WO1986002404A1

WO1986002404A1 - A device for fracturing stone, rock and the like

Info

Publication number: WO1986002404A1
Application number: PCT/SE1985/000402
Authority: WO
Inventors: Karl Gustaf Derman
Original assignee: Gislaved Ab
Priority date: 1984-10-18
Filing date: 1985-10-18
Publication date: 1986-04-24
Also published as: SE444837B; AU5017785A; SE8405218L; EP0231186A1; SE8405218D0; JPS62501091A

Abstract

A device for fracturing cleavable material, such as stone, rock, concrete and the like comprises a fracturing member introducable in a hole in said material and expansible in a direction transversely of the axis of the hole.

Description

A DEVICE FOR FRACTURING STONE, ROCK AND THE LIKE The pre.sent invention relates to a device for fracturing cleavable materials, such as stone, rock, concrete and the like.

Fracturing or cleaving of such cleavable materials as stone, rock, concrete and the like can be provided by boring a hole in the material and expanding the hole to such an extent that the surrounding material is broken or fractured. The expansion of the hole can be provided by detonating an explosive introduced in the hole. However, this is a method which has restricted applicability requiring great security precautions and specially educated personal. For this reason there have been developed methods for fracturing cleavable material by means of which the expansion of the bore necessary for fracturing the material is provided by other means than by detonating an explosive.

Thus, it is previously known to fill up the bore hole with a cement solution having the properties of expanding during the hardening to such an extent and by such a pressure that a fracturing of the surrounding material is provided. Thereby, it is a substantial drawback that the cement is expensive and that the breaking or fracturing requires a time of about 24 hours.

It is also previously known to provide the expansion of the bore hole necessary for conducting the fracturing by sealing the opening of the bore and supply water under high pressure to the bore. This method requires complicated and expensive equipment and can lead to difficulties for the reason that it is necessary to provide an absolutely tight bore before the water is supplied requiring that cracks in the walls of the bore have to be tightened before the fracturing can be conducted.

The object of the present invention is to provide a device for fracturing cleavable materials, such as stones, rock, concrete and the like, in which the above drawbacks have been overcome and by means of which it is possible to expand bores provided in stone, rock, concrete and the like in a simple, rapid and cheap way to such an extent that there is provided a fracturing of the material surrounding the bores.

In order to comply with this object the device according to the invention comprises a member for expanding a bore provided in the cleavable material, the device being characterized in that the member for expanding the bore is constituted by a fracturing member which is introdu'cable into the bore and is expansible in a direction transversely of the axis of the bore.

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In a preferred embodiment the fracturing member comprises walls which are displacable transversely of the axis of the bore and encloses a pressure chamber, and the device comprises a pressure fluid pump connected with the pressure chamber by means of a pipe for supplying pressure fluid to the pressure chamber in order to expand the fracturing member by displacing the displacable walls of the fracturing member from each other. In accordance with the invention there is provided an especially advantageous device which is easy to handle by manufacturing the displacable walls of the fracturing member from elastomeric material for example in the form of a thick-walled rubber hose.

In the case that the displacable walls of the fracturing member consist of elastomeric material it is suitable that the walls are connected with a device for preventing an uncontrolled expansion of the walls in the longitudinal direction of the bore. A device of this kind can comprise two end members between which the walls are positioned and which are connected with each other by means of a connecting device which is adapted to prevent displacement of the end members away from each other.

In the case that the displacable walls of the fracturing member consist of elastomeric material it represents a difficult problem that the elastomeric material has a tendency to creep out through the clearance space between the end members of the fracturing member and the surrounding wall of the bore when the-pressure is applied to the fracturing member. The present invention defines different features and combinations of features of the fracturing member for solving this problem. Thus, in accordance with the invention it is possible to reduce the size of the clearance space by reducing the difference of the diameters of the bore and the fracturing member. The reduction of the diameter difference can lead to problems with regard to the introduction of the fracturing member in the bore as the bore is rarely exactly straight but in accordance with the invention these problems can be solved by providing a flexible connecting device for the end members, for example a wire.

