Technical field The invention relates to a method, a drilling module in combination with a drilling crown and use in connection to pre bolting with top hammer drilling, including automatic drilling with and installation of drilling modules and interconnectable self drilling drill modules. The invention relates to rock chambers or tunnels in a rock volume reinforced through pre-bolting with a plurality of assemblies consisting of a plurality of drilling module sin combination with a drilling crown.

Background

In connection with the construction of facilities in rock, such as tunnels or rock chambers, rock of lower mechanical strength must sometimes be bypassed. In order to avoid undesirable collapse of rock and to maintain a desired cavity contour, this rock may need to be reinforced. A common method of reinforcing the rock is pre-bolting.

In order to pre-bolt rock, for increasing the stability thereof before the removal of rock material, bolts or tubes are used, which have different dimensions and lengths and which are drilled around a contour like a shield with different c/c-measures (figure 1 ). Drilling modules, herein also referred to as bolts, pre-bolts, tube bolts and rock reinforcement tubes, are drilled into the rock by means of different types of rock drilling machines. The pre-reinforcement system most commonly used today comprises drilling and moulding reinforcement bars of different dimensions (16-32 mm). This system requires that the hole that has been drilled does not collapse before the bolt has been installed.

If the quality of the rock is so inferior that the hole collapses after the drilling, a self-drilling pre-bolt may be installed. A self-drilling bolt is provided with a drilling crown which remains in the hole. Such a bolt is, furthermore, hollow, since water needs to be conducted to the crown for the drilling. After installation of the bolt, the same inner space of the bolt is used and an injection packer is mounted in the end of the bolt, and concrete is injected into the bolt. However, known techniques with self-drilling bolts have deficiencies with respective automation, material properties of drilling modules and the straightness of the drilling holes.

As rock chambers or drill tunnels become increasingly larger and there are increased requirements on mechanical strength, straightness and length of bolts, tube bolts are preferred. The systems used today comprise steel tubes with dimensions between 0 76 and 140 mm. Drilling and installation is done by means of down the hole rock drills, wherein the tube and the rim remains after removal of the down the hole drill hammer after drilling. In connection to the drilling with larger dimensions, a special drilling equipment is required, but for smaller dimensions, for example 0 76 mm diameter, a rock drill machine with liner tube drilling by means of a top hammer may be used. However, this method is time-requiring.

The disadvantages of today’s system is that personnel has to change/put in tube extensions during installation, that the system requires special equipment or extensive rearrangement, and requires personnel and time, which affects the economy negatively. Summary of the invention

Generally, the invention provides for the installation of tubular bolts in a safe way in regard to work environment, with a minimum of personnel and time-efficiently, and thereby economically, by using the automatic rod handling (figure 3) which is presented by rock drilling machines with top hammer technology. The tube length is adapted to the feed length of the drill rig, from 18 to 20 feet-feeders, wherein the tubes are loaded in corresponding alternating positions in the normal rod handling system of the machine. This results in an automated, work environment- friendly, time-optimized and thereby economically advantageous installation of the tube bolt.

More specifically, the invention provides a method for reinforcement of a rock volume by means of pre-bolting, wherein the method comprises: providing a top hammer drilling machine for the rock volume, said drilling machine being configured for automatic feeding of and drilling with a plurality of drill modules; initially loading the top hammer drilling machine with at least one of said plurality of drilling modules, wherein this drilling module is provided with a drilling crown (in rock drilling also referred to as a drill bit); initially loading a storing magazine of the top hammer drilling machine with at least one of said plurality of drilling modules for its automatic feeding in a sequence during drilling; automatically feeding sequentially and drilling said drilling crown and said plurality of drilling modules (2, 3) into a resulting drill hole in the rock volume by means of the top hammer drilling machine; fixing the drilling crown and said plurality of drilling modules in the drill hole by injecting a fixation substance in the drilling hole; wherein said plurality of drilling modules have a maximum outer diameter of 50 mm - 60 mm, preferably 55 mm, and wherein the drilling crown has a maximum outer diameter which is 5 mm - 16 mm, preferably 11 mm, larger than the maximum outer diameter of said plurality of drilling modules.

