Study On Structural Characteristics Of Soil-Rock Mixtures Based On Electrochemical Impedance Spectroscopy

As a kind of extremely uneven and discontinuous geotechnical material,the soil-rock mixture is widely distributed in the residual slope of land surface in China,which is highly valued in the field of geotechnical material research because of its diversity of destructive inducement and the complexity of mechanical behavior.The properties of soil-rock mixtures are characterized by their structural characteristics.At present,the structural characteristics of the study due to the limitations of technical means,mainly focused on the characteristics of its block,while the fine particles structure and soil-rock interface and other basic structural units have been neglected for a long time.In view of this,electrochemical impedance spectroscopy(EIS)method is used to study the structural characteristics of the interior remolded soil-rock mixture.Based on the electrochemical impedance spectra,the paper constructs the material index,three-phase physical index,impedance spectrum Nyquist curve characteristic and the mapping relation between the equivalent circuit model parameters,and puts forward the high frequency extremum point,impedance extremum curve,distribution characteristic point,distribution characteristic curve,A series of semi-quantitative and quantitative mathematical model tools,such as three-level equivalent circuit of soil-rock mixture,and equivalent impedance coefficients.On this basis,the basic structural element of the soil-rock mixture,the influence of the structural element on the mechanical index and the influence of the Block stone on the structure of the soil-rock mixture are deeply studied.The following main conclusions were obtained:(1)This paper proposes a series of mathematical model tools for measuring and evaluating the internal structural characteristics of soil-rock hybrids based on electrochemical impedance spectroscopy(EIS),which is initially proved to be reasonable.It has a certain application prospect in the evaluation of the.structural characteristics of soil-rock mixture;(2)The granular nature of the soil-rock mixture structure is fine-grained cementite,coarse-grained block stone and soil-stone cementation body,and the structural basic unit that bears the mechanical function is fine-grained cement body and soil-stone cementation surface.Both the material indexes such as the water content,the amount of stone,and the particle size of the stone are generally presented as power-related correlations with significant convergence characteristics;(3)In the non-convergent section of the soil-rock mixture electrochemical impedance spectroscopy,the internal cohesion of the soil-rock mixture is mainly borne by the fine-grained cement and is positively correlated with the material variable(? +In S?).The internal friction angle is mainly assumed by the soil-cement interface,and it is linearly related to the material variable In S? under the condition of determining the moisture content;(4)Block stones have a positive effect on the continuity of the structure of the soil-rock mixture.Under the conditions of low and medium stone content,the increase in the content and particle size of the block stones is beneficial to the stability of the skeleton structure of the soil-rock mixture.