Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICS
The present invention relates to a method of
excavation and to an excavation. The excavation and method of
the present invention has particular application to mines and
methods of mining.
The general concept of undercut and fill mining has
been known and used for many years. Such mining has been
effected for the most part in ore bodies which are tabular at
an angle to the horizontal. Vertical or diagonal decline
tunnels have been placed beside the ore body enabling lateral
mining of the ore body. At each progressively lower level of
the ore body, an entire "room" is opened with access to the
decline tunnel. The room must, of necessity, be braced and
supported to prevent collapse of the overlying portion of the
back fill and soil above the room, which back fill and soil may
become unstable by the sloping of ore from the room. Depending
on the size of the room and the depth and weight of the
overburden, the bracing and structural supporting system may be
wood, steel, concrete or any other suitable structural material
or combination of them. The erection or removal of the
structural support system generally adds significant time and
cost to the project. Further, regardless of the strength of
the structural system, the very fact that the overburden is
unstable adds to the inherent danger in the excavation and
mining operation.
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Once all of the extractable ore has been taken from
the room at a given level, the room is back filled. Generally,
the fill material is comprised of low strength, cemented,
hydraulically placed tailings. The filling operation results
in a low strength, brittle, block of fill having little shear
strength. Overburden stress is therefore readily transferred
through the block rather than contained by it. As a room at
the next level down is opened for excavation, the stress, and
hence the instability of the overburden is increased,
necessitating increased structural bracing and support, adding
to the inherent danger. As the mining operation descends
sequentially from one level to the next lower level, the mass
of unstable overburden, and hence the risks, the structural
support necessary and the time necessary to erect and dismantle
the support, all increase.
The excavation and method of excavation of the present
invention reduces some of the disadvantages of the
aforementioned traditional methods and excavations made
thereby. The present invention is based on the well known
principle of load shedding in the vertical direction.
However, the present invention accomplished this through the
action of a series of separate monolithic beams of relatively
narrow width which are generally parallel and typically made of
concrete. Multi-strength and multi-media bulk back fill is
used between the beams to reduce the cost and soften the fill.
C As level after level of the ore is mined and subsequently
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beam-reinforced, a cross-wise lattice-work of beams is
developed; the method of the present invention reduces the risk
inherent in any excavation operation and minimizes the
structural support necessary at each level and the time
necessary to erect and dismantle the structural support, while
strengthening the strata support around the excavation.
Although particularly suited for mining, the method of the
present invention may be used for any type of excavation.
The present invention relates to both an excavation
and a method of excavation. The excavation structure disclosed
in the present invention can be, but need not be produced by
the presently disclosed method of excavation of the invention.
In one aspect of the invention the equation comprises a
decline and a series of spaced tunnels connected to the decline.
In another aspect of the invention, the excavation
comprises a decline and a first series of spaced tunnels
connected to the decline, the tunnels being filled with support
material comprising beam reinforcement and backfill. A second
series of tunnels is then opened in contiguous relation between
the filled tunnels of the first series, to complete the
excavation of that portion of the level, which second tunnel
series is then beam reinforced and backfilled.
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A third series of spaced tunnels is then excavated at
the next underlying level, being laterally inclined in a second
direction, and connected to the decline at a second level. The
second direction is laterally transverse to the first
direction. These tunnels then are filled with support
material, being beam reinforced in like fashion to the
preceding series of overlying tunnels, and then backfilled.
A fourth series of tunnels is excavated between the
tunnels of the third series, beam reinforced, and backfilled.
The process is then repeated at succeeding underlying levels,
resulting in a fifth series of spaced tunnels extending in a
third lateral direction and connected to the decline at a third
level, the third direction being transverse to the second
direction. This fifth series of tunnels is similarly filled
with support material.
Excavation of the third level is then completed by
excavating a sixth series of tunnels located between the
tunnels of the fifth series, which sixth series is then
reinforced and subsequently backfilled to the overlying
concrete roof.
At the next lower level, the fourth level, a series of
spaced tunnels is laterally directed in a fourth direction
other than that of at least the two overlying levels, and
connected to the decline at the fourth level.
