vorlesungsfolienspezialtiefbauankerenglisch
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Transcript of vorlesungsfolienspezialtiefbauankerenglisch
Ground anchors
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 2Winterterm 2008/09
Codes and regulations for ground anchors
• DIN 1054:2005-01: Subsoil – Verification of the safety of earthworks and foundations
• DIN EN 1537:2001-01: Execution of special geotechnical works - ground anchors
• DIN 4125:1990-01: Ground anchors: Short-term anchors and permanent anchors (particularly the data about the creep masses ks)
• construction control permits are required for:
anchor head structures of the short-term anchors (temporary anchors)
anchor systems of long-term anchors (permanent anchors)
comparison see Table 3.1
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 3Winterterm 2008/09
Terms and definitions• value of load loss (Kraftabfallmaß) kl up to the proof load (Prüflast) Pp.
• creep value (Kriechmaß) ksvalue to show the time dependent increase of the displacement of the anchor head under the effect of a constant anchor force and changing time
• ks depends on the type of anchorthe design of the foundationthe manufacturing of the anchor the anchor force.
• (sb – sa): difference of the displacement of the anchor headat two different times
• log (tb / ta): logarithm of the observation time difference(log tb – log ta)
( )ab
abs t/tlog
ssk −=
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 4Winterterm 2008/09
Definition of the creep value ks
( )( )12
12
/log ttssks
−=
( )( )ab
abs tt
ssk/log
−=
Creep value ks:
DIN EN 1537
DIN 1054
comment: DIN 1054 uses different indizes to avoidconfusion with limit states GZ 1 u. GZ 2
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 5Winterterm 2008/09
Determination of the creep value ks
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 6Winterterm 2008/09
• External anchor resistance (Herausziehwiderstand) Ra,kthe resistance of an anchor at the contact area beween the grout bodyand the soil at a creep value of ks = 2,0 mm from the tension test
• Resistance of the tendon Ri,k is calculated as follows:
withAs cross sectional area of the tendonft,0.1,k charakteristical value of stress at a palstic strain of 0,1 %
• Design value of anchor resistance (Bemessungswiderstand) Rd
smaller design value of either- external anchor resistance Ra,d of the anchor or. - resistance of the tendon Ri,d.
Terms and definitions
k,.,tsk,i fAR 10⋅=
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 7Winterterm 2008/09
• usable load (Gebrauchskraft) Ekload, which is determined from the statical design of theload cases according to DIN 1054:2005-01 form the effectsof of the construction, which shall be anchored
• proof load (Prüfkraft) Pp force, which is applied during anchor tests
• lock-off load (Festlegekraft) Po , force, which is applied to the anchorafter an anchor test
Terms and definitions
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 8Winterterm 2008/09
Temporary anchor (Kurzzeitanker)• anchor with a planned usage time of < 2 Jahre
Permanent anchor (Daueranker)• anchor with a planned usage time of > 2 Jahre
The choise of the corrosion system is very much dependant on thedifferentiation between temporary anchor and permanent anchor.
Terms and definitions
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 9Winterterm 2008/09
Overview of certified permanent anchors
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 10Winterterm 2008/09
Composite anchors
• the grouted body fully encapsulates the tendon within thetendon bond length
• the anchor forces are transferred from plane or structured tendoninto the grouted body. The grouted body transferrs the forcesinto the subsoil
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 11Winterterm 2008/09
Pressure-pipe anchors
• in the part of the grouted body the tendon is kept within a structured steel pipe and led to a ground plate of steel.
• the tendon can be freely pulled between the ground plate of steeland the head of the anchor.
