CA1243512A - Rock anchor and method of placing it - Google Patents
Rock anchor and method of placing itInfo
- Publication number
- CA1243512A CA1243512A CA000421106A CA421106A CA1243512A CA 1243512 A CA1243512 A CA 1243512A CA 000421106 A CA000421106 A CA 000421106A CA 421106 A CA421106 A CA 421106A CA 1243512 A CA1243512 A CA 1243512A
- Authority
- CA
- Canada
- Prior art keywords
- borehole
- anchor rod
- grout
- anchor
- rod
- 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
Links
Landscapes
- Piles And Underground Anchors (AREA)
Abstract
ABSTRACT
A method and apparatus for placing a rock anchor in a borehole. The rock anchor to be secured within a borehole in rock is an axially elongated anchor rod with a sleeve secured to it.
The sleeve includes elastic spring-like tongues inclined outwardly from the anchor rod in the direction toward the trailing end of the anchor rod when it is inserted in the borehole. The tongues serve to centre the anchor rod within the borehole and to hold the anchor rod within the borehole. The anchor rod can be inserted into the borehole before a hardenable grout is injected. A grout hose is placed around the anchor rod within the borehole and then is gradually withdrawn as the grout is injected to fill the space around the anchor rod. Alternately, the grout can be filled into the borehole and then the anchor rod and the attached sleeve can be inserted before the grout sets up in the borehole. Either way the rock anchor is protected from corrosion.
A method and apparatus for placing a rock anchor in a borehole. The rock anchor to be secured within a borehole in rock is an axially elongated anchor rod with a sleeve secured to it.
The sleeve includes elastic spring-like tongues inclined outwardly from the anchor rod in the direction toward the trailing end of the anchor rod when it is inserted in the borehole. The tongues serve to centre the anchor rod within the borehole and to hold the anchor rod within the borehole. The anchor rod can be inserted into the borehole before a hardenable grout is injected. A grout hose is placed around the anchor rod within the borehole and then is gradually withdrawn as the grout is injected to fill the space around the anchor rod. Alternately, the grout can be filled into the borehole and then the anchor rod and the attached sleeve can be inserted before the grout sets up in the borehole. Either way the rock anchor is protected from corrosion.
Description
35~
The invention is directed to a rock anchor and to a method of placing the rock anchor in a borehole. The borehole is primarily upwardly inclined where the anchor is to be secured by a hardenable material. The anchor rod can be inserted into the borehole first, followed by the injection of the hardenable material, or grout. Alternatively, the grout can be injected into the borehole first and then the anchor rod can be inserted. Further, the anchor rod includes a member for holding the anchor rod in the borehole until the hardenable material or grout sets.
In supporting the walls of underground excavations, rock anchors in the form of anchor bolts are, as a rule, inserted immediately after excavation to secure the excavated wall surfaces. Since the rock anchors are required in large numbers, it is important that they be inserted with a view to minimizing costs.
In simple anchors, which are not prestressed, a plastic, quick-setting cement mortar or grout is first pumped into the borehole and then the anchor rod is pushed immediately into the wet grout.
Since the direction and position of the anchor rod cannot be ascer-tained while it is being inserted into the borehole, it often assumes an eccen-tric position in the borehole. As a result, corrosion protection about the entire axial length of the anchor rod cannot be provided by the grout. Such a situation is particularly dangerous in rock formations where water is present, since the water would have a corrosive effect on the anchor rod. Due to the consistency and setting time of the grout and the dead weight of the anchor bars, particularly where the anchor bars have a vertical component within the borehole, there isthe further danger that the anchor bar rods may become at least partially displaced out of the borehole or out of the grout before the grout has set and secured the anchor rod within the borehole.
:,', :~,435~
Therefore, the primary object of the present invention is to assure that the anchor rod can be secured within the bore-hole and protected aga nst corrosion and, at the same time, prevent the anchor rod from slipping out of the borehole during setting of the grout.
