US 3702060 A
A resin reinforced anchor for a rock bolt consists of an expansion shell of a known type modified to mount a resin container. The resin container carries a resin and a hardener-containing capsule therein in such a way that actuation of the expansion shell breaks the hardener-containing capsule, mixes its contents and the contents of the container, and releases the mixed contents, to adhere the expansion shell to the sides of a drill hole.
Claims available in
Description (OCR text may contain errors)
United States Patent Cumming [451 Nov. 7, 1972 [541 RESIN-BONDED EXPANSION SHELL  Inventor: James Deans Cumming, Havelock,
Ontario, Canada  Filed: Feb. 25, 1971  Appl. No.: 118,843
 US. Cl. .,.61/45 B, 52/98, 52/741  Int. Cl. ..E21d 20/02  Field of Search.....61/45 B, 63; 52/98, 698, 704, 52/741, 744; 85/63, 65, 72, 79
 References Cited UNITED STATES PATENTS 2,829,502 4/1958 Dempsey ..61/45 B 2,952,129 9/1960 Dempsey ..61/45 B 3,298,144 1/1967 Fischer ..52/98 3,308,585 3/1967 Fischer ..61/45 B X 3,108,443 10/1963 Schuermann et al ....52/741 X FOREIGN PATENTS OR APPLICATIONS 1,268,624 6/1961 France ..6l/45B 1,245,292 7/1967 Germany ..6l/4SB Primary Examiner-Dennis L. Taylor Attorney-Maybee and Legris [5 7 ABSTRACT A resin reinforced anchor for a rock bolt consists of an expansion shell of a known type modified to mount a resin container. The resin container carries a resin and a hardener-containing capsule therein in such a way that actuation of the expansion shell breaks the hardener-containing capsule, mixes its contents and the contents of the container, and releases the mixed contents, to adhere the expansion shell to the sides of a drill hole.
14 Claims, 12 Drawing Figures PAIENTEDnuv 1 1912 3.702.060
sum 1 or 4 INVENTOR JAMES D. CUMMING ATTORNEYS PMENIEDunv 1 I972 SHEET 2 BF Q LVVEN'IOR.
JAMES D. CUMMING BY. fad
ATTORNEYS PATENTED V 7 7 sum 3 0F '4 FIG. 8
IN V EN TOR. JAMES D. CUMMING BY% ATTORNEYS PATENTEDuuv' 11912 SHEET '4 [IF 4 1x \/E.-\' TOR JAMES 0. CUMMING BY I ATTORNEYS RESIN-BONDED EXPANSION SHELL BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to rock bolt assemblies and more particularly to an expansion shell assembly which enables an expansion, securing a rock bolt, shell to be securely bonded or adhered in place by a suitable grout or adhesive.
2. Description of the Prior Art 'The prior art describes several ways in which to enhance the gripping, stabilizing and reinforcing effects of a rock bolt set and tensioned in a drill hole passing through unstable rock strata. For example, it has been known to pump a cementitious grout material into a drill hole after a rock bolt has been inserted either before or after the bolt has been tightened to the desired tension. This practice tends to bond the entire length of the bolt to the rock strata through which it passes and provides for a strong and usually stable installation. The practice suffers from the disadvantage that pumps, hoses, grout supplies and fittings must be carried. to the site of each rock bolt, usually in a mine, and, therefore, under difficult conditions, connected to the rock bolt and the pump operated. Further, grout of this kind frequently requires setting times of several hours. These factors tend to make this type of rock bolt reinforcement time consuming and, hence, very expensive.
In other cases, while there is no need to fill the entire drill hole with a grout or other reinforcing material, the nature of the rock strata, at the expansion shell and which the expansion shell is required to grip, may be such that it must itself be reinforced in order to support the expansion shell. Other forms of rock strata may be such that air must be excluded to prevent deterioration of the rock upon exposure, thus eventually weakening it and releasing or partly releasing any expansion shell which has been embedded therein.
