CA1294157C - Hollow fiber glass roof bolt - Google Patents
Hollow fiber glass roof boltInfo
- Publication number
- CA1294157C CA1294157C CA000549972A CA549972A CA1294157C CA 1294157 C CA1294157 C CA 1294157C CA 000549972 A CA000549972 A CA 000549972A CA 549972 A CA549972 A CA 549972A CA 1294157 C CA1294157 C CA 1294157C
- Authority
- CA
- Canada
- Prior art keywords
- hollow
- collar
- rod
- bolt
- roof
- 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 - Fee Related
Links
Landscapes
- Piles And Underground Anchors (AREA)
- Excavating Of Shafts Or Tunnels (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
Abstract
HOLLOW FIBER GLASS ROOF BOLT
ABSTRACT OF THE DISCLOSURE
The present invention is directed to a hollow roof bolt based on a) a hollow rod, b) a collar which is internally tapered and fitted over one end of the rod and c) a hollow plug located in the end of the rod having the collar, the plug being externally tapered such that it forces the rod to expand and thereby conform to the internal taper of the collar.
The present invention is additionally directed to the rod in combination with a roof plate such that the roof plate fits flush against the distant end of the collar.
ABSTRACT OF THE DISCLOSURE
The present invention is directed to a hollow roof bolt based on a) a hollow rod, b) a collar which is internally tapered and fitted over one end of the rod and c) a hollow plug located in the end of the rod having the collar, the plug being externally tapered such that it forces the rod to expand and thereby conform to the internal taper of the collar.
The present invention is additionally directed to the rod in combination with a roof plate such that the roof plate fits flush against the distant end of the collar.
Description
~o-2892 PU~187 BACKGROUND OF THE INVENTION
Field of the Inven~ion The present invention is directed to a hollow 5 roof bolt to be used in conjunction with pumpable grouting resins to provide support in underground constructions such as in the mining and tunneling industry.
Descrip~ion of the Prior Art In underground operations such as mining or excavation, the unsupported rock formation is stabilized and supported by various methods. In one method, a bore hole is drilled into the rock formation and a me~al bolt is inser~ed into the bore hole. The bolts are secured 15 into the bore hole by the engagement of an expansion shell on the end of the bolt. A roof plate is retained on the other end of the bolt that extends from the bore hole such that the plate abuts the roo~. Rotating the bolt expands the expansion shell to enga~e the rock wall 20 of the bore hole. The bolt is tensioned with the resultant ef~ect o compressing the rock strata between the expansion shell and roof plate, thereby reinforcing the strata to resist ~orces that apply shear stresse~ to the rock formation. Over a perlod of time in soft rock 25 strata, the expanded shell slips in the bore hole, reducing tension and decrea~in~ the amount of roof support provided by the bolt.
Another method of providing roo support i9 by the use of grouted bolts. The bolts, which may be metal 30 or plastic are again inserted into bore holes; however, instead of an expansion shell the bol~s are bonded into the bore hoLe by the use of a two-component resin composition, i.e., either a polyester resin and a catalyst or a two-component polyurethane, which rnay be contained in a cartridge. One or more of the cartridges are positioned in the bore hole and are broken by the insertion of a bolt into the bore hole. The bolt is 5 rotated to mix the components and provide a homog~neous curable resin mixture. The cured resin firmly holds the bolt in position in the bore hole and reinforces the strata.
The quali~y of the cured resin can be reduced 10 by either under rotating the bolt in the bore hole (which does not provide sufficient mixing and leads to a heterogeneous as opposed to a homogeneous resin) or by over rotating the bolt in the bore hole. In either event, the holding strength of the bolt is reduced. In 15 addition, the bore hole could have an undetected void into which the resin can penetrate leaving less resin in the annulus between the bore hole and the bolt, also reducing the holding strength of the bolt. Further, the length of bolt which can be inserted into a bore hole 20 with resin cartridge adhesives is usually limited to less than 10 feet. These difficulties may be overcome by injecting the resin into the annular space between the bore hole and the bolt or by the use of a hollow bolt. Grouted bolts are disclosed in U.S. Patents 25 4,461,600; l~,289,427; 3 9 896,627; ~,526~l~92; 4,501,516;
4,4g7,595; 4,490,074; 4,430,025; ancl 3~797,254.