• the trasmission of the force comes from the outside soil; thegrouted body gets mainly pressure; transversal fissures and cracksdue to logitudional tension stresses are mainly avoided
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 12Winterterm 2008/09
Terms for grouted anchors according to DIN EN 1537
LeLtf
LfreeLtb
Lfixed
101
2 3 4
5
67
89
5 Component6 Ground / rocks7 Drilled hole8 Duct9 Tendon10 Grouted body
1 Anchoring point at the prestressing jackduring straining
2 Anchoring point at the anchor head inoperating state
3 Support plate4 Support
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 13Winterterm 2008/09
Boring (drilling) methods for anchors
Driving method
Overburden-drilling method(OD method)
Auger drilling
Rotary percussion drilling (falling hammer)
Rotary percussion drilling (outside hammer)
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 14Winterterm 2008/09
Drilling (boring) methods for anchors – areas of application
Rocks, concreteWateryesCore drilling
in firm cohesive soils or soft rocksnonoAuger drilling
non-cohesive / cohesive soils or soft rocksAir, wateryesOverburden drilling
Rocks, rigid cohesive soils without waterAir-Rotation-percussion drilling, falling hammer
RockAir-Rotation-percussion drilling, outside hammer
loose to medium dense deposited non-cohesive soils (used also in drilling against pressing ground water)
noyes
Driving method
main areas of applicationflushingcasingDesignation of the drilling methods
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 15Winterterm 2008/09
Drilling, installation, grouting, regrouting
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 16Winterterm 2008/09
1. Drilling (boring) of the boreholedriving, rotation-percussion drilling, flush drilling orauger drilling
Ø 89 bis 230 mmCased drilling in
not stable
auger drilling in stable soilsrotation-percussion drilling
Drilling, installation, grouting, regrouting
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 17Winterterm 2008/09
No casing
Flushing backrunbetween rods and bore
hole wallRisk of settlementRisk of erosion at bore
hole wall due to theflushing backrun
Drilling, installation, grouting, regrouting
1. Drilling of the boreholerotation-percussion drilling-flushing-no casing
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 18Winterterm 2008/09
Casing in not stablesoils or rock
Rotaiton-percussion drilling
In stable soils or rockonly driving with inner
rod an no casing
Drilling, installation, grouting, regrouting1. Drilling of the boreholerotation-percussion drilling-flushing-with casing
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 19Winterterm 2008/09
Cased boring
Controlled conveying of soil between inner rod
and outer casingInner rod always far in front of the outer casing
Drilling, installation, grouting, regrouting
1. Drilling of the boreholeoverburden drilling (rotation-rotation)
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 20Winterterm 2008/09
Two engines withdifferent direction of
rotation
Rotation of outer casingand inner rod is
independent
Movement betweenouter casing and
inner rod is possible
Drilling, installation, grouting, regrouting
1. Drilling of the boreholeoverburden drilling (rotation-rotation)
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 21Winterterm 2008/09
Drilling, installation, grouting, regrouting
1. Drilling of the boreholeoverburden drilling (rotation-rotation)
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 22Winterterm 2008/09
2. Insertion of the tendon and filling of theborehole with cement suspension
Bore holecasing
Distance piecestendon
Drilling, installation, grouting, regrouting
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 23Winterterm 2008/09
bore hole tendon
Grouting area
Drilling, installation, grouting, regrouting
3. Drawing of the casingprimary grouting
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 24Winterterm 2008/09
tendon
Grouting area
Drilling, installation, grouting, regrouting
3. Drawing of the casingflushing of the apparent tendon free length
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 25Winterterm 2008/09
tendon
Regrouting area
Drilling, installation, grouting, regrouting
4. Regrouting of the anchor
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 26Winterterm 2008/09
5. Testing and strainig of the anchorto the desired load after hardening of the grout
Testing and strainig of the anchor
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 27Winterterm 2008/09
Testing and strainig of the anchor
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 28Winterterm 2008/09
6. Completed anchorTesting and strainig of the anchor
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 29Winterterm 2008/09
Example for anchor boring rigs
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 30Winterterm 2008/09
Anchor boring machine – anchor boring carriage
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 31Winterterm 2008/09
anchor boring carriage
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 32Winterterm 2008/09
Grouting
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 33Winterterm 2008/09
Grouting
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 34Winterterm 2008/09
Grouted body and secondary grouting
• increase in baring capacity of up to 100 % is possible
• grouting pressure can be as high as 40 bar to 80 bar (only with sufficient overburden).
