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Influence Of Freeze-Thaw Cycle On The Particle Size Of Malan Loess

Posted on:2019-02-25Degree:MasterType:Thesis
Country:ChinaCandidate:Z LiFull Text:PDF
GTID:2310330569979688Subject:Geological Resources and Geological Engineering
Abstract/Summary:PDF Full Text Request
Freezing thawing cycle has great influence on the engineering properties of soil.After repeated frost heave and thaw settlement,the strength and load carrying capacity of the soil change greatly.Experts and scholars at home and abroad have done a lot of research on soil permeability,porosity and internal friction angle.Studies have shown that soil particles are also affected by freeze-thaw cycles.The arrangement rules and connection modes between soil particles are the main factors to determine the deformation and structural strength of loess.Therefore,this paper focuses on the change of soil particle size and particle size in the process of soil freezing and thawing cycle,and further discusses the effect of freezing thawing cycle on soil microstructure.In this paper,the control variable method is used to control soil samples with different moisture content and freeze-thaw cycles according to moisture content and freeze-thaw cycles.The original Ma Lan loess was selected as the research object.After the soil sample was dried,the soil samples were arranged into different moisture content to carry out the freeze-thaw cycle test.The particle size of the dry particle size and particle size analyzer was measured by Malvern dry method.The particle size of the soil samples after different water content and different freezing and thawing cycles was quantified.The change rule of particle size under the influence of moisture content and freeze-thaw cycles is explored.Freeze-thaw cycles of Ma Lan loess with 5%,7%,10%,15% and 20%water content under the same conditions were carried out.It is found that withthe increase of soil moisture content,the percentage of fine particles in soil samples increases and the average particle size decreases.The freeze-thaw cycle has great influence on the particles of >10 um and the percentage content of <4um particles.The percentage content of <4 um particles increases with the increase of water content,and the percentage content of >10 um particles decreases with the increase of water content.The content of the particles in the middle part of 4~10 um varies slightly,and the particles of 5~10 um still show a tendency to decrease with the increase of water content,and the particles of 4~5um show an increasing trend.The freeze-thaw cycles of the samples with the same water content were 1,3,5,7,10,15 and 20.It was found that the effect of freeze-thaw cycles on the particles was greater as the number of freezing and thawing cycles increased.With the increase of freeze-thaw cycles,the percentage content of <4 um particles showed a significant upward trend,and the percentage of >10 um particles decreased.The particles of the intermediate particle size part of <5 um basically showed a steady rising trend,and the particles of >6 um showed a tendency to decrease basically;when the number of freezing and thawing cycles of 5~6 um was less,the trend of the particles decreased when the number of freezing and thawing cycles was more.The more the number of freeze-thaw cycles,the smaller the average particle size,and the smaller the concentration range of particle size.
Keywords/Search Tags:freezing and thawing cycle, particle size, loess, water content, freezing and thawing cycles
PDF Full Text Request
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