AU2018223938B2

AU2018223938B2 - Method and system for generating a drilling pattern, and a rock drilling rig

Info

Publication number: AU2018223938B2
Application number: AU2018223938A
Authority: AU
Inventors: Andreas Andersson; Pär HÄRSTRÖM; Per TURNER; Pär VÖRDE
Original assignee: Epiroc Rock Drills AB
Current assignee: Epiroc Rock Drills AB
Priority date: 2017-02-27
Filing date: 2018-02-21
Publication date: 2023-11-02
Anticipated expiration: 2038-02-21
Also published as: SE1750209A1; CL2019002068A1; CA3050246A1; NO20190918A1; ZA201904625B; CN110337528B; AU2018223938A1; FI130553B; WO2018156073A1; FI20195700A1; CN110337528A; SE540915C2

Abstract

The present invention relates to a method for generating a drilling pattern for excavating a cavity in rock. The method comprises: - determining a face contour (FC) being a representation of the rock face to be drilled and constituting a cross section of the cavity in a plane (NP) representing the rock face to be drilled, - determining a first bottom contour (BC0) being a representation of a cross section of the cavity to be drilled at a first distance from the face contour (FC), - determining at least one second bottom contour (BC1, BC2) being a representation of a cross section of the cavity to be drilled at a second, different from said first, distance from the face contour (FC), and - when determining said holes to be drilled, determining holes to be drilled between the face contour (FC) and the first bottom contour (BC0), and holes to be drilled between the face contour (FC) and the second bottom contour (BC1,BC2).

Description

METHOD AND SYSTEM FOR GENERATING A DRILLING PATTERN, AND A ROCK DRILLING RIG

Field of the invention

The present invention relates to rock excavation, and in particular to a method and system for generating a drilling pattern during rock excavation. The invention also relates to a rock drilling rig, as well as a computer program and a computer-readable medium that implement the method according to the invention.

Background of the invention

Rock excavation, in particular underground rock excavation, may be carried out using various techniques, where excavation using drilling and blasting technology is a commonly used method. The excavation may consist in the creation of a rock cavity having a predefined shape and geographical location. This may be the case, for example, when creating tunnels or other kinds of underground cavities. Excavation using drilling and blasting is, in general, carried out in a manner in which drilling is performed in rounds, where a round of holes is drilled to thereafter be loaded with explosives to blast the rock. Following removal of rock being detached by the blasting, a new round of holes are drilled to blast a subsequent portion of the cavity to be created. This is repeated until excavation of the desired cavity has been completed. In order to achieve a rock excavation that results in a desired cavity being created, each round of holes are being drilled according to a drill plan, or drilling pattern, which essentially determines location, direction, length and possibly diameter of the holes to be drilled. The object of the drilling pattern is to create a cavity using drilling and blasting that has a cross-sectional shape and geographical alignment that in reality corresponds to the planned, i.e. desired, shape and alignment.

Cavities of this kind may be of various designs. For example, the cavity may be designed to have essentially the same cross-sectional appearance following an essentially straight line. However, as is oftentimes the case, properties of the cavity, e.g. in terms of cavity cross section and curvature, may vary along the length of the cavity. This may require utilization of different drilling patterns for different sections of the cavity to be excavated.

With regard to, for example, tunnels, but also other kinds of cavities, these are oftentimes associated with highly precise requirements regarding conformance with the desired cavity cross section and geographic alignment/extension. For example, lining such as concrete lining may be utilised, where over-break of rock result in an increased consumption of lining and oftentimes also an increase in the requirement of rock reinforcement. Insufficient breaking, under-breaking, on the other hand, may require additional drilling and blasting to obtain the desired cavity. Hence, well- designed drilling patterns and subsequent drilling in accordance with the drilling patterns is essential in order to achieve the desired result.

Summary of the invention

It would be advantageous to achieve a method and system that may be utilised to obtain a drilling pattern for rock excavation that may reduce surplus rock when excavating a cavity in conformance with predetermined geographical

alignment/extension.

According to the present invention, it is provided a method for generating a drilling pattern for excavating a cavity in rock, the drilling pattern determining holes to be drilled in a face of the rock, the determination of the holes to be drilled being a determination of location, direction and length of the holes to be drilled, the holes being arranged to be drilled by a drilling rig, the holes of the drilling pattern being drilled prior to subsequent blasting of the face of the rock, the method being characterised in:

- determining a face contour being a representation of the rock face to be drilled and constituting a cross section of the cavity in a plane representing the rock face to be drilled,

- determining a first bottom contour being a representation of a cross section of the cavity to be drilled at a first distance from the face contour, - determining at least one second bottom contour being a representation of a cross section of the cavity to be drilled at a second, different from said first, distance from the face contour, and

- when determining said holes to be drilled, determining holes to be drilled between the face contour and the first bottom contour, and holes to be drilled between the face contour and the second bottom contour.

The drilling pattern may be generated prior to excavation of the cavity commences.

The drilling pattern may comprise holes to be drilled subsequently to the generation of the drilling pattern. The plane representing the rock face to be drilled may be determined as any plane generating a cross-section of the cavity, e.g. representing a cross-section at most three or four metres from the closest part of the rock face to be drilled, where the rock face may be bowl-shaped, in a direction opposite the direction of excavation, such that the plane substantially or completely clears the unbroken rock. As was mentioned above, the drilling pattern being used in rock excavation using drilling and blasting technology is an important factor in order to achieve a cavity having a cross section and geographical extension that conforms to a high extent to the planned alignment of the cavity. Drilling patterns, also known as drill plans, define the location, position, of the holes to be drilled in a rock face of the rock to be excavated, and also the direction and length of the holes. The drilling pattern may also determine the diameter of the hole to be drilled, where e.g. holes along a periphery of the contour, i.e. cavity profile, outline or cross-section, to be drilled may be of a different diameter than holes more to the centre of the rock portion to be excavated. Contour is used in the following as a representation of cavity

profile/outline/cross-section.

The drilling pattern is generated on the basis of the contour/profile of the cavity to be created, and a plurality of consecutive rounds of drilling and blasting are in general required to create the desired cavity, such as a tunnel.

Drilling patterns may be generated in various manners as is known to the person skilled in the art, and are oftentimes generated beforehand, i.e. prior to excavation of the cavity commences, e.g. in a control/planning centre, to then be downloaded to the rock drilling rig for use in the excavation.

Rock excavation often results in surplus rock being broken, and this is also often necessitated by constructional constraints that hinders optimal positioning of a drilling rig/drilling machine used in the excavation, which thereby renders it difficult to drill holes that result in excavation without surplus rock being broken. Surplus cavity formed during tunnel excavation is oftentimes subject e.g. to subsequent concrete lining, where the surplus rock being broken also results in additional consumption of concrete e.g. in concrete lining operations and may also generate an increase in required rock reinforcement following blasting. Drilling patterns are in general designed to reduce the amount of surplus rock being broken, but it may not always be possible to drill completely according to the predetermined drilling pattern.

According to the invention, when generating the drilling pattern, a face contour is determined, which represents the rock face to be drilled, the face contour constituting a cross-section of the cavity in a plane, denoted navigation plane, which as

mentioned may be determined as any plane in which a cross-section of the cavity in a longitudinal direction, i.e. direction of excavation, and which is suitable to use to represent the rock face to be drilled, can be represented. The navigation plane may e.g. be a plane in which a cross-section at most e.g. three or four metres from the closest part of the rock face to be drilled, e.g. in a direction opposite the direction of excavation so that the plane substantially or completely clears the unbroken rock. The navigation plane may further be defined at any angle in relation to the actual rock face to be drilled, and hence need not be parallel to this rock face.