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In an eighth tunnel series aspect of the invention,
the excavation is as described in the previous paragraph and
further comprises an eighth series of tunnels between the
seventh series of tunnels, which are similarly filled with
support material.
The tunnels herein referred to are considered as being
horizontally directed. They may in fact be inclined, due to
the formation and other circumstances; at angles of inclination
permitting excavation thereof by mechanized equipment.
The tunnels of succeeding underlying levels are
laterally inclined from the immediately overlying level,
located above, the immediately overlying level being laterally
inclined from the preceding level.
The first and second series of tunnels are connected
to the decline by a first connecting passage. The third and
fourth series of tunnels are connected to the decline by a
second connecting passage. The fifth and sixth series of
tunnels are connected to the decline by a third connecting
passage. The seventh and eighth series of tunnels are
connected to the decline by a fourth connecting passage. The
second connecting passage does not underlay the first
connecting passage, being horizontally offset from the first
passage. The third passage is similarly horizontally offset
from the second connecting passage. The connecting passages
are preferably horizontal.
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The first series of tunnels at each level are
generally of substantially Equal width. The spacing between
these first series tunnels at each level may be substantially
equal to or greater than the widths of the tunnels. The second
series of tunnels at each level generally are equal in width to
the spacing between the first series tunnels. Thus, the
excavation of each level it completed by the second series of
tunnel excavations for that level.
The support material typically initially filling an
excavated, reinforced and backfilled tunnel comprises à layer
of previous material, a layer of impervious material, a
structural layer and optionally a layer of bulk fill. The
previous material is preferably unconsolidated, and may be
sand. The layer of impervious material is laid above the layer
of previous material and comprises plastic. The structural
layer which is preferably concrete but may include other
structural material, such as steel or other metals, is
deposited upon the layer of impervious material. If metal
plate is used, it may serve as both the impervious and
structural layers. The layer of bulk fill is backfilled above
the concrete layer. The bulk fill may be low-strength cemented
sand or uncemented sand.
In another aspect of the invention, the excavation
comprises a decline and a first series of spaced tunnels of
substantially equal widths extending parallel to one another in
a first substantially horizontal passage at a first level. The
spacing between adjacent tunnels is substantially equal to or
greater than the widths of the tunnels.
In a subsequent aspect of the invention, the first
series of tunnels is filled with support material. A second
series of tunnels is driven between the filled first series of
tunnels, the tunnels of the second series being connected to
the decline by the first passage.
In a subsequent aspect of the invention, the second
series of tunnels and the first passage are filled with support
material. A third series of spaced tunnels of substantially
equal widths extends parallel to one another in a second
horizontal direction and is connected to the decline by a
second horizontal passage at a second, lower level. The second
direction is transverse to the first direction and the spacing
between adjacent tunnels of the third series is substantially
equal to or greater than the tunnel widths.
In a subsequent aspect of the invention, the third
series of tunnels is filled with support material. A fourth
series of tunnels is driven between the filled third series of
tunnels, the tunnels of the fourth series being connected to
the decline by the second passage.
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In a subsequent aspect of the invention, the fourth
series of tunnels and the second passage are filled with
support material. A fifth series of spaced tunnels of
substantially equal widths extends parallel to one another in a
third horizontally passage at a third level. The third
direction also may be transverse to the first direction. The
spacing between adjacent tunnels is substantially equal to or
greater than the widths of adjacent tunnels.
In a subsequent aspect of the invention, the fifth
series of tunnels is filled with support material. A sixth
series of tunnels is located between the filled fifth series of
tunnels, the tunnels of the sixth series being connected to the
decline by the third passage.
In a subsequent aspect of the invention, the sixth
series of tunnels and the third passage are filled with support
material. A seventh series of spaced tunnels extends parallel
to one another in a fourth horizontal direction and is
connected to the decline by a fourth horizontal passage at a
fourth level. The fourth direction is transverse to the third
direction. The fourth direction generally would be transverse
to the second direction. The spacing between adjacent tunnels
is substantially equal to or greater than the widths of the
adjacent tunnels.