The problem with regard to the tendency of the elastomeric material to creep into the clearance space between the end members and the wall of the bore can be solved in accordance with the invention also by providing end members of the fracturing member which are expansible in the direction of the walls of the bore. Thereby it is possible to solve also the problems caused by the fact that the bores frequently have a greater diameter at the opening than at the bottom and by the fact that the bores are often out-of-round.

a- * f -^~~-. t^~- ~~- --—- ^■.--.---, ***~ 9 The problem of the tendency of the elastomeric material to creep out in the clearance space between the end members of the fracture member and the surrounding wall of the bore can be reduced in accordance with the invention also by providing a connecting device of the end members which is adapted slightly to expand when the pressure is supplied to the fracturing member. In combination with the friction of the elastomeric material against the wall of the bores this feature of the fracturing member provides a substantial reduction of said problem.

In a further embodiment of the device according to the invention the displacable walls of the fracturing member consists of a reinforced elastomeric material, whereby it is possible to provide a suitable relationship between the expansion of the material in the axial direction and in the radial direction when pressure is supplied to the fracturing member.

It is, of course, possible to combine two or more of the features defined above for providing a device according to the invention.

The invention is described in the following with reference to the accompanying drawings.

Fig. 1 shows an embodiment of a fracturing device according to the invention, the fracturing member of the fracturing device being shown in axial section.

Fig. 2a is an axial section of a modified embodiment of a fracturing member included in a device according to the invention.

Fig. 2b is an axial section showing the connection of two fracturing members of the kind shown in Fig. 2a with each other.

Fig. 3 is an axial section of a further embodiment of a fracturing member included in a device according to the invention.

Figs 4a-4h shows different embodiments of a detail of a fracturing member according to the invention.

Fig. 5 is an axial section of a portion of a fracturing member according to the invention.

..__.___, i Figs. 6a and 6b are axial sections of end portions of two different embodiments of fracturing members included in devices according to the invention.

Figs. 7a-7c are an axial section, a side view and a cross-sectional view of an embodiment of a fracturing member included in a device according to the invention.

Fig. 8 is a cross-sectional view of a modified embodiment of the fracturing member shown in Fig. 7.

Fig. 9 is an axial section of a further embodiment of a fracturing member included in a device according to the invention.

Fig. 10 is an axial section of a further embodiment of a fracturing member included in a device according to the invention.

Fig. 11 is a cross-sectional view of a further embodiment of a fracturing member included in a device according to the invention.

In Fig. 1 there is shown the principal construction of a device for fracturing a cleavable material 2, for example consisting of rock. In the rock there is provided a hole 4 provided by boring in the conventional way. A fracturing device according to the invention comprises a fracturing member 6, a pressure fluid pump 8 and a hose 10 for connecting the pressure fluid pump 8 with the fracturing member 6. A fracturing or breaking of the cleavable material 2 is intended to be provided by expanding the bore 4 to such a degree that the material surrounding the bore is fractured or broken. The expansion of the bore 4 is provided by means of the fracturing member 6 positioned in the bore by the fact that the fracturing member 6 is expansible in a direction transversely of the axis of. the bore 4. The fracturing member 6 consists of a wall 12 of an elastomeric material which in the embodiment shown has the form of a thick-walled rubber hose, an end member 16 provided with an inlet plug 14, an end member 18, a connecting device 20 for connecting the end members 16 and 18 with each other and support and sealing means 22 and 24 for connecting the wall 2 with the end members 16 and 18, respectively.

In the embodiment of the device for fracturing cleavable material shown in Fig. 1 the end members 16 and 18 and .the connecting device 20 consist of rigid material, preferably metal. The connecting device 20 is constituted by a rod which by means of threads is firmly connected with the end members

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•^■ ___.>__. i ϊi ^ : 16 and 18. Thus, the end members 16 and 18 are rigidly connected with each other. The support and sealing means 22 and 24 are fi mly connected with the wall 12 and the end members 16 and 18, respectively. Thus, in spite of the fact that the wall 12 consists of an elastomeric material it is not expansible in the longitudinal direction of the bore 4 because of the fact that it is restrained between the end members 16 and 18.

