Quantitative Evaluation Method Of Collapsibility And Compaction Degree Of Loess Based On Electrical Index

Loess collapsibility is a challenge faced by engineering construction in loess area,which often induces various engineering disasters.How to evaluate and treat the collapsibility of loess economically and effectively is an important subject in geotechnical engineering.Resistivity is an inherent property of soil,which can effectively reflect its own state and its response characteristics to the environment.This paper takes loess in Gansu as the research object,through laboratory test and theoretical analysis,the relationship between the collapsibility coefficient,resistivity and physical properties of remolded loess is studied,the resistivity evaluation model of loess collapsibility coefficient is established,resistivity model is proposed based on the quantitative evaluation of soil compaction,the relationship between the cementation coefficient and cohesion was investigated.The main research contents and achievements are as follows:(1)In this paper,the relationship between the collapsibility coefficient and resistivity of loess and its physical property indexes is systematically studied,and the evaluation method of loess collapsibility based on electrical indexes is proposed.The effects of moisture content,density and overburden load on the collapsibility coefficient of loess were systematically studied by laboratory collapsibility tests.The experimental results show that the collapsibility coefficient of remolded loess decreases with the increase of water content,decreases with the increase of density,and increases first and then decreases with the increase of pressure.Through indoor resistivity test,it is verified that Kellers resistivity model is also applicable to loess,and the resistivity has a power function relationship with water content and density.By eliminating the parameter of water content,the relationship between the collapsibility coefficient and the resistivity is obtained,and the collapsibility evaluation of loess is realized through the resistivity and physical indexes.(2)Based on the Keller resistivity model and the fitting formula of resistivity and water content density,the density was converted to compactness,and the relationship formula of resistivity and compactness was obtained.Newton iterative method is used to solve the equation,and MATLAB is used to solve the equation.The compactness of soil can be obtained directly from the resistivity and various parameters,and the quantitative evaluation of the compactness of soil based on resistivity is realized.(3)Through indoor resistivity test and direct shear test,the relationship between the cementation coefficient and cohesive force and the content of clay particles was studied,and the relationship between cementation coefficient and cohesive force was compared.The experimental results show that the cohesion of soil samples increases with the increase of clay content,and the resistivity of unsaturated soil samples first increases and then decreases with the increase of clay content.Because of its special macroporous structure,the resistivity and cementation coefficient of loess saturated with sodium chloride solution are lower than those of mixed soil samples.The cohesive force and cementation coefficient of loess are smaller than those of mixed soil samples,showing a certain correlation.