3 Terms, definitions and symbols

The main terms are used in common with all Eurocodes. For the purposes of this standard the following definitions apply:

3.1.1

anchor

fr: tirant d'ancrage

de: Anker

an installation capable of transmitting an applied tensile load to a load bearing stratum

3.1.2

anchor head

fr: tete d'ancrage

de: Ankerkopf

the component of a ground anchor which transmits the tensile load from the tendon to bearing plate or structure

3.1.3

acceptance test

fr: essai de réception

de: Abnahmeprüfung

a load test to confirm that each anchor conforms with the acceptance criteria

3.1.4

apparent tendon free length

fr: longueur libre équivalente

de: Rechnerische freie Stahllänge

the length of tendon between the connection of the tendon to the stressing jack and a point along the tendon, deduced from load testing of an anchor

3.1.5

bleed

fr: ressuage

de: Absetzma

the separation of water from grout paste

3.1.6

borehole diameter

fr: diamètre de forage

de: Bohrlochdurchmesser

the diameter of a borehole as defined by the drill bit or casing diameter, excluding any enlargements

3.1.7

characteristic internal anchor resistance

fr: résistance interne caractéristique du tirant

de: Charakteristischer Innerer

Ankerwiderstand the characteristic load capacity of the anchor tendon

3.1.8

client's technical representative

fr: représentant technique du client

de: Technischer Bauherrnvertreter

represents the client and is fully acquainted with all aspects of the works related to the use of the anchors, including specialist knowledge of ground anchor technology

3.1.9

coupler

fr: coupleur

de: Koppelelement

a device for joining lengths of bar or strand which comprise an anchor tendon

3.1.10

creep limit

fr: Vitesse limite de fluage

de: Grenzkriechmaβ

the maximum creep displacement rate permitted at a specific load level

3.1.11

critical creep load

fr: traction critique de fluage

de: Kritische Kriechkraft

the anchor load corresponding to the end of the first linear part of a plot of anchor load against creep rate

3.1.12

datum load

fr: traction de reference

de: Vorbelastung

the level of anchor load from which the anchor head displacement is measured during a stress test. In general, a value of 10 % proof load is adopted

3.1.13

encapsulation

fr: protection

de: Korrosionsschutzumhüllung

a corrosion protection applied at least to the tendon bond length

3.1.14

external anchor resistance

fr: resistance externe du tirant

de: Herausziehwiderstand des Ankers

the load resistance of an anchor at the interface between ground and fixed anchor length

3.1.15

fixed anchor length

fr: longueur de scellement du tirant

de: Krafteintragungslänge

the designed length of an anchor over which the load is transmitted to the surrounding ground, through a grout body

3.1.16

free anchor length

fr: longueur libre du tirant

de: Freie Ankerlänge

the distance between the proximal end of the fixed anchor length and the tendon anchorage at the anchor head

3.1.17

grout

fr: coulis

de: Verpreβmörtel

a setting material which transfers load from the tendon to the ground over the fixed anchor length, and which may

fill the rest of the borehole and/or contribute to corrosion protection

3.1.18

investigation test

fr: essai préalable

de: Untersuchungsprüfung

a load test to establish the ultimate load resistance of an anchor at the grout/ground interface and to determine the characteristics of the anchor in the working load range

3.1.19

load loss limit

fr: pert de tension admissible

de: Grenzkraftabfall

the permitted cumulative loss of load at the end of a specified time period

3.1.20

lock-off load

fr: traction de blocage

de: Festlegekraft

the load transferred to an anchor head immediately on completion of a stressing operation

3.1.21

permanent anchor

fr: tirant d'ancrage permanent

de: Daueranker

an anchor with a design life which is in excess of two years

3.1.22

proof load

fr: traction d'épreuve

de: Prufkraft

the maximum test load to which an anchor is subjected

3.1.23

suitability test

fr: essai de contrôle

de: Eignungsprüfung

a load test to confirm that a particular anchor design will be adequate in particular ground conditions

3.1.24

system test

fr: essai de système

de: Systemprüfung

a test which is carried out on an anchor system to verify its competence to perform as required

3.1.25

temporary anchor

fr: tirant d'ancrage provisoire

de: Kurzzeitanker

an anchor with a design life of less than two years

3.1.26

tendon

fr: armature

de: Zugglied

the part of a ground anchor that is capable of transmitting the tensile load from the fixed anchor length to the anchor head

3.1.27

tendon bond length

fr: longueur de scellement de I'armature

de: Verankerungslange des Zuggliedes

the length of the tendon that is bonded directly to the grout and capable of transmitting the applied tensile load

3.1.28

tendon free length

fr: longueur libre de I'armature

de: Freie Stahllänge

the length of tendon between the anchor head and the proximal end of the tendon bond length

A typical anchor is shown in Figure 1.

3.2 Symbols

At
Cross sectional area of anchor tendon
Ed
Design value of the effect of an action
Ed,dst
Design value of the effect of destabilising action
Ed,stb
Design value of the effect of stabilising action
Et
Elastic modulus of anchor tendon
f
Friction loss as a percent of Pp
ftk
Characteristic tensile strength of a tendon
ft0,1k
Characteristic tensile stress at which there is a permanent strain of 0,1%
fr
Relative area of ribs of ribbed or profiled wire or bar
ks
Creep displacement rate
k1
Load loss
Lapp
Apparent tendon free length
Le
External length of tendon measured from the tendon anchorage in the anchor head to the anchorage point in the stressing jack
Lfixed
Fixed anchor length
Lfree
Free anchor length
Ltb
Tendon bond length
Ltf
Tendon free length
P
Anchor tendon load
Pa
Datum load
Pc
Critical creep load
P'c
Approximation to critical creep load
P0
Anchor lock-off load
Pp
Proof load
Ptk
Characteristic load capacity of tendon
Pt0,1k
Characteristic tensile load at which there is a permanent strain of 0,1 %
Ra
External anchor resistance
Rak
Characteristic external anchor resistance
Rik
Characteristic internal anchor resistance
Rd
Design resistance of an anchor
Rk
Lower of characteristic internal and external resistances
s
Anchor head displacement
t
Time from application of load increment or load lock-off
α
Slope of creep displacement/log time plot
ΔP
Difference between proof load and anchor datum load
Δs
Measured extension of anchor tendon under load increment ΔP
γq
Variation factor for anchor load
γR
Partial factor on anchor resistance

Key

  • 1 Anchorage point at jack during stressing
  • 2 Anchorage point at anchor head in service
  • 3 Bearing plate
  • 4 Lold transfer black
  • 5 Structural element
  • 6 Soil/rock
  • 7 Borehole
  • 8 Debonding sleeve
  • 9 Tendon
  • 10 Grout body
Figure 1 — Sketch of a ground anchor - Details of anchor head and head protection omitted

EN 1537:1999 Execution of special geotechnical works – Ground anchors