Further, a first bottom contour being a representation of a cross section of the cavity to be drilled at a first distance from the face contour, substantially in a direction into the rock to be drilled, where the distance at least substantially correspond to a length, such as a maximum length, of the holes to be drilled as measured from the face contour. Since the face contour may be at a distance from the rock, the actual hole length in rock may be shorter. It is further determined at least one second bottom contour, being a representation of a cross section of the cavity to be drilled at a second, different from said first, distance from the face contour. When the drilling pattern is generated it is determined holes to be drilled between the face contour and the first bottom contour, and holes to be drilled between the face contour and the second bottom contour. In this way, holes can be drilled towards different contours, i.e. profiles/cross sections of the cavity to be drilled, so that the blasting following a round of drilling may result in a cavity having a high correspondence to the desired cavity outline.

The first distance may be longer than said second distance, so that holes to be drilled between the face contour and the first bottom contour may be longer than holes to be drilled between the face contour and the at least one second bottom contour. In this way, changes e.g. in the cross section and/or curvature of the cavity to be drilled may be accounted for by the additional bottom contour. Holes to be drilled between the face contour and the second bottom contour does not extend to said first bottom contour.

The holes to be drilled between the face contour and the first bottom contour may be arranged to end substantially at the first bottom contour, and holes to be drilled between the face contour and the second bottom contour may be end substantially at said second bottom contour.

The second bottom contour may hence be an intermediate bottom contour, and, a plurality of such intermediate bottom contours between the face contour and first bottom contour may be defined, where each of said intermediate contours may represent a cross section of the cavity at different distances from the face contour towards the first bottom contour.

The holes to be drilled between the face contour and an intermediate contours may be arranged to end substantially at the intermediate contour towards which the hole is to be drilled.

The number of intermediate contours may be determined in different manners, e.g. based on a curvature and/or change in width or height of the cavity to be excavated. The number may also be e.g. determined beforehand, such as by an operator or other personnel. The first bottom contour may be used to generate the drilling pattern for a first part of the face contour, i.e. holes of the first part of the face contour extending substantially to the first bottom contour, and the at least one second bottom contour, and/or each of the intermediate bottom contours may be used when generating a drilling pattern of a second part of the face contour being different from said first part, where each intermediate bottom contour may be used for different parts of the face contour.

Further, according to embodiments of the invention, e.g. exemplified below, the number of intermediate contours may be determined based on the size of the part/portion of the face contour that is not to be drilled towards the first bottom contour.

According to embodiments of the invention, the first part of the face contour, i.e. the part for which holes is to be drilled towards the first bottom contour, may be determined using the first bottom contour. For example, the first bottom contour may be projected onto the plane of the face contour, and the part of the face contour encompassed by the projection may be used as said first part of the face contour.

Similarly, the one or more second parts may be determined using said one or more second/intermediate bottom contours in a similar manner, where overlaps in the generation of the different parts of the face contour may be disregarded so that the parts are non-overlapping. The parts of the face contour may also e.g. be determined using a limiting contour according to the below.

According to embodiments of the invention, a limiting contour may be determined, which is a representation of the cross section of the cavity at a distance from the face contour in a direction away from the rock to be excavated. The limiting contour may be used, for example to take into account limitations regarding manoeuvrability of the drilling rig when drilling the holes of the drilling pattern, so that such limitations may be accounted for already when generating the drilling pattern. The limiting contour may, for example be a representation of the cross section of the cavity at a distance from the face contour in a direction towards already drilled rock substantially corresponding to the length of a feed beam of the drilling rig. It is in general the rear end of the feed beam that will impose limitations to manoeuvrability during drilling, and ensured manoeuvrability can be obtained by determining the manoeuvrability of the rear end in relation to the cavity contour prevailing at its location. According to embodiments of the invention, the limiting contour is determined utilising a

representation of actual rock walls, resulting from blasting of one or more previous rounds of drilling, where the representation of the actual rock walls can be generated e.g. by one or more scanners, e.g. located on the drilling rig. In this way, the limiting contour may be larger, and e.g. manoeuvrability of the feed beam may be determined in relation to actually excavated rock, which, e.g. in case of over-breaking, may allow further manoeuvrability. According to embodiments of the invention, the limiting contour is at any distance from the face contour in the direction away, e.g. opposite, from the general direction that the cavity is to extend into the rock.

According to embodiments of the invention, the first part of the face contour is determined utilising interpolation between the limiting contour, which hence is located in one direction from the face contour and the first bottom contour, which is located in another direction from the face contour, where the interpolation is made in the plane of the face contour.

This first part of the face contour may represent a part for which holes having a length determined by the distance between the face contour and the first bottom contour, i.e., for example, the maximum length of holes to be drilled in the round, can be drilled without giving rise to problems regarding manoeuvrability of e.g. a feed beam. Since the face contour defines the maximum surface to be drilled, the interpolation may be delimited also by the face contour so that the first part forms part of the face contour and does not extend outside the face contour even if this would be the result from the interpolation. In this way, in particular because of the use of the limiting contour, a part/portion of the face contour can be determined, where it can be ensured that the holes of the drilling pattern can be drilled, and to a desired, e.g. full, length, fulfilling set conditions, avoiding e.g. feed beam manoeuvring imposing limitations once drilling is started. The drilling rig may comprise at least one feed beam carrying a drilling machine, where the drilling machine may be slidable along the feed beam. According to embodiments of the invention, the first part of the face contour is determined using projection of the limiting contour and/or said first bottom contour onto the face contour instead of utilising interpolation. The method utilising projection may be used also when interpolation is used, where in addition to the interpolation, projection may be utilised, by projecting one or both the limiting contour and the first bottom contour onto the face contour, to further reduce the area of said first part. In this way, instead, the remaining part is increased, and for which holes of a reduced length may be drilled. For example, this may be utilised when otherwise the remaining part of the face contour becomes undesirably small so it may e.g. be difficult to get room for a further, or a desired number of, holes or rows of holes to be drilled in the remaining part.

The one or more further parts of the face contour may be determined in a similar manner, e.g. utilising interpolation and/or projection, for each part utilising an intermediate bottom contour instead of the first bottom contour. With regard to the portion of the face contour for which holes having a shorter length than holes of said first part, i.e. the remaining part of the face contour, it can be determined, e.g. on the basis of the width of the remaining portion of the face contour and/or the number of holes to be drilled on this remaining portion, the number of intermediate bottom contours to be used. A drilling pattern is hence generated for different parts/portions of said face contour for each of said intermediate contours utilising said intermediate contour,

respectively, using interpolation and/or projection. The holes of these at least one additional drilling pattern will hence have a shorter longest length than the holes of the first part of the face contour above. A drilling pattern encompassing the full, or substantially the full, face contour can consequently be determined, where the drilling pattern may be seen as an aggregate of drilling patterns for different parts of the face contour, where different longest hole lengths are used for the different parts of the face contour, and where the longest hole length of a drilling pattern may be determined by a distance between the face contour and intermediate or first bottom contour. Further, when holes of drilling patterns for different parts of said face contour are located within less than a first distance from each other, thereby considered to have overlapping coverage of the rock to be drilled, holes of at least one of the drilling patterns can be omitted. For example, the hole having the shortest, or longest for that matter, length, can be arranged to be omitted. The use of contours according to the above may allow generation of an aggregate drilling pattern that comprises holes having a drillability, i.e. the holes will be able to be drilled by the rock drilling rig. This drillability of the holes may be determined e.g. by ensuring a manoeuvrability of the feed beam in relation to surrounding rock, which may be accomplished through the use of said limiting contour. In this way, a drilling pattern can be generated that may ensure that holes of the drilling pattern are also drillable in reality, so that adaptions of the drilling pattern during ongoing drilling of a round due to holes not being possible to drill can be reduced, which thereby may reduce the risk of over-breaking and/or under-breaking of rock resulting from adaptions of the drilling pattern during ongoing drilling. According to embodiments of the invention, the drilling pattern is generated following drilling and blasting of a previous round.