A third method or provLding roof support is accomplished by combinin~ the use o an expans-Lon shell with a grouted bolt as di.sclosed in U.S. Patents 30 4,140,429; 4,413,930; 4,419,805; and 4,000,623. ~ile adequate roof support may be obtained by the use of such bolts, these bolts are generally complicated in design and thus too expensive for commercial use.
Mo-2892 - 2 -~2~57 It is an object of the present lnven~lo~ to provide an inexpensive, hollow roof bolt which may be adhesively bonded to a bore hole by injecting a grouting resin. In a preferred embodiment of the invention, 5 lightweight bolts made of plastic, preerably fiber-glass, are used. Becau~e of their lightweight nature, these bolts are easy to handle 9 ancl also pro~ide an efficient means for reinforcing rock strata. It is also an object of the present invention to provide an 10 efficient method of holding a roof plate against the surface of the roof through the use of the hollow roof bolt. These objects may be achieved by the hollow roof bolt described in detail hereinafter and entails the use of a collar which is fitted over one end oE said hollow 15 bolt and a hollow plug which is inserted in~o the end of the bolt to expand the end against the inside of the collar.
U.SO Patent 3,797,254 also discloses a method of expanding a hollow tubular reinforcing member;
20 however, these bolts are generally made of metal and rely upon resin cartridges to provide the adhe~ive.
East German Patent 146,362 and German Offenlegungs-schrift 2,145,572 disclose methods o securing plastic rods in ~ransformers either by expanding a hollow ~od or 25 by forming a rod with an expanded end.
SUMMARY OF TSE INVENTION
The pre~ent invention is directed to a hol.low roof bolt based on a) a hollow rod, 30 b) a collar which i~ internally tapered and fitted over one end of the rod and c) a hollow plug located in the end of the rod having the collar, the plug being externally tapered such that it forces the rod to expand and thereby conform to the 35 internal taper of the collar.
Mo-2892 ~ 3 -r~?~
The present invention i9 additionally directed to the rod in combination with a roof plate such that the roof plate fits flush against the distant end o the collar.
BRIEF DESCRIPTION OF THE DR~WINGS
Flgure 1 is a sectional view of a rock formation representing an embodim~nt of the invention showing the roof bolt in a bore ho].e.
Figure 2 is side view of the collar shown in 10 Figure 1.
Figure 3 is a bottom view of the collar shown in Figure 1.
Figure 4 is a sectional view through line 4-4 of Figure 3.
DETAILED DESCR.IPTION OF THE INVENTION
In Figure 1 hollow fiberglass rod 2 ls shown inserted into bore hole 1. An internally tapered collar 3 is positioned over the rod and held in place by an externally tapered hollow plug 4. The collar holds a 20 roof plate 5 against the rock formation. Grout stop bushing 6 i9 used to center the hollow rod in the bore hole and to prevent grout from running out of the annular space between the hollow rod and the sides of the bore hole. A grout tube 7 extends through the roof 25 plate 5 and grout stop bushing 6 to provide a means o~
entry for the grout to fill the annular space between the bore hole and the hollow fiberglass ro~. When grout 1~ injected throu~h the center portion of the hDllow rod, air can escape through grout tube 7.
Figure 2 represents a side vi.ew of collar 3.
The distant end 8 of collar 3 preferably has a hemispherical shape. Collar 3 also has ribs 9 to provide support between the upper hemispherical end of the collar and the bottom portion. The taper from ~he Mo-2892 - 4 -upper to the lower end of collar 3 could be ~olid;
however, the rib-type structure uses signiicantly less material and still provides su~ficient strength and support to the collar. Figure 3 represents a bottom 5 view of the collar 3 showing ribs 9 spaced equidistantly around the collar and the hollow center portion 10.
Figure 4 represents a section view through line aa of Figure 3. Figure 4 shows the internal taper o hollow center position 10 of collar 3.
