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Support for Open Pit slope
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1.
These nmining to inclundergr
INTRODUC
notes speciapplicationsude retainround cave
CTION
ifically coves. Howeve
ning walls, rns. Figure
Figu
er the desigr, the princi
concrete e 1 shows so
ure 1: T
1
n of rock anples and dedams, bu
ome typical
Typical Anc
nchors, rocesign proceuildings, bl application
chor Applica
Support of
k bolts and dures showridges, tunns.
ations
f Rock Slopes in
Robert BerAugust 2
dowels in wn can be ennels, sha
n Open Pits
rtuzzi 2012
open pit xtended fts and
The denumero
The merequired
weight,
Factor o
Does thincreas
(1) A cop
esign methoous text boo
HoeLon
Tho
KorWedRoc
Han
WindesPre
HutBi T
ethods set d for each a
of Safety,
he reinforcine the resist
py of this pap
ods are inoks, for exam
ed, E. and ndon, 1974.
omas, H.H.
rari, K. anddge Failureck Mechanic
nna, T.H. F
ndsor, C.R. sign and evss 1993.
chinson, DTech Publis
out in the aanchor. The
w
F
ng load supting force?
per is attache
all cases mple:
Bray, J.
The Engine
d Fritz, P. e. Design cs, ASCE, 1
Foundations
and Thompvaluation co
.J. and Diehers, Canad
above textse simple ca
w H2
2ta
FoS Resist
Distur
pplied by th
ed to these n
2
the use o
Rock Engi
eering of La
Stability AMethods i
1977 (1).
s in Tension
pson, A.G. omprehensiv
derichs, M.da 1996.
s enable thase of plana
an–
tan
tingForce
rbingForce
he cable bo
otes.
of simple s
neering, In
arge Dams
Analysis of n Rock Me
n. McGraw
Rock reinfve. Rock E
.S. Cable b
he designer ar sliding is s
olt act to de
Support of
statistics an
st. of Minin
Part 1. Wil
Rock Slopechanics, 1
Hill, 1982.
forcement tEngineering
bolting in u
to arrive aset out belo
crease the
f Rock Slopes in
Robert BerAugust 2
nd are cov
ng and Me
ley 1976.
pes for Pla6th Sympos
technology,g Vol 4. Pe
underground
at the workow.
disturbing
n Open Pits
rtuzzi 2012
vered in
etallurgy,
ane and sium on
testing, ergamon
d mines,
ing load
force or
There is(active)can onlincreas
Assume
Therefo
Solving
s some just) cable. Ony be develoes the resis
e the cable
Resisting fo
Disturbing f
ore,
Shear resis
Therefore
for T
tification forn the other hoped after ssting force.
is not tensi
orce = sa
force = w
N
stance = s
F
T
r assuming hand, if the some movem
oned (pass
shear resisalong failure
weight of bl
N = Wcos
cH
sinWcos
FoS cH/ s
Tp FoSWsi
3
it decreasecable is no
ment has ta
sive)
stance alonge plane
lock acting
+ Tsin ( -
s Tsin
in Wcos
in cH/sin
∅
s the disturot tensionedaken place a
g failure pla
along failur
)
tan∅
Tsin tan
Wsin
Wcos ∅
Support of
bing force ifd (passive) tand therefo
ane + com
e plane
∅
n∅ Tcos
f Rock Slopes in
Robert BerAugust 2
f it is pre-tethe reinforc
ore it is sugg
mponent of T
n Open Pits
rtuzzi 2012
ensioned cing load gested it
T acting
(1)
Assume
Solving
Equatioproposeparame For exa
using th
Once th
These m
e the cable
Resisting fo
Disturbing f
for T
ons (1) and ed that diffeeter, i.e. hig
ample,
Fc =
F =
Fw =
Fu =
hese values
he working
chorest
cho
des
free
corr
matters are
is pre-tensi
orce =
force =
F
T
(2) assumerent FoS sher FoS for
1.5 for c
1.2 for f
1.0 for w
2.0 for w
s Equation (
T
load has be
oice of anchtressable)
oice of safet
sign of anch
e length (un
rosion prote
dealt within
ioned (activ
= shear res
= weight oacting al
FoS cH/ s
Ta FoSWs
sin
e a uniformhould be us
r ill defined
cohesion, c
friction,
weights and
water press
(1) becomes
T Wsin
een obtaine
hor type (p
y factors
or bond zon
bounded zo
ection
n the follow
4
ve)
sistance alo
of block actiong failure
in Wcos
Wsin Tcos
sinα‐ cH/ sin
∅ Fo
m FoS for ased, depenparameters
c
d forces and
sures
s
cH/1.5sin W
∅/ .
d, the follow
pre-tensione
ne
one)
wing sections
ong failure p
ing along faplane
Tsin tan
s
Wcos tan∅
Scos
all the unknoding on the
s.
d
Wcos ∅/
wing matter
ed, strand o
s.