The term “a plurality” may mean “at least one” herein.

In the patent claims and in connection to the disclosure of the invention, the term top hammer drilling machine 1 , 6, 7, 7’ is used in a wide sense, more precisely as a collective concept that includes feeding beam 7’, beam 7 which carries the feeding beam 7’, rod handling device (with its carousel plates) etc., and the drilling machine (including its neck 1 ), which may be of the type Epiroc COP 3038. The drilling machine is not disclosed in its entirety.

It has been found that the combination of the diameters of the drilling modules and the drilling crown under these conditions is very important in order to accomplish drilling with a good straightness.

The drilling modules are tubular, and, in an assembled state, they form a continuous tube in which both cooling water may be applied and mortar may be injected for the permanent fixation of the rock reinforcement, which finally, as will be realized by the person skilled in the art when reading this disclosure, typically is formed by some drilling modules, preferably riveted together via the threadings of the drilling modules, a drilling crown and hardened mortar.

Drilling modules are interconnected by means of threadings, preferably of the type T45, which, in combination with the pressure of the drilling, the rotation and, in particular, the hammering, and in combination with the properties of the chosen steel material of the drilling modules, result in riveting and press fitting. This is advantageous since the drilling energy can be transferred more efficiently between the drilling modules. It is also important that efficient impact surfaces are present at the threading joints between the drilling modules. Furthermore, the choice of the steel quality is important for the drilling modules, which, according to tests, should comprise steel having a rupture strength of 650 MPa +/- 20%, preferably +/- 10%.

The invention also comprises a single drilling module for pre bolting of a rock volume, comprising, in combination, a power transfer between a top hammer drilling machine and a drilling crown, on one hand, a pre-bolt in a rock volume, wherein the drilling module preferably comprises steel having a rupture strength of 650 MPa +/- 20%, preferably +/- 10%. As mentioned hereinabove the combination of a drilling module and a drilling crown is a part of the invention. The drilling module has a maximum outer diameter of 50 mm - 60 mm, preferably 55 mm (+/- 1 mm), and the drilling crown has a maximum outer diameter of 5 mm - 16 mm, preferably 11 mm (+/- 1 mm), larger than the maximum outer diameter of the drilling module. The use of conventional top hammer machine with modifications is a part of the invention, wherein feeding and drilling with the rock reinforcement tube is automotive and wherein the tubes and the rod handling system of the drill rig have been modified in order to be adapted to each other.

Brief description of the drawings

Figure 1 shows a schematic view of pre-bolting around a rock chamber or a tunnel. The figure shows an example having three shields in a series with overlap between the shields, in order to achieve the best possible stability.

Figure 2 shows the design of the tube bolt with intermediate connections.

Figure 3 shows a preliminary drawing of a rod handling system. Figure 4 shows a flow chart of the method.

Detailed description Figure 1 shows a schematic representation of pre-bolting around a rock chamber 8” or a tunnel 8” in a rock chamber 8’. Pre-bolts arranged in a formation of three partly overlapping shields are shown. In this example, each shield 8 comprises approximately 20 pre-bolts interconnected by a plurality of individual drilling modules 2, thereby forming the three shields, said shields typically having an inclination inside the rock volume 8’ in relation to a roof of the rock chamber 8’ or the tunnel 8” in a way which is familiar to the person skilled in the art.

The tube bolt comprises a drilling crown 5, a start tube 3 and four module tubes 2. The diameter of the drilling crown is 0 66 mm and the outer diameter of the tubes is 0 55 mm. The small difference between the diameter of the drilling crown and the tube results in the tube giving support during the drilling and thereby resulting in a more straight hole. In other words, a preferred ratio between the outer diameters of the drilling crown and the drilling modules (the module tubes/the tubes) is 6 to 5, which, alternatively, may be defined as the outer diameter of the drilling crown being generally 20% larger than the outer diameter of the drilling modules.

The threading between the tubes, between the tubes and the drilling crown and between the neck and the tubes is a so called T45-threading. There are two impact surfaces, 41 and 4b, between the respective parts which enables an optimized drilling for the whole length of the tube. The tube has an inner diameter of 0 28 mm. During drilling, the tube is used for water supply, and when the tube is installed, an injection packer is mounted at the end of the tube.

