EP0546128B1 - Injection pipe and process for setting a rock anchor - Google Patents

Abstract

PCT No. PCT/EP92/01208 Sec. 371 Date Nov. 22, 1993 Sec. 102(e) Date Nov. 22, 1993 PCT Filed May 30, 1992 PCT Pub. No. WO93/01363 PCT Pub. Date Jan. 21, 1993An injection bore anchor for use with rock having particularly low cohesive properties has at least two injection valves arranged in the front region of the injection bore anchor and formed as non-return valves so that it is possible for the grout suspension issuing from a longitudinal channel running through the injection bore anchor to flow out but not the reverse. In order to place the injection bore anchor, the injection bore anchor is initially used as a bore rod, wherein a flushing fluid is guided through a longitudinal channel and the bores in the region of a bore-crown. Subsequently, a grout suspension is introduced through the longitudinal channel into the bore hole for filling the bore hole, wherein subsequently the residual grout suspension located within the channel is displaced as far as the region of the bore-crown by a displacement body introduced into the channel. By a grout suspension being introduced again after the initial setting of the grout suspension in the bore hole and the rout suspension now flowing out due to the injection valves, exerting a cracking open effect on the grout located here and/or penetrating in the still existing cracks and gaps, the bore hole in the region of the bore hole bottom and the surrounding rock is expanded and thus the size of the region penetrated by the grout is considerably increased, so that it is possible to secure reliably the position of the injection bore anchor in the surrounding rock.

Description

The invention relates to an injection pipe according to claim 1. It also relates to a method for setting a rock bolt according to claim 22.

Injection drill anchors are known as such. Structurally they correspond essentially to boring bars or injection pipes which are used immediately after the drilling of the rock as a rock anchor and consequently remain within the drilling as a lost tool.

For example, from DE-A-37 24 165 an injection drill anchor is known which consists of at least one anchor rod section provided with an external thread over its entire length there is, at one end of the borehole bottom, a plate-like drill bit radially projecting beyond the anchor rod section and provided with cutting edges is welded. A longitudinal channel axially extending through the anchor rod section ends in the area of the drill bit in an axial flushing bore, with further crossbores serving for flushing purposes being provided in an area immediately adjacent to the drill bit. Such an injection drilling anchor is fundamentally suitable for drilling holes and then placing rock anchors, whereby a hole is first created using a suitable flushing medium, which flushing medium emerges through the flushing hole of the drill head and the above-mentioned cross holes, which picks up rock that is loosened as a result of the drilling process and rinses towards the mouth of the borehole. The longitudinal channel is then used in connection with the transverse bores to introduce a hardenable medium, e.g. a mortar suspension, which in the area of the drill head enters the annular space between the outside of the anchor rod section and the inside of the borehole and this, from the bottom of the borehole to its mouth progressively filled in. During this filling, cracks and gaps remaining in the individual rock layers are filled and in this way a reliable bond between rock anchor and rock is produced, which is further improved by the thread extending over the outside of the anchor rod section.

The brochure "Riploy, Extension rod equipment", P. & V. (Mining & Engineering) Limited, Sheffield, England 1971 and DE-A-34 00 182 also include screwable drill heads for boring bars or drill anchors known.

Rock anchors are known to be used in tunnel and tunnel construction to stabilize cavity walls and are also used to secure slopes. Their mode of operation is essentially based on the production of a bond between the rock layers which follow one another in the longitudinal direction of the anchor. Stabilization is difficult in all cases in which the layers to be joined together are to be regarded as low in cohesion, so that special measures are always required to achieve reliable anchoring.

From FR-A-2 306 307 an injection pipe is known which is designed as a drill pipe and is equipped at its end facing a drill tip with a plurality of injection valves having lateral outlet openings. The outside of the drill pipe is partially provided with a conveying helix and at its end facing away from the drill tip with a coupling member which enables the attachment of extension rods. The longitudinal channel defined by the drill pipe is continued via outlet bores in the area of the drill head, so that drilling can be carried out using a flushing medium. After drilling a hole, a mortar suspension is introduced over this drill pipe, which, among other things, exits laterally via the injection valves and penetrates the surrounding soil in this area. A rod-shaped tie rod is inserted into the actual drill pipe, which is in turn fixed in place using a mortar suspension. A similar injection tube is known from AT-A-361 857, which consists of a tubular body which is sealed on the borehole bottom side via a cover, which in turn has several is equipped axially with spaced injection valves and is otherwise profiled inside and outside thread-like. The compression valves are formed by smooth-walled pipe sections with cross bores, which are surrounded on the outside by an elastically deformable sleeve. The injection tube is equipped to accommodate several rod-like anchor elements as well as a centrally located injection hose. Cement milk is in turn pressed out laterally via the compression valves, which penetrates adjacent soil formations and forms consolidation zones which serve to improve the anchoring. Following this squeezing of cement milk via the injection valves, cement milk residues remaining within the injection tube are rinsed out and anchor elements are inserted which protrude from the injection tube at the upper end and which are in turn fixed within the injection tube by means of inserted cement milk.

It is the object of the invention to further improve an injection tube of the type described in the introduction, in particular with a view to use in extremely low-cohesion mountains. This object is achieved in a generic injection tube by the features of claim 1.

