Note: Descriptions are shown in the official language in which they were submitted.
CA 02869235 2014-10-01
1
METHOD FOR DRILLING HOLES IN SOIL OR ROCK MATERIAL AND FOR
FIXING AN ANCHOR IN A BOREHOLE AND APPARATUS THEREFOR
The present invention relates to a method for drilling holes in
soil or rock material and for fixing an anchor in a borehole,
wherein an expanding element fixed to a drill or anchor rod and
a spreading element to be expanded, in particular in the form of
a sleeve, are introduced with the drill or anchor rod provided
with a drill bit, into the soil or rock material at the same
time as the borehole is being formed, in particular by rotary
and percussive or rotary drilling, the spreading element is
expanded to butt against the wall of the borehole after
completion of the borehole by the drill or anchor rod and the
expanding element arranged thereon being retracted into the
interior of the spreading element, and the drill or anchor rod
is secured at its end protruding from the borehole by an anchor
plate on an outer side of the borehole, and apparatus for
drilling holes in soil or rock material and for fixing an anchor
in a borehole, including a drill bit fixed to a drill or anchor
rod and an expanding element fixed to the drill or anchor rod
and an expandable spreading element, in particular in the form
of a sleeve, wherein an anchor plate is arranged on the drill or
anchor rod, in the end region facing the outside of the
borehole.
In the context of mounting or fixing an anchor equipped with a
spreading element in a borehole, it is known to introduce such
an anchor with at least one expandable element arranged on its
periphery in the front end region either into a previously
completed borehole or at the same time as the borehole is being
formed, in order to subsequently provide the fixation of the
anchor, in particular spreading anchor, within the borehole and
the abutment of the expandable element on the borehole wall by
the expansion of the expandable element. After such a
2
CA 02869235 2014-10-01
provisional mounting or fixation of the anchor on the borehole
wall, the introduced anchor frequently is permanently fixed in
the borehole by subsequently introducing a curable suspension
such as grout.
In doing so, the anchorage or expansion of the spreading element
is achieved, as is for instance described in AT-409785, by
retracting the spreading element fixed to an anchor rod or by
retracting an expanding element into a spreading sleeve,
whereupon the spreading sleeve is brought into abutment on the
borehole wall. In both cases, it is necessary for the completion
of the borehole to cut off the anchor rod length that protrudes
from the borehole following such retraction, and to subsequently
attach an anchor plate to the free end of the drill or anchor
rod and brace the same in a separate operation, wherein it is
either possible to further fix the anchor by introducing a
curable suspension, or the anchorage formed by spreading the
spreading element into the interior of the mountain or expanding
the expanding element onto the borehole wall is completed.
Such a mode of operation, on the one hand, involves time-
consuming operating steps and, on the other hand, requires all
the elements forming an anchorage to be completed to be attached
or hinged to the respective device, and brought into the
positions intended for their final purposes of use, each after
having finished a preceding operating step. Such a mode of
operation, in addition to being time-consuming, is also cost-
intensive and, in particular, considerable drill rod lengths
are, moreover, discarded by sawing to ultimately required
lengths, thus not only causing a decrease in the overall length
of the anchorage but also requiring a plurality of additional,
non-automated operating steps.
3
CA 02869235 2014-10-01
The present invention aims to provide a method for drilling
holes in soil or rock material and for fixing an anchor in a
borehole, and apparatus therefor, which enable positioning in a
single operating step of all the elements required for a
permanent anchorage and, moreover, allow the entire length of an
introduced drill or anchor rod to be used for anchoring so as to
provide an anchorage with enhanced reliability as compared to
conventional anchorages.
To solve this object, the method according to the invention is
characterized in that, after the expansion of the spreading
element, the drill or anchor rod is subjected to a rotary
movement in the direction of the interior of the borehole until
there is abutment with the interior of the borehole, and that
the drill or anchor rod is fixed to the outside of the borehole
by bracing the anchor plate by means of a nut formed as a
locating element for an insertion device. In that the drill or
anchor rod, after the expansion of the spreading element, is
subjected to a rotary movement in the direction of the interior
of the borehole until abutting the interior of the borehole, it
has, on the one hand, become possible to provide or utilize the
entire length of the anchor rod for an anchorage and, on the
other hand, become superfluous to cut the length of the end of
the anchor rod protruding from the borehole, thus avoiding
considerable weakening of the whole anchorage system. In that,
furthermore, the drill or anchor rod is fixed to the outside of
the borehole by bracing the anchor plate by means of a nut
formed as a locating element for an insertion device, in
particular during the reintroduction of the anchor rod into the
borehole, it has become possible to position all elements
required for the formation of a permanent anchorage in a single
operation, such a mode of operation allowing for not only a
substantial gain in time by the automation of the process, but,
in particular, also the achievement of a significantly safer
4
CA 02869235 2014-10-01
anchorage by avoiding the temporary detachment and/or subsequent
mounting of individual elements.