In the end member 16 and the adjacent end of the rod 20 there is formed a channel 26 which is connected with the pressure fluid pump 8 through the hose 10. At its inner end the channel 26 opens radially in the space between the outer surface of the rod 20 and the inner surface of the wall 12, between which surfaces there is provided a pressure chamber 28.

When supplying pressure fluid, preferably pressure oil, to the pressure chamber 28 from the pump 8 through the hose 10 and the channel 26 there is provided a radially directed expansion of the wall 12 which is pressed against the walls of the bore 4. The pressure in the pressure chamber and thereby the contact pressure of the wall 12 against the walls of the bore 4 is increased until the strength of the material 2 surrounding the bore 4 is exceeded and the material is fractured. The pressure required can reach for example 1000 kp/cπr. It is possible to construct the fracturing device in accordance with the principles of the invention so that pressures as high as 3500 kp/cm^ can be reached.

In the device shown in Fig. 1 it is a problem that the elastomeric material of the wall 12 strives to creep out through the clearance spaces 29 between the support and sealing means 22 and 24 and the wall of the bore 4 when pressure fluid is supplied to the pressure chamber 28. This can lead to ruptures in the elastomeric material within the area of connection between the wall 12 and the support and sealing means 22 and 24. It is obvious that such ruptures make it impossible to reach the pressure required for the fracturing of the cleavable materal 2.

In accordance with the invention this problem is solved by constructing the fracturing member in a special way. Thus, the problem can be solved by constructing the fracturing member so that said clearance spaces are very small, by providing radially expandable support and sealing means so that said clearance spaces are closed when pressure is supplied to the fracturing member or by constructing the fracturing member so that the wall 12 which consists of elastomeric material is allowed to expand to a restricted degree also in the axial direction when the pressure is supplied to the fracturing member. The last-mentioned axial expansion can be provided by constructing the connecting device 20 so that it is elongated to a certain restricted degree when applying the pressure to the fracturing member and/or by constructing the support and sealing means so that the end members of the wall 12 are allowed to be slightly displaced from each other when the pressure is supplied to the fracturing member.

The construction of the fracturing member so that tt is possible to reduce the width of the clearance spaces 29 resides in the measure of providing a flexible fracturing member. Thereby it is possible to introduce the fracturing member in a bore having a diameter which is only slightly greater than the diameter of the fracturing member even if the bore is not exactly straight. The two embodiments of fracturing members shown in Figs 2 and 3 are flexible for contributing to the solving of the problem of preventing the elastomeric material of the wall 12 from being pressed out through the clearance spaces 29 between the end members of the fracturing member and the wall of the bore. It can also be mentioned that the flexibility of the fracturing member provides that the clearance space 29 will be uniform around the end members even if the bore is of curved shape. It is realized that the end members would take an eccentric position in the bore if a straight, rigid fracturing member were used in a curved bore leading to a non-uniform clearance space between the end members and the wall of the bore so that the clearance space would be of substantial dimensions at one side of the fracturing members.

In Fig. 2a there is shown an embodiment of a flexible fracturing member included in a device according to the invention. The fracturing member comprises an elastomeric material wall 30 of the same kind as the wall 12 in the embodiment according to Fig. 1. The wall 30 is connected with the end members 32 and 34 by support and sealing means 36 and 38, respectively. The end members 32 and 34 are connected with each other by means of a flexible element 40 which in the embodiment shown in Fig. 2a consists of a twisted steel wire. The steel wire 40 is connected with the end members 32 and 34 by means of connector elements 42 and 44, respectively, having clamping portions 46 and 48 within which the connector elements are clamped to the steel wire 40. The steel wire 40 is connected with the plug 52 of the end member 32 through a channel 50 in the connector element 42 and forms between its strands the necessary channels for transferring the pressure fluid to a pressure chamber 54 between the outer surface of the steel wire 40 and the inner surface of the wall 30. In principle the embodiment of the fracturing member shown in Fig. 2a has the same function as the fracturing member according to Fig. 1.