Support of
plane
ailure plane
n∅
own parame degree of
.
s have then
or bar, tem
f Rock Slopes in
Robert BerAugust 2
e – compon
meters. It haconfidence
n to be addr
mporary/per
n Open Pits
rtuzzi 2012
ent of T
(2)
as been in each
(3)
ressed:
manent,
2.
The mafew excthe slopmining usual toenvironperman The curlong strit is said Active s3, and is offeremass to
CHOICE O
ajority of opceptions whpe to be suor that it is o design cament is fou
nent suppor
rrent practicrand anchord to be “act
support invoprovides efed by an ano occur befo
OF SUPPOR
pen pits havhich continuupported isto be mine
able anchound to be rts (e.g. Figu
ce in open prs which maive”, if not t
olves stressffective supnchor grouteore any sup
Figure
RT PHILOS
ve an operae operating
s not exposed out or durs as temphighly aggrure 3).
pit mining inay or may nhen it is ter
sing the cabport prior toed over its
pport from th
2: Typ
5
SOPHY
ating life of g for 20 yeased until seumped againorary suppressive in w
n Australia inot be pre-tmed “passiv
ble anchor oo any movefull length a
he cable an
pical Tempo
less than 2ars or moreeveral yearsnst as mininorts (e.g. Fwhich case
is to use thetensioned. ve”.
over an unbement of theand require
nchor is mob
orary Strand
Support of
20 years al. Also it is s after the ng progress
Figure 2) une the only o
e term cableIf the anch
bounded lene rock masss some mobilised.
d Anchor
f Rock Slopes in
Robert BerAugust 2
though theoften the ccommence
ses. Therenless the poption is to
e anchor tohor is pre-te
ngth, Figures. Passive
ovement of
n Open Pits
rtuzzi 2012
re are a ase that
ement of fore it is articular
o design
o refer to ensioned
es 2 and support the rock
Generacheape
The excSignificfrom a p
ally, passiveer and easie
No
Ten
ception to tant shear dpassive anc
Figure
e support er to install.
need to ens
nsion is not
the rule howdisplacemenchor can be
3: Typ
systems a
sure an unb
applied.
wever, is wnt can occue mobilised
6
pical Perman
re adopted
bounded len
when large, r along sucand hence
nent Strand
d in open
ngth of anch
continuousch a structur
an active sy
Support of
d Anchor
pit mines
hor.
s, flat structre before thystem is us
f Rock Slopes in
Robert BerAugust 2
because t
tures are uhe available sually consid
n Open Pits
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hey are
ndercut. support
dered.
3.
A fully etensile resistanlittle resthe grou 3.1.
Within tdiameterespect Typical
ANCHOR T
encapsulatecapacity th
nce to sheasistance to ut over a su
Cable Anc
the Australer or 15.2 mtively.
cable anch
Borbe m
Cabtypi
Bonsystthe occgrea
Freesecin g
Spabetw
Cen
Nosanc
Gro
-
-
-
A wcomsettand
Greof th
TYPE
ed reinforcinat can be d
ar where theshear and
ubstantial le
chors
ian contextmm diamete
hor installati
rehole – themaintained
ble Anchor cally 15.2 m
nd Length –tem this colength of aur. Over thase or oil.
e Length – tion the starease and t
acers – utilween strand
ntralisers –
se Cone – achor.
out – cemen
Type A (no
Type B (higfaster set obtaining fr
Type C (low
water cemenmmonly usetlement. Thd produces a
eases – are he anchors.
ng bar or bodeveloped oe bolt crossthe develo
ength.
cable ancher strand wit
ons are pre
e diameter sbetween th
– the cabmm diamete
– this sectioomprises allanchor behhe bond le
over this sends are frethen coverin
ised approds and grou
are used to
a nose con
nts which ar
ormal or ord
gh early strrarely justi
resh supplie
w heat) whic
nt ratio of 0.d. Normallhese causea grout of u
only used .
