Seasonal Frozen Soil Properties (silty Clay) And Experimental Research

The area of the permafrost occupies a large part of total land area in China. Thepermafrost and seasonal frozen soil accounts for21.5%and53.5%of the land area,respectively. The seasonal freezing and thawing of soil is harmful to the buildings, sothe study of seasonal frozen soil is significant. China has begun the permafrost study inthe last century and drawn some important conclusions. The thaw characteristics are animportant part in the permafrost research, and thaw settlement coefficient is directindicator to determine the characteristics of permafrost thaw. In our paper, according tothe geographical features of the seasonal frozen soil area, we selected the typical soil ofthe Northeast-clay, and studied thaw characteristics of soil. We selected the moisturecontent, dry density, freezing temperature and freezing and thawing cycles as theinfluencing factors of the test. We have done the different levels of single factor andorthogonal experiments in the open system and close system. In the single-factorexperiment, we used origin date analysis software and have drawn the relationshipbetween thaw settlement coefficient of clay and moisture content, dry density, the coldjunction temperature and freeze-thaw cycles by regression analysis. In the orthogonalexperiment, we have determined the various factors how to affect the thaw settlementcoefficient of the seasonal frozen soil. According to the measured date, using spssstatistical analysis software, we have make a multiple linear regression model betweenthaw settlement coefficient and the moisture content, dry density, the cold junctiontemperature and the freeze-thaw cycles. The model can predict the thaw coefficient ofseasonal frozen soil areas. We also analyzed the moisture migration characteristics aftersoil freezing and thawing cycle in the open system and closed system. We characterizedthe internal structure of clay by scan electron microscopy and the internal matter of clayby X-ray diffraction before freezing, frozen and after frozen. Simultaneously, wecharacterized the micro-structure (the surface area, average pore diameter, pore volume) by BET method.