Method of pre-stressing a tendon
AssigneeGrinaker-LTA Limited
InventorFrancis David Shaw
Life of this patent
Estimating the term…
Abstract
A tendon 10 is installed in a hole 34 in a mine hanging wall 36 by making use of a barrel 14 and a wedge arrangement 16. One end of the tendon is anchored in the hole 34 such that the other end protrudes therefrom. The barrel 14 is positioned over the protruding end of the tendon 10. A tensioning jack applies a tensile load to the tendon 10 and an oppositely disposed load to a shear ring 20 of the barrel. When the desired preload is reached the shear ring 20 fails permitting the tensioning jack 40 to displace wedge elements 30 of the wedge arrangement 16 inwardly thereby locking the barrel on the tendon and maintaining the desired preload in the tendon.
Claims26
A barrel for use in pre-stressing a tendon, which includes
- a body having a leading end and a hole therethrough;
- and
- a spacing member in the form of a shear ring fast with the body and configured to transmit a compressive load applied by a setting member to the body, the spacing member being designed to yield in the direction of the leading end of the body when a predetermined compressive load is applied thereto.
A pre-stressing kit which includes a barrel having a body through which a hole extends;
- a wedge arrangement, at least part of which is receivable, in use, in the hole in the body of the barrel between the body and a tendon extending therethrough;
- and a spacing member formed integrally with the body through which, in use, a compressive load applied by a setting member to the body of the barrel is transmitted until a predetermined load is reached at which stage the spacing member permits the setting member to apply a load to the wedge arrangement to set the wedge arrangement between the body of the barrel and the tendon to secure the barrel in position on the tendon.
A setting device for use in pre-stressing a tendon using a barrel and wedge system, the barrel of which includes a body and a spacing member in the form of a shear ring fast with the body, the setting device including a nose having a leading end and defining an annular radially inwardly open channel-shaped formation adjacent the leading end;
- and a shear ring engaging member which is in the form of a discontinuous ring held captive in the channel-shaped formation and which is configured to engage and transmit a load to the shear ring of the barrel.
A barrel for use in pre-stressing a tendon which includes
- a body having a leading end and a hole therethrough through which a part of a tendon to be tensioned can pass;
- and
- a zone of weakness which is configured to yield in the direction of the leading end of the body when the body is subjected to a predetermined compressive load.
A barrel for use in pre-stressing a tendon which includes a unitary body formed from a single piece of steel, the body having a leading end and a hole therethrough through which a part of a tendon to be tensioned can pass, part of the body being connected to the remainder of the body by a zone of weakness configured to yield in the direction of the leading end when the body is subjected to a predetermined compressive load so that said part of the body is displaced relative to the remainder of the body when the body is subjected to said predetermined compressive load.
In the pre-stressing of a tendon anchored at one end, by making use of a tensioning jack having a nose bearing against a tapered barrel around the other end of the tendon, there is provided a method which includes steps of providing a spacing member through which a load applied by the nose to the barrel is transmitted, the spacing member being designed to yield at a predetermined load between the nose and the barrel;
- and using such yield to cause the nose to set a wedge arrangement in the barrel to grip the tendon.
A barrel for use in pre-stressing a tendon which includes
- a unitary body which is generally circular cylindrical in shape and has a hole extending axially therethrough through which part of a tendon to be tensioned can pass, the hole having a diameter which decreases over at least part of its length towards a leading end of the body, the leading end of the body being rounded;
- and
- a zone of weakness which is configured to yield in the direction of the leading end of the body when the body is subjected to a predetermined compressive load.
A barrel for use in pre-stressing a tendon which includes
- a unitary body which is generally circular in shape and has a hole extending axially therethrough through which a part of a tendon to be tensioned can pass, the hole having a diameter which decreases over at least part of its length towards a leading end of the body, the leading end of the body being rounded;
- and
- indicating means integral with the body to indicate when a predetermined compressive load has been applied to the body.
A barrel for use in pre-stressing a tendon which includes a body having a hole therethrough through which a part of a tendon to be tensioned can pass;
- and an annular recess in an outer surface of the body, the width of which decreases when the body is subjected to a predetermined compressive load.
Dependencies are inferred from the claim text.