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In a subsequent aspect of the invention, the seventh
series of tunnels it filled with support material. An eighth
series of tunnels is located between the filled seventh series
of tunnels, the tunnels of the eighth series being connected to
the decline by the fourth passage.
Relative lateral inclinations of the tunnels at
descending levels may be selected so as to provide repeating,
progressive directional sequences, reoccurring each three or
four levels, so as to provide in effect, a vertically
superimposed lattice work of laterally inclined beams.
The method of excavation of the present invention
comprises excavating a decline and then driving a first series
of spaced tunnels in a first direction at a first level of the
decline. The first series of tunnels would then be filled with
support material. A second series of tunnels would then be
driven between the filled tunnels of the first series.
In selecting angles of lateral inclination of the
tunnels at descending levels of the excavation care is taken
that the overlying beam support structures, which in effect
constitute the roof portions for the immediately underlying
tunnels in area of excavation, extend generally transversely of
the tunnels, so as to limit the unsupported span of the
respective beam structures until such time as the respective
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tunnels are backfilled into potential load supporting relation
with the superposed beams.
The tunnels of the second series would then normally
be filled with support material and a third series of spaced
tunnels may then be driven in a second direction from a second
level of the decline, the second direction being laterally
transverse to the first direction. The tunnels of the third
series would then be filled with support material and a fourth
series of tunnels then driven between the filled tunnels of the
third series.
The tunnels of the fourth series may be filled with
support material and a fifth and succeeding series of spaced
tunnels then driven in a predetermined changed directions at
respective deeper levels of the decline.
In carrying out the presently disclosed method of
excavation a succeeding series of tunnels, excavated at a given
level normally utilize a common connecting passage to access
the decline, from which access passage the tunnels extend,
often from both sides of the passage, by virtue of its location
intermediately of the area encompassed by the respective level.
The present invention thus provides, in the excavation
of a level, being one of a number of proposed descending levels
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of excavation, the subject level extending laterally from
adjacent a decline passage, being accessed therefrom by a
connecting passage, wherein a first plurality of generally
parallel, mutually spaced apart tunnels extend at a
predetermined angle of lateral inclination from the connecting
passage, the improvement comprising a plurality of separate,
first monolithic beams within the tunnels, Mach being in load
transfer relation with an underlying layer and having fill in
load transfer, strata stabilizing relation deposited thereon,
to substantially backfill the excavation above the beams.
There is further provided at that level a plurality of
second tunnels each extending laterally contiguously between
adjacent tunnels of the first plurality of tunnels, the second
tunnels each having therein a monolithic second beam
substantially contiguous with adjacent ones of the first
plurality of monolithic beams.
The second tunnels have fill deposited on the beams to
fill the excavation there above.
In the preferred embodiment the subject monolithic
beams comprise a concrete layer extending widths and along
substantially the length of the respective tunnel. The
concrete of the beams may include reinforcement elements
therein, depending upon the anticipated load requirements in
the respective strata.
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In order to facilitate the construction of the beams
and to ensure optimum utilization of them, a layer of
substantially unconsolidated material such as sand is generally
deposited in the base of the tunnels, over which an impermeable
layer, such as a layer of plastic is laid, to form a bed for
the respective beam, onto which it is poured. Furthermore,
during tunnellin~ of the succeeding level there beneath, the
sand layer protects the beam by permitting safe undercutting in
relation thereto, so that generally the sand falls away and is
removed.
While being influenced, dimensionally, by the nature
of the material being excavated, in a fully mechanized
operation the tunnels of the initial series, at any one level
would be size limited, particularly laterally to a range of
abut three to five metros, to satisfy equipment and operational
requirements; in particular to reduce the requirement for
structural bracing and reinforcement, while the subsequent
loaded stress levels of the concrete beams placed in the
tunnels also are limited. Tunnel heights are generally about
three metros or greater, primarily to satisfy equipment and
operational requirements.
In the preferred mode, the initial unconsolidated
layer such as sand, typically about one half moire thick has an
impervious plastic sheet laid there over, to serve as a diaphragm
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both in the pouring of the concrete, to facilitate the curing
thereof, and to assist in containment of the hydraulically
placed back fill layers there above.