7
olt in resin oover a relatses a joint. opment of fu
hors are noth nominal
esented in F
should be she borehole
ble anchor er and ultim
on of the an of the ancind the geongth the st
ection tense of grout. ng with a pl
oximately evut/breather t
o keep the a
e is someti
re commonl
inary) Portl
rength) is raify its greaes.
ch is often u
.35 – 0.38 hy, the only
e the cemenniform stren
in active su
or grout is ctively short In contrastull axial-loa
ormally conultimate cap
Figures 2 an
uch that at wall and an
can consisate capacity
nchor is bonchor. In anological featrands shou
ion is impaThis is achastic sheat
very two mtubes.
anchor withi
mes used t
y used inclu
and cemen
arely warraater expens
used for ve
has proven admixturesnt grains tongth throug
upport syste
Support of
characteriselength of tht, cement g
ad may requ
nstructed fropacities of 1
nd 3 and es
least 10 mmny cable str
st of one oy of nomina
nded to the active syst
tures upon uld be clean
rted to the hieved by coh.
metres to m
n the centre
to assist the
ude:
t which is n
anted. Its lese and the
ry long anc
satisfactorys required ao stay sepahout the ho
ems over th
f Rock Slopes in
Robert BerAugust 2
ed by its larhe bolt andgrouted cabuire deform
om either 1184 kN and
ssentially co
m clearancerand.
or more stral 250 kN.
rock. In a tem this co which slidn with no tr
anchor. Alovering the
maintain se
e of the bor
e installatio
normally ade
esser bleede usual diff
hors.
y for anchorare those to rated until
ole.
he unbonde
n Open Pits
rtuzzi 2012
rge axial its high
les offer mation of
2.7 mm d 250 kN
omprise:
e should
rands of
passive omprises ing may races of
ong this strands
paration
rehole.
on of the
equate.
ding and ficulty in
rs and is prevent they set
d length
Typical given o VariousHutchincivil eng
Ancperpsup
Beaplatmob
Barbea
details of n Figures 2
s cable optnson & Diedgineering.
chor Block –pendicular
pport system
aring Plate te plays a vbilised.
rrel and Wearing plate a
temporary 2 and 3.
tions are avderichs, 199
Figure
– this simplyto the cab
ms in hard ro
– even in very signific
edge Anchoand the cabl
and perma
vailable as 96). Figure
e 4: Ty
8
y involves uble installatiock unless
fully groutecant role in
ors – these le strands.
anent stran
shown in 4 shows a
ypical Perm
using neat gon. Anchothe surface
ed cables tn allowing a
provide po
nd anchors
the pages typical per
anent Bar A
Support of
grout to creor blocks a is very irre
esting has all the supp
sitive conne
used in civ
that followmanent bar
Anchor
f Rock Slopes in
Robert BerAugust 2
ease as flat are not neeegular.
shown theport availab
ection betw
vil enginee
w (reproducr anchor as
n Open Pits
rtuzzi 2012
surface, eded for
e anchor le to be
ween the
ring are
ed from used in
Plain SStrand
9
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
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10
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
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Epoxy Coated/Enncapsulatedd Strand
11
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
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Swaged
d/Buttonedd Strand
12
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
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Birdcag
ged Strandd
13
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
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Nutcag
ged Strand
14
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
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Bulbed
d Strand
15
Support of f Rock Slopes in
Robert BerAugust 2
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16
Support of f Rock Slopes in
Robert BerAugust 2
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17
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
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3.2.
Rock bocan be
Bar anczone wanchor.
3.3.