The invention provides apparatus comprising an anchor rod provided at its leading end with an apparatus having elastic, spring-like tongues extending both outwardly and rearwardly from the anchor rod, and a grout hose provided at its leading end with an annular enlarged portion, the anchor rod being adapted to be inserted into a borehole to define an annular space around the rod, which annular space is adapted to be filled by means of the grout hose with hardenable material, for example cement mortar, the grout hose being placed over the anchor rod in use and being pulled out while the hardenable material is injected, the enlarged annular portion occupying the annular space for cementing and sealing purposes.
The grout hose is arranged to center the anchor rod and seal the grout as the hose is pulled out of the borehole during the continuous injection of the grout.
~2~35~ 21182-247 The advantage of this grouting operation is that the anchor rod is centered along its axial length by the grout hose.
Also, the centerlng effect is achieved at the discharge end of the grout hose without any additional parts or operations. Moreover, a quick setting grout can be used, since it is injected after the anchor rod has been placed.
A member in the form of a sleeve secured preferably by clamps or the like, on the anchor rod, with elastic spring-like tongues extending outwardly from the sleeve and projecting in the direction opposite to the direction in which the rod is inserted into the borehole may be provided to hold the anchor rod in the borehole until the grout has set. The inclined position of the tongues causes them to fit against the surface of the borehole.
The sleeve can also be used to hold the anchor bar at its leading end within the borehole before the grout is injected.
It can also be used to hold ~Z~35~LZ
the anchor rod in the borehole when filled with grout. FurtherJ the sleeve can be used as a spacer for centering the anchor rod. The arrangement of the tongues projecting outwardly from the sleeve away from the anchor rod assures what the injected grout is not displaced when the anchor rod is pushed through the grout within the borehole. Thus, the anchor rod can be pushed through the grout without any great expenditure of force. As the anchor rod is pushed into the borehole, it is centered by the spring-like tongues which slide along the surface of the borehole. After the anchor rod has been fully inserted into the borehole, the spring-like tongues in contact with the borehole surface secure the anchor rod from slipping out of the borehole.
In the rock anchor assembly, it is preferred that the anchor rod has ribs formed thereon on two opposite sides of the rod with said ribs forming a helically extending interrupted thread. It is further preferred for a securing meanS to be attached to the trailing end of said anchor rod outwardly of the borehole into which the rock anchor assembly is placed, and said means includes a nut threaded onto said ribs.
In drawings which illustrate embodiments of the invention: Figure 1 is a partial longitudinal section through a rock anchor with a holding member at the leading end of the anchor rod inserted within the borehole; Figure 2 is a transverse cross-sectional view taken along the line II-II in Figure l; Figure 3 is a partial longitudinal section through a rock anchor illustrating the method where grout is injected into the borehole using a grout hose encircling the anchor rod; and Figure is a partial longitudinal section through a rock anchor illustrating the method where the anchor rod is inserted into the borehole already filled with grout.
In the embodiment shown in Figure 3, the rock anchor includes an ~2~3~Z
anchor rod 2 pushed into a borehole 1 drilled in a rock formation. The anchor rod 2 is formed from a hot-rolled steel rod provided with ribs on opposite sides with the ribs extending along a helical line to form a partial or inter-rupted thread. Such anchor rods can be cut to length as desired and can be anchored at any desired location by threaded nuts.
The anchor rod 2 has a leading end inserted into the borehole first, and a trailing end extending outwardly from the entrance of the borehole. At its leading end, the anchor rod has a spreading member 3 having an axially extending sleeve 4 encircling the rod and connected with the rod so that it is not displaced during any pulling or pushing action effected on the rod. The sleeve 4 has a leading end and a trailing end with the leading end closer to the leading end of the rod. At the trailing end of the sleeve, elastic spring-like tongues 5 project in the direction of the trailing end of the rod; that is, in the direction opposite to the direction in which the anchor rod is inserted into the borehole. The spreading member can be clamped or screwed onto the leading end of the anchor rod 2. Generally, the spreading member 3 is formed of metal. ~lowever, it can also be made from a plastics material of corres-ponding strength.