_?•^■;. »^•*— - ^{•• ■}__,.__.•_> ■—• _ ■__, _ιi ____^ j Due to the fact that the element connecting the end members with each other is flexible in the embodiment according to Fig. 2 there is provided the special advantage that the clearance space between the end members 32 and 34 and the wall of the bore can be small as it is in spite thereof possible to position the fracturing member according to Fig. 2 in a bore which is not exactly straight. Also when using fracturing members of great length it is advantageous to utilize the embodiment according to Fig. 2a, as a fracturing member of this kind can be rolled to a space-saving position for facilitating transportation and storing.

In Fig. 2b there is shown how two fracturing members of the kind shown in Fig. 2a can be coupled together. It is realized that according to the principle shown in Fig. 2b it is possible to connect a desired number of fracturing members with each other to a unit of desired length.

In Fig. 3 there is shown an axial section of a fracturing member which despite from the construction of the rod 20a connecting the end members 16 and 18 with each other is of the same construction as the fracturing member according to Fig. 1. Because thereof, there is in Fig. 3 used the same reference numerals as in Fig. 1 with the exception of the rod 20a. As appears from Fig. 3 the rod 20a has reduced diameter at its central portion facilitating the intro- • duction of the fracturing member in a curved bore. Thus, the special design of the rod 20a makes it possible for the walls 12 to be displaced inwards facilitating the introduction.

In a further modification of the fracturing member the rod which connects the end members with each other can be constituted by a pipe flattened at its central portion by means of rolling.

Figs 4a-4h show different embodiments of the support and sealing means by means of which the elastomeric material wall 12 is connected with the end members and with the end portions of the rod or the connector elements of the steel wire constituting the connecting device between the end members.

In the embodiment shown in Fig. 4a the end member 16 provided with the plug 14 is connected with the element 56 and the elastomeric material wall 12 is connected with the element 56 and with the end member 16 by support and sealing means consisting of a support ring 58 and a sealing element 60. The wall 12 consisting of elastomeric material can be fixed to the sealing element 60 by means of vulcanization even if this is not necessary. The sealing element 60 is sealing against the element 56 by means of an 0-ring 62. When pressure is supplied to the fracturing member so that the wall 12 is displaced into engagement with the wall of the bore 4 a radial expansion of the sealing element 60 (as shown with broken lines) takes place so that the clearance space between the sealing element 60 and the wall of the bore is closed and the elastomeric material of the wall 12 is thereby prevented from creeping into said clearance space. It also appears that the radial expansion of the sealing element 60 allows a restricted axial expansion of the wall 12 which contributes to a prevention of the displacement of the elastomeric material into the clearance space.

The embodiment shown in Fig. 4b comprises like the embodiment according to Fig. 4a an end member 16 provided with a plug 14 and connected with the element 56, a wall 12 consisting of an elastomeric material, a support ring 58 and a sealing element 64. The difference between the embodiments according to Figs 4a and 4b resides in the construction element 60 and the sealing element 64. In the embodiment according to Fig. 4b the sealing element consists of a sheet metal cap which is fixedly connected with the support ring 58 and can be fixed to the elastomeric material of the wall 12 by means of vulcanization, even if this is not necessary. As shown by means of broken lines the sealing element 60 is radially expanded when pressure is applied to the fracturing member so that the clearance space between the sealing element and the wall of the bore is closed and the elastomeric material is thereby prevented from creeping- out through the clearance space.

In the embodiment according to Fig. 4c the sealing member 66 is constituted by a ring of semi-rigid material, for example hard polyuretane, which expands in the way shown by means of broken lines when pressure is supplied to the fracturing member in order to close the clearance space between the sealing element and the wall of the bore. The sealing between the wall 12 and the element 56 is provided by the fact that the wall 12 has at its end portion a peripheral sealing lip 68 which is forced into sealing engagement with the outer surface of the element 56 by the pressure fluid supplied between the wall 12 and the element 56.