The components of the present invention include a hollow rod of sufficient strength and length to provide the desired support to the rock formation. The hollow rod may be metal or plastic, preferably plastic and most preferably fiberglass, and should have a 15 tensile strength of greater than 10,000, preferably greater than 16,000 and most preferably greater than 30,000 lbs. Over one end of the hollow rod is fitted an internally tapered collar. The collar is held in place by a hollow externally tapered plug fi~ted into the end 20 of the rod. The hollow tapered plug forces the rod to expand and conform to the internal taper of the collar.
The collar and hollow plug may also be made of either metal or plastic, provided that it has sufficient strength to hold the rock formation in place~ The 25 collar and hollow pLug are preferably made of plastic.
Though the hollow rod, collar and hollow plug may be made of different materials and still be used ln combination, it is preferred that if the rod is nonmetallic~ then the colLar should also be nonmetallic.
The strength of the attached collar mag be lncreased by using an adhesive on the internal taper.
To provide even more strength, it is preferred to insert the hollow plug into the rod in order to expand the hollow rod and then mold the collar directly onto the 35 expanded hollow rod.
Mo-2892 - 5 -The roof plate may also be made o either metal or plastic. Even though it i~ less critical for -the roof plate to be made of the same material as the collar, it is still preferred that the roof plate be S made of the same material as the rod, plug and collar.
The shape and size of -the collar is designed to hold a roof plate against the rock formation. The outer surface of the distant end of the collar, i.e., the part of the collar closest to the bore hole, may be of any 10 shape provided that it fits flush against the corresponding part of the plate. The preferred convex shape for the distant end of the collar and the corresponding concave portion of ~he plate is hemi-spherical. This shape allows the plate to rotat2 on the 15 collar so that it can fit firmly against the rock formation. With other shapes for ~he collar and plate, the plate cannot rotate on the collar and must remain at a fixed angle, generally perpendicular, to the hollow rod.
The plate has a grout tube passing through it such that a pumpable grout can be injected into the annular space between the 'bore hole and the hollow rod.
While it is possible to introduce the grout ei~her through the hollow rod or through the grout tube and to 25 allow air to escape through the other opening, it is preferred to introduce the grout into the a~mular space between the hollow rod and bore hol.e rom t'he 'lowest point. Accordingly, when the hollow rod is placed upw~rdly and vertically lnto the bore hole as sho~n ln 30 Fl~ure 17 it ls preferred to introduce t'he grout through the grout tube 50 that it enters the annular space from the lowest point and not through the hollow tube where the grout would enter the annu'lar space from the highest point. To the contrary, when the hollow rod is inserted Mo-2892 - 6 -3~S7 lnto the bore hole vertical'ly and downwardly to provide support, i.e., the opposite of Figure 1~ it is preferred to introduce the grout through the hollow rod so that the grout enters the annular spaee from the lowest 5 point.
The plate and grout tube may be made of any material which has sufficient burst strength to withstand the grout pumping pressure. However, high strength thermoplastic materials are preferred, 10 especially when the hollow rod and collar are also made of thermoplastic materials.
Grout stop bushing may be used on the hollow rod for the purpose of preventing the pumpable grout from running out the annular space between the bore hole 15 and the hollow rod. The grout stop bushing may be located at any point along the length of the hollow rod, but is generally located near the end of the rod which is closest to the roof plate so that a sufficient portion of the anntllar space is filled with grout to 20 provide consolidation of the rock strata. No particular shape or material is required for the grout stop bushing provided that it preforms its previously described function. The grout stop bushin~ i5 afflxed firmly to the hollow rod to prevent it from moving during instal 25 lation o~ the bolt into the bore hole and pump:lng of the grout. The outsLde diameter of the bushing i'3 genera'Lly larger than t'he diame~er of the hole in orcler to ass,ure a good seal. For ex~mp'le, i~' the bore 'hole has a diameter o 1-3/3 inches, t'he bushing diameter shouLd be 30 about 1-1/2 inches. A preferred bushing i~ made oE a semi-hard rubber and has three (although more or less may be present) 1/8 inch thick bore hole wipes spaced at 1/4 inch intervals. If grout stop bushing is used, it is important that ~he grout tube extend through the 35 grout stop bushing.