In order to enable the drill or anchor rod to be safely
reintroduced into the interior of the borehole after the
expansion of the spreading element, in particular without
unfastening the anchorage from the wall of the borehole, the
method according to the invention is further developed such that
the drill or anchor rod is introduced into the interior of the
borehole after the expansion of the spreading element by acting
on a shear pin fixed to the drill or anchor rod or passing
therethrough and protruding into a recess of the expanding
element until it breaks. Following the expansion of the
spreading element by retracting the drill or anchor rod and
introducing the expanding element into the spreading element,
the drill or anchor rod is maintained in the interior of the
expanding element by a radial compressive stress utilized by the
spreading element, so that, at a new attempt to rotate the drill
rod, such movement will be substantially more difficult to
perform than the original rotary and/or percussive movement of
the drill or anchor rod for the formation of the borehole. Such
radial clamping of the drill or anchor rod and the forced
setting in motion of the drill or anchor rod causes a shear pin
fixed to the drill or anchor rod or passing therethrough and
protruding into a recess of the expanding element to be stressed
until it breaks such that, after the shear pin has broken off, a
rotary movement of the anchor rod out of the expanding element
in the direction towards the interior of the borehole will be
enabled, thus bringing the drill rod into abutment on the
interior of the borehole by a new rotary movement. During such a
mode of operation, the expanding element itself is stationarily
maintained by the radial compressive stress of the spreading
element and, optionally, a sleeve provided therefor.
5
CA 02869235 2014-10-01
= In order to safely ensure the breaking of the shear pin, the
method according to the invention, according to a further
development, is conducted such that the drill or anchor rod,
which is designed as a threaded rod, is merely subjected to a
rotary movement to act upon the shear pin. Such a mode of
operation ensures that the expanding element will not be
inadvertently driven out of the interior of the spreading
element by a possibly excessive percussive stress, which would
render the anchorage loose and/or useless.
In that, as in correspondence with a further development of the
method according to the invention, the anchor plate is braced
against the outside of the borehole by subjecting the nut fixed
to the drill or anchor rod by means of an internal thread merely
to a rotary movement, it has additionally and, in particular,
simultaneously become feasible by the merely rotating action on
the drill or anchor rod for introducing the latter into the
interior of the borehole after the expansion of the spreading
element to brace the anchor plate arranged on the drill or
anchor rod and fixed to the anchor rod by a nut having an
internal thread. Such a mode of operation thus not only renders
superfluous the cutting to length of the anchor rod, but also
enables the introduction and mounting of any elements required
for fixing an anchor in soil or rock material in a single
operation step.
In order to safely maintain within the borehole also a curable
material to be introduced into the interior of the borehole and
ensure a material bond with the anchor rod and the borehole, the
method, as in correspondence with a further development of the
method according to the invention, is conducted such that a
borehole cover fitted to the anchor plate in the direction of
the interior of the borehole for sealing the borehole against
6
CA 02869235 2014-10-01
= the outside is introduced into the borehole at the same time as
the anchor plate is being braced.
To solve the initially mentioned objects, an apparatus for
drilling holes in soil or rock material and for fixing an anchor
in a borehole is essentially characterized in that the drill or
anchor rod is configured as a threaded rod capable of being
subjected to a rotary movement after the expansion of the
spreading element, said threaded rod cooperating with an
internal thread of the expanding element, and that the drill or
anchor rod interacts with an insertion device via a nut for
bracing the anchor plate. In that the expanding element is
formed with at least one recess in its end region facing the
interior of the borehole, which recess cooperates with at least
one shear pin engaging said recess and protruding beyond the
outer contour of the drill or anchor rod, it has become feasible
to make even more reliable the movement of retraction of the
drill or anchor rod and the new driving of the latter into the
interior of the borehole, since any inadvertent displacement of
the expanding element on the drill rod will be safely prevented.