The preferred concrete beams generally comprise a
layer of one to one and a half metros thick, typically of 3000
pounds per square inch concrete, poured onto the plastic and
contained laterally by toe walls of the tunnel. Reinforcement
for the concrete may be introduced, if structurally required.
Alternatively structural metal, such as steel, may be
used. If metal plate of substantial area covering form is
used, it may serve as the impervious layer.
Is is contemplated that the efficient utilization of
the reinforcement concrete may be enhanced by suitably
profiling the upper surface of the underlying sand layer, along
the length of the respective tunnel, to thereby form to a
desired configuration the undersurface of the beam so formed.
In the driving of the underlying tunnels in the succeeding
level, as a for-instance, the succeeding beams encountered
could provide sequential barrel-vau]ted roof portions. It is
recognized that certain consequences could flow, in regard to
back filling of such transverse, barrel-vaulted roof which
might diminish the accrued advantage of such structural
improvement.
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These various aspect of the invention may be repeated
in sequence to the lowest level of the excavation as desired.
The excavation and method of excavation of the present
invention will be described with reference to a method of
mining and a mine, a preferred embodiment of which is
illustrated in the drawings, wherein:
Figure 1 is an exploded series of time sequential isometric
views of three levels of an ore body, each of which have
been partially subject to the excavation of the present
invention;
Figure 2 is a plan view of the upper level shown in
Figure 1, with a plan view of the underlying and subsequent
middle level of Figure 1 being shown in dashed form;
Figure 3 is a plan view of the middle level of Figure 1,
with a plan view of the underlying and subsequent lower
level of Figure 1 being shown in dashed form;
Figure 4 is a plan view of the lower level of Figure l; and
Figure 5 is a time lapsed sequential section taken along
lines 5-5 in Figures 1, 2, 3 and 4 at respective times when
the subject level which those Figures illustrate had been
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driven, reinforced and backfilled, but prior to drilling of
the succeeding, lower level.
Referring first to Figure 1, it represents three slabs
or levels of a geological body, 10 exploded for ease of
reference and shown at sequential time intervals. An upper
slab, 12 lies above a middle slab, 14 which, in turn, lies
above a lower slab, 16. Relative to the other slabs, the upper
slab, 12 is shown at the earliest time interval. As the
preferred embodiment will be described and illustrated with
reference to mining operations and the mine illustrated, it
will be assumed that the geological body, 10 is beneath the
earths surface, which is not shown, and is, in part, an ore
body. However, the present invention may be used in connection
with any load bearing material such as rock, soil or sand.
Ore bodies are generally tabular and lie at a random
angle to the surface. Access to the ore body may he made by a
sloped decline tunnel from the surface at the edge of the ore
body. The decline typically may be a conventional trackless
passage. The decline typically enables removal of the
excavated material from the excavation, in this case mined ore,
and supply of fill material. In Figure 1, a portion of the
decline, 18 is shown in each slab. However, the decline, 18 is
continuous from the surface to the lowest level of the
excavation. The decline is located in that portion of the slab
where there is no ore to be mined.
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After at least a portion of the decline, 18 is
excavated, a first access passage, 24 is provided, and a series
of spaced tunnels, 20 is driven in a first direction, 22 at the
first level, 12 of the decline, 18. The tunnels of the first
series, 20, shown in plan view in Figure 2, are parallel to
each other and driven in a horizontal plane. They are
connected to the decline by the horizontal passage, 24. The
tunnels of the first series, 20 are of substantially equal
widths w and the spacing S between adjacent tunnels of the
lo first series, 20 is substantially equal to or greater than the
widths W of adjacent tunnels, 20.
The widths of the tunnel are determined by, among
other factors, the material through which they are drilled.
