The Soluble Of Coarse Particles Sulfate Saline Soil In Melt Sinking Test And Influencing Factors Of Research

Saline soil is the general term of saline soil,alkaline soil and all kinds of saline and alkaline soil.At present,saline soil is widely distributed in the world,and buildings and structures in the saline land area are greatly affected by the hazard of saline soil.The phenomenon of salt expansion or melt sinking will cause the foundation of buildings and structures to change or even destroy.In the process of high-speed railway construction,due to the melt sinking characteristics of the saline soil itself.It will cause the subsidence of the railway subgrade in the saline land area.However,high speed railway requires high settlement of subgrade.For example,the post-construction settlement of ballastless track should not exceed 15 mm.With the construction of high-speed railway and other infrastructure facilities at home and abroad,the construction of high-speed railway in the coarse particles saline land area has become an urgent problem to be solved.At present,domestic and foreign scholars have made a lot of research achievements on the melt sinking of saline soil.However,most of the studies on settlement focus on fine grained saline soils,and few studies on coarse particles saline soils.Moreover,there is a lack of refined research on the influencing factors of coarse particles saline soil.Based on the project of the high speed railway from Teheran to Isfahan,Iran,this paper makes a detailed study on the factors affecting the melt sinking characteristics of coarse particles sulfuric acid soil.The main method is to conduct indoor geotechnical test analysis of soil samples taken on site,and take the results of soil sample analysis on site as the standard.Within a certain floating range containing standard values,coarse particles sulfuric acid soils with different grading types and different salt contents were prepared manually in the laboratory.The subsidence test was carried out on the prepared saline soil under the dual factors of grading type and salt content,to explore the influence of different factors on the melt sinking characteristics of coarse granular saline soil.The empirical formula of the melt sinking coefficient was obtained by summarizing the law,and the variation law of the melt sinking coefficient of different soluble salts was explored.Finally,numerical simulation analysis is carried out to further explore the distribution of melt sinking in the soil.(1)Indoor basic geotechnical testBasic geotechnical tests,such as particle analysis test,compaction test,air-dried moisture content test,soluble salt content test and so on,were carried out on the saline soil taken at the site through basic geotechnical tests in the laboratory.The basic parameters of the field soil samples were obtained,which provided the basis for the subsequent laboratory melt sinking tests to explore the influencing factors of the melt sinking tests.Determine the particle size distribution and salinity level of soil samples prepared for the laboratory melt sinking test.(2)Laboratory melt sinking test of coarse particle sulfuric acid soilAccording to the analysis results of the soil samples taken on site,within a certain range of the parameters of the soil samples taken on site,The coarse particles sulfuric acid soil with different gradation and different salt content was prepared manually.The dissolution experiment of coarse particles acid soil was carried out on a self-designed melt sinking experiment device,and the results of the dissolution experiment were analyzed.The effects of variable salinity and different grading types on the melt sinking characteristics of saline soil were analyzed.(3)Empirical formula for the melt sinking coefficient was establishedOn the basis of the results of the influences of different factors on the melt sinking characteristics of saline soil,curve fitting was performed for the results of various working conditions.Thus,the empirical formula for the melt sinking coefficient of coarse particles sulfuric acid soil is obtained,and the empirical formula is used for calculation.The calculation results are compared with the field results to verify the applicability and accuracy of the formula.(4)Experimental comparison of different types of soluble salts in the melt sinking characteristics of saline soilAccording to the indoor artificial preparation of sulfuric acid soil preparation of chloride saline soil and sulfates and chloride mixed saline soil,and in accordance with the same test method test.Comparing the results of the melt sinking test of sulfate saline soil and chloride saline soil,The experimental parameters were total sulfate,50% of sulfate and chloride,and total chloride,The different characteristics of chlorine salt and sulfate in the melt sinking test were compared and analyzed.The reduction factor coefficient of the melt sinking coefficient was obtained,and the empirical formula of the chloride melt sinking coefficient was obtained.(5)ANSYS numerical simulation analysis of the melt sinking testNumerical simulation of saline soil melt sinking was carried out with ANSYS,and the results of laboratory melt sinking test were verified.The calculated results are compared with the field test results.At the same time,the degree of settlement in saline soil at different depths is explored to intuitively show the change rule of settlement with depth.A more intuitive melt sinking process of saline soil was obtained.