The spring-like tongues 5 are spread outwardly from the sleeve; that is, from the anchor rod 2, so that they slide along the surface 6 of the bore-hole 1 while the anchor rod 2 is being inserted into the borehole. When the anchor rod 2 has reached its final position within the borehole, the tongues 5, in contact with the surface of the boTehole, prevent the anchor rod 2 from sliding out of, or being displaced outwardly from, the borehole.
After the anchor rod 2 is inserted into end held within the borehole in this manner, a grout hose 7, shown in Figure 3, is placed over the anchor rod 35~;2 within the borehole. An annular enlarged portion 9 is formed at the discharge end 8 of the grout hose 7. The enlarged portion 9 is formed of a flexible material, such as a plastics material. The enlarged portion 9 at the discharge end of the grout hose 7 has a double function: it centers the grout hose rela-tive to the borehole surface 6 and, at the same time, provides a seal for the annular space between the grout hose 7 and the borehole surface 6. A hardenable material 10, such as a cement mortar or grout, is injected through the grout hose 7 in the direction of the arrow 11 of Figure 3 and, as the borehole fills up with the grout, the hose 7 is pulled in the direction of the arrow 12. During this operation, the anchor rod 2 is centered relative to the borehole surface 6 by the discharge end 8 of the hose 7 so that the anchor rod 2 remains in a cen-tral position relative to the borehole surface while the grout 10 is injected and sets. During the grouting operation, the annular space not yet filled with the grout and which encircles the hose, is sealed by the enlarged portion 9 so that pressure can build up in the space to be filled, at least to a certain degree.
The final condition of the rock anchor with the borehole completely filled with the grout 10, is shown in Figures 1 and 2. The surface of the rock formation encircling the entrance to the borehole is provided with a shotcrete deposit l against which an anchor plate 15 is supported. A threaded nut is secured onto the trailing end of the anchor rod and bears against the outer surface of the anchor plate 15 for completing the rock anchor assembly. The threaded nut secures the anchor plate 15 against the entrance end of the borehole.
In Figure I, another method for placing -the rock anchor is shown in which the borehole 1 is filled with the grout 10 before the insertion of the anchor rod 2. The anchor rod 2 is pushed into the grout 10 to the position as ~Z~3~2 illustrated. In this arrangement, the anchor rod is provided with several spreading members 3; that is, one member is located at the leading end of the rod and one or more members can be spaced along the axial length of the rod at uniform or random distances. The spring-like tongues of the spreading members 3 slide along the surface 6 of the borehole 1 as the anchor rod 2 is inserted and, since the width of the tongues is relatively small, shown in Figure 2, they do not substantially interfere with the insertion of the anchor rod 2 into the cement mortar or grout 10. The spring force of the tongues, however, is suffi-cient to center the anchor bar relative to the borehole surface 6. When the final insertion position of the anchor rod 2 is attained, the tongues spreading outwardly against the borehole surface 6 prevent the anchor bar from slipping out of the borehole while the grout 10 is setting and secures the anchor rod within the borehole.
The invention is directed to a rock anchor and to a method of placing the rock anchor in a borehole. The borehole is primarily upwardly inclined where the anchor is to be secured by a hardenable material. The anchor rod can be inserted into the borehole first, followed by the injection of the hardenable material, or grout. Alternatively, the grout can be injected into the borehole first and then the anchor rod can be inserted. Further, the anchor rod includes a member for holding the anchor rod in the borehole until the hardenable material or grout sets.
In supporting the walls of underground excavations, rock anchors in the form of anchor bolts are, as a rule, inserted immediately after excavation to secure the excavated wall surfaces. Since the rock anchors are required in large numbers, it is important that they be inserted with a view to minimizing costs.
In simple anchors, which are not prestressed, a plastic, quick-setting cement mortar or grout is first pumped into the borehole and then the anchor rod is pushed immediately into the wet grout.