• multiple re-grouting with little quantities of grout reaches more increasethan single regrouting with high pressure and large quantity of grout
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 35Winterterm 2008/09
Grouted body
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 36Winterterm 2008/09
Testing methods
DIN EN 1537: 2001-01
• Investigation tests(in E DIN EN 1997-1 Grundsatzprüfung)
• Suitability tests
• Acceptance tests
DIN 1054: 2005-01 reffers to DIN EN 1537 for
anchor testing.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 37Winterterm 2008/09
Testing
Investigation testsBefore production of anchors in the field
• charakteristic external anchor resistance Ra,k of theground anchor - joint between grout and surrounding soil;
• creep load of the anchor system or• creep behaviour of the anchor system at failure or• loss of stressing load kl of the anchor system at servicability
limit state;• tendon free length Lapp.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 38Winterterm 2008/09
Testing• Investigation test:
- limit load of the anchor with respect to the underground and the used materials.
- knowledge on the expertise of the contractor and of the failure of the anchor at the joint of the grouted body and the surrounding soil.
• conduction of the investigation test- in soils, having no previous investigation tests and if there is
no information on the underground- load increase of the field anchor compared to other anchors before
(comparable underground)
• production and geometry of the investigation test shall correspond te thefield anchors variation or the drilling diameter or the anchor lengthesdoes NOT lead to proportional changes in the external anchor resistance
• anchors are loaded up to the failure and cannot be used as constructionanchors
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 39Winterterm 2008/09
testing
Investigation test
For one anchor
• proof of load bearing capacity of the anchor at a proof load Pp;
• the creep behaviour or the loss of prestresing load kl
• down to proof load Prüflast Pp;
• tendon free length Lapp.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 40Winterterm 2008/09
Anchor testing
Acceptance test
For each anchor:
• proof of load bearing capacity of the anchor at a proof load Pp;
• the creep behaviour or the loss of prestresing load kl
• tendon free length Lapp.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 41Winterterm 2008/09
Testing methods according to DIN EN 1537, 9.4
Verschiebung
Ank
erkr
aft i
n %
Pp
Vorbelastung Pa
Testing method 1:
• The anchor is loaded stepwise in one or several
cycles until the test load is reached.
• For every cycle, the shift of the anchor head
is measured at maximum stress force for
a predetermined period of time.
DIN 1054: 2005-01 only testing method 1!
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 42Winterterm 2008/09
Testing method 2:
Testing methods according to DIN EN 1537, 9.4
Verschiebung
Ank
erkr
aft i
n %
Pp
Vorbelastung Pa
• The anchor is loaded stepwise in one or several
cycles until the test force is reached or
until failure.
• For every cycle, the drop of the stress force at
the anchor head is measured at maximum
stress force for a predetermined period of time
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 43Winterterm 2008/09
Testing methods according to DIN EN 1537, 9.4
Testing method 3:
• The anchor is loaded stepwise from the
pre-load to the maximum stress force.
• The shift of the anchor head is measured
for every load step under constant force.
Verschiebung
Ank
erkr
aft i
n %
von
Pp
Pt 0,1k
Dt= 30-60 min
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 44Winterterm 2008/09
Analysis of ultimate limit state (ULS)
General considerations :
• proofs for load-bearing capacity and usability of grouted anchorsare regulated in DIN 1054:2005-01
• characteristic extraction resistance (external load-bearing capacity)- just as in the case of piles - cannot be determinedby using the earth-static method
• extraction attempts (anchor tests) have to be conducted
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 45Winterterm 2008/09
characteristic load requirements for grouted anchors :
• stability analysis as characteristic cross section sizes from the effects on the anchored structures
• characteristic load (usable force) Ek .
− Loads which have been determined on the basis of mechanical examinations of the rocks,
− Loads resulting from the water pressure,− Loads resulting from the rope pressure,− Loads acting on the anchor head .
Effects and loads
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 46Winterterm 2008/09
Design values
• design value of the loads Ed is obtained by multiplying the characteristic load with the applicable partial safety coefficient .
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 47Winterterm 2008/09
Resistance of the steel tension member
k,.,tsk,i fAR 10⋅=
M
k,id,i
RR
γ=
mit
As Crosssectional are of the tendon
ft,0.1,k the characteristic value of the stresstendon
0.1 % remaining strain
γM partial safety factor
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 48Winterterm 2008/09
Calculation values for ground anchors
9501190125710501
1080135712571230140
835850101810301
950960101810501
10801099101812301
36,0
83567280410301
95076080410501
108186980412301
32,0
83546155210301
95052555210501
108059655212301
26,5
152022815017701 (22)15,7
152021314017701 (22)15,3
ft,0.1,k
[N/mm²]
fp0,1
[kN]
As
[mm²]
ft,k
[N/mm²]
Anzahl (max. Anzahl)
[-]
Durchmesser
[mm]
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 49Winterterm 2008/09
Partial safety factors according to DIN 1054: 2005-01
1,101,101,10γA
Esternal anchorresistance of the
gouted body
1,151,151,15γMResistance of the
tendon
LF 3LF 2 LF 1Resistance of
grouted anchorsGZ 1B
For permanent anchors applies LF 1!
