| Since the 1970 s, especially since the early 21 st century, our country carried out Western Development Program, so there has been a qualitative development in the economy of China’s western region. In order to fuel economic growth, the railway in the western region has being become more and more, especially when we constructed railway on the Saline Land, the problems about frost heaving of Saline soil has gradually come into the scholars’ sights. So far, the development of our country’s railway has more than 100 histories. In particular, since the reform and opening in 1978, the development of China’s economy promoted railway’s development to come into a new stage. However, there are many challenges in the progress of constructing railway, especially in the cold Saline Land. Since there are different kinds of Saline Land, climates in different areas, in the different seasons, the subgrade of railway will produce different scales frost heaving, which will cause track irregularity, even influence train’s normal running. Thus, the research about the characters of different kinds of Saline Soil’s frost heaving becomes very important.The thesis is in a setting of the construction of railway subgrade from xitieshanite to North Hobson area in Qing Han province, because the area is close to the Salt Lake. And it belongs to Saline Land area. Its climate is Plateau Continental Climate and its annual average temperature is below-1.7°, so it is very cold there. Besides, because in the area, fine sandy soil in different position has different rate of water and different rate of salt. Therefore, studying and researching the frost heaving discipline in different rate of water and salt of subgrade soil in this area is very necessary, and it can provide theoretical basis and technical support for the subgrade construction in the fine sandy land and for how to take measures to prevent frost heaving.The experiment about frost heaving in door simulates the freeze of dirtsample in the low temperature to observe its frost heaving ratio. In the progress, the experiment needs some equipments and instruments which include DW-40 low temperature test chamber, dial indicator, Frost heave test platform, Specimen box and so on. I will allocate the dirtsample into two groups which have different initial dry density. Moreover, I will also allocate the dirtsample into five groups which have different rate of water and different rate of salt. The initial dry density of the first group is 1.6g/cm3 and the initial dry density of the second group is 1.9g/cm3. The rate of water is respectively 10%, 12%, 14%, 16%, 18%. The rate of salt is respectively 0%, 3%, 5%, 10%, 15%,25%. Then I will put the allocative dirtsample into the DW-40 low temperature test chamber and wait to observe and record its frost heaving ratio when the temperature drop to set value. In the experiment, I experiment the fine soil in the area which has different rate of water and different rate of salt in the door when the temperature drops. Through experiment, I find that with the dropping of the temperature, the frost heaving ratio of the fine sand which has higher initial dry density will increase gradually and finally become steady until the temperature is up to-30°.When the Chloride fine sand has the same initial dry density and the same rate of salt, and its rate of water is not out of its saturated water capacity, the frost heaving ratio of dirtsample will grow with the growing of the rate of water. When the initial dry density is lower, namely, it is 1.6g/cm3 and the rate of water is in the range of 14%, Cold shrinkage will come about in the progress of frost heaving. When the rate of water is higher of 14%, I can observe the dirtsample will have clear frost heaving. When the initial dry density is higher, namely, it is 1.9g/cm3, the dirtsample will directly have frost heaving but not clear Cold shrinkage. When the rate of salt is low of 5%, the frost heaving ratio will grow with the growing of the rate of salt. When the rate of salt is high of 5% and it grows from 5% to 10%, 15%,25%, the frost heaving ratio of dirtsample has the tendency of becoming low. And the frost heaving ratio will gradually decrease with the growing of the rate of salt.When the experiment is over, I induce and analyze the data. And by fitting, I find that the frost heaving ratio of Chloride saturated fine sand will approximately be cubics function with the change law of the rate of water, and will approximately be linear function with the change law of the rate of salt. And I get the empiricalformula of frost heaving ratio when the dirtsample is under the same initial dry density and different rate of water and salt. Eventually, when I use ANSYS to analyze figures, and make use of the experimental results to calcula te these figures, I find that compared with the non frost heave condition, under the frost heave condition, whether we consider Dynamic load increment in train load or not, the dirtsample will be bound to have frost deformation. If the subgrade is not even, frost heaving will damage the railway’s ride comfort, and make the planimetric position and Longitudinal section height of railway change. Seriously, it will make the train break off. So when we construct on the related road section, I suggest that we should take measures to prevent frost heaving in order to reduce the effect on the train, and improve the security and ride comfort of the train. |
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