner freezing-pipes on the outside soil is insignificant due to the temperature shielding of outside freezing-pipes, which leads to identical frozen wall thickness in the case of different freezing tube spaces and multiple freezing pipes crossing. Little difference in temperature distribution is found inside the frozen wall. The research results indicate a similar shape of the frozen wall to the layout of the outside freezing pipes during freezing process, and unchanged thickness and average temperature of frozen wall in 28 hours.

Key words: artificial ground freezing, frozen wall, temperature field, shield junction, model test