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 50Winterterm 2008/09
Values of operating experience for external anchorresistance in non cohesive soils
Krafteintragungslänge Lfixed [m]
Her
aus z
iehw
ider
s ta n
d R
aim
Bru
chz u
s ta n
d[k
N]
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 51Winterterm 2008/09
Values of operating experience for external anchorresistance from cone penetration test results
max
. Her
ausz
iehw
ider
stan
d R
aim
Bru
chzu
stan
d [k
N]
(ks
unbe
rück
sich
tigt)
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 52Winterterm 2008/09
Limit values of the sleeve friction for anchors in cohesive soils: a) without re-grouting, b) with re-grouting; from Ostermayer
Krafteintragungslänge Lfixed [m]
Krafteintragungslänge Lfixed [m]
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 53Winterterm 2008/09
Suitability test for determination of the external load resistance
• according to DIN EN 1537 and DIN 1054 should be performed on at least 3 anchors at every site
• confirms the creep size ks
• result of the suitability tests:- external anchor Ra,k of the grouted body- calculating tendon free length Lapp.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 54Winterterm 2008/09
Characteristic external resistance Ra,k
• load which gives a creep value of ks = 2mm isdefined as Ra,k
• in Germany only testing method 1 according to DIN EN 1537
• suitability tests: at least 3 stressing tests
• smallest proof load is decisive
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 55Winterterm 2008/09
Testing device
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 56Winterterm 2008/09
Suitability test at a supporting system type Berlin wall
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 57Winterterm 2008/09
Testing conditions of suitability tests
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 58Winterterm 2008/09
Creep value ks
( )( )ab
abs tt
ssk/log
−=
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 59Winterterm 2008/09
Creep value ks – external anchor resistance Ra
Prüfkraft Pp
0
0.4
0.8
1.2
1.6
2
Krie
chm
aß k
s [m
m]
1,7 mm
Ra = Pp
ks ≥ 2 mm ks < 2 mm
Prüfkraft Pp
0
0.5
1
1.5
2
2.5
Krie
chm
aß k
s [m
m]
Pp
Ra
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 60Winterterm 2008/09
Suitability tests (load cycles) according toDIN EN 1537, testing mehtod 1 and (DIN 4125)
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 61Winterterm 2008/09
Suitability tests (testing method 1)
Zyk-lus 1
Zyklus 2
Zyklus 4
Zyklus 5
Zyklus 6
Zyklus 3
25
40
55
70
85
100
10
50
75
100
125
ηk⋅Ek
≤ 20
, D
IN E
N 1
537:
Ank
erkr
aft i
n %
Pp
+ D
IN 4
215:
Ank
erkr
aft i
n %
Ek
Mindestbeobachtungszeitbei maximaler Kraft je Kraftstufe
15 bzw. 60 o. 180 min(120 od. 1440) min
1 (60 od. 180) min
1 (60 od. 120) min
1 (15 od. 30) min
1 (15 od. 30) min
1 (1) min
Vorbelastung Pa
Verschiebung
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 62Winterterm 2008/09
Suitability tests (load cycles) according toDIN EN 1537, testing mehtod 1 and (DIN 4125)
Zyk-lus 1
Zyklus 2
Zyklus 4
Zyklus 5
Zyklus 6
Zyklus 3
25
40
55
70
85
100
10
50
75
100
125
ηk⋅Ek
≤ 20
, D
IN E
N 1
537:
Ank
erkr
aft i
n %
Pp
+ D
IN 4
215:
Ank
erkr
aft i
n %
Ek
Mindestbeobachtungszeitbei maximaler Kraft je Kraftstufe
15 bzw. 60 o. 180 min(120 od. 1440) min