Pre-tenzone ofgood grthe strais dictatthe freeused bediscussnot govthe “dracalculat
where:
x
In most
Bar Ancho
olts of 19, 2used havin
BA
chors can bwhich may in. However,
1. they
2. they
Pre-tensio
sioned ancf a strand arout bond. ands or bar ted by the ge length is feneath founsed in Sectivern, the miaw-in” of theted using th
Ifmin = Min
E,A = Elas
P = Req
xo = Exte6 m
t cases, this
ors
23, 26, 29, 3g ultimate c
R DIAMETEmm
19
23
26
29
32
25
38
be fitted witn some cas the main a
y have very
y can be ins
oned or Act
chors compranchor the s
The free lein grease f
geometry offrom the slondations theon 4.4. Fonimum freee wedges ahe following
imum free l
stic modulu
quired proof
ension requmm)
s minimum f
32, 35 and capacities a
ULTIMAT
ER REGU
h one or twses result idvantages
y little stretch
stalled upwa
tive Ancho
rise a free lstrands areength of botfilled plasticf the applicaope face to e free lengt
or strand ane length wout the anchosimplified e
I
length
s and cross
f load
uired to ach
free length
18
38 mm diamas given in T
TABLE 3.1TE BREAKI
ULAR GRADkN
280
410
525
655
800
950
1130
wo nuts or win a shorterof bar anch
h
ards more e
rs
length and e alternatelyth bars andc sheathingation. For e the postulath is usuall
nchors, anduld be dicta
or head to pequation:
Ifmin EAPx
s sectional a
hieve draw
as derived
meter bar inTable 3.1.
1 NG LOAD
DE SU
with a mechr anchor zohors are:
easily than s
a bond or ay spread and strands is . In many cexample whated slidingy controlled
d where geoated by the rovide a giv
xo
area of anc
n in of the
from this m
Support of
n either regu
UPER GRADkN
305
450
570
710
870
1040
1230
hanical sheone that the
strand anch
anchor zoned crimped tusually ach
cases the rhen used for surface. W
d by the coometry of thextension r
ven lock off
hor
wedges (n
ethod is les
f Rock Slopes in
Robert BerAugust 2
ular or supe
DE
ell in the ane equivalen
hors
e. Within ttogether to hieved by erequired frer slope stabWhere anch
one pullout he applicatirequired to f load. This
normally ab
ss than 1 m
n Open Pits
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er grade
chorage nt strand
he bond provide
encasing e length
bilisation hors are criterion on does achieve may be
out 5 to
.
4.
An anch
Our levranges regard Therefo 4.1.
The uncnot unre For comanchors 4.2.
The ancThe maanchor grout inthe top grout isnot a go As a guuniform
The abo For a grmargin
SAFETY FA
hor has to b
1. Fail
2. Pull
3. Pull
4. Pull
el of knowlefrom beingto grout/ro
ore in consid
Failure of S
certainty regeasonable t
mparison ths and 63-65
Failure of S
chor force, aximum shezone, until
nvolves adhof the bond
s not faulty overning cri
uide, the ultm over the bo
1.0 MPa fo
2.0 MPa fo
3.0 MPa fo
ove values
roup of barssketch whic
For 2 stran
For 3 stran
For 4 stran
ACTORS A
be designed
ure of the s
l-out of the
l-out of the
l-out of a m
edge regardg precise in ock bond fdering desig
Strands or
garding theto work at s
he current 5% for temp
Steel/Grou
T, is transfeear is at theslip occurs
hesion, frictd zone and and the striterion.
timate bondond length
r clean plai
r clean stra
r clean “bird
are based o
s or strandsch shows th
ds, reductio
ds, reductio
ds, reductio
AND DESIG
d for the foll
strands or b
strands or b
grout/rock b
ass of rock
ding the ultithe case o
ailure and gn safety fa
r Bar
e ultimate ststresses up
practice in porary anch
ut Bond
erred as shee top of theprogressiv
ion and mebreaks dowands are fre
d stress betshould not
n bar
nd or defor
d caged” str
on a minimu
s, the effecthe interactio
on factor is
on factor is
on factor is
19
GN CRITER
lowing poss
bar
bar through
bond zone b
containing
mate load vof failure of
very unceactors one m
trengths of sto 100% of
civil enginors.
ear betweee bond zonvely down thechanical inwn the adheree of greas
tween the sexceed:
rmed bar
rand
um grout co
tive perimeton between
0.8
0.6
0.4
RIA
sible modes
the grout
by shear (i.e
the whole o
values for ththe steel th
ertain with must first co
strand and f the quoted
neering is to
en the wire se and decrhis zone. Tnterlock. Inesion compose etc., failu
strand and
ompressive
ter is multip strands in
Support of
s of failure:
e. like a pis
or part of th
he four condhrough to qregard to
onsider the b
bar is very d minimum b
o use 50-6
strands of theases towa
The bond ben practice sonent. Howure of the s
grout which
strength of
lied by a reda double ca
f Rock Slopes in
Robert BerAugust 2
ston in a cyl
he anchor.
ditions listequite imprecrock massbases of de
low. Therebreaking str
60% for pe
he cable anards the enetween strasome slip owever, provstrand/grout
h is assume
f 30 MPa.
duction factable installa
n Open Pits
rtuzzi 2012
inder)
ed above cise with failure.
esign.
efore it is ress.
rmanent
nd grout. d of the nds and ccurs at
vided the bond is
ed to be
tor, see ation.
