Experimental Study On The Salt Accumulation Layer Impact On Salt Expansion Of Coarse-grained Salty Soil

The Hexi corridor is one part of the ancient Silk Road, now known as important sections of the Eurasia Land Bridge, it not only plays an important role in economy of Gansu, Xinjiang, Qinghai, these three provinces, but also has a larger contribution on trade between Asia and Europe. With the growing of economic and trade activities, communication projects, pipeline projects, house-building projects, water projects and airport projects increase in this area, and there is saline soil which has many engineering diseases and is difficult to deal with widely distributing in this district, So the study of saline soil becomes very urgent and necessary. Previous scholars’ research mainly focus on the collapsibility, expansibility, and corrosivity of saline soil, but seldom involve the discussion on the limit depth of salt expansion, which affects some of the basic design principle and enacting measures of engineering diseases treatment. This article will research on this aspect, hope to offer a reliable basis for further researches and engineering practice in this field.In this article, through the analysis of field problems, abstracting its model, testing main parameters and rules in laboratory, in order to explain the mechanism and be able to process quantitative calculation. In view of this idea, in laboratory, the salt expansion of soil samples, which were prepared with different salt content, buried depth and salt thickness is observed under the condition of single cooling process. Results of experiment show that:1) Only salt content of salt accumulation layer reaches5.3%, it will affect salt expansion deformation near the earth’s surface, when it is less than5.3%, the salt expansion deformation of salt accumulation layer is absorbed by neighboring layers, only forms compaction effect of the neighboring layers without salt expansion deformation near earth’s surface.2)Only when thickness of salt accumulation layer is greater than38mm will affect the amount of salt expansion near the earth’s surface.3) The on-the-spot investigations in Dunhuang and other places find that, although a lot of thickness of salt enrichment layer is more than150mm, it has little impact on the salt expansion deformation of near surface, because of the salt content is low, this shows that effects of the thickness of salt accumulation layer on salt expansion amount is not so great as the content of salt.