The pipe section used is equipped with a check valve, which allows an outflow transversely from the central longitudinal channel, but blocks a backflow. This check valve is intended to be used to hydraulically burst open the mortar body surrounding the pipe section in the area of this compression valve after the initial introduction of mortar into the borehole and in accordance with the supply pressure to expand the mortar suspension or other hardenable medium in terms of volume. In any case, the aim is to subsequently expand the mountain area, which is penetrated by the mortar suspension and thus contribute to the bond between the rock and the injection pipe, or to the consolidation and stabilization of the rock. This results in an anchoring effect comparable to an expansion dowel, which can be spatially expanded to a high degree in accordance with the supply pressure of the mortar suspension and the nature of the surrounding mountains. As soon as the further supply of mortar suspension is stopped, a backflow into the longitudinal channel of the injection pipe is prevented by this compression valve, so that the curing process can then begin. Corresponding to the expansion of the area covered by the mortar suspension with the involvement of the injection valve (s), there is a reliable bond between the injection pipe and the rock even with low-cohesion rock.

The injection pipe is designed in the manner of an injection drill anchor and equipped with a drill bit on the bottom of the drill hole. This is the essential, but not exclusive, application of the subject matter of the invention. The use of compression valves according to the above explanations naturally presupposes that after an initial filling of the drilled hole with a mortar suspension using the injection drill anchor located within the same, the already existing outlet openings of the drill head and the area of the anchor rod section near the drill head can be blocked. This can be done, for example, by inserting a displacement body, by inserting it into the longitudinal channel within the same, after filling the borehole, existing mortar suspension is displaced through the outlet openings mentioned and transferred into the mountains. This displacement body then remains within the longitudinal channel and is inserted into it so far that in each case the compression valves are exposed on the inside. Another procedure is made possible with injection drill anchors according to the invention. Its essential feature is at least one valve assigned to the outlet openings of the drill bit and the area of the anchor rod section near the drill bit, which is inserted into the longitudinal channel and is designed in the manner of a check valve. According to the invention, two valves or groups of valves are located in the area adjacent to the drilling base, namely the compression valves already mentioned on the one hand and the valves assigned to the outlet openings, inter alia, of the drill bit. Both valves differ in their preload and never function at the same time. For example, the pre-tensioning of the injection valves is such that they only open at a pressure sufficient for the subsequent injection, but not at the pressure under which the rinsing liquid is initially during drilling and the mortar suspension initially introduced to fill the borehole. The valves associated with the drill bit or the area near the drill bit are therefore dimensioned such that they open at a pressure under which the flushing liquid or the initially introduced mortar suspension is located. It is therefore essential that the two groups of valves mentioned always open one after the other, namely during different work phases and thus never at the same time. The training of both is also essential Types of valves in the manner of non-return valves, as a result of which a flowable medium flows through these valves in only one direction, namely out of the longitudinal channel into the surrounding mountain area.

According to the features of claims 4 and 5, the compression valve is preferably arranged only in an area adjacent to the drill bit. This can be, for example, an area starting from the drill bit of up to 50% of the length of the anchor rod section adjacent to the drill bit. In this way it is ensured that in particular the area adjacent to the bottom of the borehole experiences a spreading effect and thus a secure fixation in the surrounding mountains.

It is also conceivable to provide several injection valves along the injection drill anchor, so that the anchoring effect can be improved in a larger spatial area. In this case too, the compression valves are preferably arranged in such a length range - starting with the drill bit - that is at most 50% of the total length of the injection drill anchor or of the anchor rod section (s). This can be determined in individual cases in accordance with the found condition of the mountain strata to be connected.

The features of claims 6 and 7 are directed to a particularly simple and inexpensive embodiment of the compression valves to be used, in particular check valves. These valves can be placed anywhere along the anchor rod sections. They essentially exist from a hose section made of an elastic material, which is pushed over the anchor rod section and in its final assembly position sealingly covers a transverse bore. The locking rings mentioned protrude radially beyond the hose section and secure its axial position, in particular during drilling.

Instead of a transverse bore - and indeed in a uniform circumferential distribution - several transverse bores can also be provided in order to allow the mortar suspension to emerge as uniformly as possible. The hose section can particularly advantageously consist of a fiber-reinforced rubber material or a material of comparable elasticity, which is in any case dimensioned such that the valves remain inoperative during the initial filling of the borehole, that is to say remain in the closed state. The injection valves open only when the supply pressure is increased, a prior closing of the outlet openings of the drill head and other outlet bores used for flushing purposes being required, for example by means of a closure body.

According to the features of claim 8, a locking body is provided for each bore of the anchor rod section or the tubular element of the compression valve, which is held by the enveloping body in a position sealing the bores. In this case, the enveloping body forms a return spring that holds the locking body in the closed position. The blocking body as such can in principle have any shape and is designed, for example, as a ball, cone, truncated cone, etc. This design of a compression valve can be regarded as particularly reliable and in particular for very suitable for high pressures.

The features of claims 9 and 10 are directed to different variants insofar as the blocking body can be designed as a component which is separate from the enveloping body or is integral or integral therewith.

The features of claims 11 to 13 are directed to further embodiments of the locking body and the bore interacting with it. If a reinforcing insert is used, the locking body is very rigid, which can be advantageous at very high pressures. The bore has an inwardly tapering shape and the locking body is adapted to this design. In this way, an easier insertion of the locking body into the bore results when the pressure is reduced.

The compression valve can be particularly advantageously designed as an intermediate element between two tubular elements, for example the tubular cylinders taking over the function of locking rings correspond structurally to anchor rods, so that a central tubular element which projects beyond the tubular cylinders on both sides can be used as a screw-in for connection to an anchor rod end. This has the advantage that the pressing valve does not result in structural elements protruding from the anchor rod, after said envelope body is practically flush with the tubular cylinder or locking rings. This comparatively "smooth" design of the anchor rods favors the outflow of a flushing liquid loaded with rock particles during the drilling operation.