Mo-2892 - 7 -In order to install the hollow bolt, a bore hole is initially drilled inko the rock formatlon to be supported to the desired depth. The roof plat~ is then pressed firmly against the formation surface and a hollow bolt is inserted into the bore hole to such a depth that the distant end of the collar contacts the plate. The bolt and plate assembly is held in place by the grout stop bushing. The pumpable grout is then introduced into the annular space through the grout tube when the bolt is lo inserted upwardly or through the hollow bol~ when the bolt is inserted downwardly. Any air or other fluid is forced from the bore hole through the remaining opening.
The grout is pumped in the bore hole until grout appears from the other opening. There are several different types of pumpable grouts including, but not limited to cements and epoxies. The preferred grout is a low viscosity, fast setting, high strength polyurethane (StrataGee* grout available from Mobay~. It is known the prior art to use hollow bolt lengths of greater than about 1 foot, preferably about 1 to 20 ~eet and most preferably about 5 to 15 feet in grouted installations.
As previously discussed, these rods must have sufficient burst strength to withstand the grout pumping pressure.
The rods generally have an outside diameter o~ at leask 3/4 inch, preferably about 1 inch or greater and a hollow cora (inside dlameter) o~ about 1/4 inch.
The prefexred use of thermoplastic, especially fiberglass, hollow bolts offer several major advantages over the use of hollow steel rods. The hollows bolts weight about 1/4 as much as hollow steel bolts of equivalent size, have a greater tensile strength and can be fabricated at a substantially reduced cost. The lighter weight of the hollow fiberglass bolt permits Mo-2892 -8-* Trademark f 9-'~
d~ 7 easier handling and installation, results in reduced transportation C08ts and allows for the use of ~ longer bolt when required.
Although the invention has been described in 5 detail in the foregoing for the purpose o~ illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing rom the spirit and scope of the invention except as it may be 10 limited by the claims.
Mo-2892 - 9 -
Field of the Inven~ion The present invention is directed to a hollow 5 roof bolt to be used in conjunction with pumpable grouting resins to provide support in underground constructions such as in the mining and tunneling industry.
Descrip~ion of the Prior Art In underground operations such as mining or excavation, the unsupported rock formation is stabilized and supported by various methods. In one method, a bore hole is drilled into the rock formation and a me~al bolt is inser~ed into the bore hole. The bolts are secured 15 into the bore hole by the engagement of an expansion shell on the end of the bolt. A roof plate is retained on the other end of the bolt that extends from the bore hole such that the plate abuts the roo~. Rotating the bolt expands the expansion shell to enga~e the rock wall 20 of the bore hole. The bolt is tensioned with the resultant ef~ect o compressing the rock strata between the expansion shell and roof plate, thereby reinforcing the strata to resist ~orces that apply shear stresse~ to the rock formation. Over a perlod of time in soft rock 25 strata, the expanded shell slips in the bore hole, reducing tension and decrea~in~ the amount of roof support provided by the bolt.
Another method of providing roo support i9 by the use of grouted bolts. The bolts, which may be metal 30 or plastic are again inserted into bore holes; however, instead of an expansion shell the bol~s are bonded into the bore hoLe by the use of a two-component resin composition, i.e., either a polyester resin and a catalyst or a two-component polyurethane, which rnay be contained in a cartridge. One or more of the cartridges are positioned in the bore hole and are broken by the insertion of a bolt into the bore hole. The bolt is 5 rotated to mix the components and provide a homog~neous curable resin mixture. The cured resin firmly holds the bolt in position in the bore hole and reinforces the strata.
The quali~y of the cured resin can be reduced 10 by either under rotating the bolt in the bore hole (which does not provide sufficient mixing and leads to a heterogeneous as opposed to a homogeneous resin) or by over rotating the bolt in the bore hole. In either event, the holding strength of the bolt is reduced. In 15 addition, the bore hole could have an undetected void into which the resin can penetrate leaving less resin in the annulus between the bore hole and the bolt, also reducing the holding strength of the bolt. Further, the length of bolt which can be inserted into a bore hole 20 with resin cartridge adhesives is usually limited to less than 10 feet. These difficulties may be overcome by injecting the resin into the annular space between the bore hole and the bolt or by the use of a hollow bolt. Grouted bolts are disclosed in U.S. Patents 25 4,461,600; l~,289,427; 3 9 896,627; ~,526~l~92; 4,501,516;
4,4g7,595; 4,490,074; 4,430,025; ancl 3~797,254.
