Experimental study on long-term salt-frost heave deformation of sulfate saline soil in cold and arid regions

To explore the in-situ deformation mechanism of salt frost heaving in saline soil under long-term freeze-thaw cycles, the in-situ deformations of salt-frost heave of sulfate saline soil under long-term freeze-thaw conditions are measured to analyze the influence laws and the mechanism of four main factors including salt content, water content, initial dry density, and load on the residual dry density of sulfate saline soil under the long-term freeze-thaw conditions. The results indicate that under long-term freeze-thaw action, the compactness of saline soil tends to develop toward a looser state, and the residual dry density of soil is not affected by the initial dry density. The residual dry density of saline soil decreases with the increasing of salt content and increases with the increase of water content. Within the moisture content range of 10% to 20%, the dry density of soil decreases with the increase of the number of freeze-thaw cycles. Moreover, the lower the moisture content, the faster the rate of change in the dry density of soil and the greater the variation range. When the load is greater than 12.5 kPa, the salt frost heave accumulation of saline soil can be effectively reduced. Under the critical load, the dry density of the soil does not change with the number of freeze-thaw cycles, and the critical load can be determined by the initial dry density of the soil. The long-term salt frost heave development process of saline soil is a continuous formation of suspended pores within the soil under the action of freeze-thaw cycles. Loads have an inhibitory effect on the formation of overhead structures.