GB1589607A - Method of securing an anchor to rock or soil and a soil or rock anchor - Google Patents

Method of securing an anchor to rock or soil and a soil or rock anchor Download PDF

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Publication number
GB1589607A
GB1589607A GB34378/77A GB3437877A GB1589607A GB 1589607 A GB1589607 A GB 1589607A GB 34378/77 A GB34378/77 A GB 34378/77A GB 3437877 A GB3437877 A GB 3437877A GB 1589607 A GB1589607 A GB 1589607A
Authority
GB
United Kingdom
Prior art keywords
tendon
tubular member
rock
soil
borehole
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB34378/77A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DIVIDAG STRESSED CONCRETE Ltd
Original Assignee
DIVIDAG STRESSED CONCRETE Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by DIVIDAG STRESSED CONCRETE Ltd filed Critical DIVIDAG STRESSED CONCRETE Ltd
Priority to GB34378/77A priority Critical patent/GB1589607A/en
Publication of GB1589607A publication Critical patent/GB1589607A/en
Expired legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
    • E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
    • E02D5/74—Means for anchoring structural elements or bulkheads
    • E02D5/80—Ground anchors
    • E02D5/808—Ground anchors anchored by using exclusively a bonding material
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D20/00—Setting anchoring-bolts
    • E21D20/02—Setting anchoring-bolts with provisions for grouting
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21D—SHAFTS; TUNNELS; GALLERIES; LARGE UNDERGROUND CHAMBERS
    • E21D21/00—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection
    • E21D21/0026—Anchoring-bolts for roof, floor in galleries or longwall working, or shaft-lining protection characterised by constructional features of the bolts
    • E21D21/006—Anchoring-bolts made of cables or wires