Typically the widths of the tunnels are between three I and
five (5) metros to satisfy equipment and operational
requirements. By thus keeping the widths of the tunnels, 20
relatively narrow, the requirement for structural bracing and
reinforcement is reduced and the concrete beams to be placed in
the tunnels during subsequent filling operations are kept from
being over stressed. Typically the heights H of the tunnels
are about three (3) metros or greater to satisfy equipment and
operational requirements. While the tunnels and the horizontal
passages described and illustrated are typically horizontal,
they may be sloped at an angle which can he negotiated by a
tracked vehicle
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It is after this step of the method that the
excavation is illustrated in -the upper slab, I of Figure 1 and
in Figure 2. At this stage, the excavation comprises the
decline, lo and a first series of spaced horizontal tunnels, 20
connected to the decline, 18 ho a first horizontal passage, 24.
The first series of tunnels, 20 are then filled with
support material. This phase, represented in Figure 5 of the
drawings, enables the void left by thy tunneling to be filled
in order to structurally stabilize the ore body, 10. Although
the tunnels of the first series, 20 are filled, the first
horizontal passage, 24 is not filled at this stage.
The support material, shown in Figure 5 is a Tim elapse
cross section of all three levels of Figure 1 showing the
entire series of excavation, reinforcement and back fill for
the illustrated three levels when respectively completed. It
generally comprises a layer of previous unconsolidated
material, 26, which subsequently generally falls into the
succeeding, lower level during the driving thereof), a layer of
impervious material, 28, a structural layer of load bearing
material, 30 and a layer of bulk fill, 32. The previous
material, 26 is typically a half (1~2) moire layer of sand
plastic may be used as the impervious layer, 28. Preferably,
the load bearing material is concrete. However structural
metal such as steel may be used. If metal plate is used, it
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may serve as both the impervious end structural layers. A one
(1) to one and a half (1 1i2~ moire layer of concrete is
typical, although the exact thickness will be determined by the
span adopted for the underlying tunnels. The widths of
crossing tunnels in the levels above and below will determine
whether or not reinforcement of the concrete is required. The
bulk fill layer, I may be low strength cemented sand or
uncemented sand. In the embodiment shown in the bottom level
of Figure 5, the bulk fill, 32 lies above the concrete, 30,
which lies above the plastic, 28, which, in turn, sits on the
previous sand layer, 26. The various layers act as fill
layers, while the structural concrete layer acts also as a beam
to shed the load of the levels above. The initial presence of
the unconsolidated layer, 26 enables drilling of tunnels in the
layer beneath without any damage to the structural layer, which
structural layer then forms the roof for the succeeding,
underlying tunnels.
A second series of tunnels snot shown in the drawings
is then driven in the spaces, 34 between the filled tunnels of
the first series, 20. Because the tunnels of the first series,
20 are parallel and of equal widths and are illustrated as
being equally spaced, the tunnels of the second series, 34 will
be likewise. At this stave of the operation, the excavation
comprises a decline, 18 and a first series of spaced tunnels,
20 connected to the decline, 18, the tunnels of the first
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series, 20 being filled with support material, and a second
series of tunnels, 34 between the filled tunnels of the first
series, 20. It will be understood that size of the tunnels, 34
of the second series will equal the spacing between the
tunnels, 20, and may well exceed the size of the tunnels, 20.
The tunnels of the second series t34) and optionally
the first horizontal connecting passage, 24 are then filled
with support material. The decline, 18 is then further
extended to the next level, 14 of the excavation. A third
lo series of spaced tunnels, 36 is then driven in a second
laterally oriented direction, 38, the second direction, 38
being transverse to the first laterally oriented direction,
22. By driving the third series of tunnels, 36 in the second
direction, 38, the third series of tunnels underlie and are
traversed by the hems former by the reinforcement of the
tunnels, 20 of the first level and tunnels ~34) of the second
series above. The lateral orientation Al relation between the
tunnels, 36 of the third series and those of the first level,
12 there above may be seen from Figure 2, where the dash lines
represent the second level, 14 after drilling of the third
series of the tunnels, 36.
The horizontal tunnels of the third series, 36 are
connected to the decline, 18 by the second horizontal passage,
40. The tunnels of the third series, 36 are of substantially
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equal widths W and the spacing S between adjacent tunnels of
the third series, 36 is shown to be substantially equal to, but
could well be greater than the widths of adjacent tunnels, 36.
