巖石壓剪斷裂的理論與實驗研究.pdf

1、中南大學博士學位論文巖石壓剪斷裂的理論與實驗研究姓名：陳楓申請學位級別：博士專業(yè)：采礦指導教師：孫宗頎20020908ABSTRACThitlisthesisthemechanismofrockfractureduetocompressionshearloadingandaseriesofrelatedkeyissueshavebeensystematicallyinvestigatedouthebasisofmicroandmacro

2、scopicIevelThemethodadoptedthroughoutthepresentstudiesisacombinationoftheoreticaJanalysisnumericalcalculation(includingnumericalsimulation)、andexperimentalinvestigationTheneartipstressfieldcausedbycompressionshearloading

3、wasfirstanalysedandcalculated，theobtainedmaximumprincipalstresseswerethendepictedinthetopfigsThestrainsnearcracktipsfordifferentinclinedanglesofcrackwerealsomeasuredinexperimentslnordertofurtherunderstandthecompression—s

4、hearstressfieldTheresultsshowedclearlythatthestressfieldinthevicinityofcracktipinducedbycompression—shearloadingismuchmorecomplicatedthantheonecausedbytensileshearloadingItisoffollowingtwoimportantbehaviors：【Theneartipst

5、ressfieldinthis10adcaseisquitedifferentaccordingtowhethorornotthecrackfacosareclosedand2AnadditionallocaItensilestresscanbeeasilyinducedatthetipsofunclosedcracksubjectedtocompressionshearloadingTheproblemsconcerningcrack

6、co—planarextension，whicharecloselyrelatedtomodeiifracturetoughnessofrock，werethendiscussedbasedonabovestressanalysisTheconditionfofcrackcoplanarextensionwasgiveninthisthesisTheauthorproposedanewprocedurefortheanalysisofr

7、ockfractureduetocompressionshearloading，inwhichtwospecimengeometry—loadingsystemswereused1ethecenter—crackedBraziliandisk(CCB)andtlledoubleedge—crackedBraziliandiskfECB)underdifferentloadcasesSemi—analyticalformulaeforth

8、ecalculationofbothmodeIandmodeIIsirundervailOUS10adcasesweredeftvedusingweightfuncfionmethod，andaprocedureformodeIIfracturetoughnesstestingwithECBspecimenwassuggestedTheSⅢvaluesevaluatedbyderivedformulaeshowahighprecisio

9、ncomparingwiththenumericalsolutionsThesuggestedspecimengeometrynotonlypermitsonetoachievepuremodeItoanycombinationofmodeIandmodeIIloadingitisalsoeasytofabricateespeciallyforECBspecimenTheproblemofcrackclosureundercompres

10、sionshearloadingwerealsotackledinthisthesisAclosuremodelforwingcrackextensionwasproposedbyintroducingaCoulombfrictionbetweencrackfacosThesirvaluesatwingcracktipsevaluatedbyderivedclose—fo『ITnedformulaeareveryclosedtonume

11、ricalsolutions，theprecisionofthesevaluesarealsohigherthanthatofsimilarworkgivenintheintemationalgteraturesInthefieldofmicroscopicfracture，theauthorhaspayedspecialattentiontothephenomenologyandmechanismofmicrofracture，thu

12、sanacousticemission(AE)techniquehasbeenusedinexperiments，Itcailbefoundtbat也ev／avespectrumparametersofAEseemmoresensitivetotheprogressofmicrofracturethantheloaditselEInordertogetfurtherknowledgeofmicrofracturemechanismthe

13、authorproposedatwo—phasemicroscopicmodelin血estudyofbrittlefractureofrockInwhichbri吡erockwasmodeledasatwophasecompositematerialconsistingofhardermineralgrainsandweakercolloidsStressfieldinthecolloidsareawascalculatedusing

14、FEM，theresultswerethellcomparedwimthenumericalexperimentsolutionsConsideringtheimportantroleoftensilestressintherockfractureprocesstheauthorsuggestedtwolocalstrainenergydensitycriteriaie1Circumferentialstrainenergydensit

15、factorcriterion(CSED)。and2DialatationaIstraineriergydensitycriterion(DSED)Finally，sonleengineeringapplicationsofcompressionshearfractureofrockwerediscussedattheendofthethesisKeywords：rock；compressionshearfracture；stressi