When reintroducing the drill or anchor rod into the interior of
the borehole, it is, moreover, possible to merely introduce the
drill rod into said interior by simply turning off the shear
pin, and the expanding element will be held in a secure bond
with the spreading element so as to ensure the anchorage of the
anchor to the borehole wall.
In that the drill or anchor rod interacts with the insertion
device for the drill or anchor rod via a nut for fixing the
anchor plate, it has become feasible, on the one hand, to
introduce any parts required for the formation of an anchorage
in a single operating step and, on the other hand, to achieve a
minimization of the elements required for the setting of an
anchor. By such a configuration it has, furthermore, become
7
CA 02869235 2014-10-01
possible to arbitrarily subject the nut to a rotary movement via
the internal thread on the anchor rod designed as a threaded rod
and hence, for instance, fix the anchor plate to the exterior of
the borehole, and, by the insertion device engaging the external
thread, to safely and reliably introduce the whole device into
the interior of the borehole and retract the same by the
distance required for spreading the spreading element, and
subsequently drive it in again.
In that, as in correspondence with a further development of the
invention, the expanding element is formed with at least one
recess in its end region facing the interior of the borehole,
which recess cooperates with at least one shear pin engaging
said recess and protruding beyond the outer contour of the drill
or anchor rod, it has become feasible to safely pull back, or
carry along, the expanding element into the interior of the
spreading element during the retraction of the drill or anchor
rod.
In that, as in correspondence with a further development of the
invention, the thread of the expanding element extends over a
portion of the length of the expanding element, it has, in
particular, become feasible to keep the wedge-likely tapering
parts of the expanding element thread-free, and hence avoid
further unnecessary weakening of the same, yet provide a safe
retention of the expanding element on the anchor rod.
According to a further development of the invention, a
particularly simple expansion of the spreading element will be
enabled in that the spreading element is designed as a spring
cage comprising a slot extending at least over a portion of its
length. Such a device, on the one hand, ensures the safe
retention of the spreading element on the anchor rod and, on the
other hand, ensures the reliable spreading of the same against
8
CA 02869235 2014-10-01
the wall of the borehole. Such a spring, cage can be designed
either with a smooth outer contour or with a teethed outer
contour in the manner of a "dowel".
In order to achieve, in particular, the automated insertion of a
drill or anchor rod and introduce all elements required for the
formation of an anchorage in a single operation, a substantially
frustoconical borehole cover abutting the anchor plate is
arranged on the drill or anchor rod according to a further
development of the invention.
In order to ensure the reliable expansion of the spreading
element, the device according to the invention is further
developed to the effect that, in a manner known per se, a stop
sleeve crimped to the drill or anchor rod is provided on the
drill or anchor rod for the spreading element. Such a device
ensures the reliable spreading of the spreading element and
hence the safe abutment on the inner wall of the borehole.
In the following, the invention will be explained in more detail
by way of exemplary embodiments illustrated in the drawing.
Therein:
Fig. 1 depicts an apparatus according to the invention for
forming a borehole and for fixing drill or anchor rods in the
interior of the formed borehole;
Fig. 2 is a top view of a modified variant of the apparatus
according to Fig. 1;
Fig. 3 is a partially sectioned, schematic view of the apparatus
of Fig. 2 in a state fixed to the wall of the borehole; and
Fig. 4 depicts an enlarged sectional view of the borehole cover.
In Fig. 1, a drill or anchor rod is denoted by 1, to whose end
facing a borehole interior 15 a drill bit 2 is fixed in a non-
extendible manner. The drill or anchor rod 1, over its entire
9
CA 02869235 2014-10-01
length, is designed as a threaded rod, on which an expanding
element 3 is mounted in such a manner that the recesses 4 formed
within the expanding element 3 overlap a shear pin 5 protruding
beyond an outer periphery of the drill or anchor rod 1. The
expanding element 3 in its inner periphery, which is not
apparent from the drawing, can be wholly or partially formed
with a thread cooperating with the thread 6 of the drill or
anchor rod 1. Such a configuration ensures the captive
maintenance of the expanding element 3 in its selected position
and, in particular, prevents the shear pin 5 from being
inadvertently torn off.