It is with this latter form of expansion shell bonding that the present invention is concerned. That is to say, the present invention is concerned with the local reinforcement of rock strata adjacent an expansion shell and with the bonding of the expansion shell thereto rather than to the form of reinforcement which requires that the entire drill hole he filled with a cementitious grout or the like.
Typical of one form of prior an expansion shell assembly for a rock bolt in which local reinforcement of the rock strata adjacent the expansion shell is employed is disclosed in the Dempsey US. Pat. No. 2,829,502 of Apr. 5, 1958. In this patent a more or less typical rock bolt and expansion shell is provided with a capsule which is simply placed upon the end of the expansion shell which is to be inserted in the drill hole and moved upwardly into the drill hole, resting upon that end of the expansion shell. A string or wire is secured to the capsule and when it is desired to release the bonding material carried within the capsule, the string is pulled thereby rupturing the capsule and permitting the contents to escape, flowing downwardly around the expansion shell where it may set in order to bond the expansion shell to the adjacent rock wall of the drill hole. This construction has two significant disadvantages. First, the capsule is simply rested upon the end of the expansion shell and must be carefully introduced into the drill hole by balancing it upon the end of the expansion shell until both the capsule and the expansion shell have been inserted in the drill hole. It will be appreciated that this can be a delicate operation in the dark confines of a mine where the operation must be performed overhead in rather cramped conditions. Secondly, the capsule can be ruptured only by pulling upon the trailing string or wire which extends from the capsule along the rock bolt leaving an exposed end once the rock bolt has been set in position. If the string should break, if it should become snagged or caught upon the rough walls of the drill hole or if it should become tangled during insertion so that an exposed end is not available, the installation cannot be completed and the bolt must be withdrawn, a new capsule substituted and an attempt made again. Clearly, for mine operations where working conditions are difficult, the device typified by the above mentioned Dempsey patent is less than completely satisfactory.
Another form of construction for a similar purpose is that disclosed in the Demsey US. Pat. No. 2,952,129 of Sept. 13, 1960. This patent discloses an apparatus which eliminates the need for the trailing string or wire but which requires that the capsule or cannister containing the bonding material be of a frangible substance such as glass which can be broken by ramming it against the blind end of the drill hole when the rock bolt is inserted therein. The disadvantage of this construction is, of course, that the length of the drill hole must be rather nicely calculated with reference to the length of the rock bolt so that it is short enough that the capsule can be broken in this manner and yet long enough that the rock bolt may be fully inserted before encountering the blind end of the hole. Further, the use of frangible containers of the kind contemplated by this patent increases the risk of breakage of these containers, accidentally, in handling and installation.
SUMMARY OF THE INVENTION The present invention seeks to provide an expansion shell which may be bonded and reinforced in its installed position by a bonding composition which may be carried to the appropriate position, securely fixed upon the end of the expansion shell, protected against accidental breakage and arranged for automatic opening upon the tightening of the rock bolt into its desired condition of final tension. The present invention does not rely upon the pulling of any trailing strings nor of the breaking of the cannister against the blind end of the drill hole, indeed, the bonding agent capsule may be broken and activated at any point in the drill hole as conditions may require.
DESCRIPTION OF THE DRAWINGS The invention will be illustrated in conjunction with the accompanying drawings in which like reference numerals denote like parts in the various views and in which:
FIG. 1 is an axial section through a drill hole, showing an expansion shell embodying the said invention installed therein, a portion of the expansion shell being shown in longitudinal section;
FIG. 2 is a view similar to FIG. 1 with the rock bolt partly tightened;
FIG. 3 is a view similar to FIGS. 1 and 2 showing the expansion shell in its fully tightened position;
FIG. 4 is a section view taken along line 4-4 of FIG.
