BOREHOLE PLUGGING DEVICE

Abstract

The invention relates to the field of drilling and blasting operations, and more particularly to confining gaseous explosion products in a charge cavity, and can be used in rock blasting using borehole charges. The technical result of the invention is that of reducing the specific charge of explosive per cubic metre of blasted rock mass, increasing the fragmentation of the rock mass, making it possible for explosive to be loaded into and work effectively in a borehole with excess water pressure (flooded boreholes), providing ease of use and structural simplicity, providing ease of transportation and storage since the device can be dismantled to compact dimensions, and reducing the weight of the structure. A further technical result is the possibility of using devices of a single type in boreholes of different lengths and types (flooded or non-flooded), thus making it possible for the claimed device to be used as a universal device for all types of boreholes. The above-mentioned technical result is achieved in that the claimed borehole plugging device, which is made of a pliable polymer material and has elements with a shape, the outside diameter of which is commensurate with the diameter of a borehole, and an axial internal cavity, is characterized in that it consists of a rod with a cruciform cross section, having identical dome-shaped, slotted elements fixably mounted thereon from each end.

Claims

1. Borehole plugging device is made of pliable polymer material and features shaped elements the outer diameter of which is commensurate with the borehole diameter, with an axial inner cavity consisting of a rod with cruciform cross-section, on both ends of which uniform dome-shaped elements with slots can be fixed.

2. Borehole plugging device similar to that of pos. 1 with a difference that the dome-shaped elements feature flanges by means of which and a retainer they are fixed in the dents formed in the rod.

3. Borehole plugging device similar to that of pos. 1 with a difference that the dome-shaped elements have lobe form.

4. Borehole plugging device similar to that of pos. 3 with a difference that the lobes are of varying length with arrangement of each long lobe between the shorter ones.

5. Borehole plugging device similar to that of pos. 1 with a difference that there are 2 to 4 dome-shaped elements fixed on the rod.

6. Borehole plugging device similar to any of pos. from 1 to 5 with a difference that the dome-shaped elements feature symmetrical arrangement of the slots.

Description

CONCISE DESCRIPTION OF DRAWINGS

[0006] FIG. 1 shows the borehole plugging device in one of possible design variants from different points of view in 3D.

[0007] FIG. 2 shows the principle of the conjunction of the dome-shaped element on the rod. FIG. 3 shows an example of the fitting of the borehole plugging device in a borehole. FIG. 4 to FIG. 6 show measurement protocols of experimental blasting using the borehole slugging device.

[0008] In the drawings: 1rod, 2dome-shaped element, 3rod dent, 4flange of the dome-shaped element for seat on the dent, 5ignition channel, 6discharge channel, 7big contact, 8small contact.

IMPLEMENTATION OF THE INVENTION

[0009] Stemming is the process of filling with inert material of a part of the charge cavity; the inert material itself used to confine the explosive charge, to reduce the scattering range of the splitters is also called stemming. Stemming is used to lock the explosion products, to increase the efficiency of the explosion. The borehole plugging device, as stated in the claimed solution, is a replacement for the existing method of stemming.

The borehole plugging device (see FIG. 1) consists structurally of three elements: the rod (1) and at least two dome-shaped elements (2), one of which is fixed on the rod from one end and the other one on the other rod end. The cross-section of the rod is cruciform. Such solution allows for the required strength of the structure with simultaneous reduction of the material quantity for the manufacturing of the rod. Thus, the weight of the structure is less whereas the manufacturing is simplified.
For fixation of the dome-shaped elements (2) the rod (1) can feature dents (3) (notches) in the places of the upper and the lower connection of the dome-shaped elements. For fixation of the dome-shaped elements (2) on the rod (1) by these dents (3), the dome-shaped elements (2) can feature flanges (4) for their retention (see FIG. 2).
The rod (2) of the borehole plugging device can envisage mounting of two to four dome-shaped elements (2). Also, the rod design provides for using the borehole plugging device completely assembled within a large range of diameters. Thus the fragmentation of the rock mass in the open terrain depends on a multitude of factors, e.g., the geology, the type of the explosive utilized, the development design, the drilling equipment, on the diameters of the boreholes drilled. The operation diameters of the borehole plugging device are assigned to the borehole diameters ranging from 65 to 270 mm. The rod of the structure is unchangeable whereas the lobes get together on the rod depending on the borehole diameter.
In flooded boreholes or where the borehole length exceeds 15 m, 3 to 4 dome-shaped elements with slots are mounted on the rod. These slots can also be of lobe shape, including also those symmetrical relative to the centre axis. At lobes of different length with the arrangement of each long lobs between the short ones, the slots of the structure of the borehole plugging device ensure at fitting in the borehole such structural features, which are shown in FIG. 3fitting of the borehole plugging device in the borehole. The big contact (7) goes through the big lobe, the small contact (8) goes through the small lobe. In the slots between the lobes, there is the discharge channel (6) letting out the shock wave from the ignition channel (5).
The slots, e.g. as lobes of the borehole plugging device are intended for direct contact with the borehole walls in such structure with diameters ranging from 130 to 170 mm. The small contacts (8) ensure optimal angle of attack and angle of resistance within the range of diameters 130 to 150 mm.

[0010] The big contacts (7) ensure optimal angle of attack and angle of resistance within the range of diameters 150 to 170 mm. The design of the borehole plugging device envisages channels for ignition means (5) whereas such solution protects the ignition means during the propulsion of the structure through the borehole.

[0011] The discharge channel (6) is intended for discharge of the initial pressure (piston effect). In case of a borehole with excessive water pressure, the discharge channels let the water flow but the explosive remains in the charge cavity of the borehole.

[0012] In the course of experimental tests on industrial basis in the enterprises of the mining branch, the borehole plugging device utilised in the borehole charges as stemming device, has demonstrated the following results: [0013] reduced specific charge of explosive per cubic meter of blasted rock mass; [0014] Increased fragmentation of the rock mass; [0015] possibility of charging and full-scale operation of the explosive in a borehole with excessive water pressure (flooded boreholes). [0016] comfort in use, shipment and storage due to dismantling down to compact dimensions; [0017] reduced weight of the structure.

[0018] FIG. 4 to FIG. 6 shows the results of the measurement during tests of the borehole plugging device. They demonstrate that the detonation velocity in the experimental boreholes is almost the same, however slightly slower detonation is observed in boreholes with the borehole plugging device.