The locking rings can be connected to the anchor rod section in accordance with the features of claims 14 and 15 either by screwing or welding.

The problem described at the outset is achieved by the features of claim 22, based on a corresponding method. Thereafter, after an initial introduction of mortar suspension over the longitudinal channel of the injection drill anchor located in the borehole, this longitudinal channel is freed from the mortar suspension still present in this, at least to the extent that the injection valves are exposed radially on the inside. It is also necessary that due to the final position of the displacement body, all of the conventional outlet openings are closed in a suitable manner. As a result, that is, at the earliest after an initial setting or an initial hardening of the mortar surrounding the anchor rod section, it is hydraulically blasted. This process can be carried out by introducing a liquid medium such as water, but also by mortar suspension. The pressure prevailing during the flushing or the initial introduction of mortar within the longitudinal channel is less than 15 bar, while a pressure of more than 15 bar, in particular 60 bar to 100 bar, is required for the subsequent blowing up of the mortar. Accordingly, the elasticity of the hose section of the compression valves mentioned is dimensioned in such a way that they only open at the increased supply pressure that is required to blow up the mortar, but remain in the blocked state below this pressure. After blasting, mortar suspension can subsequently be introduced into cracks and cracks formed in this way and further into the surrounding mountains. As a result of the penetration, the cohesion of the rock loosens it, so that the penetration area of the mortar and surrounding rock layers is widened. As a result, after the mortar has hardened, a spreading anchoring area is formed which penetrates deeply into the surrounding mountains and forms a secure anchorage for the rock anchor.

Removal of the mortar suspension remaining in the longitudinal channel after initial filling of the borehole can be carried out in different ways according to the features of claims 23 and 24. First of all, a displacement element can be exerted on the still liquid mortar suspension by a displacement body inserted into the longitudinal channel and this can be displaced out into the surrounding mountains via the outlet openings in the area of the drill head. This displacement body then remains in the longitudinal channel, specifically in a position in which all outlet openings of the drill head or the region of the anchor rod section close to the drill head are closed. It therefore performs the function of a valve in connection with these outlet openings and is expediently designed in such a way that when moving in the direction of the end of the injection drill anchor located away from the drill head, there is a locking effect with the walls of the longitudinal channel, thus self-locking. It is the end position of the displacement body within the longitudinal channel also created such that the compression valves mentioned are exposed radially on the inside.

It is convenient for complete removal remaining mortar suspension still located within the longitudinal channel is still rinsed out. Instead of the subsequent introduction of a displacement body, a valve can also be provided in the area of the drill bit, specifically within the longitudinal channel, which is designed in the manner of a non-return valve, which valve is located upstream of the outlet openings of the drill head, which are used for flushing purposes designed such that it opens at the pressure at which the mortar suspension flows during the drilling operation and during the initial filling of the borehole. This is such a pressure at which the compression valves remain locked. If such a valve is used, the mortar suspension remaining within the longitudinal channel after the initial filling of the borehole is removed only by flushing, this valve remaining in the closed state, which requires a correspondingly low pressure of the flushing medium.

The process of multiple hydraulic sprinkling of the hardened mortar or other medium can analogously also be used for injection pipes, which are mainly used to consolidate rock by introducing mortar.

• Fig. 1 eine schematische Darstellung einer Seitenansicht eines erfindungsgemäßen Injektionsankers;
• Fig. 2 eine Detaildarstellung der Einzelheit II der Fig. 1 in teilweise geschnittener Darstellung;
• Fig. 3 ein erstes Ausführungsbeispiel eines Verdrängungskörpers;
• Fig. 4 ein zweites Ausführungsbeispeil eines Verdrängungskörpers;
• Fig. 5 eine Schnittdarstellung eines dem Bohrkopf benachbarten Bereiches des Injektionsbohrankers;
• Fig. 6 eine Schnittdarstellung einer anderen Ausführungsform eines dem Bohrkopf benachbarten Bereiches eines Injektionsankers;
• Fig. 7 eine Schnittdarstellung der wesentlichen Teile einer bevorzugten Ausführungsform eines Verpreßventils;
• Fig. 8 eine Ansicht einer anderen Ausführungsform eines Verpreßventils;
• Fig. 9 eine Darstellung einer Variante eines Details IX der Fig. 7.

The invention will be explained in more detail below with reference to the embodiment shown in the drawings. Show it:

• Figure 1 is a schematic representation of a side view of an injection anchor according to the invention.
• FIG. 2 shows a detailed illustration of the detail II of FIG. 1 in a partially sectioned illustration;
• 3 shows a first embodiment of a displacement body;
• 4 shows a second exemplary embodiment of a displacement body;
• 5 shows a sectional illustration of a region of the injection drill anchor adjacent to the drill head;
• 6 shows a sectional illustration of another embodiment of a region of an injection anchor adjacent to the drill head;
• Fig. 7 is a sectional view of the essential parts of a preferred embodiment of a compression valve;
• 8 is a view of another embodiment of a compression valve;
• FIG. 9 shows a variant of a detail IX of FIG. 7.

1 in FIG. 1 denotes an injection drill anchor or a so-called self-drilling injection anchor, which in the exemplary embodiment shown is composed of the anchor rod sections 2, 3 and 4. Each anchor rod section is covered in a known manner on the outside over its entire length with a round thread, which among other things, the improvement the form fit with a mortar or a other hardenable medium, eg synthetic resin, which otherwise fills a borehole.

