Page 96 - Water Standards

shortentheexcavations p anofunder g roundcavernsma ybese-
lectedaccordin gtothes p ecificconditions :
1 Rock-boltsu pp ortedcranebeam ( includin grockwall
t yp eandrockbencht yp e ) .
2 Sus p endedcranebeamhun gontheabutmentofrein-
forcedconcretearchcrown.
7.2.25Thedesi g nandconstructionofrock-boltsu pp ortedcrane
beamshallmeetthefollowin g s :
1 Whentheclassofsurroundin grocksofcavernsisⅢand
above, rock-boltsu pp ortedcranebeamshouldbeado p ted.
2 Thecranebeamshallbefoundedonstablerockmass.
Attentionshallbep aidtotheimp actofthelateraldeformationof
rockwalls.Corres p ondin gen g ineerin gstren g thenin gmeasures
shallbetakenwhenencounterin gunfavorableg eolo g icalcondi-
tionssuchasfaults ,weakfracturezone, unstableblocks ,aral-
p
lelbeddin g s , etc.
3 Theconstructionmethodshallbedesi g nedtohavearea-
sonableblastin gmethodandp arameters , strictl ycontrollledover
breakandunderbreakandensuretheformin gofrockwallsur-
face( rockbench) .
4 Whencaverns ( e.g .,accesstunnel ,busbartunnel ,
etc. )arearran g edbelowrock-boltsu pp ortedcranebeam, atten-
tionshallbep aidtotheimp actofthecavernexcavationonthe
foundationofbeamandthecorres p ondin gstructuralmeasures
shallbetaken.
5 Thetensileanchorboltsintotherocksfortherockbolt
su pp ortedcranebeamshallp assovertheblastin gdisturbin g
zone.Theanchora g elen g thintostablerockmassma ybedeter-
minedb ycalculationanden g ineerin ganalo gyandshallnotbe
lessthanthede p thofs y stematicboltsofthesamelocation.

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