The tube bolt is drilled in place and installed by means of a rock drill rig with a rod handling system (figure 3). Before the installation is started, a feeder and the rod handling magazine are loaded with tubes. The loading of tubes is performed by means of a telfer crane which is adapted to the hedges in which the tubes are delivered. The feeder of a drill rig is loaded with start tubes 3, drilling crown 5 and a module tube 2. The rod handling system is modified with new carousel plates 6 and is loaded with four module tubes 2. After the installation of all the tube bolts, the tubes are injected and voids around the tubes are filled with injection mortar. The tube is subjected to molding or injection with pressure if needed.

The invention relates to an interconnectable, self-drilling rock reinforcement tube which comprises a drilling crown, a starting tube and four module tubes adapted to modern rod handling systems on rock drill machines. Before the installation is started, the starting tube with the drilling crown is mounted on a feeder arm. The module tubes are mounted in a rod handling carousel. The parts of the rock reinforcement tube are assembled during the drilling. Typically, the drilling is supervised by one single operator, which is located at a distance from the front parts of the machine during drilling.

The invention is unique since it enables an automatic installation of tube bolt up to 18 meters with an ordinary rock drill machine with top hammer drilling. The system saves resources and time, resulting in economic gains as the stand-still-time for rock reinforcement activities is minimized. The invention is also applicable with reduced or no automatic feeding of drilling modules while still maintaining several of the advantages of the invention.

The invention thus comprises details according to the disclosure hereinafter. References are made to, amongst others, a flow chart 9 which shows the method of the invention.

A method of reinforcing a rock volume by means of pre-bolting, which method comprises: arranging 11 a top hammer drilling machine 1 , 6 for the rock volume, said top hammer drilling machine being configured for automatic feeding of and drilling with a plurality of drilling modules 2, 3; initially loading 12 the top hammer drilling machine 1 , 6 with at least one of said plurality of drilling modules 2, 3, wherein this drilling module is provided with a drilling crown 5; automatically feeding 13 sequentially and drilling 13 said drilling crown 5 and said plurality of drilling modules 2, 3 into a resulting drill hole in the rock volume by means of the top hammer drilling machine 1 , 6; fixating 14 the drilling crown 5 and said plurality of drilling modules 2,3 in the drilling hole by means of injecting a fixation substance into the drilling hole; wherein said plurality of drilling modules 2, 3 have a maximum outer diameter of 50 mm - 60 mm, preferably 55 mm, and wherein the drilling crown has a maximum outer diameter of 5 mm - 16 mm, preferably 11 mm, larger than the maximum outer diameter of said plurality of drilling modules 2, 3. In other words, it is preferable to have a ratio between the outer diameters of the drilling crown and the drilling modules (the module tubes/the tubes) of 6 to 5, which, in alternative way, may be expressed as the outer diameter of the drilling crown being generally 20% larger than the outer diameters of the drilling modules. The maximum range of this ratio, which the inventor believes would result in the advantages of the invention, is from 65 to 60 (corresponding to 8.3% larger) up to 75 to 50 (corresponding to 42% larger).

The method may further comprise providing 10 the storage magazine of the top hammer drilling machine 1 , 6 with carousel plates 6 for holding the drilling modules 2, 3 with said outer diameter.

The method includes that said plurality of drilling modules 2, 3 may be tubular and that, in an interconnected condition, they form a continuous tube. The method further comprises interconnecting said plurality of drilling modules 2, 3 by means of threadings, preferably of the type T45.

By this method, at least one drilling module 2, 3, which is included in said plurality of drilling modules 2, 3 may have at least one first impact surface 4b, which is formed at an outer end of a thread of said threadings, at a second impact surface 4a which is formed by a seat at an inner end of said thread, wherein the first and second impact surface 4a, 4b interacts with respective impact surfaces of an adjacent drilling module 2, 3, which is included in said plurality of drilling modules 2, 3.