Description

(54) A METHOD OF SECURING AN ANCHOR TO ROCK OR SOIL AND A SOIL OR ROCK ANCHOR (71) We, DIVIDAG STRESSED CONCRETE LIMITED, a British Company of Southam Industrial Estate, Southam, Leamington Spa, Warwickshire, hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a method of securing an anchor to rock or soil, and to a soil or rock anchor.
Various methods of securing an anchor to rock or soil are known and basically comprise forming a borehole in the rock or soil, inserting an elongate rod, multi-strand cable or the like (known as a tendon) into the borehole, and injecting a cement, resin or like grout into the borehole so as to fill the space between the surface of the borehole and the tendon over a desired length of the tendon (known as the bond length) adjacent the blind end of the borehole. After the grout has set, the tendon may be tensioned as required and an anchor plate on the tendon urged against the face of the rock or soil to form the finished anchor.
One of the problems which has arisen with such anchors is that the tendon is prone to corrosion in the borehole. Whilst it is relatively easy to protect the tendon over its major length by corrosion resistance coatings, it is not easy to protect the tendon over its bond length. It is an object of the invention to provide an improved method of securing an anchor to rock or soil, and an improved anchor for use in such a method, whilst protecting the tendon over its bond length.
According to the invention, a method of securing an anchor to rock or soil comprises: providing a tendon as hereinbefore defined, passing over one end of the tendon a corrosion resistant metallic tubular member having its outer periphery formed with transverse ribbing, squeezing the tubular member to secure it to the tendon, inserting said tendon into a borehole so as to position the tubular member adjacent the blind end of the borehole, and placing cement, resin or like grout between the borehole and the ribbed periphery of the tubular member so that when the grout has set, any tensile load in the tendon will be transmitted to the surrounding rock or soil through the tubular member and surrounding grout.
The tendon may be supplied coated with polypropylene or other plastics and, in such a case, the coating should be removed over at least a major portion of the length of the tendon which is to be in contact with the tubular member before the tubular member is positioned on the tendon. If desired, the tubular member may also overlap a portion of the remaining coating so that it will sealingly engage the coating on being squeezed.
The method may include arranging between the tendon and tubular member one or more inserts of material harder than the tendon and tubular member so that the or each insert will bite into the tendon and tubular member when the latter is squeezed.
By providing such inserts, the bond between the tendon and tubular member can be greatly increased. The or each insert may be part-annular in cross-section and may have projections on its arcuate surfaces which bite into the tendon and tubular member.
The invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a longitudinal cross-section through a preferred form of ribbed tubular member, Figure 2 is a cross-sectional view showing the tubular member partly crimped to one end of a tendon, Figure 3 shows the tendon and the attached tubular member in position as a rock or soil anchor in a borehole, Figure 4 is a perspective view of a set of inserts, and Figure 5 is a cross-sectional view of the tendon and attached tubular member with inserts as shown in Figure 4 crimped between them.
A tubular member 1 is preferably formed from stainless steel and has its outer periphery formed with ribbing 2. The ribbing may be in the form of convolutions or may be helical.
As shown in Figure 2, the tubular member 1 fits with working clearance on a tendon 3, which may be in the form of a cable as shown or a solid bar. After correctly positioning the tubular member on the tendon, it is squeezed a section at a time so as to crimp it on to the tendon. In Figure 2, the lower half is shown crimped, and Figure 3 shows the uniform outer diameter of the tubular member 1 after it has been crimped for its full length.
It is known to protect the tendon with a coating of polypropylene to prevent corrosion of the tendon. In such a case, and before the tubular member is crimped to the tendon, it is essential to strip the polypropylene coating from the area to be gripped by the tubular member 1. Failure to remove the coating will result in insufficient grip between the crimped tubular member 1 and the tendon 3. However, we advise that the tubular member 1 should overlap the coating slightly prior to being crimped. In this manner, an impervious seal will be achieved between the tubular member 1 and the polypropylene following crimping.
After the tubular member 1 has been crimped to the tendon 3 to form the anchor, the tendon is inserted in a borehole 4 so that the tubular memer is positioned near the blind end of the borehole as shown in Figure 3. Cement, resin or grout 5 is then injected into the borehole so that it fills the space between the tubular member 1 and borehole 4 as shown. After the grout has set, the tendon may be tensioned in the usual way.
Such tensile loading will be transmitted to the surrounding rock or soil through the tubular member 1 and the grout 5. The ribbing 2 provides a key for the grout 5, and the grip between the tendon 3 and the crimped tubular member will generally be sufficient to withstand the tensile loading that will normally be applied to the tendon 3.
In order to improve the bond between the tubular member 1 and the tendon upon crimping, a pair of inserts 6 as shown in Figures 4 and 5 may be arranged between the tubular member and tendon. The inserts 6 are formed from a harder material than the tubular member 1 and tendon 3 and have ribs 7, 8 or other projections on their inner and outer surfaces respectively which bite into the tendon and tubular member during crimping. A single insert of suitable form or three or more inserts could be used to improve the bond.
Although the tubular member 1 as described has a single axial bore for receiving the tendon 3, it could be formed with several bores for receiving individual strands of a tendon comprising multiple strand cable.
WHAT WE CLAIM IS: 1. A method of securing an anchor to rock or soil comprises: providing a tendon as hereinbefore defined, passing over one end of the tendon a corrosion resistant metallic tubular member having its outer periphery formed with transverse ribbing, squeezing the tubular member to secure it to the tendon, inserting said tendon into a borehole so as to position the tubular member adjacent the blind end of the borehole, and placing cement, resin or like grout between the borehole and the ribbed periphery of the tubular member so that when the grout has set, any tensile load in the tendon will be transmitted to the surrounding rock or soil through the tubular member and surrounding grout.
2. A method according to Claim 1, including removing any polypropylene or other plastics coating from at least a major portion of the length of the tendon which is to be in contact with the tubular member before the tubular member is positioned on the tendon.
