Pore Structure Features Of Loess And Their Relationship With Structural Index

Studying the developmental characteristics and laws of loess porosity,finding out the mechanism of loess disaster,reducing soil erosion,preventing geological disasters and solving related engineering problems had important scientific and practical significance for the construction of the Loess Plateau region.In this study,the eolian loess in different regions of Lü-liang mountainous area was taken as the research object.Based on field investigations,physical and mechanical tests,and microscopic tests,we studied the relationship between microscopic pore characteristics and and macroscopic structure index of loess.The main achievements were:(1)The results of the particle size and mineral composition of the loess in the study area showed that the grain size of loess,the relative content of quartz and feldspar decrease from northwest to southeast,and the content of clay mineral gradually increases.The characteristics of the gradual transition of the loess granularity from northwest to southeast and from the loess belt to the middle loess belt were verified.(2)Based on the results of scanning electron microscopy,it was found that the pore structure parameters(mean pore size and surface porosity)were greatly different from regions to horizons.The less surface porosity and pore diameter of loess,and the more structural the loess was,the weaker the deformability,and from the side,the important control effect of pore size on the pore structure of loess was reflected.(3)The results of three-dimensional CT scan test verify the regularity of the decrease of the total pore volume of the loess from north to south and from the top to the bottom,and indirectly reveal that the soil increases with the southward migration and the depth of the soil.The macro-characteristics of structural enhancement and further discussion of the strength of loess in different regions have confirmed the relationship between pore distribution characteristics and structural strength in this study.(4)According to the results of the unconfined compressive strength test,the stress-strain curve with an inverse “Z” shape under saturated soil was generalized,and “Adaptive first mutation point” and “Adapted to the second mutation point” were proposed.The concept and the calculation of the structural parameters of the soil in different regions were calculated,and the relationship between the structural parameters of the loess structure and the physical properties of the soil was explored.The structure of the loess in the Lü-liang District was higher than that of the west area of Shanxi Province.The sexual parameters were affected by the basic physical properties of the soil.(5)The pore structure characteristics of loess largely determine the structural strength of the soil.Based on the theory of soil mechanics,quantitative evaluation model of loess physical properties,pore structure parameters,and structural indexes was established.The model,and based on the grey relational theory,determined the influence of the average diameter on the structural parameters of the structure;the three-dimensional CT image data was used to objectively verify the accuracy of the quantitative expression.and based on the grey relational theory,it is determined that the fractal dimension has a great influence on the structural parameters of the structure;and the accuracy of the quantitative expression is further verified by the three-dimensional CT image data.