The rock drilling rig may comprise a plurality of feed beams, each carrying a drilling machine, and the determination may be performed for the particular feed beam that is to drill an intended hole. According to embodiments of the invention, the drilling pattern is determined when the cross section, contour, of the cavity is narrowing or widening in the direction of excavation, and/or a curvature of the cavity is changing. It is oftentimes in situations of these kinds that limitations regarding e.g. the manoeuvrability of the feed beam may have the most negative impact when drilling a drilling pattern where this manoeuvrability has not been accounted for. The drilling pattern may also be determined when a straight portion is to be drilled immediately following a narrower portion of the cavity, in which case the narrower portion may impose limitations regarding e.g. manoeuvrability regarding e.g. a feed beam of the drilling rig.

According to embodiments of the invention, the drilling pattern is determined when the cross section, contour, of the cavity is changing such that different drilling patterns are used for consecutive rounds of drilling and blasting. According to embodiments of the invention, the drilling pattern is determined when excavation of the cavity has progressed to an extent at least corresponding to the length of the feed beam.

It will be appreciated that the embodiments described in relation to the method aspect of the present invention are all applicable also for the system aspect of the present invention. That is, the system may be configured to perform the method as defined in any of the above described embodiments. Further, the method may be a computer implemented method which e.g. may be implemented in one or more control units of a rock drilling rig. Further characteristics of the present invention and advantages thereof are indicated in the detailed description of exemplary embodiments set out below and the attached drawings.

Brief description of the drawings

Fig. 1 A-B illustrates an exemplary representation of a part of a tunnel to be excavated;

Fig. 2 illustrates an exemplary embodiment of a rock drilling apparatus in which embodiments of the invention may be utilised;

Fig. 3 illustrates an exemplary method for generating a drilling pattern according to embodiments of the invention; Fig. 4 illustrates an exemplary method for reducing the risk that under-breaking of rock occurs;

Fig. 5 illustrates a further method for generating a drilling pattern according to embodiments of the invention;

Fig. 6A illustrates an exemplary representation of a part of a tunnel to be excavated, including a bottom contours utilised when generating a drilling pattern according to embodiments of the invention;

Fig. 6B illustrates an exemplary representation of a plurality of bottom contours in the tunnel example of fig. 6A;

Fig. 6C illustrates a limiting contour in the tunnel example of fig. 6A. Fig. 7 illustrates determination of a contour for drilling of full-length holes, forming part of a rock face to be drilled;

Fig. 8 illustrates the cross sectional appearance of the contour for drilling of full- length holes in relation to the rock face to be drilled; Fig. 9 illustrates the cross sectional appearance of the contour for drilling of holes having a reduced length in relation to the rock face to be drilled;

Fig. 10 illustrates a method for determination of contours for drilling holes having a reduced length, the contours forming part of a rock face to be drilled;

Fig. 1 1 illustrates holes to be drilled from a face contour towards bottom contours according to embodiments of the invention;

Fig. 12 illustrates a method for increasing the cross-sectional appearance of the contour for drilling of holes having a reduced length in relation to the rock face to be drilled;

Fig. 13 illustrates an example of an excavation situation where the invention may be utilised;

Fig. 14 illustrates a further example of an excavation situation where the invention may be utilised.

Detailed description of exemplary embodiments

Embodiments of the invention will be exemplified in the following with reference to examples relating to excavation of a tunnel. Figs. 1 A-B illustrates an exemplary representation of a section of a tunnel to be excavated in rock. The tunnel may be any kind of tunnel for any suitable use, and e.g. comprise a tunnel forming part of a mine, or a tunnel for road or railway transport.

According to the example, the tunnel is represented by a tunnel line TL, which essentially is defined by points TLn-3, TLn-2... TLn+2 which may be interconnected. The extension, alignment, of the tunnel in the longitudinal direction may hence be obtained by interconnecting the tunnel line points. The disclosed section of the tunnel to be excavated represents a section of the tunnel about n tunnel line points into the tunnel. The tunnel line points are defined in a 3D-coordinate system being used in the excavation, e.g. a global coordinate system or a coordinate system local to the area of excavation, so that the desired tunnel can be excavated in conformity with the pre-planned tunnel alignment.

Any suitable number of tunnel line points may be used in the representation of the tunnel, where the number e.g. may depend on the length of the tunnel to be excavated, and any suitable, constant or varying, distance between the tunnel line points may be used, e.g. in dependence of curvature. For example, the distance between tunnel line points may represent the length of the longest holes to be drilled during a round for subsequent blasting. The length of the holes to be drilled may e.g. correspond to the length along a feed beam that a drilling machine may slide, and e.g. be in the order of 0-10 metres.

In order to obtain a 3D-representation of the tunnel alignment, e.g. a representation of the desired tunnel cross section, in the following denoted tunnel contour, or tunnel profile, may be defined for each tunnel line point, e.g. in a plane perpendicular to the tunnel line TL. The tunnel contours of different tunnel line points may be defined in a same plane, but may also be defined in different non-parallel planes. An example of a tunnel contour 101 is disclosed in fig. 1 B, exemplifying a tunnel contour 101 of tunnel line point TLn, and which also indicates the location of the associated tunnel line point TLn in relation to the tunnel contour 101 . For simplicity, the tunnel line point TLn is shown as being located essentially in the centre of the tunnel contour 101 of fig 1 B, but it may be arbitrarily located on, or principally anywhere on a plane of, the tunnel contour 101 for as long as the relation between tunnel line point and tunnel contour is defined. Positioning of the desired tunnel contour to encompass the associated tunnel line point may be advantageous e.g. from a navigation point of view during actual excavation.

The interconnected tunnel line points together with the associated tunnel contours, which may vary in shape from one tunnel line point to another can be used to form a 3D-volume through interpolation representing the tunnel and which is being defined in a coordinate system to allow excavation at a desired location. Consequently, the tunnel is represented by tunnel contours distributed along the tunnel line TL representing the desired extension of the cavity to be excavated. In case the tunnel contours differ from one tunnel line point to another, e.g. interpolation can be utilised in a straight-forward manner to obtain a tunnel cross-section also at any point between the defined tunnel line points. In case the tunnel contours are defined in a same plane 2D-interpolation may be utilised, while otherwise 3D-interpolation may be utilised to determine an intermediate tunnel contour in any desired plane.

Tunnel/cavity excavation of this kind often involves generation of a drill plan, in the following denoted drilling pattern, for drilling of a set, or round, of drill holes in a rock face for subsequent blasting. The drilling pattern defines the holes to be drilled, e.g. in the coordinate system of the tunnel, and may define position, length and direction for each hole. Holes having different diameters may also be drilled, and hence a hole diameter may be defined by the drilling pattern as well. Following drilling of a round, the drilled holes are charged with explosive material that is detonated following drilling and charging of the holes of the drilling pattern.

