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防de留rc注ut佩ti菊ng皮a麦im兼sAI觉MS辰–棚W喊ha谱t沉ar针e瓦we冷t帮ry学in捉g器to老d萄o?Ext怎rac箱ta鸟vo堪id押to才all托ow番cav请ing雁to桨oc收curIn访it窃ia待te榴c厦av套in烫g够wi镜th减m籍in呜im铜um路s请tr富es懒s会da眉ma补gePro丧pag拆ate喘th近ec习ave灵to竹re熊duc口eu摩nde饰rcu勤ta挂but厨men柏ts升tre扎sse僚sUnd暖erc屯utt细ingAi笑msUn青de般rc子ut盼S弹tr寄at注eg向ie翠sMan躲age先men斤tCon侵fig废ura败tio老nCon朝tro基lDra外wCon即tro脂lPr涌ePo蓄stAd角va差nc躲edEx罗tr稀ac震ti添on潜m拔et段ho绑dFa衣nFla冈tInc立lin合edLa贡gs逢/L初ea骄dsBla化stDr着awEx乌tr蝇ac旱ti负on优m央et低ho兵dsCON悼SID幕ERA商TIO总NSDe寨pt子h/粱st廉re残ss蹈r缓eg违im熟ena持rr胀ow郑u流nd格er干cu闪ts尚–于h旧ig弟h睡s舅tr拖es炊se观sSk买il枪l扫le扫ve齿l席of泳c殃re谁ws喷mo陆st苍c屋ri艇ti府ca拍l只as悦pe贞ctTec掌hno弟log跪y爆3rdwor居ld猜cou肿ntr绘iesReq览uir乓eb硬loc焰k僵pr盯od叶uc柄ti希on传m甲et偏ho凳dton斑nag版eUnd仓erc社ut锄hei刃ght掀s森st赤re争ss是d遍am趴ag晚e嚼–断l虚ow肆t怕on程s服–捡hi远ghEx速tr毯ac状ti澡on膀m枝et闸ho希dsBlockcavefanundercutwithoutseparatelevelEx悟tr偿ac排ti不on上m撑et梅ho熟dsConceptualPlanofflatundercutshowingpossibleproblemareasEx兆tr械ac雪ti包on进m葵et蕉ho役dsInclinedundercutpotentialproblemareasUnd姿erc喝utt滑ingAi放msUn规de袖rc裂ut掀S桌tr链at壤eg聚ie接sMa啊na煮ge蔽me据ntCon灶fig都ura伸tio依nCo饰nt劣ro插lDr滋awCon顿tro蛙lPrePo叶stAd议va脂nc拉edExt植rac焰tio旋nm尾eth闹odFanFl坑atIn灿cl绒in瘦edLa讲gs融/L弦ea宁dsBla汗stDra雀wUn酱de任rc吗ut歪m唐an协ag旨em橡en谎t“Man求age剪men芽ti强sp英rob拉abl顽yo遇ne嫌of墓the聚mo待st裂neg吓lec籍ted旷as论pec型ts叹of糕blo耍ck茶cav洲ei唱mpl笔eme城nta策tio砍n;塘wit余hu衔nde芒rcu劫tti非ng带pro今ble铃ms型bei集ng电due如to桶po台or仓man岔age仆men榴tr追ath次er友tha移nd悲esi客gn”Und阶erc堡ut奴man仔age弄men麦tLag很co孔ntr玻olUndercutfrontlagdistance(caveline)UndercutfrontstressconditionDamage<5mIdealMinimum8mModerateModerate10-12mHighSevere>12mVeryhighUndercutfrontcrushingSu阅pe采r眼ca岛ve愤s沙–辜12边-1登8m性l哪ag穴s炕to拍le桃ra此te皮d裙to抵7菊5%婚H通R<12堵ml迹ags潜fr罪om私75%出HRUnd额erc筛ut代man拦age冲men把tLag深co艇ntr位olUndercutstage

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