Since the direction and position of the anchor rod cannot be ascer-tained while it is being inserted into the borehole, it often assumes an eccen-tric position in the borehole. As a result, corrosion protection about the entire axial length of the anchor rod cannot be provided by the grout. Such a situation is particularly dangerous in rock formations where water is present, since the water would have a corrosive effect on the anchor rod. Due to the consistency and setting time of the grout and the dead weight of the anchor bars, particularly where the anchor bars have a vertical component within the borehole, there isthe further danger that the anchor bar rods may become at least partially displaced out of the borehole or out of the grout before the grout has set and secured the anchor rod within the borehole.
:,', :~,435~
Therefore, the primary object of the present invention is to assure that the anchor rod can be secured within the bore-hole and protected aga nst corrosion and, at the same time, prevent the anchor rod from slipping out of the borehole during setting of the grout.
The invention provides apparatus comprising an anchor rod provided at its leading end with an apparatus having elastic, spring-like tongues extending both outwardly and rearwardly from the anchor rod, and a grout hose provided at its leading end with an annular enlarged portion, the anchor rod being adapted to be inserted into a borehole to define an annular space around the rod, which annular space is adapted to be filled by means of the grout hose with hardenable material, for example cement mortar, the grout hose being placed over the anchor rod in use and being pulled out while the hardenable material is injected, the enlarged annular portion occupying the annular space for cementing and sealing purposes.
The grout hose is arranged to center the anchor rod and seal the grout as the hose is pulled out of the borehole during the continuous injection of the grout.
~2~35~ 21182-247 The advantage of this grouting operation is that the anchor rod is centered along its axial length by the grout hose.
Also, the centerlng effect is achieved at the discharge end of the grout hose without any additional parts or operations. Moreover, a quick setting grout can be used, since it is injected after the anchor rod has been placed.
A member in the form of a sleeve secured preferably by clamps or the like, on the anchor rod, with elastic spring-like tongues extending outwardly from the sleeve and projecting in the direction opposite to the direction in which the rod is inserted into the borehole may be provided to hold the anchor rod in the borehole until the grout has set. The inclined position of the tongues causes them to fit against the surface of the borehole.
The sleeve can also be used to hold the anchor bar at its leading end within the borehole before the grout is injected.
It can also be used to hold ~Z~35~LZ
the anchor rod in the borehole when filled with grout. FurtherJ the sleeve can be used as a spacer for centering the anchor rod. The arrangement of the tongues projecting outwardly from the sleeve away from the anchor rod assures what the injected grout is not displaced when the anchor rod is pushed through the grout within the borehole. Thus, the anchor rod can be pushed through the grout without any great expenditure of force. As the anchor rod is pushed into the borehole, it is centered by the spring-like tongues which slide along the surface of the borehole. After the anchor rod has been fully inserted into the borehole, the spring-like tongues in contact with the borehole surface secure the anchor rod from slipping out of the borehole.
In the rock anchor assembly, it is preferred that the anchor rod has ribs formed thereon on two opposite sides of the rod with said ribs forming a helically extending interrupted thread. It is further preferred for a securing meanS to be attached to the trailing end of said anchor rod outwardly of the borehole into which the rock anchor assembly is placed, and said means includes a nut threaded onto said ribs.
In drawings which illustrate embodiments of the invention: Figure 1 is a partial longitudinal section through a rock anchor with a holding member at the leading end of the anchor rod inserted within the borehole; Figure 2 is a transverse cross-sectional view taken along the line II-II in Figure l; Figure 3 is a partial longitudinal section through a rock anchor illustrating the method where grout is injected into the borehole using a grout hose encircling the anchor rod; and Figure is a partial longitudinal section through a rock anchor illustrating the method where the anchor rod is inserted into the borehole already filled with grout.