FIG. 5 is an exploded fragmentary view showing a portion of the expansion shell assembly;
FIG. 6 is a view similar to FIGS. 1 and 2 showing the expansion shell and rock bolt in its fully tightened position and illustrating an additional feature of the invention;
FIG. 7 is a fragmentary view of a modified form of bonding material cannister;
FIG. 8 is a view similar to FIG. 1 showing an alternative form of the invention;
FIG. 9 is a view of the device of FIG. 8 in a partly tightened condition;
FIG. 10 is a view similar to FIGS. 8 and 9 showing the expansion shell in a fully tightened position;
. FIG. 11 is an exploded view of the expansion shell of FIGS. 8, 9 and 10, and
FIG. 12 is a section view along line 12-12 of FIG. 11 with the components of FIG. 11 in their assembled condition.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the embodiments illustrated in FIGS. 1 to 7 inclusive, FIGS. 1, 2, 3 and 6 illustrate a blind drill hole 10 formed in rock which it is desired to support and reinforce by means of the rock bolting assemblies illustrated. Typically, the rock within which the drill hole 10 will be formed will be stratified in nature but the drawings have made no attempt to illustrate this.
A rock bolt 11, typically between 3 feet and 8 feet in length carries an expansion shell generally indicated at 12 adjacent that end which is inserted in the blind hole. The rock bolt 11 is threaded at 13 and this end is threadably engaged with the internal threads 14 carried in the axial bore of a wedge-shaped expander member 15 illustrated in FIG. 5.
Associated with the expander member 15 of the expansion shell are a pair of opposed rock engaging members 16 which are supported by a generally U-shaped bail 17.
The end of the rock bolt 11 remote from the expansion shell 12 is also threaded over a short axial distance at 18 and this threaded portion 18 carries a threadably engaged nut 19 lying adjacent an integrally formed, non-circular head 20 formed on that end of the bolt remote from the expansion shell 12. Also surrounding the rock bolt 11 adjacent the non-circular head 20 and the nut 18 is a domed, resiliently deformable washer 21 which is adapted to bear upon the rock face 22 surround the drill hole 10. The assembly so far described is substantially conventional and operates in a conventional manner. In order to insert and secure the rock bolt and its expansion shell within the drill hole 10, the rock engaging member 16 are, first, bent outwardly away from the expander member 15 as shown in FIG. 1 so that the lower skirt portions 16a of the rock engaging member 16 will resiliently engage the drill hole and drag along the sides thereof as the bolt is inserted therein. When the bolt has been substantially fully inserted, a slight pull on the rock bolt in a direction to withdraw it from the hole will drive the wedge 15 between the rock engaging member 16, will cause the rock engaging serrated surfaces to move parallel to the sides of the drill hole and will set the expansion shell in position. A hand or power operated wrench is then applied to the non-circular head 20 of the bolt 11 and the entire bolt 11 is rotated within the now stationarily held expander member 15 thereby drawing it downwardly between the rock engaging member 16 to move firmly seat them and engage them with the wall of the drill hole 10. In conventional rock bolt assemblies, the operation of installing such an assembly is complete when the bolt 11 has been rotated to tighten it to the desired tension.
However, as was explained earlier, some rock conditions require that the expansion shell be more securely bonded to the drill hole than can be achieved by the simple expansion of the shell as described above.
The present invention provides for this bonding as follows.
The end of the expander member 15 remote from the non-circular head 20 on the rock bolt 11 is provided with an axially extending collar 23. Secured to this collar 23 by means such as screw threads (as seen in FIG. 1) or by means of a bayonet joint (as shown at 24 in FIG. 5) is a container 25 within which is contained a curable resin compound. The container 25 may be of plastic or thin sheet metal and is formed, at its lower end 26 with either internal screw threads or internal bayonet lugs to engage the collar 23 of the expander member 15 in order that it may be mounted in the position shown in FIG. 1. The end of the container 25 which is secured to the axially extending collar 23 is sealed by a frangible sealing disc 27. Within the container 25 is a frangible capsule 28 containing a curative (accelerator or catalyst) for the curable resin compound which is within the container 25. The capsule 28 is closed at its upper end by a cap 29 and conveniently is made of plastic or glass having a thinner lower portion 29 as distinct from a thicker wall portion 30 so as to ensure its ready breakage as the tightening of the shell proceeds.