After the explosion, broken rock is taken away and following scaling, if required, i.e. clearing and loosening of cracked and/or partly loose rock resulting from the blasting, a new round is drilled and blasted to progress the excavation of the tunnel. This is then repeated until the complete volume of the desired tunnel/cavity has been excavated. When generating a drilling pattern of a round to be drilled the object is in general to design the drilling pattern such that the cavity formed by the blasting following the drilling results in a cavity having a spatial extension that at least clears the rock encompassed by the 3D-representation of the desired cavity, such as the cavity defined by an interpolation of the tunnel line points and associated contours. In reality surplus rock is oftentimes excavated in addition to the breaking of rock forming the desired cavity. This is due to a difficulty in breaking rock precisely according to desired cavity boundaries. It is, however, usually a requirement that the desired cavity is also excavated in full, i.e. the complete cross section of any given point of the tunnel being cleared from rock, and in order to ensure that at least this is accomplished surplus rock is oftentimes broken to ensure that under-breaking does not take place. The drilling pattern may be designed in an attempt to reduce the breakage of surplus rock as much as possible while still ensuring that at least the desired cavity is excavated. Fig. 2 illustrates an exemplary movable rock drilling rig 201 that may be utilised e.g. in tunnel excavation. The rock drilling rig 201 is an underground drilling rig and is shown in position for drilling a round of holes in a rock face 202 during tunnel excavation, e.g. along the tunnel line TL of fig. 1 A. As can be seen in fig. 2, the rock drilling rig 201 according to the disclosed example is provided with three booms 203-205, each of which is carrying a drilling machine 206-208 via feed beams 209-21 1 . Accordingly, the disclosed rock drilling rig 201 may drill up to three holes at a time. Drilling rigs of the disclosed kind are known per se. The drilling machines 206-208 are, in this example, hydraulically driven and power supplied from one or more hydraulic pumps 212, which in turn are driven by one or more electric motors and/or combustion engines 213, also in a manner known per se. The drilling process may be controlled by an operator from a cabin 215.

The drilling rig 201 further comprises a control system comprising at least one control unit 214, which controls various of the functions of the drilling rig 201 , e.g. by suitable control of various actuators/motors/pumps etc. Drilling rigs of the disclosed kind may comprise more than one control unit, where each control unit, respectively, can be arranged to be responsible for different functions of the drilling rig.

The drilling rig 201 is arranged to be repositioned as excavation progresses and comprises, according to the present example, wheels 216, 217 for allowing drilling rig movability. Crawler drives or other suitable means may alternatively be used to allow manoeuvring of the drilling rig 201 .

Fig. 2 hence discloses a drilling rig that following a previous blast and clearing of broken rock has been moved forward in the excavating direction, i.e. along the tunnel line TL, towards the rock face 202 resulting from the previous blast and the drilling rig 201 has been positioned for drilling the subsequent round for blasting of the next section of the tunnel/cavity to be excavated. In order to correctly excavate rock according to the predetermined tunnel alignment, the exact position of the rock drilling rig 201 in the prevailing coordinate system must be determined. This can be accomplished in various ways and, for example, by aligning one of the feed beams, e.g. feed beam 21 1 to a laser beam of a theodolite (not shown), where the position of the theodolite in turn has been established using fixed points. The drilling rig in 201 general comprises a local rig coordinate system, and through the use of the drilling rig coordinate system the position of the drilling rig can be determined using the location of the feed beam in the drilling rig coordinate system and the location of the feed beam as determined in the coordinate system of the tunnel. In addition to the feed beam being aligned with a laser beam of a theodolite, the position of the feed beam along the laser beam must also be determined. This can be performed e.g. by straight-forward measurement or in any other way.

For example, the length of the tunnel that so far has been excavated from the beginning of the excavation, i.e. the drilled and blasted length of the tunnel, may e.g. be marked on the tunnel wall to facilitate positioning of the drilling rig. As is realized, any other suitable method of positioning the drilling rig in the coordinate system of the tunnel to be drilled may be utilized. According to embodiments of the invention, the drilling rig is provided with fixed points, which may be used to position the drilling rig using e.g. a theodolite, and where the rig fixed points are also defined in the coordinate system of the drilling rig, so that thereby e.g. the position of a feed beam may be determined in the coordinate system of the tunnel.

As before mentioned, prior to drilling of the rock face 202 commences, a drilling pattern is generated, and fig. 3 illustrates a flowchart for generating a drilling pattern to be drilled prior to blasting the current rock face 202. The positions of the holes to be drilled on the rock face are schematically illustrated by "x" markings, where these positions are determined by the drilling pattern. The drilling pattern to be used is oftentimes determined prior to the excavation of a tunnel commences e.g. in a planning centre, where the holes are planned such that the subsequent blasting as close as possible corresponds to the desired cavity to be excavated. The generation of the drilling pattern that is optimal from an excavation point of view, e.g. with regard to surplus rock being broken, may be difficult, in particular when excavation is in progress and the excavation has progressed to a position along the tunnel line that does not correspond to a position for which drilling is planned to be performed on the planning stage. According to the invention, it is provided a method for generating a drilling pattern that may be used when a rock face is to be drilled and which may reduce the amount of surplus rock being broken during the excavation. This is accomplished, inter alia, through the use of a plurality of bottom contours.

The method 300 according to embodiments of the invention of fig. 3 starts in step 301 by determining whether a drilling pattern is to be generated. This may be initiated e.g. by an operator of the drilling rig 201 , e.g. by suitable input to the drilling rig control system, or by any other suitable means. The method continues to step 302 when a drilling pattern is to be generated while otherwise the method remains in step 301 .

In general when generating a drilling pattern, holes to be drilled close to the periphery of the rock face are subject to limitations regarding possible hole direction. This is due to the inherent diameter/size of the drilling machine/feed beam. That is, it is not possible to drill precisely along a contour outline but drilling will have to be performed slightly outwards in relation to the desired direction to make room for drilling machine/feed beam when drilling the next round of holes following blasting of the current round. This is known per se, and the general principle is illustrated in fig. 4, in which a desired width of a tunnel to be drilled is indicated with a. The actual drilling is represented as a saw tooth pattern 401 , in which the distance b is essentially governed by the dimensions of the drilling machine/feed beam, and where the distance b ensures that the width of the tunnel can be maintained at the subsequent round.

That is, if the distance b is made smaller in one round, this may make drilling difficult in a following round, so that the drilling e.g. will be directed more outwards due to space limitations. Fig. 4 merely illustrates a general principle, and the outward angulation c may be determined in any suitable manner, in general in an attempt to limit over-breakage of rock, where the outward angulation c may vary from one round to another.

According to the invention, a drilling pattern is generated in a manner that utilizes a plurality of bottom contours, i.e. cavity cross-sections towards which holes are being drilled from the face contour FC in order to obtain an excavation this corresponds to the desired outline of the cavity to be excavated. In step 302 a face contour FC of the current rock face to be drilled is determined. The face contour FC is determined for a plane, here denoted navigation plane NP as is commonly the case, from which hole length, direction etc. of the holes to be drilled is determined. The navigation plane and face contour are exemplified in fig. 6A, which illustrates a tunnel line TL similar to the tunnel line of fig. 1 A, but where in addition the desired outline 601 of the tunnel as seen from above is also illustrated. In addition, the actual rock walls 602 of the already excavated portion of the tunnel are shown, including the rock face 603 about to be drilled as the excavation progress. As has been discussed above, the tunnel line points are defined in the coordinate system being used in the excavation, and in the present example drilling has reached a point between TLn and TLn+1 .

Even if, prior to the excavation of the tunnel commences, it may be an intention to drill consecutive rounds at consecutive tunnel line points, drilling may not progress precisely according to pre-planned drilling patterns, where each round of drilling and blasting may be expected to reach the next tunnel line point of the tunnel line TL. For example, the blasting may not break the full length of a hole, and/or a larger portion of rock may be broken, e.g. due to more porous rock. According to embodiments of the invention, however, the drilling pattern for the next round is established only once the location of the rock face to be drilled has been determined, and is independent from the current progress in relation to the tunnel line points.

