Experimental Study on the Dielectric Properties of Subgrade Compacted Filler Considering Changes in Moisture Content
Dielectric properties are the basis of electromagnetic nondestructive testing technology for subgrade.In order to analyze the dielectric properties of subgrade filler and its relation with water content,the dielectric constants of six typical fillers,including sandy soil,clay,improved soil and saline soil,were tested by TDR under different compactness and water content.The results show that the dielectric constant of compacted fillers is mainly affected by salt content,moisture content,soil type,compaction degree,etc.The dielectric constant of conventional subgrade fillers is mainly controlled by moisture content,and the change in compaction degree between 90.0％and 96.0％has no significant impact on the dielectric constant of fillers.The water content-dielectric constant relationship of general cohesive soil,sandy soil,and improved soil can be fitted using the Alharathi model to meet the accuracy requirements of engineering applications.The parameters of the Alharathi model under different compaction degrees are relatively similar,a=0.100-0.140,b=-0.270--0.140.The fitting parameters of lime improved soil with different compaction degrees are quite different.In practical application,the influence of lime mixing ratio and compaction degree on the relational model of dielectric constant and water content should be considered.
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