1 (60 od. 180) min
1 (60 od. 120) min
1 (15 od. 30) min
1 (15 od. 30) min
1 (1) min
Vorbelastung Pa
Verschiebung
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 63Winterterm 2008/09
Design value of external anchor resistance
Design value of external anchor resistance Ra,d
Partial safety factor of resistance of the grouted body γA
A
k,ad,a
RR
γ=
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 64Winterterm 2008/09
Ed design value of effects
Rd design value of the anchor resistance
Minimum from Ri,d and Ra,d
Proof of load bearing capacity in the ultimate limit state GZ 1B
dd RE ≤
QQ,kGG,kd EEE γγ ⋅+⋅=
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 65Winterterm 2008/09
Partial safety factors for effects and loads for ground anchors in USL 1B
1,001,301,50γQ
Ungünstige veränderliche Einwirkungen
1,001,101,20γE0g
Ständige Einwirkungen aus Erdruhedruck
1,001,201,35γGStändige Einwirkungen
LF3LF2LF1BezeichnungEinwirkungen
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 66Winterterm 2008/09
Nachweis der Gebrauchstauglichkeit
• Abnahmeprüfung nach DIN EN 1537:2001-01, 9.4 Prüfverfahren 1,(Maßgaben für das Kriechmaß ks entsprechend DIN 4125)
• Für jeden Anker sind die maximale Festlegekraft P0 und die rechnerische freie Ankerlänge Lapp zu bestätigen.
• Festlegekraft P0 maximal 60 % der charakteristischen Bruchkraft des Zuggliedes Ptk (DIN EN 1537:2001-01)Anmerkung: Dies entspricht nicht den nationalen Vorstellungen. Vielmehr ergibt sich die Festlegekraft P0 i.d.R. aus Gebrauchslastkriterien (siehe z.B. EAB).
• Ermittlung von Verschiebungen und Verkantungen des durch die Verpressanker zusammengespannten Bodenblockes.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 67Winterterm 2008/09
Nachweis der Gebrauchstauglichkeit
Angaben der DIN EN 1537 stehen teilweise im Widerspruch zur DIN 1054, so dass letztere maßgebend wird.
Es gilt
• Prüfkraft Pp beträgt für Kurzzeitanker 1,25⋅ Ek und für Daueranker ηk⋅Ek
ηk ≥ 1,50 für den aktiven Erddruck oder für Auftriebskräfteηk ≥ 1,33 für den Erdruhedruck
• Kraftaufbringung entsprechend DIN EN 1537 in drei Stufen gleich großer Kraftzunahme bis Pp, einer Entlastung bis zur Vorbelastung Pa und daraufhin Anspannung bis zur Festlegekraft P0
• Einzuhaltende Kriechmaße ks aus der DIN 4125: 1990- 11, 11.3
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 68Winterterm 2008/09
Abnahmeprüfung - Kriechmaß
Kurzzeitanker ≤ 1,0 mm
Daueranker ≤ 2,0 mm
≤ 0,5 mm≤ 0,5 mmKriechmaß ks
-bindigerBoden
nichtbindigerBoden, FelsBaugrund
verlängerte Beobach-
tungszeiten5-15 min2-5 minBeobachtungszeit
Kriechmaß ks nach DIN 4125: 1990-11
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 69Winterterm 2008/09
Abnahmeprüfung - Kraftaufbringung
Verschiebung
Ank
erkr
aft i
n %
Pp
0,33
0,66
1,00
Vorbelastung Pa
Mindestbeobachtungszeit
Festlegekraft P0
Stufe 1
Stufe 2
Stufe 3
Kraftaufbringung entsprechend DIN EN 1537 in drei Stufen gleich großer Kraftzunahme bis Pp, einer Entlastung bis zur Vorbelastung Paund daraufhin Anspannung bis zur Festlegekraft P0
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 70Winterterm 2008/09
Freie Ankerlänge Lapp
• Rechnerische freie Stahllänge Lapp aus denKraft-Verschiebungskurven der Eignungsprüfung
• Für jeden Anker mit der Abnahmeprüfung zu bestätigen.
