【目的】沿海城市轨道交通主要穿越海相深厚软土,需要大量使用冻结法施工,而该地区典型土层热物理特性是冻结法设计的关键依据。研究土质、冻融条件等因素对海相人工冻土冻结温度、热物理性质和冻融性质的影响可为该地质条件下的隧道施工提供基础资料。【方法】选取宁波地区3种典型土层,即淤泥质黏土、粉质黏土和砂质粉土,开展冻结温度和热物理参数测定,以及封闭与开放系统下冻胀融沉试验。【结果】3种土层冻结温度为-0.43~-0.23℃,且以砂质粉土的较高,粉质黏土的次之,淤泥质黏土的较低;不同土层热物理性质不同,但其常温土的导热系数和容积热容量大小呈现一致性,表现为砂质粉土最大,粉质黏土次之,淤泥质黏土最小;冻土的导热系数、容积热容量和导温系数均大于常温土,冻土导热系数为常温土导热系数的1.37~1.77倍,且颗粒越粗差异越大;各土层冻胀率和融沉系数相差较大,冻胀率较大的土层其融沉系数也较大,表现为淤泥质黏土>粉质黏土>砂质粉土;开放系统补水冻结过程下各土层冻胀率和融沉系数分别为封闭系统冻结过程不补水工况下冻胀率和融沉系数的1.23~1.88倍和1.21~1.84倍。不论是开放系统还是封闭系统,海相土体各土层的融沉过程相似,可分为缓慢融沉、快速融沉和稳定融沉3个阶段。【结论】海相土体的冻结温度、热物理性质和冻融性质与其土质、状态和冻融条件等因素密切相关,在进行海相土体冻结法设计与施工时,应充分考虑其物理特性的差异性。 【OBJECTIVE】 Coastal urban rail transit mainly traverses the deep soft soil of the sea, requiring a large amount of freezing construction. The thermal physical characteristics of the typical soil layer in this area are the key basis for the design of freezing method. The influence of soil conditions, freeze-thaw conditions and other factors on the freezing temperature, thermophysical properties and freeze-thaw properties of marine artificial frozen soil can provide basic information for the tunnel construction under the geological conditions. 【Method】 Three typical soil layers in Ningbo were selected, namely silt clay, silty clay and sandy silt. The freezing temperature and thermophysical parameters were measured and the frost heave and thaw settlement under the closed and open system were carried out. 【Result】 The results showed that the freezing temperature of the three soil layers was -0.43 ~ -0.23 ℃, followed by the higher silty silt, followed by the silty clay, and lower the silt clay. The thermophysical properties of different soil layers were different The thermal conductivity and volumetric heat capacity of the soil at room temperature are consistent, showing the largest sandy silt, the second silty clay, the smallest silt clay; thermal conductivity, volumetric heat capacity and thermal conductivity of frozen soil are greater than normal temperature soil, The thermal conductivity of the frozen soil is 1.37 ~ 1.77 times that of the soil at room temperature, and the greater the difference of the coarse particles, the more the frost heaving rate and the thawing settlement coefficient of each soil layer are different, and the thaw settlement coefficient Which is silt clay> silty clay> sandy silt. The frost heave rate and thaw settlement coefficient of each soil under the open system water replenishment freezing process are respectively the frost heaving rate and melting rate Shen coefficient of 1.23 to 1.88 times and 1.21 to 1.84 times. Whether open system or closed system, the melting process of marine soil is similar to each soil layer, which can be divided into three stages: slow thawing, rapid thawing and stable thawing. 【Conclusion】 The freezing temperature, thermophysical properties and freeze-thaw properties of marine soils are closely related to the factors such as soil quality, status and freeze-thaw conditions. When designing and constructing offshore soil freezing methods, the physical properties The difference.