At this stage of the operation, illustrated by the
middle slab, 14 of Figure 1 and by Figure 3, the excavation
comprises a decline, 18 and a first series of spaced tunnels,
20 in a first direction, 22, the tunnels, 20 being connected to
the decline, 18 at a first level, 12 and filled with support
material. A second series of tunnels, 34 is between the
tunnels of the first series, 20, the tunnels of the second
series, 36 being filled ilk support material. A third series
of spaced tunnels, 36 is in a second direction, 38 and is
connected to the decline, 18 by a second horizontal passage, 40
at a second level, 14. The second direction, 38 is transverse
to the first direction, 22.
The tunnels of the third series, 36 are then filled
with support material and a fourth series of tunnels, 42 is
then driven between the filled tunnels of the third series,
36. The relation between the tunnels of the fourth series, 42
to those of the third series, 36 is analogous to the relation
between the tunnels of the second series, 34 and those of the
first series, 20. In other words, the tunnels of the fourth
series, 42 are parallel and of substantially equal widths W and
the spacing S between adjacent tunnels of the fourth series, 42
lo 3 by
is substantially equal to or greater than to the widths of the
adjacent tunnels, 42.
At this stage of the operation, which is not
illustrated, the excavation comprises a decline, 18 and a first
series of spaced tunnels, 20 in a first direction, 22, the
tunnels of the first series, 20 being connected to the decline,
18 at a first level, 12 by a first horizontal passage, 24 and
filled with support material. A second series of tunnels, 34
is between the tunnels of the first series, 20, the tunnels of
the second series, 34 and the first horizontal passage, 24
being filled with support material. A third series of spaced
tunnels, 36 is in a second direction, 38 and connected to the
decline, 18 at a second level, 14 by a second horizontal
passage, 40, the second direction, 38 being transverse to the
first direction, 22 and the tunnels of the third series, 36
being filled with support material. A fourth series of
tunnels, 42 is between the tunnels of the third series, 36.
The tunnels of the fourth series, 42 and the second
horizontal passage, 40 are then filled with support material.
A fifth series of spaced tunnels, 44 is driven in a third
direction, 46 at a third level, 16 of the decline, 18 by a
third horizontal passage, 48. The third direction, 46 is
transverse to the first direction, 22.
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An alternate fifth series of spaced tunnels, 50 may be
driven in an alternate third direction, 52 at the third level,
16 of the decline, 18, the tunnels of the alternate fifth
series, 50 being connected to the decline by the third
horizontal passage, 43. The alternate third direction, 52 is
transverse to both the first, 22 and second, 38 directions.
The relative transverse directions of adjoining levels creates
a cross-wise lattice-work of beams as level after level of the
ore body, 10 is excavated and subsequently filled.
As was the case for the tunnels, 20 of the first
series and tunnels, 36 of the third series, the tunnels, 44 of
the fifth series are parallel and of substantially equal widths
W; the spacing S between adjacent tunnels, 44 of the fifth
series is substantially equal to or greater than the widths w
of the tunnels, 44.
At this stage of the operation, which is illustrated
by the lower level, slab 16 in Figure 1 and by Figure 4, the
excavation comprises a decline, 18 and a first series of spaced
tunnels, 20 in a first direction, 22, the tunnels, 20 being
Jo connected to the decline, 18 at a first level, 12 by a first
horizontal passage, 24 and filled with support maternal. A
second series of tunnels, 34 is driven between the tunnels of
the first series, 20, the tunnels of the second series, 34 and
optionally the first horizontal passage, 24 being filled with
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support material. A third series of spaced tunnels, 36 is in a
second direction, 38 and connected to the decline, 18 by a
second horizontal passage, 40 at a second level, 14. The
second direction, 38 is transverse to the first direction, 22
and the tunnels of the third series, 36 are filled with support
material. A fourth series of tunnels, 42 is between the
tunnels of the third series, 36, thy tunnels of the fourth
series, 42 and optionally the second horizontal passage, 40
being filled with support material. A fifth series of tunnels,
44 or 50 is in a third direction, 46 or 52, respectively and
is connected to the decline, 18 by a third horizontal passage,
48 at a third level, 16, the third direction, 46 or 52 being
transverse to the second direction and, in some cases, 52
transverse to the first direction, 22.