mit At = Querschnitt des StahlzuggliedesEt = Elastizitätsmodul des StahlzuggliedesΔ s = elastische Dehnung des Zuggliedes am AnkerkopfΔ P = Pp – Pa
( )P
sEAL ttapp Δ
Δ⋅⋅=
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 71Winterterm 2008/09
Freie Ankerlänge Lapp
tbetfapp L,LLL ⋅++≤ 50 etfapp LL,L +⋅≤ 101
etfapp LL,L +⋅≥ 800
Grenzwerte für Lapp
• obere GrenzeVerbundanker Druckrohranker
• untere Grenze
LeLtf
LfreeLtb
Lfixed
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 72Winterterm 2008/09
• Liegt die rechnerische freie Stahllänge Lapp außerhalb der Grenzwerte,
so kann der Anker wiederholten Belastungszyklen unterzogen werden,
um zu überprüfen, ob sich das Verhalten ändert. Sollte sich keine
Änderung des Last-Verschiebungsverhaltens einstellen, darf der
Anker von der Technischen Bauherrenvertretung abgenommen werden.
• Auf die Berücksichtigung einer signifikanten Reibung innerhalb der
freien Ankerlänge wird hier nicht weiter eingegangen.
Siehe hierzu DIN EN 1537:2001-01, 9.9.
Freie Ankerlänge Lapp
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 73Winterterm 2008/09
Weitere Nachweise
a) Werden Kurzzeitanker für Erdruhedruck bemessen, dann ist zusätzlich derNachweis zu führen, dass bei Annahme eines umgelagerten aktiven Erd-drucks die zulässige Ankerkraft für den Regelfall eingehalten wird.
b) Bei häufig sich wiederholenden Verkehrslasten (auch Wind) darf die Änderung der Kraft im Stahlzugglied nicht größer sein als 0,2 ⋅ Ek. Die zulässige Schwingbreite im Bereich des Stahlzuggliedes und seiner Verbindungen darf nicht überschritten werden. Ein Nachweis ist nur erforderlichsoweit die schwellende Last nicht durch die Vorspannung abgedeckt ist.
c) Für das zu verankernde Bauteil sind die Nachweise für die Gebrauchskraftund Prüfkraft zu führen. Bei der Bemessung und Prüfung von temporären Bauwerken dürfen dabei bei Gebrauchskraft die nach DIN 4125:1990-11 zulässigen erhöhten Spannungen angesetzt werden.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 74Winterterm 2008/09
d) Durch konstruktive Maßnahmen ist sicherzustellen, dass der Ausfall eines Verpressankers nicht zum Versagen des durch die Anker gesicherten Bauwerks oder Bauteils führt. Wenn hierfür in besonderen Fällen ein Standsicherheitsnachweis erforderlich ist, darf er unter Berücksichtigung aller Reserven der Tragkonstruktion und des Bodens (z.B. Gewölbebildung des Bodens und Ausnutzung der Streckgrenze für die Spannungen des Stahlzugglieds) geführt werden.
e) Die Standsicherheit der gesamten Konstruktion einschließlich des Veranke-rungsbereiches im Boden ist durch die Verfahren gemäß Abschn. 7 (Tiefe Gleitfuge, Geländebruch, Erdauflastverfahren, usw.) nachzuweisen.
Weitere Nachweise
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 75Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 76Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 77Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 78Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 79Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 80Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 81Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 82Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 83Winterterm 2008/09
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 84Winterterm 2008/09
Beispiel: VerbundankerAufgabenstellung:
System einer permanenten Rückverankerung mit Verpressankern (Verbundanker). Aus der statischen Berechnung der Rückverankerung wurde für dieAnker eine charakteristische Beanspruchung (Ankerzugkraft)von Ek = Gk = 590 kN ermittelt (nur ständige Einwirkungen). Die Ergebnisse einer Eignungsprüfung (Kleinstwert) an einem Permanentanker liegen vor.