A third method or provLding roof support is accomplished by combinin~ the use o an expans-Lon shell with a grouted bolt as di.sclosed in U.S. Patents 30 4,140,429; 4,413,930; 4,419,805; and 4,000,623. ~ile adequate roof support may be obtained by the use of such bolts, these bolts are generally complicated in design and thus too expensive for commercial use.
Mo-2892 - 2 -~2~57 It is an object of the present lnven~lo~ to provide an inexpensive, hollow roof bolt which may be adhesively bonded to a bore hole by injecting a grouting resin. In a preferred embodiment of the invention, 5 lightweight bolts made of plastic, preerably fiber-glass, are used. Becau~e of their lightweight nature, these bolts are easy to handle 9 ancl also pro~ide an efficient means for reinforcing rock strata. It is also an object of the present invention to provide an 10 efficient method of holding a roof plate against the surface of the roof through the use of the hollow roof bolt. These objects may be achieved by the hollow roof bolt described in detail hereinafter and entails the use of a collar which is fitted over one end oE said hollow 15 bolt and a hollow plug which is inserted in~o the end of the bolt to expand the end against the inside of the collar.
U.SO Patent 3,797,254 also discloses a method of expanding a hollow tubular reinforcing member;
20 however, these bolts are generally made of metal and rely upon resin cartridges to provide the adhe~ive.
East German Patent 146,362 and German Offenlegungs-schrift 2,145,572 disclose methods o securing plastic rods in ~ransformers either by expanding a hollow ~od or 25 by forming a rod with an expanded end.
SUMMARY OF TSE INVENTION
The pre~ent invention is directed to a hol.low roof bolt based on a) a hollow rod, 30 b) a collar which i~ internally tapered and fitted over one end of the rod and c) a hollow plug located in the end of the rod having the collar, the plug being externally tapered such that it forces the rod to expand and thereby conform to the 35 internal taper of the collar.
Mo-2892 ~ 3 -r~?~
The present invention i9 additionally directed to the rod in combination with a roof plate such that the roof plate fits flush against the distant end o the collar.
BRIEF DESCRIPTION OF THE DR~WINGS
Flgure 1 is a sectional view of a rock formation representing an embodim~nt of the invention showing the roof bolt in a bore ho].e.
Figure 2 is side view of the collar shown in 10 Figure 1.
Figure 3 is a bottom view of the collar shown in Figure 1.
Figure 4 is a sectional view through line 4-4 of Figure 3.
DETAILED DESCR.IPTION OF THE INVENTION
In Figure 1 hollow fiberglass rod 2 ls shown inserted into bore hole 1. An internally tapered collar 3 is positioned over the rod and held in place by an externally tapered hollow plug 4. The collar holds a 20 roof plate 5 against the rock formation. Grout stop bushing 6 i9 used to center the hollow rod in the bore hole and to prevent grout from running out of the annular space between the hollow rod and the sides of the bore hole. A grout tube 7 extends through the roof 25 plate 5 and grout stop bushing 6 to provide a means o~
entry for the grout to fill the annular space between the bore hole and the hollow fiberglass ro~. When grout 1~ injected throu~h the center portion of the hDllow rod, air can escape through grout tube 7.
Figure 2 represents a side vi.ew of collar 3.
The distant end 8 of collar 3 preferably has a hemispherical shape. Collar 3 also has ribs 9 to provide support between the upper hemispherical end of the collar and the bottom portion. The taper from ~he Mo-2892 - 4 -upper to the lower end of collar 3 could be ~olid;
however, the rib-type structure uses signiicantly less material and still provides su~ficient strength and support to the collar. Figure 3 represents a bottom 5 view of the collar 3 showing ribs 9 spaced equidistantly around the collar and the hollow center portion 10.
Figure 4 represents a section view through line aa of Figure 3. Figure 4 shows the internal taper o hollow center position 10 of collar 3.
The components of the present invention include a hollow rod of sufficient strength and length to provide the desired support to the rock formation. The hollow rod may be metal or plastic, preferably plastic and most preferably fiberglass, and should have a 15 tensile strength of greater than 10,000, preferably greater than 16,000 and most preferably greater than 30,000 lbs. Over one end of the hollow rod is fitted an internally tapered collar. The collar is held in place by a hollow externally tapered plug fi~ted into the end 20 of the rod. The hollow tapered plug forces the rod to expand and conform to the internal taper of the collar.
