Effects of infiltrated rain during the construction stage on the deformation law of a sulphated gravel embankment in regions with seasonally frozen soil

Abstract

The sulphated gravel embankment in seasonal frozen soil regions may experience deformation problems such as salt expansion, frost heave, and settlement under rainfall percolation conditions and changes in environmental temperature, affecting considerably its normal use. In response to these issues, relying on the renovation and expansion project of an international airport in northwest China, this paper used a self-designed temperature control testing device and conducted indoor constant temperature tests and freeze–thaw cycle tests using on-site natural embankment filling, and conducted numerical simulation tests using the COMSOL Multiphysics software programme. This paper investigated the characteristics of temperature variation, moisture, salt migration, and deformation of sulphated gravel in seasonal frozen soil regions under rainfall percolation conditions. The results indicated that under environmental temperature changes in the range of −10–25 °C, the temperature at which sulphated gravel salt expansion and frost heave occur was approximately −8 °C, and the deformation sensitive depth range from 0 to 200 mm. The moisture and salt contents of soil samples would experience a sudden increase due to rainfall percolation, with the sudden increase in moisture in the soil sample with a salt content of 0.9 % lagging that of the soil sample with a salt content of 0.5 % by one freeze–thaw cycle. Rainfall percolation significantly enhanced the settlement deformation of sulphated gravel during freeze–thaw cycles. The primary causes of soil deformation include the upward migration of water vapour, the downward percolation of moisture, and rainfall. These factors contribute to the destruction of the soil structure and alter the contact modes between soil particles, resulting in soil loosening and settlement deformation.