Also thecross-s Again eunless t 4.3.
Shear s
Normal betweeforce, T where:
Figur This is unless length dabout 1 The texLittlejohrelevanvalues g
e cross-secectional are
experience there is som
Failure of t
stresses alo
whe
the
practice isn grout an
T, is related
l =
d =
=
re 5: C
the case ethe rock is
does not pr0 m.
xt by Hannhn and Bruct to some given in Ta
ctional area ea.
has shownmething ser
the Grout/R
ong the grou
ether the an
amount of s
s to designd rock usinto the fixed
T
fixed an
effectiv
working
ross section
even thougs soft. Howroportionally
na (1982) rece in 1976. Australian ble 4.1 inco
of the stran
that failureriously wron
Rock Bond
ut/rock inter
nchorage is
slip betwee
the bond ng tabulated anchor de
T = dl
nchor length
e anchor di
g bond stres
n showing t
gh it is unliwever, it my increase t
eproduces The informconditions
orporate a s
20
nds/bars sh
e of the steng with the g
d
rface are co
a tension o
en grout and
zone baseed values bsign by the
h
iameter
ss
the idealise
kely that dust be recothe capacity
data on romation is no
are given safety factor
hould not ex
el/grout bongrout or inst
omplex and
or compress
d rock
ed on an avbased on e
equation (F
d cable bolt
istribution oognised thay and typica
ock/grout boot repeated
in Table 4r of about 2
Support of
xceed 15-20
nd is not a tallation pro
depend on
sion type or
verage alloexperience. Figure 5):
t assembly
of the bondat simply inally bond len
ond valueshere. Sele
4.1. It is c.0.
f Rock Slopes in
Robert BerAugust 2
0% of the b
governing ocedure.
:
r some hybr
owable bond Thus the
within a bo
d stress is ncreasing thngths are li
s first publisected designconsidered
n Open Pits
rtuzzi 2012
borehole
criterion
rid
d stress e anchor
rehole
uniform he bond mited to
shed by n values that the
SED
QuaFresSlig
ShaFresSlig
MudFresSligMod
IGN
BasFresSligMod
Gra
MET
BrisSligModHigh
GEN
StroMedWea
For lowworkingstrength
In the abond stof 1.4 M
DIMENTAR
artzitic sansh htly to Mod
ale (e.g. Assh htly to Mod
dstone (e.gsh htly weathe
derately we
NEOUS
salt (Melbosh htly weathe
derately we
anite (Fresh
TAMORPH
sbane Metahtly weathe
derately wehly weather
NERAL
ong rock dium rock ak rock
w strength rg bond stresh, i.e.
absence of tress is ofteMPa.
ROC
RY
ndstone (e.g
erately wea
hfield Sha
erately wea
g. Melbourn
ered athered
urne)
ered athered
h)
ICS
amorphics ered to freshathered red
ock massess at the ro
shear strenen taken as
K TYPE
g. Hawkesb
athered
le)
athered
ne Mudston
h
s and wherck/grout int
Cohesionm
ngth data fo1/30 of the
21
TABLE 4.1
bury Sands
ne)
re shear strerface shou
min
or the rocke unconfined
1
A
stone)
rength datauld not exce
mass or fid compress
Support of
ALLOWABLBOND
[k
800 –500
500 –300
750 –500 –300
1500 1000 400 –
1400
10400 200
1000 700 –350
a exist, the eed half of t
eld pull-outsive strength
f Rock Slopes in
Robert BerAugust 2
LE AVERASTRESS
kPa]
– 1200 – 800
– 1000 – 500
– 1500 – 1000 – 750
– 3000 – 2000 – 1500
– 1600
000 – 700 – 300
– 1400 – 1000
0 - 700
maximum the minimu
t tests, the h up to a m
n Open Pits
rtuzzi 2012
GE
average m shear
working maximum
4.4.