Referring to FIG. 1, it can readily be seen that the initial setting of the expander member and the rock engaging members by the slight downward pull on the rock bolt 11 can be achieved with the container 25 and its contents securely mounted upon the collar 23 of the expander member 15. The position of the container 25 is protected during handling and installation of the assembly by the bail 17 which extends upwardly to partially enclose it and protect it from accidental disengagement with the expander member 15. Further, by reason of its attachment to the expander member 15 by screw threads or a bayonet joint, cartons of containers 25 may be carried underground in a mine with protective packaging and then readily assembled on expansion shells as needed without the use of tools.
Turning now to FIG. 2, an intermediate stage in the tightening of the expansion shell is illustrated. As can be seen in FIG. 2, the expander member 15 has been drawn downwardly between the rock engaging element 16 by rotation of the bolt 11 as a result of the applica tion of a hand or powered wrench to the non-circular vhead 20. The rotation of the bolt 11 within the expansion member 15 has resulted, as seen in FIG. 2, in the end 11a of the bolt 1 1 having passed axially through the expander member to first engage and then break the frangible sealing disc 27, fragments of which are shown in FIG. 2 at 27a. Further, the continued axial movement of the end 11a of the bolt 11 through the expander member and into the container has, as illustrated in FIG. 2, resulted in the breakage of the frangible capsule 28, fragments of which are shown at 28a in FIG. 2. The result of this breakage of the frangible capsule and the rotation of the end 11a of the bolt 11 within the container 25 is that the curable resin compound and the curative therefor have been exposed to one another and have been mixed by the turning action of the bolt 1 1 within the container 25.
Turning now to FIG. 3, it can be seen that the continued rotation of the bolt 11 has further advanced the end 11a of the bolt 11 into the container 25 with the result that the end 11a of the bolt 11 has engaged inwardly extending dimples 31 which are provided at circumferentially spaced points around the periphery of the container 25. The engagement of the end 1 la of the bolt 1 1 with these dimples 31 has had the effect of forcing the container 25 off the collar 23 of the expander member 15.with the result that the mixed contents of the container and the frangiblecapsule are now permitted to flow downwardly as indicated by arrows 32. This downward flow of the material within the container 25 is arrested by a resilient foam or plastic gasket or a washer 33 so as to confine the presence of this material to the area immediately around the expansion shell 12 where it will reinforce the local rock strata, and bond the expansion shell thereto.
Turning back to FIG. 1, it is to be noted that both the container 25 and the frangible capsule 28 are provided with air spaces 34 and respectively. In other words, the contents of neither the container 25 nor the frangible capsule 28 completely fill these containers.
As is well known in the art, curable resin compositions and hardeners, accelerators, catalysts or curatives therefor can be chemically compounded in such a way that almost any form of reaction which is desired can be obtained. It is desirable, in the context of the present invention, that these substances be so chosen that their mixture initiates an exothermic reaction which will cause a temperature rise in the air within the spaces 34 and 35 respectively. In the first stage, as illustrated in FIG. 2, the heated air within the space 35 in the frangible capsule 28 will result in the expulsion of the curative contained within the frangible capsule 28 into the main body of the container 25 thereby promoting the intimate mixing of the two components. This mixing will increase the exothermic reaction which will further raise the temperature of the air trapped within the space 34 with the result that, when as shown in FIG. 3, the container 25 is lifted off the collar 23, substantially all of the contents of the container 25 will be expelled therefrom into the area of the expansion shell 12.
Turning now' to FIG. 4, the assemblies of FIGS. 1 to 3 is illustrated in the finally tightened position with the cured and hardened resin compound substantially surrounding and embedding the expansion shell 12. The cured resincompound is illustrated at reference numeral 36.