In the embodiment shown in Figure 3, the rock anchor includes an ~2~3~Z
anchor rod 2 pushed into a borehole 1 drilled in a rock formation. The anchor rod 2 is formed from a hot-rolled steel rod provided with ribs on opposite sides with the ribs extending along a helical line to form a partial or inter-rupted thread. Such anchor rods can be cut to length as desired and can be anchored at any desired location by threaded nuts.
The anchor rod 2 has a leading end inserted into the borehole first, and a trailing end extending outwardly from the entrance of the borehole. At its leading end, the anchor rod has a spreading member 3 having an axially extending sleeve 4 encircling the rod and connected with the rod so that it is not displaced during any pulling or pushing action effected on the rod. The sleeve 4 has a leading end and a trailing end with the leading end closer to the leading end of the rod. At the trailing end of the sleeve, elastic spring-like tongues 5 project in the direction of the trailing end of the rod; that is, in the direction opposite to the direction in which the anchor rod is inserted into the borehole. The spreading member can be clamped or screwed onto the leading end of the anchor rod 2. Generally, the spreading member 3 is formed of metal. ~lowever, it can also be made from a plastics material of corres-ponding strength.
The spring-like tongues 5 are spread outwardly from the sleeve; that is, from the anchor rod 2, so that they slide along the surface 6 of the bore-hole 1 while the anchor rod 2 is being inserted into the borehole. When the anchor rod 2 has reached its final position within the borehole, the tongues 5, in contact with the surface of the boTehole, prevent the anchor rod 2 from sliding out of, or being displaced outwardly from, the borehole.
After the anchor rod 2 is inserted into end held within the borehole in this manner, a grout hose 7, shown in Figure 3, is placed over the anchor rod 35~;2 within the borehole. An annular enlarged portion 9 is formed at the discharge end 8 of the grout hose 7. The enlarged portion 9 is formed of a flexible material, such as a plastics material. The enlarged portion 9 at the discharge end of the grout hose 7 has a double function: it centers the grout hose rela-tive to the borehole surface 6 and, at the same time, provides a seal for the annular space between the grout hose 7 and the borehole surface 6. A hardenable material 10, such as a cement mortar or grout, is injected through the grout hose 7 in the direction of the arrow 11 of Figure 3 and, as the borehole fills up with the grout, the hose 7 is pulled in the direction of the arrow 12. During this operation, the anchor rod 2 is centered relative to the borehole surface 6 by the discharge end 8 of the hose 7 so that the anchor rod 2 remains in a cen-tral position relative to the borehole surface while the grout 10 is injected and sets. During the grouting operation, the annular space not yet filled with the grout and which encircles the hose, is sealed by the enlarged portion 9 so that pressure can build up in the space to be filled, at least to a certain degree.
The final condition of the rock anchor with the borehole completely filled with the grout 10, is shown in Figures 1 and 2. The surface of the rock formation encircling the entrance to the borehole is provided with a shotcrete deposit l against which an anchor plate 15 is supported. A threaded nut is secured onto the trailing end of the anchor rod and bears against the outer surface of the anchor plate 15 for completing the rock anchor assembly. The threaded nut secures the anchor plate 15 against the entrance end of the borehole.
In Figure I, another method for placing -the rock anchor is shown in which the borehole 1 is filled with the grout 10 before the insertion of the anchor rod 2. The anchor rod 2 is pushed into the grout 10 to the position as ~Z~3~2 illustrated. In this arrangement, the anchor rod is provided with several spreading members 3; that is, one member is located at the leading end of the rod and one or more members can be spaced along the axial length of the rod at uniform or random distances. The spring-like tongues of the spreading members 3 slide along the surface 6 of the borehole 1 as the anchor rod 2 is inserted and, since the width of the tongues is relatively small, shown in Figure 2, they do not substantially interfere with the insertion of the anchor rod 2 into the cement mortar or grout 10. The spring force of the tongues, however, is suffi-cient to center the anchor bar relative to the borehole surface 6. When the final insertion position of the anchor rod 2 is attained, the tongues spreading outwardly against the borehole surface 6 prevent the anchor bar from slipping out of the borehole while the grout 10 is setting and secures the anchor rod within the borehole.