As can be seen from fig. 6A, the resulting rock face 603 from the preceding blast is uneven, and may vary considerably. The navigation plane NP may be determined such that it substantially or completely clears the rock face 603 to be drilled, but the navigation plane NP may also be arranged to partially or fully intersect the rock face 603 to be drilled. The rock face may be established e.g. by positioning the drilling rig according to the above using the coordinate system of the drilling rig in combination with the position of the drilling rig in the coordinate system of the tunnel, where the representation of the rock face can be expressed in the coordinates of the coordinate system being used for excavation of the tunnel. When the position of the rock face in the coordinate system of the tunnel has been determined, a suitable navigation plane can be determined, where the navigation plane NP may be defined in various ways, and according to the present example, the navigation plane NP is defined such that it is perpendicular to a line, dashed line 605, representing an intended drilling direction of the round to be drilled. The intended drilling direction may, as in the present example, differ from the direction of the tunnel line TL at the point where the tunnel line TL is intersected by the navigation plane NP. For example, the direction of drilling may be determined by a line 605 that intersect the tunnel line TL at the point where the tunnel line TL is intersected by the navigation plane NP, and where the line 605 also intersects the tunnel line TL, point 604, at some suitable distance from the navigation plane NP. The distance from the navigation plane NP to point 604 may correspond to, or substantially correspond to, the longest hole length to be drilled in the round for which the drilling pattern is generated. The distance from the navigation plane NP to the point 604 may also be any other suitable distance, greater or smaller than the longest hole length to be drilled in the round. For example, the distance may be set or changed from a pre-set value e.g. by an operator in case it is desired to change the drilling direction, and in which case the navigation plane may be automatically adjusted to be e.g.

perpendicular to the drilling direction. In the present example the navigation plane NP is hence determined such that line 605 is normal to the navigation plane NP. The navigation plane NP is hence defined independently from the general appearance of the rock face 603 to be drilled, and e.g. need not be parallel to this rock face 603, but may be angled considerably in relation to the actual rock face.

The navigation plane NP may also be defined independently from a drilling direction, and may essentially have any suitable angle in relation to e.g. the tunnel line TL and/or drilling direction 605 and/or rock face. There exist various methods in the art for determining a navigation plane NP, and any such method may be utilised. For example, the navigation plane NP can be arranged to be determined e.g. by an operator of the drilling rig and/or other person involved in the generation of drilling patterns. Further, an intended drilling direction may be defined according to any suitable criteria and may have any suitable direction and hence need not be defined according to the example using tunnel line points described herein. The face contour FC is determined in the navigation plane NP, where the face contour FC can be determined by 2D or 3D interpolation as explained above using the tunnel contours of TLn and TLn+1 , depending on whether these tunnel contours are in a same plane or not, to obtain the face contour in the navigation plane NP. The tunnel line contours of adjacent tunnel line points may differ in shape from one tunnel line point to another, e.g. if the tunnel is widening, narrowing or otherwise changing shape, and may be defined in different planes, e.g. by the curvature changing such as in the present example, where tunnel line contours of tunnel line points TLn and TLn+1 are also in different planes with respect to the navigation plane NP. The navigation plane NP hence need not, and according to the present example is not, be perpendicular to the tunnel line at the point where this is crossed, and the face contour FC will therefore differ from the tunnel line contour even if the tunnel contours of adjacent tunnel line points TLn and TLn+1 are the same. The exemplified method is perhaps most advantageous when conditions for generating the drilling pattern differ from one round to another, in particular when the tunnel is widening, narrowing and/or the tunnel is curving or the curvature of the tunnel is changing.

The method then continues to step 303 in which, in a similar manner to the above, a bottom contour BCO is determined. The bottom contour BCO is determined in a bottom plane BP, which is a plane at a distance from the face contour FC. The bottom plane may be defined to be located at a distance from the face contour FC, e.g. defined by line 605 above, and hence at a distance e.g. corresponding or substantially corresponding to the longest length of the holes to be drilled in the round for which the drilling plan is generated. The bottom plane BP may also be arranged to be located at any other, greater or smaller, distance from the face contour FC. The location of the bottom plane BP may also be arranged to be adjusted by an operator of the drilling rig, e.g. by changing pre-determined distance between face contour FC and bottom plane BP in case this is desired, e.g. to extend or reduce the distance between the face contour/navigation plane and the bottom plane BP. The distance between the face contour and bottom plane may hence exceed the longest hole length to be drilled. Further, in case the planes are angled with respect to each other, the distance between the planes will vary in dependence on where on the planes measurement is made, and hence the distance may be both greater and smaller than the longest hole length to be drilled even if e.g. the distance along the tunnel line equals the longest hole length to be drilled. The bottom plane BP, and thereby bottom contour BCO may be arranged to be perpendicular to the tunnel line TL where this is intersected, i.e. at point 604 in the present example. According to embodiments of the invention, the bottom plane BP may alternatively be arranged to be perpendicular to the line 605, and hence be parallel to the navigation plane NP. The bottom plane may also be defined in any other suitable manner. The bottom contour BCO may be determined using 2D or 3D interpolation, in this case using tunnel line points TLn+1 , TLn+2. In addition to the bottom contour BCO, it is determined, step 304, at least one intermediate bottom contour. According to the disclosed example, two additional intermediate bottom contours BC1 , BC2 are determined, see fig. 6B, where the number of intermediate bottom contours can be determined in various manners. For example, the number of intermediate bottom contours may be determined on the basis of the longest hole length to be drilled, such as, for example, the distance between the face contour FC and the bottom contour BCO. The number of

intermediate bottom contours may also be determined on the basis of e.g. the curvature of the cavity that is about to be drilled. As will be discussed below the number of intermediate bottom contours may also be determined using other criteria. The intermediate bottom contours BC1 ...BCn can be generated in the same manner as BCO above, i.e. through interpolation using the tunnel contours of the adjacent tunnel line points. With regard to the location of the bottom contours BC1 ...BCn, these can be arranged to be evenly spaced between the face contour FC and the bottom contour BCO. For example, if only one additional drilling pattern is to be generated, the additional bottom contour BC1 can be arranged to be positioned at half the distance from the face contour FC to the bottom contour BCO.

According to the present example, two additional bottom contours BC1 , BC2 are generated, which are evenly spaced between the face contour FC and the bottom contour BCO. This is illustrated in fig. 6B, where the two intermediate planes BC1 , BC2 are shown. According to the present example, holes of different portions of the face contour FC are determined to be drilled towards the different bottom contours. The bottom contours BCO, BC1 , BC2 are then used to determine portions of the face contour FC for which drilling is to be performed towards the various bottom contours, step 305. Fig. 6B schematically illustrates a larger portion of the face contour denoted MCO (dashed line) representing a portion of the face contour where holes will be drilled towards the bottom contour BCO and thereby have a longer hole length than holes being drilled towards intermediate bottom contours BC1 , BC2. The division of the face contour FC into the various contours MCO, MC1 (solid line), MC2 (dash-dotted line), where MC is used to denote the maximum contour herein the reason for this being MC denoting the maximum portion of the face contour that according to the drilling pattern generation method is utilized to denote the largest portion of the face contour for which the hole length at hand may be drilled. For example, MCO is the maximum part/portion of the face contour for which holes extending to bottom contour BCO is drilled. MC1 is the maximum part/portion of the face contour for which holes extending to bottom contour BC1 is drilled, but where the part covered by MCO is disregarded from, hence, according to the present example, leaving a smaller part. Similarly MC2 is a part for which holes extending to bottom contour BC2 is drilled, but where the parts covered by MCO and MC1 are disregarded from. This will be exemplified further below with reference to the method disclosed in fig. 5.

According to the present example, the contours MCO etc. are defined by a maximum drilling angle in relation to the general drilling direction that it is desired to use when drilling the holes, i.e. line 605 according to the present example. The drilling angle may be defined e.g. in a xyz coordinate system, and the maximum allowed difference in drilling angle may be measured in a horizontal plane as in the present example, but may alternatively or in addition be measured in relation to line 605 in any plane. According to the present example, these drilling directions are denoted 621 , 622, 623, in FIG 6B, where hence a maximum allowed drilling angle difference e.g. in the horizontal plane between line 605 and lines 621 ,622, 623 may be defined. The drilling direction represented by dotted line 621 meets the bottom contour BCO at the outline of the contour (i.e. rock wall), and since line 621 is angled in relation to line 605 according to the set criteria the intersection of line 621 with the face contour FC defines the portion MCO of the face contour FC. The angle criteria may be utilised along the outline of the bottom contour BCO in relation to drilling direction 605 to thereby form an area MCO in the plane of the face contour FC.

