Study on the Influence of Relative Permittivity Fluctuation on Radar Detection Accuracy
The use of ground penetrating radar for detecting the thickness of the secondary lining in tunnel lining structures is an important means for quality acceptance during tunnel construction.However,the determination of secondary lining thickness by ground penetrating radar method is closely related to the selection of relative permittivity.Once the value of relative permittivity is not chosen appropriately,the thick-ness of the secondary lining obtained by ground penetrating radar method will lose its reference significance.The paper introduces the basic principle of ground penetrating radar method for detecting the thickness of tunnel secondary lining,and through the tracking detection of relative permittivity on three groups of standard concrete test blocks,the results show the relative permittivity of concrete under the same conditions has minimal fluctuation after reaching the age of 28 days,and its influence on the accuracy of secondary lining thickness detection is very limited.However,the results of detecting haven-built tunnel lining structures show that when detecting in different design strength sections,the influ-ence of relative permittivity fluctuation on radar detection accuracy should be considered.For the secondary lining parts involving pass/fail line determination,it is advisable to use verification methods to determine the final results.
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