In the embodiment according to Fig. 4d the sealing member 70 is constituted by two rings 72 and 74 slidably engaging each other at conical surfaces and firmly connected with the wall 12 and the support ring 58, respectively. Thereby, at least the ring 72 is constituted by a semi-rigid expansible material, such as hard polyuretane. When pressure is applied to the fracturing member the ring 72 will expand while sliding along the conical surfaces between the rings 72 and 74 as shown by means of broken lines to a position in which the ring 72 closes the clearance space against the wall of the bore. Because of the conical engagement surfaces between the rings 72 and 74 also a restricted axial expansion of the elastomeric material of the wall 12 is allowed contributing to the prevention of the creeping of the elastomeric material through the clearance space at the wall ofthe bore.

Also in the embodiment according to Fig. 4c the sealing between the wall 12 and the element 56 is provided by the fact that the wall 2 is provided with a sealing lip 68 at its end portion.-

In the embodiment according to Fig. 4e the elastomeric material wall 12 is connected with a sealing element 76 consisting of a semi-rigid, expansible material, such as hard polyuretane and having a conical surface slidably engaging a conical surface of the support ring 58. When pressure is applied to the fracturing member the sealing element 76 expands to a position closing the clearance- space against the wall of the bore while sliding along said conical surfaces, as shown by means of broken lines. Also in this embodiment there is provided a restricted, axial expansion of the elastomeric material of the wall 12 during the radial expansion of the sealing element 76. The sealing between the wall 12 and the outer surface of the element 56 is provided by the fact that the wall 12 comprises a sealing lip 68 in the same way as the embodiments according to Figs 4c and 4d.

In the embodiment according to Fig. 4f the sealing member consists of a spring washer 78 which is fixedly connected with the end surface of the elastomeric material of the wall 12 by means of vulcanization. The spring washer 78 is designed in such a way that it tilts to the position shown by means of broken lines in which position the washer engages the support ring 58, when pressure is applied to the fracturing member. In order to provide for this movement of the spring washer the spring washer can be corrugated in such a way that the washer maintains its original inner diameter but increases its outer diameter to the position in which the clearance space against the wall of the bore is closed when said movement of the washer takes place. During said movement of the spring washer there is also provided a restricted, axial expansion of the elastomeric material of the wall 12 contributing to the prevention of the creeping of the elastomeric material through the clearance space between the fracturing member and the wall of the bore.

^■3 ir^^ . ^• i a-_____ι _ The spring washer can consist of a cup spring of standard type instead of said corrugated washer.

It is not necessary to fix the spring washer 78 to the elastomeric material of the wall by means of vulcanization as there is provided a strong compression of the end surface of the wall 12 towards the washer when the pressure is applied to the fracturing member.

The sealing of the wall 12 against the element 56 is also in this embodiment provided by the fact that the wall 12 is provided a sealing lip 68.

In the embodiment according to Fig. 4g the sealing element is constituted by a coil spring 80 which is vulcanized into the elastomeric material of the wall 12 at the outer end portion thereof. When pressure is applied to the fracturing member the coil spring 80 expands radially to the position shown by broken lines in which position the clearance space between the fracturing member and the wall of the bore is closed. Thereby, it ^"is most suitable that the end surface of the wall 12 is not vulcanized to the support ring 58 but is able to slide against the ring during the radial expansion.

In this embodiment the contact surface between the wall 12 and «the support ring 58 can be conical so that the radial expansion of the coil spring 80 and the end surface of the wall ^"12 provides also for a certain axial expansion of the end surface of the wall 12.

Also in this embodiment the sealing between the wall 12 and the element 56 is provided by means of a sealing lip 68.

In the embodiment of the fracturing member according to the invention shown in Fig. 4h the sealing element is in the form of a corrugated strip 82 which expands radially to a position in which the clearance space against the wall of the bore is closed, when pressure is applied to the fracturing member. The sealing between the elastomeric material wall 12 and the element 56 is provided by means of a sealing lip like in the above embodiments of the fracturing member.

In most of the embodiments of support and sealing means described above by means of which the elastomeric material wall 12 is connected with the end members and with the element 56 the sealing between the wall 12 and the element 56 is provided by means of a sealing lip 68 which is so positioned that the

^c_.?-^_» _____—_"- . pressure fluid, usually pressure oil used for expanding the fracturing member does not have any influence on the connection between the elastomeric material of the wall 12 and the sealing member 60 or the support ring 58. This is advantageous with regard to the fact that the pressure oil has a detrimental influence on this connection.