I As will be apparent from the description of the function of the apparatus in FIGS. 1 to 3, bolt 11 has been rotated so as to impose a tension thereon. The beginning of this can be seen in FIG. 2. In FIG. ll, the
domed, resiliently deformable washer is shown in the position which it occupies when the bolt 11 is under little or no tension at all. In this Figure the nut 19 is shown as being engaged with threads 18 and in a position immediately adjacent the non-circular head 20 of the bolt 11. Rotation of the bolt 11 from the condition of FIG. 1 to the condition of FIG. 2 has imposed a tension upon the bolt 11 and has caused the washer 21 to resiliently deform towards a flattened condition as illustrated in this FIGURE. Continued rotation of the bolt 11 to produce the effect of FIG. 3 will further flatten the washer 21 but the washer will not become completely seated upon the face 22 of the rock within which the drill hole 10 has been formed even after the condition of FIG. 3 has been achieved. I-Iowever, rotation of the bolt 11 will continue until it has reached, perhaps percent, of the tension which it is intended to sustain. Once the curable resin compound has fully hardened and set as illustrated in FIG. 6, (a period which may range from a few minutes to an hour or so) the nut 19 is then rotated upon the threads 18 in order to impart additional tension to the bolt 11 and to bring the resiliently deformable washer 21 to its final, fully flattened position as shown in FIG. 6.
This aspect of the rock bolting assembly illustrated in FIGS. 1 to 7 inclusive is a most important aspect of the invention. In the prior rock bolting assemblies making use of expansion shells within which the bolt rotates to set and engage the expansion shell, the use of grouts, curable resin compounds and the like rendered the bolt immovable once the curing had taken place. In other words, once the tightening operation was complete and the bonding or grouting compound had set, further rotation of the bolt was impossible because the bolt could no longer be rotated within the cured material surrounding the expansion shell. By means of the second nut 19 associated with the non-circular head 20 of the bolt 11, this defect is completely overcome. As can be seen in FIG. 6, even after the cured compound 36 has rendered further rotation of the bolt impossible, the tension of the bolt 11 can be increased or decreased by simply tightening or slackening the nut 19. This makes it possible, periodically, to adjust the tension of the bolt 11 as conditions in the rock strata may require.
While the embodiment of the invention which has been described herein contemplates that the container 25 will be lifted off the collar 23 towards the end of the tightening operation of the bolt 11, it may sometimes occur that the rock strata adjacent the expansion shell are so hard that it is not possible to advance the bolt 11 through the expander member 15 for an axial extent sufficient for the end 11a of the bolt 11 to engage the detents 31 which provide the lifting force to disengage the container from the collar 23. In this event, the construction illustrated in FIG. 7 may be adopted.
The modified container 25a of FIG. 7 is identical to the container 25 of FIGS. 1 to 3 in every respect except that it is provided with an insert ring 37 lying beneath the inwardly projecting dimples or lugs 31a. The ring 37 is provided with a central axial aperture 38 and its sole function is to have the effect of positioning the dimples or lugs 31a closer to the end of the collar 23 of the expander member 15 so that the bolt 11 will not need to travel the same axial extent before engaging the ring 37 thereby lifting the container 250: off the collar 23 by means of which it is mounted upon the expander member 15.
Turning now to FIGS. 8 to 12 inclusive, an expansion shell of similar function is disclosed and which is adapted to be used in association with an expansion shell which is actuated by a nut on that end remote from the expansion shell rotating on bolt 11 without requiring that the bolt 111 rotate within the expander member 115.
Turning first to FIG. 11, the bolt 111 may be seen to be provided with a threaded portion 113 which engages internal threads 114 on a wedge-shaped expander member 115. The expander member 115 is provided with four wedge-shaped surfaces which are adapted to engage four rock engaging elements 116 integrally formed on collar 116a. The expander member 115 is provided with a U-shaped bail 117 which extends around and secures a container 125 within which is a frangible capsule 128. The end of the container 125 adjacent the expander member 115 is closed by a frangible sealing disc 127.
