mplicatedandisoftenaffectedbymanyfactorsincludingthegroutingmaterialandthegroutquality.Eachofthesefactorsmaycausesomeattenuation.Ingeneral,theobservedwaveattenuationmayhaveseveralcomponents,someofwhichmaybefrequency-dependentandsomefrequency-independent.Thetotalattenuationisthesumofthecontributionsofallinfluencingfactors[],andthisrelationshipappliestobothbulkwavesandguidedwaves:ln()ln()nnniiiiiiiLRR()whereiistheattenuationcoefficientoftheithcomponentcausedbytheithfactor,iListhetraveldistanceaffectedbytheithfactor,iRistheamplituderatioafterattenuationoftheithcomponent,IfiListhesameforallfactors,thenwehavenitiLLorntii()wheretisthetotalattenuationcoefficient.Accordingtothecause,attenuationmaybegroupedintothefollowingcategories:(a)Dissipativeattenuation:Anenergylossduetonon-elasticresistanceofthemedium.Itincreaseswiththewavetraveldistanceandmaybecomep更严重。
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