The tunnels of the fifth series, 44, 50 are then
filled with support material. A sixth series of tunnels, 54 is
then driven between the filled tunnels of the fifth series, 44,
50. The relation between the tunnels of the sixth series, 54
to whose of the third series, 44, 50 is analogous to those of
the first, 20 and second, 34 and to those of the third, 36 and
fourth, 42 series. The tunnels of the sixth series, 54 are
parallel and of substantially equal widths W, and the spacing S
between adjacent tunnels of the sixth series, 54 is
substantially equal to or greater than the widths W of the
tunnels.
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The tunnels of the sixth series, 54 and optionally the
third horizontal passage, 48 are then filled with support
material. A seventh series of spaced tunnels, not shown, may
be driven in a fourth direction at a fourth level of the
decline, 18, the fourth direction being transverse to the third
direction, 46 (or 2). The fourth direction may also be
transverse to the second direction, 38. The tunnels of the
seventh series may be identically laterally oriented to those
of the first series of tunnels, 20, by which the lateral
orientation pattern of tunnels could repeat every three levels.
The tunnels of the seventh series would then be filled
with support material. An eighth series of horizontal tunnels
may then be driven between the filled tunnels of the seventh
series. The tunnels of the eighth series may correspond in
lateral orientation, size and spacing to the tunnels of the
second series, 34 in that they are parallel and of
substantially equal widths W. The spacing S between adjacent
tunnels of the eighth series is substantially equal or greater
than the widths of adjacent tunnels. The tunnels of the eighth
series are connected to the decline, 18 by a fourth horizontal
passage.
The tunnels of the eighth series and the associated
fourth horizontal passage are then filled and the next level
downward is excavated, in each case the tunnels of each level
being transverse to those of the level above.
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The various steps in the method of the invention may
be repeated in sequence or otherwise to the lowest level of the
excavation.
If it is desirable to retain an open room at any level
of the excavation, this can be done by omitting the filling
step in respect of selected tunnels. If the room is desired to
be of substantial width, the structural reinforcement layer in
the tunnels of the level above might be additionally suitably
strengthened.
The completed excavation will appear to be similar in
make-up for each application of the method, but the number of
tunnels being simultaneously driven can vary according to the
rock competency. It should be understood that each series of
tunnels may be subdivided into sub-series with intermediate
filling or that more than one series of tunnels may be drilled
at any level if ground conditions permit such an approach.
While the conventional system of hydraulic or
pneumatic drilling, blasting and load-haul-dump mucking may be
used to excavate, the method of the present invention may be
used with tunnel boring machines and similar rock cutting and
boring machines. Fill may be placed by a pneumatic blower or
by wheeled transportation. Survey control of the operation
should be constant and may be effected by the use of a laser
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system. Ventilation of the excavation may be effected by way
of the decline through the horizontal passage at the level
hying excavated.
The method of excavation and the excavation of the
present invention is particularly suited to the mining of wide
ore bodies. It is the width of wide ore bodies that leads to
problems in that the excavation becomes less stable as the
width increases. The method and form of the excavation
disclosed and claimed sheds the load from the roof of any
tunnel to the supporting strata below. By using low strength
bulk fill between the high strength concrete beams, the fill
can absorb pressure instead of transmitting it. By contrast,
in the traditional undercut-and-fill system, the fill used is
not strong enough to be stable over wide spans. By using a
cross-wise lattice, the method and excavation of the present
invention reduces the exposed span to a width controlled by
engineering decision rather than by the vagaries of the ore
body. The strength of the excavation is increased while the
risk imposed by the general lack of homogeneity in rock masses
is reduced.
While a specific embodiment of the invention has been
disclosed and illustrated herein, it is to be understood that
variations and modifications are possible without departing
~33~ I
from the spirit or essence of this invention. The method of
excavation and the excavation may be applicable to operations
other than mining, although the disclosure and drawings are
directed to an embodiment in the mining field.
7290b/1-29