With 5, 6 connecting sleeves are designated, in which the ends of the opposite anchor rod sections are screwed and by which the cohesion of the anchor rod sections is ensured. The connecting sleeves are designed as tubular bodies formed with inside and outside thread-like deformations and the connecting sleeve 5 is equipped with a plurality of spacers 7 in the form of round bars welded on the outside. With 8 a plate-like, in terms of diameter the anchor rod section 2 clearly superior, borehole side equipped with cross-cut bits is designated, which is welded to the anchor rod section 2.

9 finally designates a clamping nut intended for screwing onto the end of the anchor rod section 4 and for interacting with an anchor plate, which is not shown in the drawing and is known per se.

The anchor rod sections 2, 3 and 4 and the drill bit 8 contain a central longitudinal channel extending in the direction of the axis 10, from which further continuous transverse channels can branch off in the area of the drill head. In principle, transverse channels can also be provided in the area of the anchor rod section 2 near the drill head. Said channel and the transverse bores serve in a manner known per se during the creation of a bore to guide a flushing medium and after the bore has been created to introduce one Mortar suspension, a resin or a comparable curable other medium that is suitable for producing a composite between the injection anchor 1 on the one hand and the surrounding borehole walls on the other hand.

The front anchor rod section 2, which carries the drill bit 8, is equipped in the exemplary embodiment shown with two compression valves 11, which are of identical design to one another. These compression valves 11 are attached along an area 12 which, starting from the drill bit 8, is at most 50% of the total length of the injection drill anchor 1. The compression valves 11, which are of identical design, are designed in such a way that, starting from the longitudinal channel of the boring bar section 2, they allow media to pass under pressure in the radially outward direction - in the opposite direction, namely directed radially inward, on the other hand, act as check valves.

To explain a possible structural design of such a compression valve 11, reference is made below to the illustration in FIG. 2:

The anchor rod section 2 is provided at the location of the compression valve 11 with locking rings 15 which are pushed onto the anchor rod section and are welded to the latter leaving a distance 14. However, a screw connection can also be considered.

Within the distance 14 between the locking rings 15 there is a transverse bore 16, preferably in the middle section between the locking rings 15. Also preferably, a plurality of such cross bores 16 are provided - with a uniform circumferential distribution. These transverse bores form a continuous connection to the longitudinal channel mentioned and their meaning and purpose will be explained in the following.

17 with a tube section sealingly surrounding the anchor rod section 2 is made of an elastic material, for example rubber, which extends between the locking rings 15, by means of which the axial position thereof is secured. The thickness of the hose element 17, which expediently consists of a fabric-reinforced rubber, is carried out in such a way that it runs essentially flush with the locking rings 15. The system of locking rings 15 and hose section 17 forms a compression valve which functions in the manner of a check valve, the mode of operation of which will be explained in more detail below.

The injection drill anchor shown in the drawings is intended for use in specially used, low-cohesive rock and it is initially used for setting like a boring bar, through the longitudinal channel of which a suitable flushing medium, e.g. water, flows during the drilling process, which flows through the central flushing hole of the drill bit 8 and optionally the further flushing bores emerging in this area, subsequently absorbs the rock material loosened by the cross-cutting of the drill bit 8 and is washed out between the inside of the borehole formed and the outside of the anchor rod sections 2, 3, 4 in the rearward direction towards the ßohrlochmuzzle . The conveying process is thereby caused by the thread-like extending over the entire length of the injection drill anchor, including the connecting sleeves 5, 6 Deformation supports. Depending on the length of the borehole and the progress of drilling, the drill rods are extended using connecting sleeves 5, 6 and further anchor rod sections 3, 4 until the final borehole depth is reached. Subsequently, a hardenable medium, for example a mortar suspension, is introduced via the longitudinal channel mentioned, which in turn exits through the flushing bores mentioned in the area of the drill head and partially penetrates into the surrounding mountains and partially flows along the outside of the injection anchor in the direction of the hole opening , whereby the existing cavity is filled. During the flushing and filling of said cavity, the flushing liquid or mortar suspension within the longitudinal channel of the anchor rod sections 2, 3, 4 is under a pressure of less than 15 bar, that is, under a pressure at which the compression valves 11 are in any case in the blocked state remain. After completion of this first phase of anchor setting, the remainder of the mortar suspension remaining in the anchor channel is displaced by introducing a displacement body, which will be explained structurally below, into the central channel of the anchor by moving said displacement body in the direction of the drill bit 8 within the injection anchor. In any case, the displacement body is displaced into such an area of the injection anchor 1 that is located between the drill bit 8 and the foremost compression valve 11. It is also essential for the final position of the displacement body that all of the usual flushing holes are closed by the latter, so that the longitudinal channel forms a closed space in this working phase. After insertion of the displacement body, it is particularly expedient for the remaining one in the longitudinal channel, if appropriate flush out any mortar suspension still present with a rinsing medium.

Subsequently, after a first setting of the mortar suspension, for example after at least 6 h, a mortar suspension under pressure is again introduced into the injection anchor 1 via the longitudinal channel, which now exits via the transverse bores 16 of the compression valves 11 and thereby the hose section 17 is correspondingly elastic expands. The escaping mortar suspension exerts an explosive effect on the mortar already in the borehole in this area or penetrates into the gaps formed in this way, so that as a result of this renewed mortar leakage in the area of the injection valves, the already existing penetration area of mortar and any loosened Mountain parts expanded or enlarged, a significant spreading effect on the structure of the overall system, consisting of mortar and rock anchor is exerted and thus helps to further secure the position of the injection drill anchor 1 in the borehole.

Alternatively, the mortar can also be blown open with rinsing liquid, e.g. Water are carried out so that a mortar suspension is only then introduced.