The maximum angle to be used in the drilling may be set in the control system of the drilling rig, and using these data contour MCO may hence be determined. Similarly contours MC1 , MC2 may be determined for each of the intermediate bottom contours BC1 , BC2. When the contours have been determined, a drilling pattern is generated in step 306.

According to the present example, the maximum contour MCO will represent the largest portion of the face contour, and when the drilling pattern is generated holes being generated for this maximum contour MCO will hence constitute a drilling pattern of holes to be drilled from face contour FC to the bottom contour BCO. The actual drilling pattern, i.e. the precise condition of the location direction the length of the holes to be drilled can be generated according to any suitable method for generating a drilling pattern for drilling a contour, in this case MCO towards a bottom contour, i.e. BCO, where various methods are known in the art.

Since the drilling pattern of the maximum contour MCO does not encompass the full face contour FC, and thereby not the total volume that is to be drilled and blasted during the round to be drilled, additional drill holes are added in a similar manner for the remaining portion of the face contour, i.e. represented by MC1 , MC2, for which portions drilling patterns can be generated in the same manner, where the drilling pattern for portion MC1 will be generated towards intermediate bottom contour BC1 instead of bottom contour BCO. Similarly, the drilling pattern will be generated for contour MC2 towards the second intermediate bottom contour BC2. That is, for each of the contours MCO, MC1 etc. the portion of the drilling pattern to be generated for this particular part of the face contour can be seen as a generating a conventional drilling pattern from a part of the face contour towards a bottom contour. Hence, according to the present example, three different drilling patterns can be generated and aggregated to a single drilling pattern. The drilling pattern for the various contours/bottom contours may also be generated in any suitable order, for example starting with the longest holes to be drilled, i.e. towards the bottom contour BCO. However, when generating the drilling pattern for border portions of the contours MCO, MC1 , MC2 there may arise an overlap regarding holes to be drilled i.e. holes for the different portions of the face contour may be determined to be drilled too close to each other. For example, the system may be set such that a minimum distance is to be maintained between holes to be drilled. Therefore, when generating the drilling pattern, holes considered to cover portions of the face contour FC for which a drilling pattern has already been generated may be disregarded. For example, holes of a longer length may be arranged to be maintained. Alternatively, shorter holes may be maintained over longer holes.

When drilling patterns have been generated for the bottom contour BC and the intermediate contours BC1 , BC2, an aggregate drilling pattern covering the full face contour FC have been generated. The aggregate drilling pattern may then be drilled, where holes may be drilled in any order, step 307. Following drilling the method is then ended in step 308.

As was mentioned above, e.g. the angular direction of the holes to be drilled can be used when defining the different contours MCO, MC1 , MC2, but other criteria may also apply. For example, input parameters to the generation of the drilling pattern may include a minimum width and/or height of each portion of the face contour that is to be drilled towards a specific bottom contour. Similarly, this may be used to determine a number of intermediate bottom contours to be used. It is, for example, contemplated that an iteration is performed where an initial number of bottom contours are generated and on the basis of this the contours MCO, MC1 , MC2 are generated, and if these are considered small or too large, the number of intermediate bottom contours may be increased or decreased.

The invention may be utilized to generate drilling patterns that following drilling and blasting generates a cavity having a high correspondence with the cavity set up to be drilled. The invention may further be utilized in situations where there are substantial changes with regard to the profile of the cavity presently being drilled. This is illustrated in FIG 13, which illustrates a tunnel that is about to divide into two separate sections 1301 , 1302. Similar to figs. 6A-B, fig. 13 discloses the face contour FC of the rock to be drilled and a bottom contour BCO and intermediate bottom contours BC1 , BC2. The use of a plurality of bottom contours according to the invention allow, as according to the present example, drilling of one tunnel section 1301 to be

commenced while with regard to the other tunnel section 1302 shorter holes, limited by intermediate contour BC1 , may be drilled so that the portion 1303 that is to remain and separate the tunnel section from each other may be maintained to as high extent as possible while the round to be drilled may still excavate as much as possible of the common portion of the tunnel.

Fig. 14 illustrates an alternative method for dividing the face contours into portions to be drilled towards different bottom contours. According to the disclosed example, the number and location of the bottom contours may be determined beforehand and projection of the bottoms contours onto the face contour FC may be utilised to establish the portions MCO, MC1 , MC2. Fig. 14 illustrates a situation where the tunnel is narrowing, i.e. the tunnel/cavity is transitioning from a wider section to a narrower section. The maximum contour MCO is defined by projecting the bottom contour BCO onto face contour FC. This is illustrated by line 1402, which represents projection of the bottom contour BCO onto the face contour FC and results in a maximum contour MCO having the smaller width indicated by line 1404 in the figure. Similarly, the portions MC1 and MC2 of the face contour FC can be determined by projecting the bottom contours BC1 and BC2 onto the face contour. A drilling pattern may then be generated according to the above.

Finally, for the sake of simplicity, the bottom contours BCO, BC1 , BC2 have been illustrated as at least essentially planar surfaces. This need not be the case, but any of or all of the bottom contours may take any desired shape. Furthermore, according to embodiments of the invention, limitations imposed by the already excavated portion of the tunnel regarding manoeuvrability of the rear end 209B, 210B, 21 1 B of the feed beam 209-21 1 can be taken into account when generating the drilling pattern. The tunnel walls of the already excavated portion of the tunnel will impose restrictions on possible manoeuvring of the feed beam(s) of the drilling rig so that holes that would be desired to drill from an excavation point of view e.g. to reduce the amount of surplus rock being excavated may not in reality be possible to drill due to feed beam manoeuvring limitations, which may render a required manoeuvring of the feed beam in order to drill the holes according to the determined drilling pattern impossible. This may be the case, for example, when the cavity to be drilled is narrowing, and/or when cavity is not following a straight line. Hence, according to embodiments of the invention, a drilling pattern may be generated that will also be drillable, and that may not be subject to manoeuvring difficulties due to surrounding rock being unaccounted for. In this way it can be ensured that rock is excavated to an extent sufficient to provide the desired cavity while simultaneously breaking of surplus rock may be reduced by creating a drilling pattern that take the actual conditions prevailing at the location of the rock face regarding manoeuvrability of the feed beam into account to thereby create a drilling pattern that may result in less surplus rock being excavated than otherwise might be the case.

Fig. 5 illustrates a method 500 where this is taken into account. Steps 501 -503 are similar to steps 301 -303 in fig. 3, and are therefore not described more in detail.

In step 504 a further contour, a limiting contour LC, is established. The limiting contour LC is also interpolated using adjacent tunnel line contours, TLn-2, TLn-1 , in a manner similar to the above at a distance from the face contour FC, and in a direction from the face contour FC opposite the drilling direction. The limiting contour is illustrated in fig. 6C, which otherwise is similar to fig. 6A. The distance between the face contour FC and the limiting contour LC may, as in the present example, e.g. be selected to equal the length of the feed beam of the drilling rig, but the distance may also be any other suitable distance. According to the present example, the limiting contour LC is used to take surrounding rock of the already excavated portion of the tunnel into account to determine drillability of the holes when determining the drilling pattern so that the manoeuvrability of the feed beam is taken into account.

