Abstract: Under the background of the national “belt and road initiatives” strategic development, the infrastructure in the western region inevitably needs to be built in the inland saline area, and its special collapsibility and salt swelling make the finegrained saline soil unable to be applied to the subgrade filling of the highway engineering. As the soil structure modifier, the PAM (polyacrylamide) has significant application value in the fields of soil improvement, soil erosion control, watersaving irrigation, agricultural production, ecological environment protection and so on. Therefore, the application of watersoluble PAM in the solidification of finegrained saline soil and then in the subgrade filling of highway engineering has important economic value. This paper intends to study the evolution law of basic physical properties of finegrained saline soil under the influence of PAM from three aspects: boundary moisture content, compaction characteristics and dry shrinkage characteristics. It is found that finegrained saline soil after treatment with a certain concentration of PAM aqueous solution has an obvious effect on improving plasticity index, strengthening water holding capacity, enhancing compaction effect, and improving dry shrinkage deformation characteristics, in this regard, we conduct experiments and record data to provide reference for engineering application.

Key words: Saline Soil, PAM, Physical Property