In particular with downward or obliquely downward oriented boreholes, after filling the borehole and introducing the displacement body and subsequent flushing of the longitudinal channel, the flushing liquid remaining within the same can be left, so that a subsequent hydraulic blasting of the mortar surrounding the injection drilling anchor within the borehole by means of mortar suspension underneath Intermediate arrangement of the liquid column located within the longitudinal channel consisting of rinsing liquid can be made.

If the expansion process in the above sense is ended or the feed pressure of the mortar suspension within the injection anchor 1 is reduced, the elasticity of the hose sections 17 prevents mortar from flowing back into the injection drill anchor 1, so that the compression valves function as check valves.

The expansion process shown above can be repeated several times if necessary. Whether the expansion process is to be repeated depends on the result of the measurement of the ability of the rock bolt to absorb tensile forces, which is carried out according to known methods. For this purpose, the remaining mortar suspension still in the longitudinal channel is rinsed out after a first widening process, immediately after the compression valves 11 have been closed. This can be done, for example, by means of a hose which is introduced into the longitudinal channel, the rinsing liquid, e.g. Water that absorbs and flushes out mortar suspension. In this way, the longitudinal channel up to the displacement body mentioned, i.e. including the compression valves 11 exposed. Then i.e. after at least an initial setting of the mortar suspension, the expansion step described above is repeated, i.e. the mortar surrounding the anchor rod section is hydraulically blasted in order to subsequently introduce further mortar suspension into the borehole.

The compression valves 11 can also be used to equally as during the first introduction of mortar suspension as outlet openings for this To be available.

In order to achieve a particularly reliable sealing effect of the compression valve 11, this can be designed such that the hose section 17 surrounds an inner hose made of a relatively soft, preferably rubber-like material, which is suitable for sealing interaction with the external thread of the anchor rod section 2 and through the outer Hose section 17 experiences a radial support effect. As an alternative to the arrangement of an inner tube, the external thread interacting with the tube section 17 can also be smoothed by applying a suitable mass, vulcanization of a rubber material basically being considered. A comparable effect is achieved if there is a smooth wall profile at the locations of the anchor rod section 2, which are used to attach compression valves 11, and thus without thread-like deformation.

As a result, the method according to the invention and the injection drill anchor used to carry it out result in a particularly secure fit of the anchor as a result of the spreading effect exerted on the borehole walls, especially in the case of mountains with little cohesion.

3 and 4 show examples of possible embodiments of a displacement body intended for use in the injection anchor. 3 shows an essentially spherical displacement body 18, which consists of a metallic core 19, which in turn is surrounded by a sleeve 20 made of an elastic material. The displacement body is dimensioned such that a displacement of the same within the central channel only with elastic deformation of the casing 20 is possible, which creates a significant frictional connection with the inner walls of the anchor rod sections. A bore 21 penetrating the shell 20 serves to facilitate the displacement of the displacement body 18 by means of a rod which acts directly on the metallic core 19.

FIG. 4 shows a displacement body 22 which has a metallic, cylindrical core 23 and a rotationally symmetrical sleeve 24 which surrounds it conically, the latter in turn consisting of an elastically deformable plastic. With regard to the dimensions, the same applies as in FIG. 3.

However, numerous modifications of the displacement body are conceivable, in particular it can also be equipped on the outside with bristles, ribs or the like, which develop a blocking effect in particular in the rearward direction in connection with the inside of the longitudinal channel. Instead of the metal-plastic material combination, a hard plastic-soft plastic material combination can also be used.

5 shows a possible embodiment of the area adjacent to the drill head 8. A comparably short part of an anchor rod section is designated therein by 25, which is welded to the plate-like drill bit 8, which is equipped with cross-cutters (not shown in the drawing). The anchor rod section 25 is in turn screwed into a connecting sleeve 26 and additionally welded to it. With 28 a central, in the direction of the axis 10 rinsing bore of the drill head 8 is designated.

The screwing of the connecting sleeve 26 to the anchor rod section 25 takes place in such a way that an unimpeded discharge of a flushing medium or a mortar suspension is possible via radially oriented flushing bores 27. The connecting sleeve 26 also serves, in a manner known per se, for screwing on the inside with further anchor rod sections.

According to the invention, a displacement body to be used in the sense of the above explanations is dimensioned such that it can be inserted into the cross section 29 of the anchor rod section 25 in such a way that all flushing bores 27, 28 are closed.

The embodiment shown of the area adjacent to the drill bit 8 is also very advantageous from a drilling or fluidic point of view, since there is a relatively large undercut 30 directly behind the drill bit 8, which promotes the removal of the rock material loosened during the drilling process.

In deviation from the above statements, it is also sufficient for the function of the displacement bodies 18, 22 if they can be frictionally fixed in a region 31 of the connecting sleeve 26 which - in the direction of the flow of a flushing medium characterized by the arrow 32 - contains all the flushing bores 27, 28 is upstream, since in principle the rinsing bores 27 in the form of radial bores can in principle be provided in a region near the boring head, and thus also in the connecting sleeve 26. It is only essential in this case that a valve function can be performed by inserting the displacement body insofar as all of the flushing bores mentioned can be closed by this.

The embodiment of the region of the injection drill anchor near the drill head shown in FIG. 6 has been modified in such a way that the function of the blocking body 18, 22 is now replaced by a fixed valve 33 that fulfills the function of the check valve. It is this valve - as will be explained in more detail below - designed such that a flow in the direction of arrow 32 is made possible, but is blocked in the opposite direction to arrow 32. Insofar as a valve is suitable for fulfilling these functions, any valve, albeit with a different design, can be used here.