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus comprising an anchor rod provided at its leading end with an apparatus having elastic, spring-like tongues extending both outwardly and rearwardly from the anchor rod, and a grout hose provided at its leading end with an annular enlarged portion, the anchor rod being adapted to be inserted into a bore-hole to define an annular space around the rod, which annular space is adapted to be filled by means of the grout hose with hardenable material, for example cement mortar, the grout hose being placed over the anchor rod in use and being pulled out while the hardenable material is injected, the enlarged annular portion occupying the annular space for cementing and sealing purposes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3204478 | 1982-02-09 | ||
| DEP32044L7.8 | 1982-02-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1243512A true CA1243512A (en) | 1988-10-25 |
Family
ID=6155208
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000421106A Expired CA1243512A (en) | 1982-02-09 | 1983-02-08 | Rock anchor and method of placing it |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1243512A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017031605A1 (en) * | 2015-08-25 | 2017-03-02 | Casado Margolles Juan María | Spring for supporting helical bolts |
| CN107059863A (en) * | 2017-06-11 | 2017-08-18 | 贵州大学 | A kind of prestressed grouting anchor pole with butterfly backing plate |
| CN113586113A (en) * | 2021-08-05 | 2021-11-02 | 新乡学院 | Novel multi-claw self-locking grouting anchor rod |
-
1983
- 1983-02-08 CA CA000421106A patent/CA1243512A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017031605A1 (en) * | 2015-08-25 | 2017-03-02 | Casado Margolles Juan María | Spring for supporting helical bolts |
| CN107059863A (en) * | 2017-06-11 | 2017-08-18 | 贵州大学 | A kind of prestressed grouting anchor pole with butterfly backing plate |
| CN113586113A (en) * | 2021-08-05 | 2021-11-02 | 新乡学院 | Novel multi-claw self-locking grouting anchor rod |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8714883B2 (en) | Friction bolt | |
| US3753354A (en) | Corrosion-protected anchoring rods for anchoring structural parts in the earth, as well as method of producing anchorings with corrosion-protected anchor rods | |
| US6698980B2 (en) | Rock stabilizing apparatus and method | |
| US5775849A (en) | Coupler for ducts used in post-tension rock anchorage systems | |
| CA2733829A1 (en) | Rock anchor cable | |
| EP0863295A1 (en) | Method and device for setting anchoring bolts | |
| US3735541A (en) | Method and device for anchoring tie-rods in ground | |
| US3933332A (en) | Self-sealing tie assembly for erecting concrete forms | |
| US5374140A (en) | Drillable ground support bolt | |
| CA1243512A (en) | Rock anchor and method of placing it | |
| KR100896963B1 (en) | Rock bolt | |
| GB1384744A (en) | Method and elements for anchoring stays and stay anchorages thus produced | |
| US5622454A (en) | Anchor bolt for stabilizing rock strata and method of installing | |
| US3234742A (en) | Groutable rock bolt assembly and procedure | |
| US4633627A (en) | Earth anchors | |
| CN213173690U (en) | Pile hole orifice sealing structure for grouting reinforcement of cast-in-place pile | |
| CH422683A (en) | Method and device for transmitting tensile forces into the interior of the earth by means of a tension rod | |
| GB2241761A (en) | Reinforcement of ground strata and foundation mixing | |
| RU2047778C1 (en) | Anchor | |
| SU848663A1 (en) | Ferroconcrete anchor | |
| KR200307723Y1 (en) | A fixture device for nail of construction | |
| GB2360047A (en) | A removable mechanical anchor with a non-stick coating | |
| WO1987005647A1 (en) | Improvements to ground anchors | |
| KR200270726Y1 (en) | Apparatus for preventing rust of rock bolt | |
| WO2010060122A9 (en) | Rock bolt component |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |