Truss systems, components and methods for trussing arched mine roofs

A truss structure, components, and method for trussing arched roofs in mines and the like. The truss structure includes, in addition to specially designed brackets and tensioned elongate connectors, one or more medially positioned upstanding post brackets for upwardly abuting against central portions of an arched mine roof. The method and concept includes, in a preferred form, applying obtuse-angle-oriented elongate connectors such as tie rods, secured to a lower portion of a post bracket concerned such that, when said elongate connectors are tensioned, an upward thrust is applied to said post brackets, whereby to produce an increased compression zone in the roof rock above the arched roof. Like-constructed interlocking roof truss structures are also provided for both longitudinally and also tranversely trussing an arched mine roof.

FIELD OF INVENTION 
The present invention relates to truss systems, components thereof, and 
methods for supporting and retaining rock formations as are found in 
hardrock mines, underground caverns, storage vaults, passageways, and so 
forth. Problems are experienced currently, especially in hardrock mines, 
relative to appropriate trussing of arched mine roofs. The structure and 
methods of the present invention take cognisance of this and supply useful 
trussing structures and methods, and also a post-bracket design wherein 
trussing can be completed in a horizontal tensioning mode, or even in an 
obtuse angle mode, pointing downwardly, such that tensioning of the truss 
actually increases the compressiive force of the post-bracket of the truss 
against a chosen undersurface of the mine roof. 
DESCRIPTION OF PRIOR ART 
Certain prior art is currently known in connection with truss systems for 
mines, for example. Such prior art consists of the following: 
______________________________________ 
U.S. Pat. Nos. 
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1,686,910 4,596,496 
3,427,811 4,630,974 
3,505,824 4,632,605 
4,349,300 4,666,344 
4,395,161 4,699,547 
4,498,816 4,776,729 
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Foreign Patent Documents 
______________________________________ 
405/288 United Kingdom 
______________________________________ 
Bureau of Mines Publication "Evaluation of Roof Trusses, Phase I", prepared 
for United States Deptartment of Interior, Bureau of Mines, by Department 
of Civil Engineering, University of Pittsburg, summary report on U.S.D.M., 
grant No. G0166088, Feb. 28, 1979. 
BRIEF DESCRIPTION OF INVENTION 
Each of the above patents and the publication listed relate in general to 
the present invention in the provision of roof trusses and the manner of 
their securement to rock formations; none of the above cited art, however, 
teach the unique concept and structures as provided herein whereby, in 
such truss structure, method and components, there is provided a means for 
applying and even augmenting compressive force of a post bracket to a 
central or other area of a mine roof. Additionally, none of the prior art 
teaches the various ways of interlocking the system for arched roofs so as 
to maximize integrity of the trussing structure and its effectiveness of 
producing the function desired. At the outset, it is to be observed that 
the truss structure herein, the brackets, bracket combination, elongate 
members, post brackets, and so on, can be employed to support rock 
formations as in hardrock mines, and likewise can be used to support, in 
general, arched mine roofs, underground caves, tunnels, storage vaults, 
toxic waste repositories, underground power stations, caverns, and so 
forth. The principal usage of the methods, trusses and components as set 
forth herein is for supporting arched roofs as are found in igneous and 
metamorphic formations. 
As to unique elements herein, the same include suitably designed end 
brackets and post brackets which are elongated appropriately so that the 
over-all trussing structure by way of the tie rods and/or elongate members 
connecting the various brackets can be in a horizontal plane or, even more 
effectively, arranged in an obtuse-angular disposition whereby tightening 
will tend to increase angle toward the horizontal (approximately 180 
degrees) and thereby provide a thrusting effect upon the post bracket 
against the underside of the mine roof. In this way the concavity of the 
arched roof can be provided for in a very convenient manner. 
The invention is extended not only as to singular transverse trusses, but 
also as to trussing systems which proceed along a substantial length, 
longitudinally, of the mine roof. 
In sum, the tensioning of the angulated anchor bolts and the vertical rock 
bolts, and the intercoupling of the end brackets with the central bracket 
member, effects a compression-stressed zone above the roof contour, making 
such zone less likely to slough off. This is created through vector forces 
at the distal ends of the rock bolts and their orientation toward the 
force vectors of the end bracket proceeding essentially in a direction 
toward the distal ends of such rock bolts. Moreover, such compressive zone 
is greatly enhanced in integrity and force field through the inclusion of 
post brackets which can be further urged upwardly by virtue of the 
obtuse-angle orientation of end connectors which are tightened or 
tensioned to produce an upward force vector against the post brackets 
utilized. 
OBJECTS 
Accordingly, a principal object of the invention is to provide a new and 
improved truss for mine openings having arched roofs. 
A further objected is to provide improved end brackets for mounting 
apertures in mine roofs whereby to maintain the positional integrity of 
such brackets. 
A further object of the invention is to provide centrally located post 
brackets in tensioning systems for supporting raised areas of an arched 
mine roof. 
An additional object is to provide methods for supporting arched roofs in 
mines.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
In FIG. 1 the mine opening 10 has a mine floor 11, ribs 12 and 13, and mine 
roof 14, which is overlaid by roof rock 15. It is noted that the mine roof 
14 is upwardly arched, i.e. downwardly convex, as is commonly associated 
with rock material such as igneous or metamorphic rock, which are 
encountered in conventional hardrock mining. The trussing structure 16 
includes a pair of end brackets 17 that are secured to opposite transverse 
extremities of the mine roof by means of respective anchor bolts 27 with 
their conventional epoxied ends, end fittings, and so forth, at 20 and 21. 
The mounting of the anchor bolts and the associated structure proximate the 
extremities at 20 and 21 is strictly conventional. 
End bracket 17 should now be described, see FIGS. 2-5. As is seen, each of 
the end brackets 17 includes a bearing plate 18 and a depending flange 19 
welded or integral therewith. Flange 19 has a through-aperture 20 for 
receiving the end 21 of elongate connector 22. Elongate connector 22 may 
be tensioned by the inclusion of nut 23, having conventional spherical 
head 24 seated into the left-hand portion of aperture 20. An angular plate 
25 is welded or otherwise secured to the lower portion of depending flange 
19 and a bottom portion of bearing plate 18, the same including aperture 
26 for the receipt of the lower portion of anchor bolt 27. Anchor bolt 27 
may likewise be provided with a tensioning nut 28, having a spherical 
portion 29 seated into the lower region of aperture 26. Angular plate 25 
may be reinforced by gusset portions 31 and 32, which are welded at 33 and 
34 to the remainder of the structure. 
Of special importance is the inclusion of an angulated aperture 35 through 
bearing plate 18 in which is received we seize the anchor bolt 27 in the 
manner indicated. 
Integral with upper surface 36 of bearing plate 18 is a tubular insert 37, 
the latter being cut on the bias and welded at 38 to upper surface 36. It 
is seen relative to FIG. 4 that, in the usual case, the depending flange 
19 will be provided with a pair of apertures 20 for accommodating the 
passage there-through of a pair of elongate connectors 22. 
Post bracket 38 in FIGS. 1 and 6 comprises an elongate, hollow post member 
39, a bearing plate 40 secured thereto and provided with central aperture 
41, and a securement portion 42, welded or otherwise secured at 43 to the 
lower extremity of post member 39. 
Securement portion 42 includes an upper plate 43' and, depending therefrom, 
a series of welded or otherwise connected side flanges 44, 45, 46, and 47. 
Each of these side flanges will be provided with a series of apertures 48 
for reception of tie rods or other suitable elongate connection members. 
In installation, bearing plate 40 abuts and thrusts against the upper 
central surface of the arched roof 14. As a practical matter, in 
installation, the anchor bolt and rock bolt apertures are drilled at A, B, 
C, and D, for example, and then the end brackets 17 are installed as 
indicated once the anchor bolts are in place and in secured condition. As 
to rock bolts 49, these are thrust home into drilled holes B and C, and 
suitable end fittings and/or epoxy are supplied for securing the upper 
extremities of these rock bolts in place. Subsequently, the post bracket 
is mounted over the rock bolt 49 and nut 50 is tightened down so as to 
place the post bracket in compression against the upper roof surface and, 
of course, the rock bolt itself in tension. The same will likewise occur 
at the hole or aperture C relative to rock bolt 49. The elongate 
connector, customarily referred to as elongate connector 22, can take the 
form shown at 22A in FIG. 1, where there is provided a segmented 
construction. In such event, the post bracket takes a form 38A, with the 
sole differences relative to post bracket 38 being that the post member is 
of reduced length; also, it is noted that the securement portion 42A this 
time includes a base flange 43 and simply a pair of depending flanges 44 
and 45 secured thereto, each of such flanges being provided with 
appropriate apertures. Accordingly, a pair of tie rods may be used, two 
sets of tie rods as the case may be, for securing the securement portion 
of the central post bracket 38 ultimately to the right-hand end bracket 
17. In such event, nuts 43" will be used at the innermost ends of the tie 
rods 46 and 47. The structure thus indicates that the elongate connector 
or connectors may comprise simply one or more tie rods which span 
completely the space between the securement portion of the central post 
bracket and the end bracket as, for example, the left end bracket 17 as 
seen in FIG. 1; or a series of tie rod lengths, for example, can be 
employed with the securement portion of bracket 38A for completing the 
tension span between the securement portion of the post bracket 38 and the 
right-hand end bracket 17. 
FIG. 7 is a view looking downwardly of the completed trussing structure 
when a series of the same are mutually spaced longitudinally along and 
underneath a mine roof, with the post brackets being secured not only to 
their respective end brackets, but also to longitudinally adjacent post 
brackets. As seen in FIG. 7, a pair of tie rods or elongate connectors are 
coupled between the securement portions of the respective post brackets 
and the respective pairs of end brackets. 
If desired, relative to FIG. 7, additional intermediate post brackets may 
be employed as, for example, the bracket 38A as seen in FIG. 1. 
Intermediate brackets may well be useful for accommodating long transverse 
spans in certain mine roof areas. 
In the drawings and the description previously given, it is seen that the 
present invention provides a method for actively trussing an arched mine 
roof, having roof rock there-above. Broadly, such method includes the 
steps of: providing a pair of mutually spaced end brackets, each having a 
tubular insert and a reaction surface provided at least one elongate 
member receiving aperture. A subsequent step is to drill 
outwardly-angulated side-opposite apertures in said roof rock proximate 
transverse terminal regions of said arch roof; subsequently, there is a 
step of anchoring said tubular insert of each of said end brackets in a 
respective one of said apertures such that said reaction surfaces of said 
end brackets are essentially parallel. Subsequently, there is provided a 
vertical post bracket having at least one elongate member securement 
portion provided with receiving apertures; the, there is the step of 
compressively securing said post bracket against said roof rock proximate 
a central portion of said arch roof between said end brackets. Thereafter, 
there is provision made of elongate members protruding through and 
extending between said securement portion of said post bracket and said 
reaction services of said end brackets at the apertures thereof. 
Subsequently, there is a step of providing means for tensioning said 
elongate members; then, actually doing so, whereby to anchor and also 
tension said elongate members between said end brackets and said post 
bracket, said end brackets being in essentially a horizontal plane, said 
securement portion of said post bracket being below the space between such 
plane and the arched roof. 
There are variations, of course, in connection with the method above 
described of the post bracket; subsequently, a step includes tightening or 
tensioning the rock bolt by nut means, for example, so as to bring the 
post bracket securely against the mine roof in an abutting relationship. 
Thereafter, or even before this step, there is presented the concept of 
tensioning the elongate member such as tie rods so that these not only 
tension the truss structure per se, but also provide a compressive force 
acting against the post bracket in an actual upward thrusting or upward 
lifting of the same by virtue of the tightening of the elongate members 
such as the tie rods shown in FIG. 1A. Actually, the nominal and 
even-torqued position of the elongate members or tie rods as at 16 in FIG. 
