| The Structure of loess influence its macro-mechanical behavior.Due to its high sand content and low concentration of clay particles and soluble salts,sandy loess differs significantly from silty loess and cohesive loess in terms of both structure and macro-mechanical behavior.Thus,it is essential to comprehend the connection between sandy loess structure and its moistening deformation qualities in order to solve geological issues in sandy loess places.The sandy loess in Dingbian County served as the primary research item for this thesis.The microstructure and moistening deformation features of sandy loess were examined and contrasted with silty loess and remolded sandy loess.The structure of the loess,as well as the effects of material composition and microstructure,were qualitatively investigated.Parameters that comprehensively describe the structural nature of sandy loess,considering various influencing factors,were proposed.It was further explained how structural nature and moistening deformation properties relate to one another.The following conclusions were mainly drawn:The sandy loess employed in this study had a 42.9% sand content and only a9.65% clay percentage.With little clay and soluble salts,it is mostly made up of primary detrital minerals and carbonate minerals.Iron and aluminum oxides,as well as clay minerals,make up the majority of the cement.The unit body is an edge-and corner-clear clastic particle.The majority of the intergranular connection is made by direct touch,and the connection is very strong.In the soil,there are many embedded and above pores,and there is a lot of room for deformation.A typical structural,under-compacted soil is sandy loess.Its large pore space changes into a medium pore space under the influence of force,and the proportion of the medium pore space rises;under the combined influence of hydraulic force,the medium pore space starts to significantly decrease,and the medium pore space is crucial for humidification and deformation.The stress-strain relationship of sandy loess shifts from a strong to a weak hardening type when the test beginning water content rises,the wetting coefficient continues to decrease,and the coefficient of humidification deformation continues to rise.The impact of microhumidity increases with increasing pressure.The structure governs the deformation properties of loess;the "variability" of the structure creates room for deformation,while the "stability" regulates how easily it can deform.Water will weaken cement,reduce intergranular resistance to rearrangement,decrease matrix suction,and reduce "stability";force will intensify the loss of intergranular linkage strength and increase deformation,reducing "stability" and increasing "variability".Increased variability.The structural soil known as sandy loess has high levels of "stability" and "variability," and it is made up of "clastic particles,hollow + mosaic pores,direct contact + cemented association." Its "water sensitivity" is less sensitive to water than powder loess and renovated loess,while its "stability" is more stable than both and its "variability" is both greater and lower than both of those materials’ levels.While the characteristic pressure at which the structure tends to zero point gradually decreases with increasing starting water content,and the relationship between the coefficient of humidification and deformation,pressure,and water content corresponds to the change of structure,the structure of sandy loess decreases with increasing pressure and exhibits three stages of decrease.Finally,the structural parameters of sandy loess proposed in this paper can dynamically reflect the effects of pressure,water content,material composition and other factors on soil structure,and under the condition of humidification and deformation,only the compression tests of in-situ and remodeled saturated samples at all levels of water content are required,which is more advantageous in terms of test difficulty and discrete degree control. |
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