3. A method according to Claim 2, including overlapping a portion of the remaining coating with the tubular member so that the tubular member will sealingly engage the coating on being squeezed.
4. A method according to Claim 1, 2 or 3, including arranging between the tendon and tubular member one or more inserts of material harder than the tendon and tubular member so that the or each insert will bite into the tendon and tubular member when the latter is squeezed.
5. A method according to Claim 4, in which the or each insert is part annular in cross-section and has projections on its arcuate surfaces which bite into the tendon and tubular member.
6. A rock or soil anchor for use in the method according to Claim 5 comprising a tendon, as herein before defined, a corrosion resistant metallic tubular member on one end which has been squeezed so as to secure it to the tendon, the tubular member having its outer periphery formed with
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. end of a tendon, Figure 3 shows the tendon and the attached tubular member in position as a rock or soil anchor in a borehole, Figure 4 is a perspective view of a set of inserts, and Figure 5 is a cross-sectional view of the tendon and attached tubular member with inserts as shown in Figure 4 crimped between them. A tubular member 1 is preferably formed from stainless steel and has its outer periphery formed with ribbing 2. The ribbing may be in the form of convolutions or may be helical. As shown in Figure 2, the tubular member 1 fits with working clearance on a tendon 3, which may be in the form of a cable as shown or a solid bar. After correctly positioning the tubular member on the tendon, it is squeezed a section at a time so as to crimp it on to the tendon. In Figure 2, the lower half is shown crimped, and Figure 3 shows the uniform outer diameter of the tubular member 1 after it has been crimped for its full length. It is known to protect the tendon with a coating of polypropylene to prevent corrosion of the tendon. In such a case, and before the tubular member is crimped to the tendon, it is essential to strip the polypropylene coating from the area to be gripped by the tubular member 1. Failure to remove the coating will result in insufficient grip between the crimped tubular member 1 and the tendon 3. However, we advise that the tubular member 1 should overlap the coating slightly prior to being crimped. In this manner, an impervious seal will be achieved between the tubular member 1 and the polypropylene following crimping. After the tubular member 1 has been crimped to the tendon 3 to form the anchor, the tendon is inserted in a borehole 4 so that the tubular memer is positioned near the blind end of the borehole as shown in Figure 3. Cement, resin or grout 5 is then injected into the borehole so that it fills the space between the tubular member 1 and borehole 4 as shown. After the grout has set, the tendon may be tensioned in the usual way. Such tensile loading will be transmitted to the surrounding rock or soil through the tubular member 1 and the grout 5. The ribbing 2 provides a key for the grout 5, and the grip between the tendon 3 and the crimped tubular member will generally be sufficient to withstand the tensile loading that will normally be applied to the tendon 3. In order to improve the bond between the tubular member 1 and the tendon upon crimping, a pair of inserts 6 as shown in Figures 4 and 5 may be arranged between the tubular member and tendon. The inserts 6 are formed from a harder material than the tubular member 1 and tendon 3 and have ribs 7, 8 or other projections on their inner and outer surfaces respectively which bite into the tendon and tubular member during crimping. A single insert of suitable form or three or more inserts could be used to improve the bond. Although the tubular member 1 as described has a single axial bore for receiving the tendon 3, it could be formed with several bores for receiving individual strands of a tendon comprising multiple strand cable. WHAT WE CLAIM IS:
1. A method of securing an anchor to rock or soil comprises: providing a tendon as hereinbefore defined, passing over one end of the tendon a corrosion resistant metallic tubular member having its outer periphery formed with transverse ribbing, squeezing the tubular member to secure it to the tendon, inserting said tendon into a borehole so as to position the tubular member adjacent the blind end of the borehole, and placing cement, resin or like grout between the borehole and the ribbed periphery of the tubular member so that when the grout has set, any tensile load in the tendon will be transmitted to the surrounding rock or soil through the tubular member and surrounding grout.
2. A method according to Claim 1, including removing any polypropylene or other plastics coating from at least a major portion of the length of the tendon which is to be in contact with the tubular member before the tubular member is positioned on the tendon.
3. A method according to Claim 2, including overlapping a portion of the remaining coating with the tubular member so that the tubular member will sealingly engage the coating on being squeezed.
4. A method according to Claim 1, 2 or 3, including arranging between the tendon and tubular member one or more inserts of material harder than the tendon and tubular member so that the or each insert will bite into the tendon and tubular member when the latter is squeezed.
5. A method according to Claim 4, in which the or each insert is part annular in cross-section and has projections on its arcuate surfaces which bite into the tendon and tubular member.
6. A rock or soil anchor for use in the method according to Claim 5 comprising a tendon, as herein before defined, a corrosion resistant metallic tubular member on one end which has been squeezed so as to secure it to the tendon, the tubular member having its outer periphery formed with
transverse ribbing, and two or more separate inserts of material harder than the tendon and the tubular member arranged between the tendon and the tubular member, each insert being part annular in cross-section and having projections on its arcuate surfaces which bite into the tendon and tubular member.
7. A rock or soil anchor according to Claim 6, in which the tendon is coated with polypropylene or other plastics, a section of which coating has been removed over at least a major portion of the length which supports the tubular member.
8. A rock or soil anchor according to Claim 7, in which the tubular member overlaps and sealingly engages a portion of the remaining coating.
9. A rock or soil anchor according to any of Claims 6 to 10, in which the tubular member is made from stainless steel.
10. A method of securing an anchor to rock or soil substantially as described herein with reference to the accompanying drawings.
11. A rock or soil anchor substantially as described herein with reference to and as illustrated in Figure 2, 3 or 5 of the accompanying drawings.
GB34378/77A 1978-05-18 1978-05-18 Method of securing an anchor to rock or soil and a soil or rock anchor Expired GB1589607A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB34378/77A GB1589607A (en) 1978-05-18 1978-05-18 Method of securing an anchor to rock or soil and a soil or rock anchor

