Study On Resistivity Characteristics Of Saline Soil In Western Jilin

Saline soil is a general term for salt and alkaline soil and various saline and alkaline soils,and is a special type of soil focused on geotechnical engineering.The hazards of saline soil to engineering construction are many,and the resulting economic losses are huge.Since saline soils have solubility,salt expansion and corrosiveness,their hazards are generally caused by these three characteristics.Since the causes,composition and characteristics of saline soils are different in different regions,the engineering hazards of saline soils in different regions are different,so it is necessary to investigate the saline soils to determine their water and salt content and other constituent components.Most of the commonly used methods for testing saline soils are based on sampling experimental tests and conductivity regression calculations.The research in this paper uses high-density resistivity combined with physical simulation experiments to decode and analyze the water and salt content in resistivity data using experimental analysis to realize the advantages of high-density resistivity method for saline soil detection with high efficiency,full coverage and rich geoelectric information.This paper takes saline soils in Nong’an County of western Jilin as the research object.Firstly,a saline ground electrical model is established according to the actual geological characteristics of the study area,and a forward and inverse numerical simulation analysis is carried out to understand the resistivity inversion characteristics of the spatial distribution of saline soils and to determine the form of detection device that is suitable for the region.Then,we analyzed the relationship between different salts,water content and resistivity characteristics by configuring different water and salt content specimen models,established the regression equation of resistivity and water and salt content,and applied this characteristic equation to the measured resistivity inversion data for water and salt content interpretation analysis.Finally,the resistivity,conductivity,salt content,water content,particle size composition,liquid-plastic limit and other parameters of the in situ soil samples were systematically tested and analyzed to understand the mutual influence of each parameter,and to verify the validity of the characteristic equation.The main research results obtained are as follows:（1）The results of the physical model simulation of saline soils show that the resistivity of saline soils decreases with increasing salt content and tends to a constant value;both soil moisture and salt content have significant effects on resistivity,and when the salt content tends to a certain value,the water content and resistivity are negatively correlated,and the resistivity gradually becomes smaller with increasing water content and decreases as a power function.When the water content increases,the resistivity decreases exponentially and is negatively correlated,and the effect of salt content on resistivity is higher than that of water content,and the resistivity of soil is significantly different for different types of salts,with the specific law of soil resistivity:Na₂SO₄>Na HCO₃>Na₂SO₄and Na HCO₃（1:1）,which shows that mixed salts are more conductive than single salts.Based on the above experimental results,the regression equation of water-salt content of saline soil resistivity was established by combining the Alchie resistivity model with the indoor test data.（2）Through the forward and backward simulation studies of the saline soil model,it is found that the Wernerαdevice has a clear morphology and higher resolution for the low-resistance anomalies in saline soils,which is more suitable for the detection of anomalies distributed horizontally near the surface;in the simulation studies of several longitudinally arranged anomalies distribution models,it is found that the low-resistance anomalies characterized by the Wernerβdevice are more accurate;for the strata with both of the above characteristics,the Wernerβdevice For the stratum with both characteristics,the discrimination ability of Wenner beta device is better than other devices.（3）The indoor experimental results were used as the basis for decoding and error analysis of the water-salt content implied by the high-density resistivity geoelectric information,and more accurate and continuous characteristics of the water-salt distribution in the subsurface half space were obtained,which in turn verified the effectiveness of the resistivity profile method for the identification and determination of soil salinization.