1A, be anywhere from 0 to 30 degrees relative to a horizontal plane 
passing through the securement portion. This feature serves not only to 
tension appropriately the over-all truss structure but also, and equally 
importantly, to provide an upward thrusting force as to post support 38 
against the area contacted by upward flange 40 so as to augment the 
compression zone in the roof rock accordingly, this will be seen in the 
drawings. 
This augmentation is above and beyond the function set forth in column 6 of 
the inventor's above-mentioned patent No. 4,776,729. The entire disclosure 
of such patent is incorporated herein by way of reference. 
In operation, as to the FIG. 1 embodiment, the anchor bolts and roof bolts 
are secured at their distal ends and are maintained in compression by the 
tightening down of the proximate nuts or other useful means relative to 
the opposite end brackets 17 and one or more post brackets as at 38 and 
38A. The elongate member 16, whether 1, 2, or more in number at each 
location, intersecure the securement portion 42 of the respective post 
bracket with the depending flanges of the end bracket 17. The length of 
the post brackets can be such that all of the connectors are initially, 
and finally, in simply a horizontal plane. However, the augmentation of 
the force field in the roof rock, above the roof surface, can readily be 
achieved where the lengths of the post brackets, of whatever number, are 
enlarged slightly such that the condition in FIG. 1A exists, and wherein 
there is an initial angular relationship between the upwardly canted tie 
rods and the horizontal plane at X of from 0 to 30 degrees and preferably 
from 5 to 10 degrees. Thus, when this condition obtains, the tensioning of 
the tie rods or elongate members, as the case may be, will produce an 
upward thrusting of the post bracket to increase measurably the 
compression within the rock formation above the roof line and thereby 
increase the force field of the structure method as shown in the 
inventor's aforementioned U.S. Pat. No. 4,776,729. 
An eminently practical step in supplying the elongate members is simply to 
provide threaded tie rods as indicated, with tensioning nuts at either 
extremity of the respective rods. This structure can obviously be modified 
to include any one of several end configurments whereby the elongate 
members, of whatever form, can be tensioned. One such approach is to forge 
one end of the elongate connectors to an "L" or "T" configurment; at the 
other end there will be positioned a collet or some suitable wedging 
structure whereby, after the tensioning of the particular elongate member, 
a means is used to retain such tension against a reaction surface such as 
surface S in FIG. 1. Quite obviously, the structure in 
FIG. 7 may include the additional post bracket 38A seen in FIG. 1; where 
such is the case either in FIG. 1 or FIG. 7 or similar structures, the 
entire elongate member or elongate connector will consist of the tie rods, 
for example, and also any inter-connecting structures such as the 
securement portion as at 42A relative to the post bracket 38A. FIG. 7 
illustrates that, preferably, a pair of elongate connectors such as tie 
rods are used so as to preclude the inadvertent inclusion of force couples 
which might tend to distort the material under high torque conditions. The 
pairs of end brackets are serially arranged and mutually spaced, as 
indicated, and other elongate connectors or members such as tie rods may 
be used to complete the longitudinal character of the truss, whereby 
longitudinally adjacent post brackets may be tensioningly secured 
together. 
While it is possible that the tubular insert as at 37 in FIG. 5 can be 
eliminated, the inclusion of the same is eminently desired; this is for 
the purpose of maintaining the structural integrity of the truss and, even 
more importantly, to ensure that the end brackets are properly mounted so 
that the reaction surfaces accommodating tie rod nuts or other tightening 
means can be maintained essentially vertical and mutually parallel, 
relative to opposite side end brackets. The method of trussing, thus, is 
laid out as previously given and also as enlarged upon through the 
structure clearly seen in FIG. 7. Further objects, operations and 
advantages are clearly set forth, not only in the specification above 
given and in the drawings, inherently, but also in the claims hereinafter 
set forth. 
Therefore, while particular embodiments of the present invention have been 
shown and described, it will be obvious to those skilled in the art that 
changes and modifications may be made without departing from this 
invention in its broader aspects, and, therefore, the aim in the appended 
claims is to cover all such changes and modifications as fall within the 
true spirit and scope of this invention.