Liftout oThis is a
Hanna model asome cangles such ththe sum
Failure of t
of a mass oa controver
1. the
2. the rem
(1982) discand “full scacases makedepending at their res
m of the indi
the Rock M
of rock encorsial subject
shape of th
strength mainder of th
cusses thesale” tests. Tes allowanc
on rock copective pulvidual cone
Fig
Mass
ompassing t because:
he failed roc
(friction anhe rock is no
e matters inThe author ce for sheaonditions (selout cones
es.
gure 6:
22
an anchor
ck mass is u
nd adhesioot known.
n detail anduses the Br strength iee Figure 6intersect th
Pull-out of
or group of
uncertain (s
on) betwee
d summariseritish Standin the rock 6). Where he overall vo
f Mass of R
Support of
f anchors m
ee Figure 6
n the faile
es the ratheard (BS 80 and allowsmultiple anolume must
ock
f Rock Slopes in
Robert BerAugust 2
must be con
6).
ed mass a
er sparse da 81-1989) ws for differenchors are t be calcula
n Open Pits
rtuzzi 2012
sidered.
and the
ata from which, in ent cone installed
ated, not
4.5.
Based ostraight
Once thpattern
It is theeconomcapacityare genfail to badditionrequire conside After ththe slopbolts pepattern
Summary
on the disct forward an
1. Assbar
2. Ass(thisfollo
3. Asslengthat
4. Chegiveopecon
5. For wed
he total supusing eithe
indi
vert
e author’s emise on dry, the spac
neral guidesbe fully effecn, a supporintensive d
ered which w
e support spe geometryer bench heshould be c
of Design
cussion presnd has the fo
sess the reqanchor are
sess the nus depends owing sectio
sess the algth of the bt the bond le
eck againste a safety fen pit applictinuous join
strand andges at anc
pport intenser variation i
vidual cable
tical and ho
experience illing whilsting may be s to the limictive and inrt pattern o
drilling. If smwill result in
spacing hasy. Typicallyeight (i.e. 2created by a
Procedure
sented abovollowing ste
quired work appropriate
mber of stron the lev
on).
lowable grobond zone,ength does
rock massfactor of at cations; chents, etc.).
chors, chechor head (u
sity has bein:
e anchor ca
rizontal spa
that 500 kt still maincalculated
its on spacin general spof less thanmaller spacn more acce
s been estay the vertica2, 3, or 4 aalternating
23
ve it can beeps:
king load pe.
rands or bavel of corro
out/rock bo and alter not exceed
s failure anleast 1 aga
eck for com
ck for miniusually less
en assesse
apacity and/
acing
kN anchors ntaining pra
from the reing. If anchpacings gren 2 m x 2ings are ind
eptable spa
ablished theal spacing snd not say subsequen
e seen that
er anchor a
ar size and osion protec
ond stress anchor hol
d about 10 m
d alter the ainst cone
mpentancy o
imum free than 1 m).
ed it is nec
/or
are typicalacticable aequired suphor spacingeater than 5m would n
dicated largcings.
e next step should prov
2.8, 3.3, et rows.
Support of
the design
and decide
the appropction and is
and therefe diameter m.
free lengthpullout (diff
of rock mas
length to p
cessary to a
ly used in nchor spacport intensit
gs are too w5 m are not not be pracer capacity
is to checkide a whole
etc.). In ad
f Rock Slopes in
Robert BerAugust 2
n procedure
e whether s
priate hole ds discussed
fore determr if necessa
h, if appropfficult to do ss, bedding
provide dra
assess the
open pit mcings. Givty. Howeve
wide apart trecommen
cticable as y anchors sh
k to see if ite number ofdition, a sta
n Open Pits
rtuzzi 2012
is quite
trand or
diameter d in the
mine the ary such
priate, to in most planes,
aw in of
support
mining to ven this er, there they can nded. In it would hould be
t fits into f rows of aggered
5.
The maBertuzz Tempor For tem10 mm free tenagents the use Perman In the prestresbecausinvestigbeen edirectiocorrosiv For thisin a thicpoly-ethmentionencapscementthereforconditio There aanchorsbetweethe borwhethefor permtend to ample i
(2) A cop
CORROSIO
atter of corrzi (1999) (2)
rary Anchor
mporary anthickness
ndon lengthcannot reac
e of individua
nent Anchor
case of a ssed steel we it provi
gations on thexcavated an, of up tove environm
s reason peck wall diffuhylene or poned cracksulated bondt grout insire essentiaons have pr
are two ves as describn the corru
rehole requir the autho
manent ancuse tempon most case
py of this pap
ON PROTE
rosion proteand summa
rs
chors, withis considere
h the constrch the presal coated a
rs
permanenwas generades an ahe load tranand inspecto 2 mm widment these c
ermanent anusioned-tigholy-propylens and to d length thede the cor
al. Full scroved the va
ery importabed above, gated and ired for an r is perman
chors are asorary anchoes.
