Abstract:In order to perfect the salt expansion theory of coarse-grained saline soil and explore the influencing factors and mechanism of the salt-frost heaving force,96 groups of coarse-grained sulphate saline soil samples are prepared artificially then indoor model tests have been carried out by self-designed test device. Test results showed that the sensitive range of temperature on the salt-frost heaving force is -0.2~-1.0. The salt content had no influence on the rules that the salt-frost heaving force increasing with temperature and determines the maximum salt-frost heaving force together with water content. For samples with same void ratio, the increasing water content led to an increased amount of the salinity which resulted in the maximum salt-frost heaving force. When the salt content kept constant, however, the increase of water content caused the decrease of maximum salt-frost heaving force. The maximum salt-frost heaving force achieved the maximum and minimum values when the void ratio was 0.58 and 0.55, respectively, which was related to the crystallization position of salt in the soil frame. Furthermore, based on the test results, a mathematical expression of frost heaving limit depth of coarse-grained sulphate saline soil is given by the hierarchical synthesis method, which is expected to provide guidance for the quantitative evaluation and design of salt-frost heaving deformation of coarse-grained sulphate saline soil.