In the embodiments of the fracturing member according to the invention shown in Figs 4a-4h there is a restricted axial expansion of the wall 12 consisting of elastomeric material, when pressure is applied to the fracturing member. This axial expansion contributes to the prevention of that the elastomeric material extrudes into the clearance space between the fracturing member and the wall of the bore by providing an increased space for receiving the elastomeric material in the areas inside the clearance space. Also the friction between the elastomeric material wall 12 and the wall of the bore provides that the elastomeric material is only in restricted extension displacing axially in the direction towards the clearance spaces.

As mentioned the axial expansion can be provided by the construction of the support and sealing means at the end portions of the fracturing member, but it is also possible to provide this axial expansion by providing a connection device between the end members which is somewhat expansible. Thus, in the embodiment of the fracturing member shown in Fig. 2a it is possible to adapt the steel wire 40 in such a way that the wire is elongated to a restricted extent when pressure is applied to the fracturing member. Thereby, there is provided not only the axial expansion of the wall 12 advantageous with regard to the sealing of the clearance space but there is also provided a restriction of the stresses on the connecting device between the end members. Thus, the friction of the wall 12 against the wall of the bore reduces the axial force to which the connecting device is subjected.

In Fig. 5 there is shown in axial section a suitable way of constructing the elastomeric material wall 12 of the fracturing member included in the device according to the invention. In this embodiment the wall 12 comprises an intermediate member 84 and two end members 86. The intermediate member 84 consists of an extruded hose which has been cut to suitable length. The end members 86 are manufactured by means of for example compression moulding and are connected with the intermediate member 84 by means of an adhesive or by means of vulcanization. In accordance with this principal construction it is possible to manufacture fracturing members having elastic material walls of different lengths.

.. _______ _, ,__ _||,_J-_f « ■__■ - _ „___,__ j As an alternative it is also possible to manufacture the intermediate member as well as the end members from a continuous hose section and to cut out the sealing lips of the end members afterwards.

In the embodiment according to Fig. 6a the wall 12 can be pretensioned by means of a tensioning member 88 positioned on a threaded portion of the element 56.

In the embodiment according to Fig. 6b there is utilized a piston-shaped tensioning element 90 for providing the pretensioning of the wall 12. The tensioning element 90 is positioned in a cylinder 92 and is displaced towards the wall 12 in order to provide the pretensioning thereof by supplying the pressure fluid used for the expansion of the wall 12 to the cylinder 92.

In Figs 7 and 8 there are shown fracturing members by means of which it is possible to provide a directional fracturing action. In the embodiment according to Figs 7a, 7b and 7c the fracturing member comprises a body 94 consisting of metal and having a through longitudinal opening 96. A rubber element 98 having a rectangular cross-sectional shape and an axial recess 100 is centrally positioned in the opening 96. At opposite sides of the rubber element 98 there are positioned in the opening 96 a couple of pistons 102 of for example nylon.

When pressure fluid is supplied to the recess 100 in the rubber element 98 the rubber element expands in order to displace the pistons 102 from each other. In the direction in which the rubber element 98 contacts the body 94 there is not provided any expansion for which reason there is in this embodiment of the fracturing member provided a directional fracturing action.

In accordance with Fig. 8 the fracturing member shown in Fig. 7 is modified in the respect that the body 94a encloses the rubber element 98a at three sides thereof while a piston 102a is positioned only at one side of the rubber element. It is realized that the fracturing member according to Fig. 8 will expand in only one direction when supplying a pressure fluid to the recess 100a.