Turning now to FIG. 8, it can be seen that the container 125, secured to the expander member 115 by the bail 117 is provided with a downwardly extending cylindrical skirt 150 which surroundsand encloses the upper ends 11612 of the four rock engaging members 116.
As the nut (not shown) on the threaded end of bolt 111 is tightened against a washer (similar to washer 21 of FIGS. 1, 2 and 3) bearing against the rock face within which the drill hole 110 has been formed, the expander member will be drawn downwardly into the expansion shell thereby radially expanding the rock engaging members 116 into firm engagement with the wall of the drill hole 110.
It will be'remembered that the bail 117 secures the container 125 to the expander member and, accordingly, the expander member will draw the container 125 down into telescoping engagement over and around the four rock engaging members 116.
As this happens, the result will be as illustrated in FIG. 9. The frangible sealing disc 127 will be driven upwardly into the container 125 by the upper ends 116b of the rock engaging members 116 and will, as its first act, break the frangible capsule 128 within the container 125. Continued downward movement of the expander member 115, carrying with it the container 125 will cause the breakage of the frangible seal 127 with the result that the mixed contents of the frangible capsule 128 and the container 125 will be permitted to flow downwardly as indicated by arrows 132 to surround and bondthe local rock strata to the expansion shell. The downward flow of the material is arrested by the foam or plastic washer 133 (see FIG. 8) in the same manner as has been described with reference to the embodiment of FIGS. 1 to 7 inclusive.
Since, in the embodiment of FIGS. 8 to 12 inclusive, the expansion shell is tightened and set within the drill hole 110 by the rotation of a nut on a threaded, free, exposed end of the rock bolt 111, there is no need to provide the post tightening nut corresponding to nut 19 of FIGS. 1, 2 and 6. The resin bonded expansion shell will remain fixed in the drill hole and the tension in bolt 111 may be adjusted by rotating the tightening nut in the appropriate direction in a manner which is well understood in the art.
In the embodiment of FIGS. 8 to 12 inclusive it will be noted that both the container and the frangible capsule 128 are provided with air spaces 134 and 135 respectively to provide an expanding air propulsion system actuated by the exothermic reaction of the mixture of the contents of the container and the frangible capsule respectively to expel substantially all of the contents of the container 125 when the frangible seal 127 is broken as illustrated in FIG. 10.
As will be apparent from the foregoing description, the invention provides for an expansion shell having a self activating grouting or bonding container associated therewith which suffers from none of the disadvantages which have been discussed with respect to the prior art. Further, the invention provides for such a bonding or grouting capsule to be associated with an expansion shell which may be used in association with either of the two most commonly used alternative expansion shells. The first, being that disclosed in FIGS. 1 to 7 inclusive, makes use of an expansion shell which is activated by rotating the entire rock bolt by means of a non-circular head formed on the end of the bolt which is exposed from the drill hole.
The second embodiment illustrated in FIGS. 8 to 12 inclusive employs an expansion shell which is actuated by axially drawing the bolt and the expander member threaded thereon downwardly to the expansion shell by means of a nut threaded upon a threaded end of the rock bolt which extends from the drill hole so that the nut, through the medium of an appropriate washer, may bear uponthe rock space surrounding the drill holeand impart an appropriate tension to the rock bolt.
Further, in the case of the embodiment of FIGS. 1 to 7 inclusive, a second tightening or tensioning arrangement is provided by means of the auxiliary nut 19 which allows for post hardening adjustment of bolt tension in a manner which has not heretofore been possible with a rock bolting assembly of this kind embodying a grouted or bonded expansion shell.
Both embodiments of the present invention have been described herein for illustrative purposes and modifications are contemplated within the scope of the invention and the appended claims.
