Study On The Natural Regionalization For Highway In Saline Soil Area

The saline soil has a very wide distribution in our country. Saline soil in each place has its obvious character of causes of forming, composition and characteristic. Therefore damage of the roads in different saline soil areas is not same too. This paper has analyzed the forming conditions and processes of saline soil in northwest area. The distributed rules and main characteristic of saline soil in Xinjiang province have been summarized emphatically in this paper. According to the natural environment characteristic and the road engineering characteristic in different saline soil areas, this paper have thoroughly studied the relation between road construction and natural environment. Through discussing about the main diseases of the roads and their influence factors in saline soil area, there is a fuzzy grade judgment model that for salt expansion of the sulphate saline soil subgrade has been proposed in this paper.On the basis of analysis of the development history, principle and index of natural regionalization for highway in our country, three-rank natural regionalization system for highway is proposed, which applies to saline soil area. The saline soil area has been divided into four areas-coast saline soil region, semi-humid and semi-arid region, arid and extreme arid region, and alpine saline soil region, according to the first rank of natural regionalization. The second rank of natural regionalization has a further division of the four regions in the first rank according to the characteristic of salt accumulation, the type of soil and the condition of climate in the four different regions.According to the main factor affecting highway diseases in saline soil area and the distribution rules of saline soil in Xinjiang province, the third rank of natural regionalization has been made and Xinjiang province has been taken as an example. Characteristic and symbolization in every region in the third rank of natural regionalization has been summarized briefly. Purposing to make the third rank of natural regionalization apply to the highway construction, road building characteristic with saline soil and the construction measures are summed up and analyzed in every region of the third rank of natural regionalization. Combining with the research achievements before, the subgrade and pavement structure is brought forward which is suitable for the natural conditions in every area, so does the cure measure of saline soil diseases.