In the embodiment of a fracturing member included in a device according to the present invention shown in Fig. 9 an expander element 104 preferably consisting of rubber is positioned between two end members 106 and 108. The end members 106 and 108 are connected with each other by means of wires or rods 110 distributed in a suitable number around the periphery of the fracturing member. The expander element 104 has a central opening 112 for the supply of pressure fluid in order to provide radial expansion of the expander element 104. The wires or rods 110 are flexible and follow the expansion of the expander element 104 while at the same time allowing the flexing of the fracturing member when this is introduced in curved bores. It is, of course, also possible to adapt the wires or rods so that they are able to allow a restricted axial expansion of the fracturing member when pressure is applied thereto in order to provide an improved clearance space sealing according to the principles described above.

In Fig. 10 there is shown a fracturing member consisting of a body 112 having a recess 114 and a metal piston 116 radially displacable therein. The piston 116 has at its- inner surface an element 118 of an elastomeric material, preferably rubber, fixed to said surface. The piston 116 is radially displacable for expanding the fracturing member by the supply of pressure fluid between the bottom of the recess 114 and the element 118 connected with the piston 116.

In the embodiment of the fracturing member shown in Fig. 11 the expansible wall 120 consists of a relatively rigid material, for example nylon, while the expansion is provided by the fact that the wall 120 comprises longitudinal outer and inner grooves 122 and 124, respectively. Thereby the grooves 122 and 124 are suitably filled up with rubber. In this embodiment of the invention it is also possible to use metal, preferably steel for manufacturing the wall 120.

Several fracturing members can be connected with each other in a simple way and can be connected with the same pressure fluid pump for providing a fracturing or breaking of the cleavable material by means of several bores at the same time. Thereby, suitable delay and check valves can be connected between the fracturing members in order to provide the desired controlling of the actuation of the fracturing members.

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-IT

Claims

C L A I M S

1. A device for fracturing cleavable material, such as stone, rock, concrete and the like, comprising a member for radially expanding a hole provided in said material, c h a r a c t e r i z e d in that said member for expanding the hole provided in the material is constituted by a fracturing member which is introducable in the hole and is expansible in a direction transversely of the axis of the hole.

2. A device as claimed in claim 1, c h a r a c t e r i z e d in that the fracturing member comprises walls movable in the direction transversely of the axis of the hole and enclosing a pressure chamber and that the device comprises a pressure fluid pump connected with the pressure chamber by means of a pressure line for supplying pressure fluid to the pressure chamber for expanding the fracturing member by displacing the walls thereof apart.

3. A device as claimed in claim 2, c h a r a c t e r i z e d in that the walls of the fracturing member consist of elastomeric material.

4. A device as claimed in claim 3, c h a r a c t e r i z e d in that the elastomeric material walls of the fracturing member are positioned between a pair of end members connected with each other by means of a connecting device.

5. A device as claimed in any of the proceeding claims, c h a r a c t e r i z e d in that the fracturing member is flexible.

6. A device as claimed in claim 4 and 5, c h a r a c t e r i z e d in that the connecting device is constituted by a wire.

7. A device as claimed in claims 2-6, c h a r a c t e r i z e d in that the wire is positioned in the pressure chamber and comprises channels for supplying pressure fluid to the chamber.

8. A device as claimed in claim 7, c h a r a c t e r i z e d in that the wire is constituted by a twisted steel wire.

9. A device as claimed in any of claims 4-8, c h a r a c t e r i z e d in that the connecting device is adapted to allow a restricted axial expansion of the fracturing member and thereby of the elastomeric material walls

A . •__>• ___-s - ..-_-..-_____ i positioned between the end members when pressure is applied to the fracturing member.

10. A device as claimed in claim 4, c h a r a c t e r i z e d in that the end members comprise support and sealing means adapted radially to expand when pressure is applied to the fracturing member in order to close the clearance spaces between the fracturing member and the walls of the hole in which the fracturing member is introduced.

11. A device as claimed in claim 4, c h a r a c t e r i z e d in that the end members comprise support and sealing means adapted to be slightly separated in the axial direction of the fracturing member when pressure is applied to the fracturing member.

12. A device as claimed in claim 10 and 11, c h a r a c t e r i z e d in that the support and sealing means comprise elements adapted to expand radially and/or be displaced in axial direction at least at their peripheries when being subjected to axially directed pressure in order to increase the space for receiving the elastomeric material walls positioned between the end members.

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