The collar and hollow plug may also be made of either metal or plastic, provided that it has sufficient strength to hold the rock formation in place~ The 25 collar and hollow pLug are preferably made of plastic.
Though the hollow rod, collar and hollow plug may be made of different materials and still be used ln combination, it is preferred that if the rod is nonmetallic~ then the colLar should also be nonmetallic.
The strength of the attached collar mag be lncreased by using an adhesive on the internal taper.
To provide even more strength, it is preferred to insert the hollow plug into the rod in order to expand the hollow rod and then mold the collar directly onto the 35 expanded hollow rod.
Mo-2892 - 5 -The roof plate may also be made o either metal or plastic. Even though it i~ less critical for -the roof plate to be made of the same material as the collar, it is still preferred that the roof plate be S made of the same material as the rod, plug and collar.
The shape and size of -the collar is designed to hold a roof plate against the rock formation. The outer surface of the distant end of the collar, i.e., the part of the collar closest to the bore hole, may be of any 10 shape provided that it fits flush against the corresponding part of the plate. The preferred convex shape for the distant end of the collar and the corresponding concave portion of ~he plate is hemi-spherical. This shape allows the plate to rotat2 on the 15 collar so that it can fit firmly against the rock formation. With other shapes for ~he collar and plate, the plate cannot rotate on the collar and must remain at a fixed angle, generally perpendicular, to the hollow rod.
The plate has a grout tube passing through it such that a pumpable grout can be injected into the annular space between the 'bore hole and the hollow rod.
While it is possible to introduce the grout ei~her through the hollow rod or through the grout tube and to 25 allow air to escape through the other opening, it is preferred to introduce the grout into the a~mular space between the hollow rod and bore hol.e rom t'he 'lowest point. Accordingly, when the hollow rod is placed upw~rdly and vertically lnto the bore hole as sho~n ln 30 Fl~ure 17 it ls preferred to introduce t'he grout through the grout tube 50 that it enters the annular space from the lowest point and not through the hollow tube where the grout would enter the annu'lar space from the highest point. To the contrary, when the hollow rod is inserted Mo-2892 - 6 -3~S7 lnto the bore hole vertical'ly and downwardly to provide support, i.e., the opposite of Figure 1~ it is preferred to introduce the grout through the hollow rod so that the grout enters the annular spaee from the lowest 5 point.
The plate and grout tube may be made of any material which has sufficient burst strength to withstand the grout pumping pressure. However, high strength thermoplastic materials are preferred, 10 especially when the hollow rod and collar are also made of thermoplastic materials.
Grout stop bushing may be used on the hollow rod for the purpose of preventing the pumpable grout from running out the annular space between the bore hole 15 and the hollow rod. The grout stop bushing may be located at any point along the length of the hollow rod, but is generally located near the end of the rod which is closest to the roof plate so that a sufficient portion of the anntllar space is filled with grout to 20 provide consolidation of the rock strata. No particular shape or material is required for the grout stop bushing provided that it preforms its previously described function. The grout stop bushin~ i5 afflxed firmly to the hollow rod to prevent it from moving during instal 25 lation o~ the bolt into the bore hole and pump:lng of the grout. The outsLde diameter of the bushing i'3 genera'Lly larger than t'he diame~er of the hole in orcler to ass,ure a good seal. For ex~mp'le, i~' the bore 'hole has a diameter o 1-3/3 inches, t'he bushing diameter shouLd be 30 about 1-1/2 inches. A preferred bushing i~ made oE a semi-hard rubber and has three (although more or less may be present) 1/8 inch thick bore hole wipes spaced at 1/4 inch intervals. If grout stop bushing is used, it is important that ~he grout tube extend through the 35 grout stop bushing.
