Experimental Study On The Pure Salt Expansion Of Silty Clay And Salt Expansion Characteristics Analysis

ABSTRACT:In the northwest of China, Saline soil subgrade has many serious problems. In order to change the bad history of salty soil subgrade, it is very important to deepen the understanding of the saline soil engineering characteristics. Saline soil will occur salt migration under a variety of factors, such as temperature, moisture and salt. When the temperature and moisture content decrease, salt will crystallize and may lead to the occurrence of salt expansion roadbed deformation, reduce or even destroy the road traffic conditions. In response to this phenomenon, scholars conducted lots of research about the salt expansion of saline soil and salt heaving mechanism. Since the process of expansion of the salt contains the salt crystallization, moisture migration, migration and other effects, considering various factors will make the research very complicated.This study is in the basis of the National Natural Science Foundation "Cold regions research on saline soil, frost heave mechanism and mechanical properties under the action of water, temperature, force". In order to simplify the problem, this thesis will not consider moisture migration and nutrient transfer in the soil, and build an empirical relationship model, which based on the experiment that study the relationship between salt crystalline and salt expansion in the soil and analysis of test data refer to the deformation law of saline soil.In this study, the silty clay which came from Xiangpi Mountain Region in Qinghai would be used. Configure different salinity, water content, salt content, degree of compaction of soil conditions after the salt wash in laboratory test. Through the indoor pure salt expansion, study on the main factors and deformation behavior of silty clay containing sodium, silty clay containing sodium chloride, silty clay containing sodium chloride and sodium sulfate and containing sodium carbonate. Based on the experimental results and theoretical analysis, make the establishment of pure salt expansion empirical formula in different types of salt silty clay between the amount of crystalline salt and soil amount of expansion. At last, use the chemical reaction and the electron microscopy scanning to analysis the phenomenon of salt expansion. This study provides some reliable test data for the subsequent research and provides a more practical model of silty clay salt expansion deformation prediction.