Folgende Nachweise sind zu führen:
• Ermittlung der Prüflast Pp
• Widerstand des Stahlzuggliedes Ri,k
• Herausziehwiderstand des Verpresskörpers Ra,k
• Nachweis der Tragfähigkeit und Gebrauchstauglichkeit nach DIN 1054: 2005-01
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 85Winterterm 2008/09
Example: composite anchor
Ltf
Lfree
Le
Ltb
Lfixed
ft,0.1,k
As bzw. At
Litzen
Ankertyp
Bezeichnung
1520 N/mm²
140 mm² je Litze
9
Litzenanker
Wert
590 kN (aktiver Erddruck infolge ständiger Einwirkungen)Ek
4,65 mLfree
Pa
Lfixed
Ltb
Ltf
Le
Et
ft,k
Bezeich-nung
60 kN
5,95 m
5,00 m
5,25 m
0,10 m
195000 N/mm²
1770 N/mm²
Wert
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 86Winterterm 2008/09
Beispiel
Ermittlung der Prüfkraft Pp
kkp EP ⋅= η
kNkN,EP kkp 88559051 =⋅=⋅= η
mit ηk ≥ 1,5 für aktiven Erddruck
kNmmkN,mm,fA,P
kNmmkN,mm,fA,P
k,.,tsp
k,tsp
18195211409950950
17847711409800800
22
10
22
=⋅⋅⋅=⋅⋅≤
=⋅⋅⋅=⋅⋅≤
Weiterhin muss nach DIN 1054, 9.4.1 (3) gelten
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 87Winterterm 2008/09
Measurement of anchor load and displacement of the anchor headfrom suitability test
24
20
16
12
8
4
Ver
schi
ebun
g [m
m]
1 10 100Zeit [min]
295 kN ks = 0,05mm
440 kN ks = 0,2 mm
590 kN ks = 0,5 mm
740 kN ks = 1,0 mm
885 kN ks = 2,1 mm0 200 400 600 800
Prüfkraft Pp [kN]
0
1
2
Krie
chm
aß k
s [m
m]
295 kN440 kN
590 kN
740 kN
885 kN
Ra,k = 870 kN
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 88Winterterm 2008/09
Load-displacement lines ofsuitability test
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 89Winterterm 2008/09
Beispiel
Widerstand des Stahlzuggliedes
k,.,tsk,i fAR 10⋅=
kN,,
kN,RR
M
k,id,i 41665
15121915
===γ
kNmm
NmmfAR k,.,tsk,i 191515201409 22
10 =⋅⋅=⋅=
mitft,0.1,k charakteristischer Wert der Spannung
bei 0,1 % bleibender Dehnung
mit
γM Teilsicherheitsbeiwert für den Widerstand des Stahlzuggliedes
⇒
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 90Winterterm 2008/09
Beispiel
Ermittlung des Herausziehwiderstands Ra,d
Bei einer Prüfkraft von 870 kN beträgt ks = 2,00 mm.
Ra,k beträgt somit 870 kN.
DIN 1054 9.4.1. (4)
Ra,k entspricht der Kraft, die ein Kriechmaß ks = 2 mm verursacht.
Ist für die Prüfkraft Pp das Kriechmaß ks < 2 mm, so ist Ra,k = Pp .
kN,,kNR
RA
k,ad,a 9790
11870
===γ
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 91Winterterm 2008/09
Nachweis der Tragfähigkeit
Beispiel
kN,RkN,,kNEREE
d,ad,
dGk,d,
979057963515901
11
=>=⋅=
≤⋅= γ
dd RE ≤mit
Rd dem kleineren Wert von Ra,d und Ri,d
kN,RkN,R d,id,a 416659790 =≤=
folgt
Der Nachweis ist nicht erbracht.
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 92Winterterm 2008/09
Nachweis der Gebrauchstauglichkeit
Vorhandene rechnerische freie Stahllänge Lapp
Beispiel
( ) m,mm,P
sEAL ttapp 3244318
608855141951409
≈=−
⋅⋅⋅=
⋅⋅=
ΔΔ
m,,m,m,m,L,LLL tbetfapp
8575501025532450
=⋅++≤⇒
⋅++≤
• obere Grenze
Special geotechnical worksGround anchorsProf. Dr.-Ing. Elfriede Ott, Faculty 02 – Civil Engineering, [email protected]
Seite 93Winterterm 2008/09
Nachweis der Gebrauchstauglichkeit
Beispiel
m,m,m,,m,LL,L etfapp
30410255800324800
=+⋅≥⇒
+⋅≥
Die rechnerische freie Stahllänge Lapp (4,32m) liegt bei dem
geprüften Anker innerhalb der zulässigen Grenzen.
Der Nachweis ist somit erbracht.
• untere Grenze