季冻区粉质黏土分凝冻胀特性试验研究OA

Take seasonal permafrost area powdery clay in Changchun as the research object,and use one-way freezing tester to simulate the temperature environment of the soil body by changing the temperature of the temperature-control roof at the top of the tester to analyze the mechanism of freezing and expansion from the apparent cold structure of the specimen,the state of internal crystallization,the vertical displacement of the specimen and the change of the internal water content.The freezing and expansion mechanism was analyzed from the apparent cold growth structure of the specimen,internal crystallization state,vertical displacement of the specimen and change of internal water content.The result shows that the specimen appeared obvious continuous ice crystals in the internal longitudinal section,and irregular ice crystals appeared in the transverse section,and the soil body underwent sub-consolidation and freezing.The apparent cold structure of the specimen is in the form of network,and there are vertical cracks with certain continuity on the surface.The vertical displacement of the specimen gradually increased with the decrease of temperature,and the trend of change was most obvious in the range of temperature change from-5 to-15 ℃,and the vertical freezing and expansion displacement of the specimen continued to increase from-15 to-25 ℃,and the trend of increase slowed down.At the end of the test,the water content inside the specimen changed significantly,the water content change at the top position was caused by water migration,and the water content change at the bottom was caused by capillary force and osmotic suction.