GB2153409A

GB2153409A - Disposable tubular borehole plug

Info

Publication number: GB2153409A
Application number: GB08431344A
Authority: GB
Inventors: Frank Meyer; Otto-Ernst Glaesmann; Walter Marsch
Original assignee: Bergwerksverband GmbH
Current assignee: Bergwerksverband GmbH
Priority date: 1984-01-26
Filing date: 1984-12-12
Publication date: 1985-08-21
Also published as: GB8431344D0; AU3794585A; FR2558892B1; ZA841167B; DE3402615C2; FR2558892A1; DE3402615A1; JPS60159211A; BE901581A

Abstract

A disposable tubular borehole plug for the injection particularly of media suitable for rock solidification, such as for example synthetic resin, comprises substantially a filling pipe (1) adapted to be assembled from portions and having at the tip a safeguard against reflux, in the form of a non-return valve (5), a mixing element and a sealing element (2) mounted at the ends in metal sleeves (11, 12) and formed as a portion of tubing of elastic material. The filling pipe (1), within the area enclosed by the sealing element (2), is additionally provided with a valve (8) and in that during injection, the sealing element (2) becomes automatically clamped and sealing-tight as a function of the differential pressure built up by the valves (5, 8). <IMAGE>

Description

SPECIFICATION Disposable tubular borehole plug The invention relates to a disposable tubular borehole plug for the injection particularly of media suitable for rock solidification, such as for example synthetic resin, and consisting substantially of a filling pipe adapted to be assembled from portions and having at the tip a safeguard against reflux, in the form of a non-return valve, a mixing element and a sealing element mounted at the ends in metal sleeves and formed as a portion of tubing of elastic material.

For the solidification of crumbling rock strata and loose stones, particularly in underground coal mining, the injection of synthetic resin has gained increasing importance. Where injections are used, particular importance attaches to the borehole plugs described as packers which are adapted for insertion into the boreholes.

German Patent Specification No. 29 03 137 already discloses a tubular disposable borehole plug of the type mentioned at the outset which makes it possible to locate it anywhere in the borehole, which has a functionable reflux and throughflow prevention device and which permits of mixing within the length of piping.

The essential disadvantage of such a disposable borehole plug lies in the fact that by reason of the retaining and sealing elements used, it can only be used in clearly defined boreholes, i.e. boreholes of constant cross-section, so that the sealing or closure of boreholes in areas of relatively large crosssection is feasible but only in an unsatisfactory manner.

With regard to the safety required when fitting the seals, a further grave drawback of the borehole plugs used hitherto lies in the fact that after it has been introduced into the borehole, let us say in a gallerywhich is not yet provided with the appropriate lining or boarding, in other words in an area of serious risk from the safety point of view, the borehole plug has to be tightened for example by means of a percussion tool.

In contrast, the invention is based on the problem of providing a borehole plug for the injection of media suitable in particular for the solidification of rocks, which makes it possible for the plug to be clamped in sealing-tightfashion to an adequate extent in undefined borehole cross-sections while at the same time, from the safety point of view, representing a further development whereby mechanical tightening by hand or by a percussion tool is no longer required.

According to the invention, this problem is resolved in that the filling pipe, within the area enclosed by the sealing element, is additionally provided with a valve and in that during injection, the sealing element becomes automatically clamped and sealing-tight as a function of the differential pressure built up by the valves.

The valve which prevents reflux and which is located at the tip of the borehole plug, i.e. is directed towards the bottom of the borehole, can be so adjusted by means of the spring employed that when the synthetic resin is forced through the filling pipe, the synthetic resin is initially so distributed through the valve located in the region of the sealing element and into the space between filling pipe and sealing element that the sealing element functioning as an automatically inflating body, bears in sealing-tight and clamping fashion against the walls of the borehole.

Within the framework of the invention, it has been found to be advantageous that the valve constructed as a non-return valve should consist of at least one aperture in the filling pipe which is enclosed by a tubular cuff. Trouble-free filling and inflation of the sealing element is thus possible without further injection being disturbed by reflux upon corresponding application of the sealing element against the borehole walls.