What I claim is:
1. An expansion shell for a rock bolt adapted to be inserted into a blind hole comprising:
a. at least two opposed rock engaging members;
b. an expander member lying between said at least two rock engaging members;
c. a container secured to that end of the expansion shell adjacent the blind end of the hole;
d. a curable resin compound in the container;
e. frangible means sealing the end of the container adjacent the expansion shell;
f. a frangible capsule in the container;
g. a curative for said curable resin compound in the frangible capsule;
h. and means to cause relative movement between two of i. the rock bolt ii. the rock engaging members and iii. the expander member thereby to break the frangible seal and the capsule thus permitting the curable resin compound and the curative therefor to mix and to escape from the container so as to adhere the expansion shell to the surrounding wall of the blind hole.
2. An expansion shell for a rock bolt as claimed in claim 1 wherein the container is secured to the expander member by means of a Ushaped bail enclosing the container within the bight of the U, the free ends of the U-shaped bail being secured to the expander member.
3. An expansion shell for a rock bolt as claimed in claim 2 wherein the relative movement is between the expander member and the rock engaging members.
4. An expansion shell for a rock bolt comprising a. at least two opposed rock-engaging members;
b. an expander member lying between said at least two rock-engaging members;
c. a container secured to an end of said expander member;
d. frangible means sealing the end of the container adjacent theexpander member;
e. a curable resin compound in the container;
f. a frangible capsule in the container;
g. a curative for said curable resin compound in the frangible capsule;
h. and means to advance axially through the expander member and, in sequence,
- i. break the frangible means sealing the end of the container,
ii. break the frangible capsule within the container,
iii. stir the contents of the container and capsule to mix them together, and
iv. disengage the container from the expander member to allow the mixed contents to escape.
5. An expansion shell for a rock bolt as claimed in claim 4 wherein the means to advance axially through the expander member is a rock bolt threadably engaged with an axially threaded aperture in the expander member.
6. An expansion shell for a rock bolt as claimed in claim 4 wherein the container, including its frangible sealing means and its contents are removably secured to the expander member.
7. An expansion shell for a rock bolt as claimed in claim 6 wherein the container is removably secured to the expander member by a bayonet joint.
8. An expansion shell for a rock bolt as claimed in claim 6 wherein the container is removably secured to the expander member by a threaded joint.
9. An expansion shell for a rock bolt as claimed in claim 4 wherein the container has at least two inwardly projecting portions which are engaged by the means to advance axially through the expander member after said means has broken the frangible seal on the container, broken the frangible capsule and mixed the contents of the container and capsule together in order to disengage the container from the expander member and release the mixed contents thereof.
10. An expansion shell for a rock bolt as claimed in claim 4 wherein a protective yoke of U-shaped configuration is provided, one leg of the yoke being secured to each rock engaging member and extending over the end of the container to offer it protection and guard against accidental displacement thereof.
11. An expansion shell for a rock bolt as claimed in claim 1 wherein a. the container contains an air space;
b. the capsule contains an air space, and
c. the curable resin compound and the curative therefor are selected to p ovide an exothermic reaction upon mixing so t at the air in the air spaces is heated to expand and force substantially all of the mixed contents from the container when it is disengaged from the expander member.
12. A rock-bolting assembly comprising a. a rock bolt having a first threaded end adapted to be inserted in a drill hole in a rock formation and a second threaded end adapted to project therefrom; b. a non-circular head formed on the second end;
c. a nut threaded on said bolt and lying in juxtaposition to said non-circular head;
. a washer surrounding the bolt and adapted to bear on the surface of the rock formation surrounding the drill hole;
e. and an expansion shell carried by said first threaded end of the bolt, said expansion shell carrying means to release a mixture of a curable resin compound and a curative therefor when said rock bolt assembly has been substantially but not entirely fully tightened in the drill hole.
13. A rock-bolting assembly as claimed in claim 12 including a resilient, deformable washer surrounding the bolt adjacent the expansion shell and in sealing engagement therewith and adapted to lie in sealing engagement with the wall of the drill hole.
14. A rock-bolting assembly as claimed in claim 13 wherein the resilient deformable washer is of a plastic material.