Chapter 5 Shock and Explosion Dynamics

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1、5ShockandExplosionDynamics5.1IntroductionAnexplosionisarapidreleaseofenergyandcanhappeninair,ontheEarth’ssurface,undergroundandunderwater.Typicalexamplesarisefromchemicalandnuclearexplosives,thermalandhydroelectricsourcesandgasignition.Section2.5ofChap.

2、2givesausefulintroductiontosourcesofexplosionandalsopresentscomprehensivedataonexplosions.Thepurposeofthischapteristogiveacomprehensivetreatmentofexplosiondynamics.ThedatagiveninSect.2.5willactasinputtovariousequationsgiveninthischapter.Thereadermustnow

3、befamiliarwiththebasisofstructuraldynamicsgiveninChap.3.Sinceexplosionsmaygeneratemissiles,thereaderisadvisedtohaveathoroughknowledgeofChap.4.Section3.4oftheBibliographyprovidescomprehensivecoverageofin-depthtreatmentofspecificareas.5.2FundamentalAnalyse

4、sRelatedtoanExplosion5.2.1StressWavesandBlastWavesStresswavesrepresentthebasisofexplosioninthesurroundingmedium,beitgaseous,liquidorsolid.Theyaredefinedasmovingpartsofthemedium,beinginastateofstresssuchthattheboundariesarewavesandtherestofthemediumconsis

5、tsofwavefronts.Stresswavesaresometimescalleddeformationwaves.Thesestresswavesaredividedintonormalandtangentialwavesrepresentingstressesinthosedirections.Normalwavesmaybedividedintopressurewavesandtensilewavesorrarefactionwaves.Thenormalwavesarealsoknown

6、asP(longitudinal)wavesandtheS(tangential)wavesastransversewaves.Ingeologicalmedia,thesurfaceistheinterfaceofindividuallayersofrockandsoilorairandsoil/rock.Theinterfacebetweenthemisknownasthefreesurface.Thesurfacewavesarethenclassifiedaccordingto6725Shock

7、andExplosionDynamicstheshapeandsenseofthetrajectoriesfollowedbymovementsinamedium.Thesurfacewavesaregivenbelow:(1)TheRayleighwave(Rwave).Thiswaveexhibitsaplanarellipticmotioninthemediumsuchthatitssemi-axesdecreaserapidlyatacertaindistancefromagivendepth

8、.(2)TheLovewave(Qwave).Thesewavesexhibitaspatialmotioninamediumandtheircomponentsareparallelandnormaltotheplaneofpropagation.(3)Thehydrodynamicwave(Hwave).ThesewavesaresimilartoRwavesandpropagatealongthesurfaceoftheliquidandarefr