Furthermore, it has been found particularly advantageous that the metal sleeves enclosing the ends of the sealing element are constructed as tubular cuffs disposed at a constant distance and adapted to be screwed onto the filling pipe from the height of the metal sleeves which in each case loosely accommodate the sealing is such as is necessary to accommodate the sealing element.

Accommodating the sealing element within the metal sleeves in this way permits of wide inflation of the sealing element and thus adaptation to borehole cross-sections which are not clearly defined. So that the sealing elements manufactured from resilient material, for example rubber, are not destroyed as they are inflated, with the resultant effect of sliding out of the sleeves, the metal sleeves are according to the invention longitudinally slotted over at least a part of their length, the resilience being adaptable to the inflation pressure. Further advantages of the invention are described in greater detail in the subclaims.

As already mentioned, the technical progress achieved by the invention resides in the fact that it is no longer necessary mechanically to tighten the borehole plug, mainly in insufficiently secure galleries, so that the safety of workers is considerable enhanced and in that adaptation to borehole cross-sections which are not clearly defined is guaranteed in a simple and economical fashion.

An embodiment of the invention is described in greater detail hereinafter and is illustrated in the accompanying drawings, in which: Fig. lisa partial representation of the borehole plug according to the invention, diagrammatically and in section, and Fig. 2 shows the embodiment of filling pipe as in Fig. 1 with an extension and an injection union disposed outside the borehole.

As Figs. 1 and 2 show, the borehole plug consists essentially of a filling pipe 1 which, as Fig. 2 particularly reveals, can be constructed to be extended at will via connecting cuffs 25 and corresponding sealing elements 26. To accommodate the metal sleeves 11 and 12 which are constructed as cuffs, the corresponding portions of the filling pipe 1 are provided with screwthreads 13 and 14. The metal sleeves 11 and 12 are screwed onto the filling pipe 1 in such a way as to be directed towards each other and, like sockets, they accommodate a hose-like sealing element 2 manufactured from elastic material, for example rubber. As a reinforcement, the sealing element 2 may carry a support mesh 24, for instance of metal or woven fabric.

Independently of the non-return valve 5 which consists of a spring 6 and a ball 7 and which is disposed at the tip of the borehole plug, the sealing element 2 is intended to be located at any desired location in the borehole 3 on the filling pipe 1 or on portions of the filling pipe 1.

Disposed in the filling pipe 1, in fact in the region which is enclosed by the sealing element 2, there is a non-return valve 8 which consists of at least an aperture 9 in the filling pipe and a cuff 10 of resilient material which encloses the filling pipe 1 and the aperture 9. In accordance with the length of the sealing element 2, so the metal sleeves 11 and 12 are at a fixed distance from each other. The height 15 of the metal sleeves 11, 12 which, like sockets, house the sealing element 2, is sufficient to enclose this latter.

Upon inflation, the sealing element 2 draws itself out of the metal sleeves 11, 12 until it cannot overcome the resistance of the undefined borehole cross-section, i.e. the walls 4 of the borehole 3. In order to avoid inflation resulting in destruction of the sealing element 2 against the edges of the metal sleeves 11 and 12, the metal sleeves 11, 12 are longitudinally slotted over at least a part of their height 15. In this way, a certain resilience of the sleeve walls is achieved.

Under the valve 5 which constitutes the safeguard against reflux, a retaining element 16 is provided which encloses the filling pipe 1 and which has the task, after the borehole plug has been inserted into the borehole 3, of locking it in its provisional position. At the same time, it is manufactured from an electrically conductive material so that the borehole plug can be earthed according to the regulations.

Expediently, the retaining element 16 may be starshaped.

As demonstrated by the embodiment illustrated in Fig. 1, the metal sleeve 12 which is directed towards the mouth of the borehole, can be provided with a sealing element 17 so that the metal sleeve 12 can at the same time be used as a connector for a portion of filling pipe.

As shown by that part of the filling pipe 1 in Fig. 2 which has the connecting nipple 19 outside the borehole, the mixing element 27 is downstream of the connecting nipple 19, in the region of the borehole mouth. This arrangement does however only constitute a particular example of embodiment.