The limiting contour LC may be interpolated using tunnel line contours as above, but if a scanned representation of the actual rock wall of the already drilled portion of the tunnel is available this can be used instead to increase accuracy when determining if holes are drillable or not. Also, for example, the rear end of the feed beam may be manoeuvred to the extreme positions, e.g. left, right, top, bottom, bottom right, top left etc. and thereby establish a representation of the cavity at the end of the feed beam. Furthermore, the limiting contour LC may be selected such that it's normal vector coincides with the direction of navigation and hence the limiting contour LC is parallel to the face contour FC. In step 505 a first maximum contour MCO is generated. This maximum contour MCO represents the maximum possible portion of the face contour FC where it is possible to drill the holes having the maximum length being drilled during the current round of drilling, while ensuring manoeuvrability of the feed beam. The maximum contour MCO is arranged to be in the navigation plane NP, i.e. the same plane as the face contour FC. The boundaries of the maximum contour MCO is limited by the periphery of the face contour FC, since this is the maximum surface to be drilled, but MCO is also delimited by a 3D-interpolation using the limiting contour LC and the bottom contour BCO in the plane of the face contour FC. This is illustrated in FIG. 7 by dashed interpolation lines 701 and 702. The resulting contour MCO, delimited also by the face contour FC, is shown as the hashed area of fig. 8, which hence shows the face contour FC and the determined MCO. The area MCO, consequently, represents the portion of the face contour FC that may be drilled with full-length holes when drilling the next round. The area resulting from the interpolation that is located outside the face contour FC, i.e. the hashed area 801 , is disregarded since this area is not to be drilled.

When the maximum contour MCO has been determined according to the above, a drilling pattern is generated, step 506, for the maximum contour MCO, which hence constitutes a drilling pattern of holes to be drilled from face contour FC to the bottom contour BCO. The drilling pattern of the maximum contour MCO can be generated according to the above. The drilling pattern may alternatively, as above, be

generated once all contours have been established. The drilling pattern of maximum contour MCO will not, as discussed above, represent the total volume that is to be drilled and blasted during the round to be drilled. Additional drill holes must be added in order to drill the full volume. Therefore, the remaining portion of the face contour, i.e. the non-hashed portion of fig. 8, shown as hashed in fig. 9 and denoted DC, is still to be drilled, using holes having a length being less than the maximum length of the holes of the round to be drilled may be used for this portion of the face contour.

In step 507, therefore, the difference surface, contour DC, constituting the difference between the face contour FC and the maximum contour MCO is determined. With regard to this surface, a drilling pattern is to be generated where holes are drilled to a shorter length than holes being drilled when drilling the generated drilling pattern of the maximum contour MCO.

According to embodiments of the invention, it is determined a number of rows of holes to be drilled on the difference contour DC. This can be established, for example using rules regarding distance between holes to be used when generating drilling patterns, where this distance can be dependent e.g. on the properties of the rock to be drilled, diameter of holes to be drilled, length of the section of rock that is about to be excavated in the current round etc., as is known per se. This determination regarding the holes, however, is oftentimes already performed, and is therefore not part of the invention. Hence, when e.g. the applicable hole distance is established, a number of rows of holes to be drilled in the difference contour DC may also be determined.

The determined number of rows of holes to be drilled, and/or alternatively the width of the difference contour DC, is then used to establish a number n intermediate bottom contours BC1 ...BCn, step 507, to be used between the face contour FC and the original bottom contour BC0. That is, according to the present example, the intermediate bottom contours are determined in a different manner in comparison to the above. For example, one bottom contour can be generated for each, e.g. vertical or horizontal, row of holes to be drilled in the difference contour DC. The intermediate bottom contours BC1 ...BCn can be generated in the same manner as BC0 above, i.e. through interpolation using the tunnel contours of the adjacent tunnel line points. With regard to the location of the bottom contours BC1 ...BCn, these can be arranged to be evenly spaced between the face contour FC and the bottom contour BC0. That is, for example, if only one additional drilling pattern is to be generated, the additional bottom contour BC1 can be arranged to be positioned at half the distance from the face contour FC to the bottom contour BC0. The distances to the additional bottom contours/planes may also be determined in any other suitable manner, e.g. in dependence of the curvature of the cavity to be drilled.

According to the present example, two additional bottom contours BC1 , BC2 are generated, which are evenly spaced between the face contour FC and the bottom contour BCO. This is illustrated in fig. 10, where the two intermediate planes BC1 , BC2 are shown. Other distributions than even distances between contours may also be utilised. A drilling pattern may then be generated for each additional bottom contour BC1 ...BCn, step 508, where the additional drilling patterns can be generated using the above described principle, by interpolating, respectively, the additional bottom contours BC1 ...BC2 and the limiting contour LC in the plane of the face contour FC, and further delimit by the face contour FC. This is illustrated by the lines 1001 , 1002 used in the interpolation in fig. 10, and the portion to be drilled to a hole depth delimited by BC1 is schematically indicated as MC1 portion of DC in fig. 9, and the portion to be drilled to a hole depth delimited by BC2 is schematically indicated as MC2 portion of DC in fig 9. Portions of the face contour FC for which drilling patterns have already been generated, e.g. MC0, are disregarded. Hence, when generating a drilling pattern for BC1 , this will, according to the present example, render one or more further row of holes to be drilled, essentially having a length corresponding to the distance between the face contour FC and the intermediate bottom contour BC1 . Again, holes regarding portions of the face contour FC for which a drilling pattern has already been generated are disregarded. Furthermore, holes being too close to already planned holes, e.g. for the maximum contour MC0 may also be disregarded, since the already planned holes in general will be holes of a longer length.

Alternatively, such holes may be omitted from the drilling pattern of MC0 instead. When the drilling pattern for the first intermediate bottom contour BC1 has been generated, a drilling pattern is generated for the second intermediate bottom contour BC2 in a similar manner, which in this example will render one or more further row of holes to be drilled, essentially having a length corresponding to the distance between the face contour FC and the second intermediate bottom contour BC2, i.e. holes having a yet shorter length. In addition to holes regarding portions of the face contour

FC for which a drilling pattern has already been generated with respect to the bottom contour BCO, holes of the drilling pattern for the first intermediate bottom contour BC1 may be disregarded, and also holes being too close to already planned holes as discussed above.

When drilling patterns have been generated for the bottom contour BC and the intermediate contours BC1 , BC2, consequently, an aggregate drilling pattern covering the full face contour FC have been generated, and fig. 1 1 schematically illustrates the holes to be drilled by solid lines extending from the face contour FC to the bottom contours, respectively. The aggregate drilling pattern may then be drilled one at a time or be treated as a single aggregated drilling pattern, step 509, where holes may be drilled in any order and not just one drilling pattern at a time. The method is then ended in step 510. Again, the drilling pattern for the various parts of the face contour may instead be generated once all contours have been established, i.e. similar to the exemplary method of fig. 3.

The drilling patterns regarding the different bottom contours may also be generated in any other order, still for the same areas, but shorter holes may be maintained instead of longer holes in the border areas should this be considered advantageous, e.g. to reduce surplus rock. Also, the different portions MC0, MC1 etc. may be determined prior to the actual drilling patterns are being determined.

Furthermore, according to embodiments of the exemplary method of fig. 5, the areas of the face contour FC not covered by the maximum contour MC0 may be enlarged, i.e. the area of MC0 may be reduced. This may be carried out e.g. in order to make room for one or more further rows of holes in case the difference contour is determined to be too small, e.g. being too narrow. Such parameters may be pre-set in the control system. Enlargement of the difference area may be accomplished by reducing the size of the maximum contour MC0. For example, the limiting contour LC can be projected to the face contour FC in the navigation plane, instead of utilising interpolation, thereby further limiting the size of the maximum contour MC0. This is exemplified in fig. 7 by dotted line 710, which hence renders the maximum contour MC0 smaller, thereby increasing the area to be drilled using shorter hole lengths. The projection may be used in combination with interpolation according to the above, but projection may also be utilised instead of the interpolation. That is, for example, only the limiting contour LC or a bottom contour BCO may be used in the

establishment of the maximum contour MCO /difference contour, e.g. as discussed with reference to the method of fig. 3, and e.g. projection according to fig. 14 may be utilised.