By this method, said plurality of drilling modules 2, 3 may comprise steel having a rupture strength of 650 MPa +/- 20%, preferably +/- 10%.

The method may comprise that: by drilling, deforming 13’ said threadings that form joints between the drilling modules 2, 3, such that a substantial press-fit is thereby obtained.

During this method said plurality of drilling modules may, in combination, on one hand, form a power transfer between a top hammer drilling machine 1 , 6 and a drilling crown 5, and, on the other hand, form a pre-bolt for a rock volume.

The method may comprise initially loading 12’ a storage magazine of the top hammer drilling machine 1 , 6 with at least one of said plurality of drilling modules 2, 3 for automatic, sequential feeding thereof during drilling.

A tubular drilling module 2, 3 for pre-bolting of a rock volume in combination with a drilling crown 5, wherein the drilling module 2, 3 has a maximum outer diameter of 50 mm - 60 mm, preferably 55 mm, and wherein the drilling crown 5 has a maximum outer diameter which is 5 mm - 16 mm, preferably 11 mm, larger than the maximum outer diameter of the drilling module 2, 3, wherein the drilling module 2, 3 is configured to form, in combination, firstly a power transition between a top hammer drilling machine 1 , 6 and the drilling crown 5, and then a pre-bolt in a rock volume.

The drilling module 2, 3 in combination with the drilling crown 5, wherein the drilling module 2, 3 may comprise steel having a rupture strength of 650 MPa +/- 20%, preferably +/- 10%.

The invention also comprises an individual drilling module 2, 3 in connection to pre-bolting of a rock volume, forming, in combination, on one hand, a power transition between the top hammer drilling machine and a drilling crown, and, a pre-bolt in a rock volume, wherein the drilling module 2, 3 is generally tubular, preferably comprising steel having a rupture strength of 650 MPa +/- 20%, preferably +/- 10%, preferably having a yield strength of 470 MPa +/- 20%, preferably having a maximum outer diameter of 50 mm - 60 mm (suitably 55 mm with an inner diameter of 28 mm), preferably having an inner diameter of 20- 30 mm, preferably having a length of 2-6 meters, preferably being hollow and respectively having inner thread connection of T45-type in its respective other end.

The drilling module or the drilling modules 2, 3 may preferably be arranged in such a way that has been disclosed with regard to the method.

Use of a top hammer drilling machine 1 , 6, which is configured for automatic feeding of, and drilling by means of, a plurality of drilling modules 2, 3 for reinforcement of a rock volume by means of pre-bolting, comprising a top hammer drilling machine 1 , 6 which is provided with carousel plates for holding and feeding of drilling modules 2, 3 having a maximum outer diameter of 50 mm - 60 mm, preferably 55 mm, wherein the top hammer drilling machine 1 , 6 is initially loaded with a drilling module 2, 3 provided with a drilling crown 5, the maximum outer diameter of which is 5 mm - 16 mm, preferably 11 mm, larger than the maximum outer diameter of said plurality of drilling modules 2, 3, wherein the pre-bolting takes place as the top hammer drilling machine 1 , 6, with automatic feeding of the drilling modules 2, 3, drilling said drilling crown into the rock followed by said plurality of drilling modules and by injecting a fixation substance for fixating the drilling crown 5 and said plurality of drilling modules 2, 3. It is particularly advantageous for the invention that a ratio between the outer diameters of the drilling crown 5 and the drilling modules 2, 3 is 6 to 5.

The invention also relates to a rock chamber 8”, which may be a tunnel, in a rock volume 8’ reinforced by the means of pre bolting with a plurality of assemblies comprising a plurality of drilling modules 2, 3 in combination with a drilling crown 5 in accordance with the method or other devices in accordance with the invention, wherein the assemblies form at least one shield 8, but typically a plurality of partly overlapping shields, preferably in a roof of the rock chamber 8”.

As will be realized by the person skilled in the art the following terms are used in the same or generally the same meaning in connection to the disclosure of the invention; drilling module, tube bolt, bolt, module tube (also start tube with a reference to the tube which is joined by threading with the drilling crown), rod (in particular in connection to a rod handling system), pre-bolt, tube, rock reinforcement tube.