Mo-2892 - 7 -In order to install the hollow bolt, a bore hole is initially drilled inko the rock formatlon to be supported to the desired depth. The roof plat~ is then pressed firmly against the formation surface and a hollow bolt is inserted into the bore hole to such a depth that the distant end of the collar contacts the plate. The bolt and plate assembly is held in place by the grout stop bushing. The pumpable grout is then introduced into the annular space through the grout tube when the bolt is lo inserted upwardly or through the hollow bol~ when the bolt is inserted downwardly. Any air or other fluid is forced from the bore hole through the remaining opening.
The grout is pumped in the bore hole until grout appears from the other opening. There are several different types of pumpable grouts including, but not limited to cements and epoxies. The preferred grout is a low viscosity, fast setting, high strength polyurethane (StrataGee* grout available from Mobay~. It is known the prior art to use hollow bolt lengths of greater than about 1 foot, preferably about 1 to 20 ~eet and most preferably about 5 to 15 feet in grouted installations.
As previously discussed, these rods must have sufficient burst strength to withstand the grout pumping pressure.
The rods generally have an outside diameter o~ at leask 3/4 inch, preferably about 1 inch or greater and a hollow cora (inside dlameter) o~ about 1/4 inch.
The prefexred use of thermoplastic, especially fiberglass, hollow bolts offer several major advantages over the use of hollow steel rods. The hollows bolts weight about 1/4 as much as hollow steel bolts of equivalent size, have a greater tensile strength and can be fabricated at a substantially reduced cost. The lighter weight of the hollow fiberglass bolt permits Mo-2892 -8-* Trademark f 9-'~
d~ 7 easier handling and installation, results in reduced transportation C08ts and allows for the use of ~ longer bolt when required.
Although the invention has been described in 5 detail in the foregoing for the purpose o~ illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing rom the spirit and scope of the invention except as it may be 10 limited by the claims.
Mo-2892 - 9 -
Claims (6)
1. A hollow roof bolt comprising a) a hollow rod, b) a collar which is internally tapered and fitted over one end of the rod such that the more narrowly tapered upper end of said collar is farther away from said end of the rod than the more widely tapered lower end of said collar, said upper end of said collar being hemispherical in shape and c a hollow plug in the end of the rod having the collar, the plug being externally tapered such that it forces the rod to expand and thereby conform to the internal taper of the collar, wherein said hollow roof bolt is prepared by inserting said hollow plug into said hollow rod and subsequently molding said collar directly onto the expanded hollow rod.
2. The hollow roof bolt of Claim 1 wherein said hollow rod is made of fiberglass.
3. The hollow roof bolt of Claim 1 wherein said collar and said hollow plug are made of a thermoplastic material.
4. The hollow roof bolt of Claim 2 wherein said collar and said hollow plug are made of a thermoplastic material.
5. The hollow roof bolt of Claim 1 wherein the upper end of said collar is adapted to fit flush against a roof plate.
6. A combination hollow roof bolt and roof plate which comprises the hollow roof bolt a Claim 5 and a roof plate, said roof plate having an opening for said hollow roof bolt and also an area around said opening Mo-2892 -10-which conforms to the hemispherical shape of the upper end of said collar.
Mo-2892 -11
Mo-2892 -11
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93958186A | 1986-12-09 | 1986-12-09 | |
| US939,581 | 1986-12-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1294157C true CA1294157C (en) | 1992-01-14 |
Family
ID=25473406
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000549972A Expired - Fee Related CA1294157C (en) | 1986-12-09 | 1987-10-22 | Hollow fiber glass roof bolt |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1294157C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2018101679B4 (en) * | 2017-12-14 | 2019-06-13 | DSI Underground Australia Pty Limited | Rock bolt assembly |
| CN111075487A (en) * | 2019-12-31 | 2020-04-28 | 西南石油大学 | Anchor rod with function of measuring surrounding rock strain and temperature coupling |
-
1987
- 1987-10-22 CA CA000549972A patent/CA1294157C/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU2018101679B4 (en) * | 2017-12-14 | 2019-06-13 | DSI Underground Australia Pty Limited | Rock bolt assembly |
| CN111075487A (en) * | 2019-12-31 | 2020-04-28 | 西南石油大学 | Anchor rod with function of measuring surrounding rock strain and temperature coupling |
| CN111075487B (en) * | 2019-12-31 | 2024-05-24 | 西南石油大学 | Anchor rod with function of measuring surrounding rock strain and temperature coupling |
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