3　Terms and Definitions

3.0.1　Prestressing strand

A low relaxation strand made of a number of twisted high tensile steel wires，used for applying prestress to rock-earth mass and concrete structures.

3.0.2　Epoxy-coated prestressing strand

A bundle of seven-wire prestressing strands coated with fusion bonded epoxy.

3.0.3　Epoxy filled and coated prestressing strand

A bundle of seven-wire prestressing strands，with the clearance filled with fusion bonded epoxy for preventing the ingress of corrosive media under capillary force or other hydrostatic forces.

3.0.4　Prestressing tendon

A structural element comprised of anchorage，prestressing strand and accessories.

3.0.5　Bonded prestressing tendon

A prestressing tendon which，as tensioned，locked and grouted，not allowing any relative slip between the tensioning section and anchored structure.

3.0.6　Unbonded prestressing tendon

A tendon braided with prestressing strands and coated with special anti-corrosive oil and claddings，as tensioned and locked，allows relative slip of the tensioning section within the anchored structure.

3.0.7　Retard bonded prestressing tendon

A prestressing strand that initially has the property of unbonded tendon as treated with adhesive and then turns into bonded tendon as the adhesive cures.

3.0.8　Prestressing anchorage tendon of tension type

A kind of tendon，for which the grout body of anchoring section deforms in tensioning as prestress is applied and the shearing stresses on the grout body and hole wall concentrate at the joint between the anchoring section and tensioning section，and attenuate rapidly towards the hole bottom.

3.0.9　Prestressing anchorage tendon of compression type

A kind of tendon，for which a supporting element is provided for the inner anchoring section，the grout concretion in front of the body is compressed as a prestress is applied.

3.0.10　Prestressing tendon of compression-dispersion type

A kind of tendon，for which multiple supporting bodies are provided for the inner anchoring section and the applied prestress is evenly dispersed on these bodies.

3.0.11　Unbonded prestressing tendon of multi-anchor and anticorrosion type

A kind of tendon，for which in addition to the features of prestressing tendon on the compressiondispersion type，each group of supporting bodies consists of bearing plates and auxiliary components.The P-type squeezed anchors of individual strands are bundled and protected to form anti-corrosive single anchor heads，and these anchor heads are embedded between the bearing plate and auxiliary component to integrate various groups of supporting bodies.

3.0.12　Anchorage

A device used totransmit the tension of prestressing tendon to the anchored structure.

3.0.13　Prestressing tendon-anchorage assembly

A stressed unit of assembled prestressing strand and anchorage.

3.0.14　Coating

The material coated on the surface of a prestressing strand to prevent corrosion and provide lubrication.

3.0.15　Sealing material

Materials used to repair PE cladding of unbonded prestressing strand，which are compatible with and have the same properties as the PE cladding.

3.0.16　Sheathing

A high density polyethylene（HDPE）tube sheathed on the prestressing tendon，with or without anticorrosive oil coating.

3.0.17　Prestressed anchorage

A technical measure that applies tensile on a prestressing tendon to stabilize rock-earth or concrete structure or to improve the inner stress of them.

3.0.18　Inner anchoring section

The inner bearing end of a prestressing tendon.It is a section integrated by bonding the inner end of tendon and anchored structure using bonding material or mechanical device made of metal.

3.0.19　Tensioning section

A section of a prestressing tendon which，by means of its elastic deformation，may be freely stretched under tensioning and apply prestress on the anchored structure when locked.

3.0.20　External anchorage head

A supporting device used to tension and lock a tendon.

3.0.21　Design tension

A tensile load applied to each strand of tendon，which is determined as per the anchorage design requirements and taking a proper margin of safety factor and various prestress loss into account.

3.0.22　Extra design tension

The actually applied tensile load by proportionally increasing the design tensile of a tendon，in order to eliminate various prestress losses.

3.0.23　Drawn-in

The retraction value of a prestressing strand that occurs during anchoring due to the relative displacement and deformation between anchorage and prestressing strand.

3.0.24　Effective prestressing

The prestress provided by a prestressing tendon after it is tensioned and locked and its tension gradually reduces to a relatively stable value.

3.0.25　Prestressing loss

The stress reduction that occurs in the process of tensioning，locking and establishment of effective prestressing of a prestressing tendon.

3.0.26　Vacuum grouting

A grouting method used for sealing hole by grouting，vacuum pump is used to remove the air and excessive water contained in the hole and grout，thus increasing the density of the grout in the prestressing tendon hole.

3.0.27　Construction method with feedback information

In rock-earth anchor construction with prestressing tendon，the initial design scheme is adjusted in time based on feedback information during construction to provide better guidance for site construction and enhance safety of rock-earth anchor.