A spreading element 7, which is provided with a longitudinal
slot 8 over a portion of its length, is maintained on the drill
or anchor rod 1 at a distance from the expanding element 3 by a
sleeve 9 crimped to the drill or anchor rod 1. The spreading
element 7 is configured such that the longitudinal slot 8 merely
extends over a portion of the length of the spreading element 7,
and that the part of the spreading element 7 facing the wall of
the borehole is designed with kind of a teething 10. The
teething 10 is provided for a better engagement in the borehole
wall.
The drill rod 1, on its end region facing the exterior of the
borehole, is provided with a cover element 11 for the borehole,
an anchor plate 12 butting against the cover element 11, and a
nut 13 provided as a locating element for a schematically
indicated insertion device 14. The cover element 11 in this case
is formed as a cone that tapers towards the interior of the
borehole to safely and reliably seal the formed borehole. The
anchor plate 12 may be a conventional anchor plate 12, which,
for instance, is brought into abutment on a tunnel wall by
exerting an external compressive stress.
10
CA 02869235 2014-10-01
The nut 13, which is designed as a. location element for the
insertion device 14, can be formed as a nut 13 with both an
internal thread and an external thread so as to be safely and
reliable guided on the anchor rod 1, on the one hand, and ensure
the safe engagement of the insertion device 14 on the outer
surface of the nut 13.
In the illustration according to Fig. 2, the reference numerals
of Fig. 1 have been retained as far as possible.
The configuration according to Fig. 2 differs from that of Fig.
1 merely in that the spreading element 7 is designed as a spring
sleeve formed with a continuous slot 8. Apart from that the
spreading element 7 designed as a spring sleeve has no other
pattern or contouring on its outer periphery.
In the illustration according to Fig. 3, which depicts the
device according to Fig. 2 in a state braced within the borehole
interior 15 and held in abutment on the borehole wall, the
reference numerals of Fig. 1 and Fig. 2 have again been
retained. From the illustration according to Fig. 3, it is
apparent that the drill bit 2 contacts the borehole interior 15
after the retraction of the expanding element 3 into the
spreading element 7 and reintroduction into the borehole. To
this end, the drill or anchor rod 1 was retracted into the
interior of the spreading element 7 along with the drill bit 2
and the expanding element 3 in a first step, while an axial
displacement in the direction to the outside of the borehole of
the spreading element 7 was prevented by the provision of the
sleeve 9 crimped to the anchor rod 1. The introduction of the
expanding element 3 causes the spreading element 7 to expand
until butting against the borehole wall, which is schematically
indicated by 16. After the expansion operation has been
completed, the drill rod assembly 1 is again urged in the
11
CA 02869235 2014-10-01
direction of the borehole interior 15 by a further movement, in
particular rotary movement, exerted by the insertion device 14
(not illustrated) engaging the nut 13. During such a rotary
movement, twisting of the expanding element 3 in the interior of
the spreading element 7 is prevented by the forces acting on the
expanding element 3 in the radial direction, of the spreading
element 7, and the rotary movement of the drill bit 1 merely
causes the shear pin 5, which is no longer visible in Fig. 3, to
tear off so as to enable the drill rod 1 to freely rotate in the
interior of the expanding element 3. The rotary movement of the
drill rod 1 is continued until the drill bit 2 is in abutment on
the borehole wall 15. While the drill rod 1 is again driven into
the borehole interior 15, the anchor plate 12 and the cover
element 11 are acted upon at the same time as the nut 13, thus
causing the two elements to close the formed borehole from
outside. Such a device thus, on the one hand, enables the drill
or anchor rod 1 to be introduced into the borehole over the
entire length of the formed borehole so as to safely prevent the
protrusion of an end of the anchor rod 1 from the formed
borehole and, on the other hand, allows any operating steps
necessary for the formation of a borehole and the fixation of an
anchorage in the borehole to be performed in a single operation.
Fig. 4 depicts a partially perspective, sectional view of an
optional variant of a borehole cover 11. The borehole cover 11
in this case is mounted on the drill or anchor rod 1 for rotary
movement via internal threads 17 and, due to the conical
configuration of the borehole cover 11, has a diameter
increasing in the direction towards the outside of the borehole.
Such a device not only enables the formation of a borehole, but
also safeguards the latter against any inadvertent penetration
of material, or the inadvertent penetration of curable material
to be optionally introduced simultaneously with the formation of
the anchorage, such as grout.
