自然崩落法全英文一二壹

(FREE-CAVING)-BLOCKCAVINGGeotechnicalContentsTypesofcavesUndercutdesignExtractionleveldesignBCgeotechissues2CAVETYPESHARDCAVES(MRMR>45,1000mdepthKratio1-2)CavestallFragmentationRock/strainburstingSOFTCAVES(MRMR<45,1000mdepth,Kratio1-2)Excavationlevel&UCstressinduceddamageUndercutcrushingStrain/rockburstingwhenMRMR>35RULESStrategicdesignControlgeotechnicalriskswithUCSupportistacticalissueMainissues -undercutdesign -extractionleveldesign -drawcontrolUndercuttingStressandburstprotectionmethodDowehaveafragmentationproblem?Dowehaveastressproblem?Weneedtoknow:StartpositionUndercutretreatdirectionCriticalHRStrategyGeometry“undercuttingisprobablyoneofthemostimportantofalltheactivitiesinvolved.Therefore,thecorrectdesignandmanagementoftheundercutiscriticaltothesuccessoftheblockcave.”BlockcaveundercuttingUndercuttingAimsUndercutStrategiesManagementConfigurationControlDrawControlPrePostAdvancedExtractionmethodFanFlatInclinedLags/LeadsBlastDrawAIM1-Extractavoidtoallowcavingto occurTheundercutsizetoinitiatecavingisrelatedtotherockmassqualityandhydraulicradiusAweakerorebodyrequiresasmallerhydraulicradiusHydraulicradiusofbetween8mand35mnormallyrequiredUndercuttingaimsAIM2-Initiatecavingwithminimum damagetorockmassAimrelatestostresscontrolStressmagnitudesincreaseasundercutsizeincreasesStresscontrolrelatestothepercentageofcavinghydraulicradiusextractedUndercuttingaimsAIM3-AdvanceHRtoreducestressesRequiresundercuttoadvancefromweakertostrongergroundPropagationofcaverequires8-12%drawofblockreserveFulldestressingnormally25-30%ofblocktonnageisdrawnTunnelsmaybesubjectedtoundercutabutmentstresseslongerUndercuttingaimsUndercutextentStressconditionRemarks25%ofHRLowLimiteddamage50%ofHRBecomingaconcernOnsetofcriticaldamage75-110%ofHRMaximumSeveredamageSupercaves(MRMR>45):Stresslevelbecomesaconcernforextraction>75%ofHRUndercuttingAimsUndercutStrategiesManagementConfigurationControlDrawControlPrePostAdvancedExtractionmethodFanFlatInclinedLags/LeadsBlastDrawUndercuttingstrategiesPreundercuttingReducedstresses,productiondelays,compactionremnantsPostundercuttingFasterproduction,stressinduceddamage>60%extractionratio-severedrawhorizondamage,500moperationlimitAdvancedundercuttingLimiteddrawhorizondamage<60%criticaldrawhorizonextractionlimitStrategiesUndercutdevelopedbeforedrawhorizonAdvantageReducedstressdamagePREUNDERCUTTINGStrategiesDrawhorizonfulldevelopedthenundercutAdvantageBlockbroughtintoproductionquickerDisadvantagesDrawhorizonstressinduceddamages,driftrepair,productiondelaysPOSTUNDERCUTTING(conventional)StrategiesDrawhorizondamagerelatestostressmagnitudeanddrawhorizonextractionStressmagnitude2-3timeshigherthanthepre-undercutlevelsSeveredamageoccursat60%drawhorizonextractionCollapseoccursat80%drawhorizonextractionLimitingoperationaldepth±500mPOSTUNDERCUTTING(conventional)StrategiesLimitedamountofdevelopmentondrawhorizonbeforeundercuttingDriftsbeforeundercut,crosscutsanddrawbellsafterundercutKeepdrawhorizonextraction<60%(Butcher1999)ADVANCEUNDERCUTTINGStrategiesAdvantagesdrawhorizondamageisreducedthecaveisbroughtintoproductionquickerthanwithapre-undercuttingstrategyaseparatelevelisstillrequiredforundercuttingthisstrategyisslowerthanpostundercuttingDisadvantagesSomedrawhorizonSlowerthanpostundercuttingADVANCEUNDERCUTTINGUn抛de摧rc糠ut促ti智ng非a羡im扩sAIM外S–近Wh扮at言are瓣we宣tr竭yin籍gt欺od肾o?Ex亏tr漫ac云t针a泥vo秋id报t幼o旋al照lo庄w腰ca漆vi买ng和t裕o听oc薯cu坦rIni前tia肃te状cav裁ing趁wi躺th溉min混imu尚ms币tre夜ss特dam键agePro兴pag哭ate沾th努ec裁ave践to贯re惭duc蔽eu怨nde阻rcu州ta驾but留men蒸ts巧tre歇sse冬sUnd痒erc夜utt暴ingAim粥sUn丑de别rc丈ut扩S暗tr谊at颤eg贪ie桂sMan需age桶men盯tCon顺fig求ura翠tio拍nCon所tro叉lDra映wCo掩nt堪ro岗lPrePo闯stAd豆va崭nc竭edExt积rac罩tio眉nm纯eth剑odFa缘瑞nFl真atInc漂lin具edLa兵gs笨/L象ea括dsBla歼stDra单wEx伤tr系ac讨ti染on孤m祸et补ho疑dsCO盲NS豪ID竿ER休AT置IO革NSDep惭th/怎str易ess六re铺gim韵ena泳rr章ow狭u塑nd络er讽cu肺ts处–锈h营ig广h怖s繁tr孙es藏se作sSki炭ll塔lev掘el鞋of攀cre零ws怕mo汤st遥c药ri坦ti吨ca初l嘱as坐pe泻ctTec构hno帅log瘦y捉3rdwo揭rl多d眠co令un鸡tr雷ie伴sReq左uir文eb剃loc聋k炭pro格duc海tio抹nm墙eth帝odton违nag句eUnd围erc象ut屈hei么ght嚷s韵str蛙ess弱da冤mag哗e–织l僵ow翼ton陪s–纹hi苏ghEx叶tr冰ac忌ti筝on静m挥et旋ho失dsBlockcavefanundercutwithoutseparatelevelExt诸rac进tio胃nm腐eth研odsConceptualPlanofflatundercutshowingpossibleproblemareasExt艘rac筋tio满nm底eth馆odsInclinedundercutpotentialproblemareasUnd惑erc陶utt词ingAi拉msUnd箩erc事ut次Str某ate违gie珠sMa累na牛ge知me骡ntCo尘nf励ig颂ur书at晌io烂nCo缓nt堂ro针lDra郊wCo描nt笋ro陵lPrePos壮tAdv捉anc隔edEx复tr冶ac鉴ti鞭on供m考et扔ho舞dFanFla霞tInc页lin僚edLa示gs同/L铅ea度dsBl蹈as惧tDr寻awUnd汪erc漏ut鹊man宗age涌men逗t“Man默age览men虽ti奋sp猎rob煤abl位yo康ne送of欧the焰mo础st爸neg么lec越ted厚as误pec勺ts膀of林blo灶ck脉cav权ei茂mpl痛eme旁nta尘tio护n;富wit系hu个nde姜rcu厌tti屿ng要pro校ble推ms晕bei发ng健due党to前po厨or球man党age喂men临tr速ath浅er毁tha功nd德esi见gn”Un匹de速rc朗ut桐m绍an左ag菜em特en威tLa岔g闭co泼nt顽ro锈lUndercutfrontlagdistance(caveline)UndercutfrontstressconditionDamage<5mIdealMinimum8mModerateModerate10-12mHighSevere>12mVeryhighUndercutfrontcrushingSup厕er洒cav工es贯–1急2-1隐8m肉lag帆st警ole侦rat蓝ed漆to坚75%溪HR<12拢ml镰ags价fr援om偿75%铅HRUn僻de欧rc戒ut喷m戴an凯ag牲em编en御tLa齿g灭co膜nt浑ro吉lUndercutstage

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