Analysis On Frost Resistance Effect And Temperature Field Of New Cold Resistance Layer In Frozen Areas

Road frost damage in seasonal frozen areas is an important problem for road maintenance. As the temperature freezes and thaws, the embankment temperature field changes repeatedly, also the moisture are in freeze-thaw cycles. This seriously affects the normal service and use of the road. Based on the frost damage mechanism and prevention measures of the seasonal frozen areas, a new type subgrade cold resistance layer is proposed. It is a combination of modified fly ash soils with rubber particles and XPS insulation board, which can effectively prevent the cold erosion, relieve the subgrade water condition and improve the road embankment temperature filed.This article evaluate the anti-freezing and thermal insulation properties of new cold resistance from the perspective of thermal parameters and outside temperature tests. A simulation analysis by ANSYS is done to analyze and predict the temperature field of the soils. The main research contents are as follows:(1) To understand the properties of the new subgrade filling material, the freezing curves are measured. The freezing point and approximate expression function of unfrozen water content are determined.(2) Considering the water state of subgrade material in the process of freezing and thawing, combining the unfrozen water contend expression function, thermal parameters of the modified soils and XPS insulation board are revised under the positive and negative temperatures.(3) Short-term and long-term outside temperature tests of the new cold resistance layer are conducted. And the comparison and evaluation of silty clay, XPS insulation board and new cold resistance layer are given after the tests.(4) ANSYS finite element software is used to stimulate the short-term and long-term outside temperature tests respectively. And the results of the simulation and the actual tests are compared. On this basis, the simulation of the cold resistance layer in actual road application is conducted. Finally, we get the evaluation of the preservation effect.Studies show that the parameters of modified soils are different from that of silty clay. Taken account into freezing temperature, unfrozen water, thermal conductivity and specific heat, the conclusion that the anti-freezing of modified soils is better can be made. Through the outside temperature tests, the thermal resistance effect of the modified soils and XPS insulation board is good. The new cold resistance layer can effectively reduce the cold to invade the soil beneath the XPS board. The results from the ANSYS finite element software show that the new subgrade cold resistance layer can improve the temperature field of the roadbed and have the effect of heat preservation and insulation.