Research On The Relationship Between Electrical Resistivity And Water-salt-gradation Of Saline Soil And Engineering Application

The operation,maintenance and safety of high-speed railways are the pillars of the development of high-speed railways,and disease is a difficult problem that needs to be solved.The problem of disease is very prominent during the operation of the high-speed railway in Gansu,because the geological environment of the LanzhouXinjiang high-speed railway is very complex and the geotechnical engineering properties are special.In this paper,a series of laboratory tests were carried out to explore the characteristics of soil resistivity change under the mutual influence of three factors: moisture content,salt content and particle gradation.At the same time,electrical resistivity tomography detections were carried out at the typical disease points with serious settlement and heaving in the Gansu section of the LanzhouXinjiang high-speed railway,and the fundamental geological reasons for subgrade settlement and heaving were analyzed.The research results provide reference for the construction and maintenance of high-speed railway in Northwest China.The main research results are as follows:(1)For soils with any salt content and gradation,when the water content is low,the resistivity decreases rapidly decreases with the increase of the water content;when the water content is high,the resistivity is almost unaffected by salt content and particle gradation,and tends to be the same.The resistivity and water content of all soil samples are in good agreement with the power function relationship.(2)When the water content is low,the resistivity of the soil decreases rapidly with the increase of the salt content.The resistivity is at a lower level in the stage of moderately saline soil and highly saline soil.In the stage of over saline soil,the resistivity increases with the increase of salt content,and presents a higher resistance value.When the water content is high,the resistivity of the soil decreases rapidly with the increase of the salt content,and remains in a low state with the increase of the salt content.(3)For non saline soil and over saline soil,when the water content is constant,the resistivity of coarse-grained soil is always higher than that of fine-grained soil,and the higher the percentage of coarse grain fraction in the particle gradation of soil samples,the greater the resistivity of soil samples.(4)The settlement position of K2037+540 of the Lanzhou-Xinjiang high-speed railway is basically the same as the low-resistance zone of the electrical resistivity tomography model,and its formation mechanism is the wetting deformation of the subgrade soil caused by the increase of local moisture content under special geological conditions.(5)The heaving deformation position of K2398+600 of the Lanzhou-Xinjiang high-speed railway is basically the same as the high-resistance zone of the electrical resistivity tomography model,and its formation is due to the salt expansion effect caused by the salt accumulation of coarse-grained saline soil caused by geological conditions,geological conditions,and engineering structures.