NST
5
1
2
per is attache
ECTION
ection is disarised below
hin the fixeded to be noruction shoutressed stend greased
t anchor aally conside
alkaline envnsfer mechated have s
dth are almcracks are d
nchors are fht, elastic ane. Corrugform a bae tendon forrugated ducale groutialidity of this
ant factors the quality smooth andanchor is c
nent (fully ss per Tablers is to use
NO. OF TRANDS
1 to 4
5 to 12
3 to 25
25 to 40
ed to these n
24
scussed in w.
d anchor leormally sufuld be such
eel or can gad strand.
an uncrackeered to be avironment anism, as wshown that
most inevitabdetrimental
fully encaseand chemicagated sheatharrier agaiorce will firsuct. A comng tests as system.
with regarof the corrud sealing thclearly depesheathed) oe 5.1. Curree a minimum
TABLE 5.1
BOREHO
otes.
detail in H
ength a cefficient to prh that air, wain ingress.
ed cement an effectivefor the s
well as actuacracks, bo
ble within tto the long
ed along theally passivehing has thenst extern
stly be transmplete fillingand subseq
d to the cugated sheahe nose conendant on tr temporaryent practicem hole diam
1
OLE DIAMET[mm]
100
150
210
250
Support of
anna (1982
ement groutrotect the t
water and c. This is no
grout bode protectionsteel. Hoal tests withoth in radiathe fixed anterm perfor
e free and fe plastic shee capacity tal agents. sferred fromg with high
quent pullo
constructionathing and tne of the anthe numbery. Typical be in Australimeter of abo
TER
f Rock Slopes in
Robert BerAugust 2
2) and in P
t cover of tendon. Wcorrosion prormally achi
dy surroundn against coowever, theh anchors thal and longnchor lengtrmance.
fixed anchoeathing mato bridge th In a comm the stranh strength ut test un
n of fully sthe sealing nchor. Ther of strandsborehole dian open pit
out 75 mm.
n Open Pits
rtuzzi 2012
ells and
at least ithin the romoting ieved by
ding the orrosion, eoretical hat have gitudinal th. In a
or length ade from e above mpletely d to the grout is der site
heathed of joints
e size of s and on ameters ts which This is
6.
There isimportaare:
In stronreadily materialittle chaas mud The firsused. Wand it ismarine down-th The sedrilling circulat A big ishole is the grou The insfollowin With regconsidea valid after stgrout do The gewhen fix
CONSTRU
s little doubance. Base
met
grou
ng, brittle rodrilled with
als form chipance of holstones and
st is that cloWhen suchs possible work the a
he-hole ham
cond is theis used. It ing water te
ssue is grousually imput escaping
stallation ong sketches
gard to grouered importareason for ressing. If oes not rem
ometry of txing the pla
UCTION AN
bt that consd on the au
thod of drilli
uting
ock (say wit percussionps when dre blockage weak sand
ogging can h clogging ofor joints a
author is awmmer becam
e problem ois not a pro
ends to was
ut leakage practicable. g from aroun
f a passive in Figure 8
uting of the ant that thegrouting firthis is don
main at the t
the rock faate assembl
D INSTALL
struction couthor’s expe
ng, cleanin
h unconfinen equipmenrilled and th
during drilldstones two
occur withinoccurs high nd bedding
ware of subme clogged
of sidewall oblem if wash the sidew
from the b The autho
nd the anch
e (un-tensi8.
hole (and te hole be furst the anchne then cartop of the fir
ce at the hly, to preven
25
LATION
ntrol, particerience ther
g and leaka
ed strength nt and in pahere is usualing. Howe
o problems h
n the hole wair pressur
g planes to bstantial pn.
smear whiashboring orwalls clean.
orehole. Inor normally hor.
oned) cabl
the inner anlly grouted horage zonre is requirerst grouting
head of thent cutting th
cularly for pre are two m
age testing
greater thaarticular a dally little smver, with wehave to be f
when downres build upbe blown
neumatic lift
ich is a par diamond c
n open pit muses a no
le bolt into
nnulus for fuin one pas
ne and thened in ensurstage.
e cable neehe cable. S
Support of
ermanent amain areas
of the hole
an 50 MPa) down-the-ho
mear of the eaker sedimfaced.
