Experimental Study on Thawing Settlement of Sulfate Soil under Single Temperature Rise

Sulfate saline soil has obvious characteristics of soil structure changes with seasonal temperature changes, which causes great damage to the project. In order to study the thawing characteristics of sulfate saline soil under the condition of single temperature rise, the indoor compaction degree is 90%, 95% and 98%, and the salt content is 0%, 2%, 5%, 8% and 10%. The sulfate saline soil sample is subjected to a single heating test in a high and low temperature test box. The results show that the thawing settlement process of sulfate saline soil can be roughly divided into four stages under the condition of single temperature rise, the temperature in the range of -15 ℃ ~ -10 ℃ (±5) is the “structural thawing” stage, and the interval of -10 ℃ ~ 0 ℃ is the stage of “melting sedimentation adjustment”, and the interval of 0 ℃ ~ 15 ℃ is the stage of “ice ablation sedimentation”, and the interval of 15 ℃ ~ 25 ℃ is the stage of “crystal thawing sedimentation”. When the salt content is 0%, the thawing settlement rate decrease with the increase of the degree of compaction. The thawing settlement rate was greater than that under the condition of 0% of salinity. When the degree of compaction varied within the range of 90% ~ 95%, the thawing settlement rate and the degree of compaction presented an inversely proportional change trend. The thawing settlement rate of 98% compacted soil decreases generally when the salt content is 2% ~ 8%, and increases sharply when the salt content is 10%. In addition, when the compaction degree is 95% and 98%, the increment of thawing settlement rate reached the maximum in the range of 15 ℃ ~ 20 ℃ and reached the maximum at 20 ℃. And when the compaction degree is 90%, the temperature reached this state is 25 ℃. Comprehensive analysis considers that the compactness of the saline soil foundation should be 95%. This study can provide a certain reference for engineering construction in sulfate saline soil area.