Research On Hydrothermal Stability Of Subgrade Structure Under Freezing And Thawing Cycles

Subgrade as a belt shaped structures, attached to the surface of the natural foundation, vulnerable to the influence of environment loads. There are so many kind of Environment factors which often affect the stability of the roadbed. Such as the freeze-thaw cycle, multiple aspects of dry wet circulation, wind erosion cycle Freezing and thawing cycle on the subgrade damage mainly for Subgrade Frost Heaving and thaw settlement, this phenomenon is the main reason is outside the four seasons temperature alternately, makes the roadbed within a temperature gradient, the temperature distribution is not uniform makes the subgrade soil moisture distribution changes caused by.Frozen soil in our country widely distributed in north area and individual high elevation of mountain, about accounted for about half of the land area. Permafrost as special soil, temperature influence the stability of the key factors. According to the < medium and long term railway network planning >, plenty of line through permafrost region or season of permafrost region, so that study on the freeze-thaw cycle under the action of the subgrade internal temperature, the distribution and variation of water and other factors is important to solve the problem of frozen soil.Destruction of Subgrade in permafrost region is mainly due to the changes inside the roadbed temperature and moisture change. This paper to Atlantic high iron Linfen section of Seasonal Frozen Subgrade as the research object, using ANSYS finite element software of freezing and thawing cycles of the Subgrade Temperature Field and the moisture field numerical simulation is conducted to investigate the gene freeze-thaw cycling failure mechanism.1. Combined with the characteristics of big west line subgrade, according to local actual temperature and geological conditions, according to the different situations of road embankment boundary conditions. Analysis the distribution of temperature field of roadbed, roadbed of the key points along the vertical and transverse temperature distribution map is obtained, and come to a conclusion that the freezing and thawing settlement change rules. Subgrade Frost Heaving and thaw sink the primary factor is the2. Water changes, this paper according to the moisture migration control equation, considering under rainfall conditions, the subgrade were moisture field numerical simulation, get the moisture distribution and migration rule and research for Subgrade distresses caused by moisture migration mechanism.3. The temperature and moisture is affecting the subgrade deformation of two important aspects, model of the third chapter and the fourth chapter calculated double field data import to the deformation of subgrade and the subgrade deformation for further simulation were calculated the deformation of each internal node of the subgrade and the most unfavorable position and the maximum deformation, understand the deformation of Subgrade in different locations.