This is illustrated in fig. 12, which is similar to fig. 14, but where the line 1201 exemplifies interpolation according to the above, which results in a maximum contour MCO having a width corresponding to line 1203.The maximum contour MCO can be reduced by projecting the bottom contour BCO onto face contour FC instead of utilising interpolation, line 1202 to increase the part of the face contour FC for which holes having a reduced length are to be drilled, the increase of the difference contour, i.e. reduction of the maximum contour MCO, being indicated by line 1205.

Furthermore, the method for generating a drilling pattern has been described above as being carried out by a drilling rig that is present at a location where a rock face is about to be drilled. According to embodiments of the invention, the generation of the drilling pattern may be carried out by a computer e.g. in a planning centre, where e.g. a drilling pattern may be generated for any location of the cavity to be drilled, so that personnel e.g. may evaluate the generated the drilling pattern, and adjust input parameters to be used in the generation of the drilling pattern.

Claims

1 . A method for generating a drilling pattern for excavating a cavity in rock, the drilling pattern determining holes (x) to be drilled in a face (603) of the rock, the determination of the holes (x) to be drilled being a determination of location, direction and length of the holes (x) to be drilled, the holes being arranged to be drilled by a drilling rig (201 ), the holes of the drilling pattern being drilled prior to subsequent blasting of the face (603) of the rock, the method being characterised in:

- determining a face contour (FC) being a representation of the rock face to be drilled and constituting a cross section of the cavity in a plane (NP) representing the rock face to be drilled,

- determining a first bottom contour (BCO) being a representation of a cross section of the cavity to be drilled at a first distance from the face contour (FC),

- determining at least one second bottom contour (BC1 , BC2) being a representation of a cross section of the cavity to be drilled at a second, different from said first, distance from the face contour (FC), and

- when determining said holes to be drilled, determining holes to be drilled between the face contour (FC) and the first bottom contour (BCO), and holes to be drilled between the face contour (FC) and the second bottom contour (BC1 , BC2).

2. Method according to claim 1 , said first distance being longer than said second distance,

- wherein holes to be drilled between the face contour (FC) and the first bottom contour (BCO) are longer than holes to be drilled between the face contour (FC) and the at least one second bottom contour (BC1 , BC2).

3. Method according to claim 1 or 2,

- wherein holes to be drilled between the face contour (FC) and the first bottom contour (BCO) end substantially at said first bottom contour (BCO), and - wherein holes to be drilled between the face contour (FC) and the second bottom contour (BC1 , BC2) end substantially at said second bottom contour (BC1 , BC2).

4. Method according to any one of claims 1 -3, wherein each of said at least one second contour is an intermediate contour (BC1 , BC2) between said face contour (FC) and said first bottom contour (BCO), each of said intermediate contours (BC1 , BC2) representing a cross section of the cavity at different distances from the face contour (FC) towards the first bottom contour (BCO).

5. Method according to claim 4, further including:

- determining the number of intermediate contours (BC1 , BC2) based on a curvature and/or change in width or height of the cavity to be excavated.

6. Method according to any one of the claims 1 -5,

- wherein said first bottom contour (BCO) is a representation of a cross section of the cavity at a distance from the face contour (FC) substantially corresponding to the maximum length of the holes to be drilled.

7. Method according to any one of the preceding claims,

- wherein said first bottom contour (BCO) is used to generate the drilling pattern for a first part (MCO) of the face contour (FC), and

- wherein said at least one second bottom contour (BC1 , BC2) is used when generating a drilling pattern of a second (MC1 , MC2), different from said first, part of the face contour (FC).

8. Method according to claim 7, further including:

- determining said first part (MCO) utilising said first bottom contour (BCO) and

- determining said second part (MC1 , MC2) utilising said second bottom contour (BC1 , BC2).

9. Method according to claim 7 or 8, further including:

- determining a limiting contour (LC), said limiting contour (LC) being a representation of the cross section of the cavity at a distance from the face contour (FC) in a direction away from the rock to be excavated, and - determining said first part (MCO) and/or said second part (MC1 , MC2) of the rock face to be drilled utilising said first (LC) contour.

10. Method according to claim 9, further including:

- determining said first part (MCO) and/or said second part (MC1 , MC2) of the face contour (FC) utilising interpolation between said limiting contour (LC) and said first bottom contour (BCO), or interpolation between said limiting contour (LC) and one or more of said second bottom contours (BC1 , BC2), the first part (MCO) and/or said second part (MC1 , MC2) being delimited also by the face contour (FC).

1 1 . Method according to any one of the claims 9-10, the drilling rig (201 )

comprising at least one feed beam (209-21 1 ) carrying a drilling machine (206- 208), further including:

- determining said limiting contour (LC) as representation of the cross section of the cavity at a distance from the face contour (FC) substantially corresponding to the length of the feed beam.

12. Method according to any one of claims 7-1 1 , further including:

- determining said first part (MCO) and/or said second part (MC1 , MC2) of the face contour (FC) utilising projection of said limiting contour (LC) and/or said first bottom contour (BCO) onto the face contour (FC).

13. Method according to any one of claims 7-12, further including:

- determining said at least one second part (MC1 , MC2) of the face contour (FC) utilising projection of said at least one second bottom contour (BC1 , BC2) onto the face contour (FC).

14. Method according to any one of the claims 8-1 1 , further including:

- on the basis of a remaining part (DC) of said face contour (FC) not being encompassed by said first part (MCO), determining the number of the least one second bottom contours (BC1 , BC2).

15. Method according to any one of the claims 1 -13, further including:

- when determining said holes to be drilled, if a hole to be drilled between the face contour (FC) and the first bottom contour (BCO) is located less than a first distance from a hole to be drilled between the face contour (FC) and the second bottom contour (BC1 , BC2), omit one of said holes.

16. Method according to any one of the claims 1 -14, further including:

- determining said drilling pattern when the cross section of said cavity is narrowing or widening in the direction of excavation, and/or a curvature of the cavity is changing.

17. Method according to any one of the preceding claims, further including:

- determining the drilling pattern as a first drilling pattern for a first part (MCO) of the face contour (FC), and at least one second drilling pattern for at least one second part (MC1 , MC2), different from said first part (MCO), of the face contour (FC), the drilling pattern being a combination of said first and said at least one second drilling pattern.

18. Computer program comprising instructions which, when the program is

executed by a computer, cause the computer to carry out the method according to any one of the preceding claims.

19. Computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to any one of the claims 1 -17.

20. System for generating a drilling pattern for excavating a cavity in rock, the drilling pattern determining holes (x) to be drilled in a face (603) of the rock, the determination of the holes (x) to be drilled being a determination of location, direction and length of the holes (x) to be drilled, the holes being arranged to be drilled by a drilling rig (201 ), the holes of the drilling pattern being drilled prior to subsequent blasting of the face (603) of the rock, the system being characterised in:

- means for determining a face contour (FC) being a representation of the rock face to be drilled and constituting a cross section of the cavity in a plane (NP) representing the rock face to be drilled,

- means for determining a first bottom contour (BC0) being a representation of a cross section of the cavity to be drilled at a first distance from the face contour (FC), - means for determining at least one second bottom contour (BC1 , BC2) being a representation of a cross section of the cavity to be drilled at a second, different from said first, distance from the face contour (FC), and

- means for, when determining said holes to be drilled, determining holes to be drilled between the face contour (FC) and the first bottom contour

(BCO), and holes to be drilled between the face contour (FC) and the second bottom contour (BC1 , BC2). Rock drilling rig (201 ) comprising a system according to claim 20.