Experimental Study On Heat Conductivity Coefficient Of Silty Clay Under Freeze-thraw Cycles

The frozen soil was a very special kind of geotechnical engineering materials, which was different from the conventional thawing soil as there had lots of ice insides. In the project, the temperature as the living conditions was one of the most important parameters for the frozen soil, which had the relationship with the structural characteristics. The thermal conductivity of the frozen soil is a very important parameter in the calculation of the temperature field, which showed the ability of heat transfer from the hotter point to the cooler point. How to suitably analysis and evaluate the soil in the state of freezing and thawing are becoming an important issue to predict the temperature field of frozen soil in the construction and research.In this thesis, the main research is the clay of the frozen soil area in the Songnen Plains. The thermal conductivity was measured accurately by the transient and steady state methods, respectively. After that, the thermal conductivity was used to predict the temperature field of soil in the freezing and thawing state. Meanwhile, because there had many factors affect the temperature field of the soil, how to build the model of numerical simulation was another key research issue of this thesis. In this thesis, firstly, the physical properties of clay were researched, which were included the test of natural and boundaries moisture, density of the soil, particle analysis and compaction. Secondly, the thermal conductivity of the frozen soil in this area was compared and measured by the transient and steady state methods, respectively. The relationship between the thermal conductivity and physical properties, such as the moisture content and soil density, were investigated. Finally, based on the transient state method, the finite element software of ABAQUS was used to predict the temperature field of clay in the seasonal frozen soil area. Through the establishment of basic model, mesh, applied load and running the thermal analysis module and other steps, the transient temperature of the soil samples were studied over time and distance from the heat center.As can be seen in this experimental study, the thermal conductivity of melting and frozen soil in the seasonal frozen region increased as the dry density and moisture content gradually increase. The simulation results show that the thermal conductivity of the frozen sample is greater than the melting sample. When it achieve the same instantaneous temperature, the farther away from the surface of the soil, it needs more time to change to the other statement.