-the-hole pep in the viciopen. In twting of the
rticular procoring is ad
mining, lean-flowing gr
o an uphole
ully encapsus. Occasio
n the remairing that a
ds to be caee Figure 7
f Rock Slopes in
Robert BerAugust 2
anchors, is of concern
) the anchorole hammehole perime
mentary roc
ercussion dnity of the wo cases irock mass
oblem if augdopted beca
kage testinrout mix to
e is shown
ulated anchonally there nder of thezone of ve
arefully con7.
n Open Pits
rtuzzi 2012
of great . These
r can be r. Such eter and cks such
drilling is hammer nvolving when a
ger type ause the
g of the prevent
n in the
hors) it is may be
e anchor ry weak
nsidered
Figure
pos
e 7: Problemssible soluti
ms kinking ions – morta
the cable inar bed, ang
26
n both up-hogled washer
oles (left) anr & enlarged
Support of
nd down-hod plate holes
f Rock Slopes in
Robert BerAugust 2
oles (right). s, domed p
n Open Pits
rtuzzi 2012
Three plate
The incimporta
F
clination of ance of ensu
Figure 8: Din t
the cable ruring the ca
Desirable tethe cable bo
elative to thable is insta
ensile or unolts depend
27
he failure plled so it ac
desirable coing on relat
p
plane is alsocts in tensio
ompressivetive orientatplane
Support of
o critical. Fn not comp
e forces cantion betwee
f Rock Slopes in
Robert BerAugust 2
Figure 8 shpression.
n be induceden cable and
n Open Pits
rtuzzi 2012
ows the
d d failure
Figure 9: Installlation of a p
28
passive dou
uble-cable b
Support of
bolt in an up
f Rock Slopes in
Robert BerAugust 2
p-hole
n Open Pits
rtuzzi 2012
Figu
29
ure 8: conti
nued
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
rtuzzi 2012
Figu
30
ure 8: conti
nued
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
rtuzzi 2012
Exampl Calcula
From eq
From eq
From eq
le
ating cable l
quation (1),
quation (2),
quation (3),
oad
w .
, Tpassive
=
=
, Tactive 1
=
=
, T 2071x
=
=
xtan 45o
1.2x2071xsin
sin 45‐1
.
.
822 kN/m r
1.2x2071xsin
sin 45‐10o
.
.
703 kN/m r
xsin45o‐20x
1.5xsin
sin 45‐10
.
.
803 kN/m r
31
o tan 60o
n45o‐20x20sin 45o
‐20
10o tan 15o co
run of slope
45o‐20x20sin 45o
‐207o tan 15o 1.2c
run of slope
20n 45o
1.5xsin45
0otan15o
1.2cos
run of slope
2071kN/
071 cos 45o tan 1
os 45‐10o
e
1 cos 45o tan 15
os 45‐10o
e
5o‐2071 cos 45o
45‐10o
e
Support of
mrunofslo
5o
o
tan 15o
1.2
f Rock Slopes in
Robert BerAugust 2
ope
n Open Pits
rtuzzi 2012
If we hacase be
Compa
ad installedecomes,
rison:
CA
Pas
Act
Spe
Pas
the cable
Tp
=
=
ASE
ssive
tive
ecified FoS
ssive, down
10° below t
sin 45 1
.
.
1008 kN/m
[k
nhole
32
the horizont
799.230o tan 15o
m run of slop
LOA
kN / m run
822
703
803
100
tal ( = -10°
3cos 45
pe
AD
of slope]
2
3
3
8
Support of
°) then the
10o
RELATIV
T1
0.86T
0.98T
1.23T
f Rock Slopes in
Robert BerAugust 2
load in the
VE
T1
T1
T1
n Open Pits
rtuzzi 2012
passive
33
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
rtuzzi 2012
34
Support of
f Rock Slopes in
Robert BerAugust 2
n Open Pits
rtuzzi 2012
35
Support of f Rock Slopes in
Robert BerAugust 2
n Open Pits
rtuzzi 2012
