细粒土含量对粗粒硫酸盐渍土路基填料盐胀特性的影响试验及分析模型

为了明确细粒土含量对粗粒硫酸盐渍土路基填料盐胀量的影响，针对 1% 和 3%含盐量工况下的砂、砾类盐渍土，采用降温试验研究了细粒土含量递增条件下粗粒硫酸盐渍土的盐胀特点。在此基础上，利用 PFC^3D技术模拟了粗粒盐渍土的盐胀变形并分析其机制，结合微观试验分析了盐胀状态中粗粒土骨架典型状态。结果表明：随着细粒土含量的增加，粗粒硫酸盐渍土的盐（冻）胀量均先增加后减少再增大，分界细粒土含量因含盐量及土类不同而异，1%、3% 含盐量的砂、砾类土样分别在15%和10%细粒土含量时产生最大盐（冻）胀量；3%含盐量砂、砾类土的起始盐胀温度约 20 ℃，1%含盐量土样的起始盐胀温度随细粒土含量及土种类不同差异较大且存在明显的界限细粒土含量，当细粒土含量低于界限值时土体的起始盐胀温度约为0.5～2 ℃，高于界限值时土体的起始盐胀温度约为 4～12 ℃；同时提出了盐胀状态中粗粒土骨架典型状态模型及其作为路基填料的细粒土含量界限值。

Salt expansion characteristics and analysis model of coarse-grained sulfate saline soil embankment fill material with increasing fines content

In order to clarify the influence of fine-grained soilcontent on the salt expansion characteristics of coarse-grained sulfate salinesoil embankment fill material, sand and gravel saline soils with sulfate saltcontents 1% and 3% were investigated. A series of cooling and salt expansiontests was carried out to examine salt expansion characteristic ofcoarse-grained sulfate saline soil under conditions of increasing finescontent. On this basis, PFC^3D discrete element method was adopted tosimulate salt expansion of coarse-grained sulfate saline soil, and typical soilskeleton of coarse-grained saline soil during salt expansion process wasanalyzed combining microscope tests results. The result shows that with theincrease of the content of fine-grained soil, the salt expansion/ frost heaveof coarse-grained sulfate saline soil first increases, then decreases andincreases finally. The boundary fines content varies with the salt content andsoil type. Sand and gravel soil samples with 1% and 3% salt content wouldproduce the largest salt expansion or frost heave at 15% and 10% fine-grainedsoil contents respectively. The initial expansion temperature of sand andgravel soil with 3% salt content is basically kept about 20℃. The initial expansion temperature of soil samples with1% salt content varies greatly with the fines content and soil types, and thereexists an obvious limit of fines content. When the content of fine-grained soilis lower than the limit value, the initial expansion temperature is about 0.5–2 ℃, when higher than the limit value, the initiationtemperature is about 4–12 ℃. A typical state model of the coarse-grained soil skeleton in thesalt-expansion state and the fines content limit of the coarse-grained sulfatesaline soil as the embankment filler are given.