The nipple 19 is of sleeve-like construction and has an internal screwthread 20. The nipple 19 is screwed onto the end of the filling pipe 1 which has an external screwthread 18, and a fixed gap 22 is observed. Prior to screwing the connecting nipple 19 onto the end ofthefilling pipe 1, the mixing element 27 is pushed into the filling pipe 1 and maintained in position by a flange-like retaining ring 21. The gap 22 is so dimensioned that the retaining ring 21 is fixed in place and cannot be destroyed.

Upon injection of a two-component synthetic resin, firstly upon penetration of the components into the filling pipe 1, the synthetic resin is blended by the mixer 27 and passes through the length of the filling pipe 1 as far as the valve 5 at the tip of the filling pipe 1. The back pressure actuates the valve 8 and the sealing element 2 is inflated until such time as it bears against the borehole walls 4. Adequate filling of the sealing element 2 with a pressure exceeding the filling pressure closes the valve 8 automatically and at the same time opens the valve 5 which is located at the tip of the filling pipe 1 so that the actual injection process can be performed.

Claims

1. Disposable tubular borehole plug for the injection particularly of media suitable for rock solidification, such as for example synthetic resin, and consisting substantially of a filling pipe adapted to be assembled from portions and having the tip a safeguard against reflux, in the form of a nonreturn valve, a mixing element and a sealing element mounted at the ends in metal sleeves and formed as a portion of tubing of elastic material, characterised in that the filling pipe (1), within the area enclosed by the sealing element (2), is additionally provided with a valve (8) and in that during injection, the sealing element (2) becomes automatically clamped and sealing-tight as a function of the differential pressure built up by the valves (5,8).

2. Borehole plug according to Claim 1, characterised in that the valve (8) which is constructed as a non-return valve consists of at least one aperture (9) in the filling pipe (1) which is enclosed by a tubular cuff (10) of resilient construction.

3. Borehole plug according to Claim 1, characterised in that the metal sleeves (11, 12) which enclose the ends of the sealing element (2) are constructed as tubular sleeves which are at a constant distance apart and which are adapted to be screwed onto the filling pipe (1).

4. Borehole plug according to Claim 1, characterised in that the height (15) of the metal sleeves (11,12) which in each case loosely accommodate the sealing element (2) is that which is necessary to accommodate the sealing element (2).

5. Borehole plug according to Claim 1, characterised in that the sealing element (2) can be used in conjunction with the metal sleeves (11, 12) at any desired locations on the filling pipe (1).

6. Borehole plug according to Claim 5, characterised inthatthe metal sleeves (11,12) are longitudinally slotted at least over part of the height (15).

7. Borehole plug according to Claim 1, characterised in that an annular retaining element (16) is provided under the reflux safeguard located at the tip of the filling pipe (2) and constructed as a non-return valve (5).

8. Borehole plug according to Claim 7, characterised in that the retaining element (16) which is manufactured from an electrically conductive material is at the same time envisaged as a means of necessarily earthing the filling pipe (1).

9. Borehole plug according Claim 1, characterised in that a sealing element (17) is disposed in the metal sleeve (12) which is directed towards the mouth of the borehole.

10. Borehole plug according to Claim 1, characterised in that at least the metal sleeve (12) which is directed towards the borehole mouth is constructed as a connecting element for the pipe portions.

11. Borehole plug according to Claim 1, characterised in that the end of the filling pipe (1) which is located outside the borehole is provided with an external screwthread (18) adapted to receive a screw-on connecting nipple (19).

12. Borehole plug according to Claim 11, characterised in that a mixing element (27) provided with a flange-like retaining ring (21) is adapted for insertion into the end of the filling pipe (1).

13. Borehole plug according to Claim 12, characterised in that for non-destructive accommodation of the retaining ring (21 ) within the connecting nipple (19) which is screwed onto the end of the filling pipe (1 ) a lock nut (23) is provided which establishes the gap (23).

14. Borehole plug according to Claim 1, characterised in that the sealing element (2) manufactured from elastic material, for example rubber, is reinforced by a support mesh (24), consisting for example of woven fabric or metal.

15. A borehole plug substantially as described with reference to the accompanying drawings.