The valve 33 consists of a valve body 34, which in turn consists of a head part 35, which is designed for the largely sealing screw connection to the inside of the socket part 26, on the one hand, and a smooth, externally smooth attachment part 36, which is formed integrally with the head part 35. The extension part 36 has a significantly smaller radius than the head part 35, so that - around the extension part 36 - there is an annular space 37.

The valve body 34 has a central bore 38, which extends coaxially to the axis 10 and is closed at its front end facing the drill bit 8.

39 designates a hose section made of an elastic material, for example a rubber-elastic material, which surrounds the rotationally symmetrical extension 36 and seals the same in the relaxed state transverse bores 40 which open into the bore 38.

It is essential that the hose section 39 is designed by its thickness dimensioning and / or a suitable choice of material such that its elasticity is substantially greater than that of the / hose sections 17, so that the valve 33 consequently enables a flow in the direction of the arrow 32 at pressures , in which the compression valves 11 remain in the closed state.

As already mentioned at the beginning, these are pressures of, for example, less than 15 bar.

The use of an injection drill anchor equipped in the sense of FIG. 6 is as follows:

The injection anchor is initially used as a boring bar in a manner known per se via a flushing medium flowing in the direction of the arrow 32, the flushing medium flowing via the valve 33 and exiting via the flushing bores 27, 28. After the borehole has been drilled, a mortar suspension or another hardenable medium is guided in the direction of arrow 32 in a manner known per se, which, according to its pressure, likewise flows exclusively via valve 33 and not via compression valves 11, i.e. emerges in the area of the flushing bores 27, 28 and - starting from the bottom of the borehole - fills the entire borehole.

Subsequently - by means of lower pressure - the mortar suspension remaining within the injection drill anchor is rinsed out, the valve 33 now preventing a further flow in the direction of arrow 32 due to the mortar suspension acting on the outside of the hose section 39, whereas the interior of the injection drill anchor is flushed out as far as valve 33 is. Incidentally, this flushing pressure is dimensioned such that the valve 33 never opens. Particularly in the case of boreholes running downwards or diagonally downwards, the rinsing liquid filling the injection bonner can remain therein, and after the mortar has hardened, this liquid can be used as a hydraulic means for blowing up the mortar surrounding the Bonranker by means of the compression valves 11. It will be the one within the Bohrankers remaining liquid column is used by this adjoining mortar to burst open, the mortar finally exits through the compression valves 11 and develops the effect already described above.

This embodiment can of course also be used in such a way that after the injection drill anchor has been rinsed out, the mortar is blown open directly by means of a mortar suspension.

It can be seen from the above statements that the injection drill anchor according to the invention is essentially characterized by two valves or valve groups, namely a first valve 33 assigned to the drill head, which serves for flushing and initial filling of the borehole and which opens at a comparatively low pressure , ie a flow in the direction of arrow 32 enables. However, this first valve has no function after the filling and hardening of the mortar suspension and subsequently acts as a blocking body which prevents any further flow through the flushing holes mentioned. It also acts as a non-return valve during the flow of flushing medium and initial mortar suspension, ie it prevents backflow in the opposite direction to arrow 32. The second valve or the group of valves used here are the compression valves which - seen in the direction of arrow 32 - Upstream of the first valve and serve to control the flow via radial bores or transverse bores 16. Naturally, several of these compression valves can be provided and these compression valves are also designed in the manner of check valves, the essential feature of which, however, is that they move away from the first-mentioned valve Only open at a significantly higher pressure present within the injection drill anchor, which is greater than 15 bar, for example between 50 bar and 100 bar. As already stated above, these compression valves are completely inoperative during flushing and the initial filling of the borehole due to their high opening pressure, ie they are in the closed state during this phase. It can also be seen from these statements that both valves or valve groups, viewed in the direction of flow, can be regarded as spring-loaded valves, the preload of which is of different magnitudes. Accordingly, any constructive modifications of valves can be used here which functionally correspond to the valves shown, which are under prestress.

At 41 in FIG. 7, a variant of a compression valve is designated, which consists of a tubular element 42 provided with an external thread and a tube-like enveloping body 43 surrounding it coaxially. The tubular element 42 can be directly part of an anchor rod - but it can also be an intermediate element intended and designed for installation between two anchor rod sections. The enveloping body consists of an elastic, preferably rubber-elastic material, which in turn can have a fabric reinforcement if necessary.

With 44, a radially inwardly tapered bore of the tubular element is designated, in which - held by the enveloping body 43 - a spherical locking body 45 is inserted. It can be seen that the blocking body 45 in connection with the elastic body in the bore 44 from the outside of the tubular member 42 elastic Pressing enveloping body 43 forms a spring-loaded check valve. The spring characteristic of this compression valve 41 is designed by appropriate dimensioning or design of the enveloping body 43 in such a way that the blocking body 45 is displaced from the bore 44 against the elastic restoring force of the enveloping body 43 only at an increased pressure in the radially outward direction and flows out into enables the outside space that is required for the subsequent blasting of an initially hardened mortar body that surrounds the anchor rod on the outside and otherwise remains inoperative, that is to say remains in the closed state.

The locking body 45 can be made of metal, e.g. Steel. However, it can also be formed from a suitable plastic. The spherical shape of the blocking body is also not mandatory and a conically shaped body can also be used for this purpose in the same way.

To axially secure the enveloping body 43, locking rings, not shown in the drawing, can in turn be provided in FIG. 7, which are screwed onto the outside of the tubular element 42 and extend on the outside essentially flush with the enveloping body 43. The final assembly position of these locking rings can also be secured by welding to the tubular element 42.

The compression valve 41 completed in the above sense can also be used in the same way as the compression valve described in FIG. 2.