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB34378/77A GB1589607A (en) 1978-05-18 1978-05-18 Method of securing an anchor to rock or soil and a soil or rock anchor

Publications (1)

Publication Number Publication Date
GB1589607A true GB1589607A (en) 1981-05-13

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Family Applications (1)

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GB34378/77A Expired GB1589607A (en) 1978-05-18 1978-05-18 Method of securing an anchor to rock or soil and a soil or rock anchor

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GB (1) GB1589607A (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2600717A1 (en) * 1986-06-24 1987-12-31 Ars Forges Boulonneries Extensible supporting bolt, supporting method, use of the bolt
EP0251887A1 (en) * 1986-06-24 1988-01-07 Forges Et Boulonneries D'ars-Sur-Moselle Extensible support bolt, supporting method, use of the bolt
FR2613438A1 (en) * 1987-03-30 1988-10-07 Ars Forges Boulonneries Improvement to an extensible support bolt and support method
WO1993003256A1 (en) * 1991-07-26 1993-02-18 J.J.P. Geotechnical Engineering Pty. Ltd. A cable bolt
WO2013131827A3 (en) * 2012-03-09 2014-05-15 Nv Bekaert Sa Strand, cable bolt and its installation

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2600717A1 (en) * 1986-06-24 1987-12-31 Ars Forges Boulonneries Extensible supporting bolt, supporting method, use of the bolt
EP0251887A1 (en) * 1986-06-24 1988-01-07 Forges Et Boulonneries D'ars-Sur-Moselle Extensible support bolt, supporting method, use of the bolt
FR2613438A1 (en) * 1987-03-30 1988-10-07 Ars Forges Boulonneries Improvement to an extensible support bolt and support method
WO1993003256A1 (en) * 1991-07-26 1993-02-18 J.J.P. Geotechnical Engineering Pty. Ltd. A cable bolt
US5570976A (en) * 1991-07-26 1996-11-05 J.J.P. Geotechnical Engineering Pty. Ltd. Cable bolt
WO2013131827A3 (en) * 2012-03-09 2014-05-15 Nv Bekaert Sa Strand, cable bolt and its installation
AU2013229665B2 (en) * 2012-03-09 2017-04-27 Minova International Limited Strand, cable bolt and its installation
US9909419B2 (en) 2012-03-09 2018-03-06 Nv Bekaert Sa Strand, cable bolt and its installation

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Legal Events

Date Code Title Description
PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee