自然崩落法全英文一二

(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挑de踏rc争ut桶ti稍ng旷a索im健sAIM蜂S–说Wh保at阁are患we踩tr距yin躲gt驶od碌o?Ext谎rac悠ta尝vo昼id慌to裹all梳ow仙cav务ing舒to歉oc险curIni诸tia通te岂cav嫌ing音wi遥th扎min狮imu我ms岭tre药ss购dam穷agePr取op美ag雾at炎e掉th不e更ca贼ve皂t翻o傍re钩du其ce耍u就nd向er闸cu应t祝ab败ut尾me说nt遣s倦tr惕es歪se你sUnd俘erc竹utt诸ingAim竹sUnd毙erc肆ut悄Str介ate云gie昏sMa鸟na从ge印me羊ntCon久fig寸ura蜓tio辛nCon顺tro锁lDra第wCon波tro递lPrePos从tAdv街anc茧edExt用rac长tio挑nm魂eth桶odFanFl辩atIn构cl释in陷edLag写s/L罪ead菜sBla挑stDr符awEx咐tr扬ac革ti粉on但m仙et猾ho区dsCO仿NS禾ID晓ER打AT内IO馋NSDep裳th/代str哨ess嘉re触gim矮ena萝rr翻ow熟u姥nd殖er理cu蛾ts朗–君h穴ig昼h凑s旱tr魔es嚼se朱sSk剧il肿l京le染ve总l携of寸c劳re毯ws跪mos峡tc携rit晃ica胁la形spe喘ctTe伴ch药no率lo新gy添3rdwo餐rl榆d拾co叔un贫tr闸ie咸sRe呀qu低ir良e扩bl泄oc岗k申pro鞋duc循tio晒nm宫eth顷odton奸nag付eUnd哗erc役ut嚼hei旷ght赤s备st蔑re抹ss坚d常am绵ag脂e震–碌l膊ow等t导on叔s涌–泊hi磁ghEx高tr爪ac依ti汪on挨m层et制ho繁dsBlockcavefanundercutwithoutseparatelevelExt姑rac课tio休nm起eth军odsConceptualPlanofflatundercutshowingpossibleproblemareasEx隆tr碰ac兴ti毁on肺m顾et韵ho丢dsInclinedundercutpotentialproblemareasUnd往erc胜utt丸ingAim初sUnd午erc同ut瘦Str福ate扮gie水sMan型age挺men然tCon岔fig葵ura紧tio坛nCo袋nt秃ro晓lDr孤awCon跳tro愤lPrePo举stAdv萄anc显edEx兽tr茄ac远ti添on活m插et猜ho妹dFanFl蛋atInc值lin令edLa么gs栋/L涉ea厉dsBla颗stDra车wUn铲de嫂rc运ut迁m魂an停ag施em钳en葛t“Man踩age灰men帅ti岔sp司rob镇abl在yo苍ne胆of给the叼mo虽st鹿neg金lec爬ted干as愿pec眯ts谢of不blo幕ck兄cav叉ei租mpl报eme行nta酸tio辨n;谜wit础hu鼠nde奴rcu万tti题ng微pro摆ble沾ms霞bei产ng熄due枣to贵po染or戒man卫age曲men鸡tr搏ath重er德tha勺nd尸esi循gn”Und餐erc袜ut球man枝age遗men掩tLa雀g将co隶nt胆ro贪lUndercutfrontlagdistance(caveline)UndercutfrontstressconditionDamage<5mIdealMinimum8mModerateModerate10-12mHighSevere>12mVeryhighUndercutfrontcrushingSup欧er扭cav傻es江–1敏2-1号8m她lag福st通ole符rat夜ed历to担75%怠HR<1苦2m常l限ag关s竖fr改om扇7诉5%泄H密RUnd罚erc过ut重man部age查men循tLag花co而ntr去olUndercutstage

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