The variant of a compression valve 46 shown in FIG. 8 is again characterized by a central tubular element 47, which is designed in the same way as the tubular element 42 according to FIG. 7. In deviation from the tubular element 42, however, the tubular element 47 is characterized by four bores 48 of the same size arranged along a surface line, which bores in turn have a radially inwardly tapering configuration. In the same way as in the embodiment shown in FIG. 7, each bore 48 is assigned a blocking body, not shown in the drawing, which is held elastically in the bore by an enveloping body 50. Alternatively, the bores 48 can also be arranged in different circumferential angular positions with respect to one another. With regard to the strength of the tubular element 42, however, the bores 48 should not be arranged in a common cross-sectional plane.

With 51, 52 tube cylinders are designated, which are provided on the inside and outside with thread, are screwed onto the tube element on both sides of the enveloping body 50 and in this respect take over the function of locking rings. If necessary, the tube cylinders 51, 52 can be secured in the final screwing position by welding to the tube element 47.

The tubular element 47 can in this case be part of an anchor rod - in principle, however, the compression valve 46 in the embodiment shown in FIG. 8 can also be regarded as an intermediate element between two anchor rod ends.

If the tubular element 47 is to be regarded as part of the anchor rod, this can be connected to another end of the anchor rod using a conventional coupling sleeve.

However, the two ends of the tubular element 47 protruding from the tubular cylinders 51, 52 can also be regarded as screw-in ends which are screwed into an opposite anchor rod end which has radial dimensions and an external thread which correspond to the tubular cylinders 51, 52. In this case, the tubular cylinders 51, 52 can be regarded as part of an anchor rod, and in this case there is an anchor rod which has no structural elements that project on the outside in the region of the compression valve.

FIG. 9 shows an enveloping body 53 which is formed in one piece with a locking body 54 which has an approximately conical shape.

The blocking body 54 in turn protrudes into a bore 55 of a tubular element 56 corresponding to the tubular elements 42, 47 and is held in this position in an elastically pre-stressed manner. In this variant of the design of the locking body, a plurality of such locking bodies can also be provided in a configuration corresponding, for example, to FIG. 8.

The enveloping body 53 in turn consists of an elastic plastic, possibly reinforced by fabric inserts, for example a rubber-like plastic, and its thickness is designed with regard to the function of a compression valve described above.

The conical shape of the locking body 54 is approximately matched to that of the bore 55, but may also have a hemispherical shape.

The locking body 54 is in the embodiment according to Fig. 9 made of the same material as the enveloping body 53. To increase the rigidity of the former, a reinforcing body can be incorporated into the elastic material, for example in the form of a sphere or hemisphere.

A compression valve designed in the sense of FIGS. 7 to 9 is particularly suitable for high pressures, in particular if several compression processes are to be carried out in succession.

Claims (30)

1. Injection tube consisting of at least one tube portion which is provided with a continuous external profiling, through which tube extends a central longitudinal channel, wherein the tube portion is provided with at least one injection valve (11) which renders it possible for the stream to flow transversely out of the longitudinal channel, which injection valve is in the form of a non-return valve which prevents the flow returning in the direction of the longitudinal channel,

   - wherein the tube portion is the anchor rod portion (2) of an injection drilling anchor (1) which consists of a plurality of anchor rod portions (2, 3,4) having connection sleeves (6),

   - wherein the longitudinal channel continues in a bore-crown (8) and issues at least into one exit orifice,

   - wherein the exit orifice(s) of the bore-crown (8) and of the region close to the bore-crown of the anchor rod portion (2) is allocated at least one valve (33), which is in the form of a non-return valve, i.e. renders it possible for material to flow out of the longitudinal channel but prevents the material from flowing back into the longitudinal passage, and

   - wherein at least one injection valve (11) on the one hand and at least one valve (33) on the other side - as seen in the flow direction - are in the form of pre-stressed valves (11,33) and in fact on the condition that the injection valve (11) opens at higher pressures than the valve (33).
2. Injection tube according to claim 1, characterised in that

   - the continuous profiling of the tube portion is in the form of a thread.
3. Injection tube according to claim 1 or 2, characterised in that:

   - the end remote from the bore-crown (8) of the anchor rod portion (2) is intended in a manner known per se for screwing on further anchor rod portions (3, 4).
4. Injection tube according to any one of claims 1 to 3, characterised in that:

   - the injection valve (11) is disposed in a region adjacent to the bore-crown (8).
5. Injection tube according to any one of the preceding claims 1 to 4, characterised in that:

   - a plurality of injection valves (11) are provided in a region adjacent to the bore-crown (8), wherein this region starts from the bore-crown (8) and extends over a length of a maximum 50% of the entire length of the injection drilling anchor (1).
6. Injection tube according to any one of claims 1 to 5, characterised in that:

   - each injection valve (11, 41, 46) consists of at least one bore hole (44, 48, 55, 17) of a tube member (42, 47, 56) or of an anchor rod portion (2, 3, 4), which bore hole is surrounded in a sealing manner on the outside by a sleeve (43, 50, 53) or a tube portion (17).
7. Injection tube according to claim 6, characterised in that coaxial stop rings (15) or tube cylinders (51, 52) are provided axially on both sides of the sleeve (43, 50, 53) or of the tube portions (17) for the purpose of securing the axial position.
8. Injection tube according to claim 6 or 7, characterised in that:

   - a blocking member (45, 54) is disposed in each bore (44, 48, 55) which encloses the said bore in a sealing manner and is held in this closing position by virtue of the sleeve (43, 50, 53).
9. Injection tube according to claim 8, characterised in that the blocking member (45) is in the form of a separate part and is made of metal or synthetic material.
10. Injection tube according to claim 8, characterised in that the blocking member (54) is in the form of a part which is connected to the sleeve (53).
11. Injection tube according to claim 10, characterised in that the blocking member (54) is in the form of a part whose material is homogenous to that of the sleeve (53).
12. Injection tube according to claim 10 or 11, characterised in that the blocking member (54) is in the form of a part whose material is homogenous with that of the sleeve (53) but the said part is provided with reinforcing inserts.
13. Injection tube according to claim 12, characterised in that the reinforcing insert is in the form of a sphere, hemisphere, cone or truncated cone or similar.
14. Injection tube according to any one of the preceding claims 7 to 13, characterised in that:

    - the stop rings (15) and the parts connected thereto of the respective anchor rod portions (2, 3,4) are connected to each other preferably in such a manner as to be non-releasable, in particular welded to each other.
15. Injection tube according to any one of claims 7 to 13, characterised in that:

    - the stop rings (15) are screwed to the corresponding portions of the anchor rod portions (2, 3, 4).
16. Injection tube according to any one of the preceding claims 6 to 15 characterised by:

    - a smooth-walled design in the region of the anchor rod portion (2) which cooperates with the tube portion (17).
17. Injection tube according to any one of the preceding claims 6 to 15, characterised by:

    - a further tube portion which consists of a soft rubber-type material and is disposed within the tube portion (17), which further tube portion is intended to lie in a sealing manner on the external thread of the anchor rod portion (2).
18. Injection tube according to any one of the preceding claims 1 to 17, characterised in that:

    - the valve (33) consists of a valve body (34) which is disposed within the longitudinal channel upstream of the exit orifices as seen in the direction of the flow of a flushing medium.
19. Injection tube according to claim 18, characterised in that:

    - the valve body (34) consists of a head part (35) which is intended to provide an attachment to the inner side of the anchor rod portion (2) and a projection (36) which is surrounded in a sealing manner by a tube portion (39) made from an elastic material and which projection is formed preferably as one piece with the head part (35), and

    - furthermore that the valve body (34) comprises a longitudinal bore hole which cooperates with the transverse bore holes (40) which are blocked by the tube portion (39), and

    - furthermore that the longitudinal bore hole is otherwise only open at one end side.
20. Injection tube according to claim 19, characterised in that:

    - the head part (35) is screwed into the anchor rod portion (2), and

    - furthermore that the valve body (34) is rotationally symmetrical, and

    - furthermore that the longitudinal bore hole extends in the direction of the axis (10).
21. Injection tube according to claim 19 or 20 characterised in that:

    - the projection (36) is dimensioned radially in such a manner that an annular chamber is produced which is delimited on the outer side by the inner side of the anchor rod portion (2).
22. Method for setting a rock anchor by using an injection drilling anchor (1) according to any one of the preceding claims 1 to 21, wherein during a first step a bore hole is produced using a suitable flushing medium and during a second step a hardening medium, for example a mortar suspension, is introduced into the bore hole by way of the longitudinal channel of the injection drilling anchor (1) as well the exit bore holes thereof, which hardening medium fills to a greatest extent the annular space between the inner side of the bore hole on the one side and the external side of the anchor rod portion (2, 3,4) on the other side and

    - wherein during a third step after having filled the annular space the mortar suspension remaining within the longitudinal channel is removed, thus releasing the injection valve(s) (11) and

    - moreover, during a fourth step by way of at least the one injection valve (11) an expanding effect is exerted in a hydraulic manner on the mortar surrounding the anchor rod portion (2) and a mortar suspension is pressed into the existing gap, crack or similar.
23. Method according to claim 22, characterised in that:

    - the mortar suspension is removed from the longitudinal channel by means of a displacement member (18, 22), by means of which the mortar suspension is pushed out through the exit orifices of the bore-crown (8) as well as the region of the anchor rod portion (2) in the proximity of the bore-crown, and

    - furthermore, that after having completed the third step, the displacement member remains within the longitudinal bore hole.
24. Method according to claim 22, characterised in that:

    - the mortar suspension is removed from the longitudinal channel, in particular when using a valve (33) by virtue of being flushed out by means of a suitable flushing fluid, e.g. water.
25. Method according to claim 23, characterised in that:

    - following the insertion of the displacement member (18,27), the longitudinal channel is flushed out by means of a suitable flushing fluid, e.g. water.
26. Method according to any one of claims 22 to 25, characterised in that:

    - within the scope of the fourth step, an expanding effect is exerted on the mortar surrounding the anchor rod portion (2,3,4) by introducing a mortar suspension and the mortar suspension is subsequently pressed into the existing gap, crack or similar.
27. Method according to any one of claims 22 to 25, characterised in that:

    - within the scope of the fourth step, an expanding effect is exerted on the mortar surrounding the anchor rod portion (2, 3,4) by virtue of introducing a flushing fluid, e.g. water and subsequently a mortar suspension is introduced and pressed into the existing gap, crack or similar.
28. Method according to any of the claims 24 to 26, characterised in that:

    - in the case of a gradient or downwards directed bore holes the flushing fluid remains within the longitudinal channel after the said channel has been flushed out and that the mortar suspension is introduced within the scope of the fourth step whilst arranging in-line the existing fluid column consisting of flushing fluid by way of which an expanding effect is exerted.
29. Method according to any of the preceding claims 26 to 28, characterised in that:

    - following on the fourth step the mortar suspension remaining within the longitudinal channel is flushed out during a fifth step and the said fourth step is repeated.
30. Method according to claim 29, characterised in that the fifth and fourth steps are repeated at least once.

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