RU2477372C1 - Open-pit bench reinforcement method - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: method involves driving of underground opening along the open-pit perimetre in its side part, drilling of rings of wells, arrangement in wells of anchors, which are reinforced with solidifying solution. Besides, upper and lower extreme wells of the ring are drilled in the plane perpendicular to longitudinal axis of underground opening and made as through wells; a cable wire is passed through wells; the cable wire ends are taken to underground opening; tension of the cable wire is provided; after that, both wells are filled with concrete, and the cable wire section located beyond the wells are passed above metal mesh arranged on the surface of bench slope. Besides, at mouths of through wells there installed are anchor locks made for example in the form of support shoes with the diameter corresponding to 3-5 diameters of the well.

EFFECT: improving the reinforcement efficiency and reliability of local sections of fractured rock mass.

2 cl, 7 dwg

Description

The invention relates to the mining industry and can be used in the open development of deep horizons of kimberlite pipes in the permafrost zone of the North.

There is a method of reinforcing slopes in quarries using ropes, passed through wells that are drilled from the camber of the blasted rock, at least two rows parallel to the strike of the ledge, while the ropes of each row are connected to each other, tensioned and fixed ( see RU 825956, class E21C 41/00, 1981).

The disadvantages of this method are the increased risk of work on the collapse of blasted rocks and high complexity due to the significant share of manual labor.

There is a method of strengthening the massif, which is made from previously mined underground mine workings along the perimeter of the quarry in the massif of its ledge outside the zone of rock movement in the instrument part of the quarry (see Mikhailov Yu.V. Underground mining of mineral deposits: Underground mining of ore deposits in difficult mining and geological conditions: textbook for students of higher educational institutions - M .: "Academy", 2008. - S.139-143). The method is used for fastening a fractured mountain range. Fastenings are carried out using anchors, which are used as metal cables. To enhance the stability of the massif, steel cables are installed in the wells, followed by cementation along the fans of the wells. At the same time, additional strengthening of the natural arch of the rock is achieved. In the mining industry, fully cemented cable anchors are used primarily to reinforce an array of fractured rocks.

However, this method is characterized by the absence of recommendations on the placement of both the wells themselves in the fan and the rows of fan holes in the fractured massif, as well as the inability to regulate from the underground workings the preservation of the external part of the massif (on its slope) from possible collapse, dumping, or shedding.

There is also a method of preventing shedding and holding rock outfalls from escarpment of ledges to transport ramps using wire mesh curtains (see Alexandrov I.N., Shmyrko A.N., Shubin G.V., Kiryushin D.I. Creating safe conditions working out of superdeep quarries in Yakutia: (on the example of refinement of the Udachnaya pipe quarry) - Novosibirsk: Nauka, 2005. - P.21-22). The main structural elements of the wire-mesh curtain are load-bearing anchors, a set of cables of various diameters, metal netting “netting”, connection elements. The mechanism of operation of the wire mesh screen is based on the retention and cancellation of the kinetic energy of the falling pieces of rock during shedding or dumping from the slopes of the ledges of the side.

The main disadvantage of the prototype is the impossibility of deep strengthening of the fractured massif, when there is a high probability of significant volumes of rocks falling out of the massif with the destruction of the wire mesh curtain. In addition, this method is distinguished by high requirements for the bearing capacity of the anchors, and therefore, significant labor costs for drilling wells for metal anchors and their installation in cramped working area conditions.

The problem to which the claimed invention is directed, is expressed in increasing the efficiency and reliability of strengthening local sections of a fractured rock mass.

The technical effect obtained when solving the problem is expressed in the integrated strengthening of the fractured massif, both from the inside of the massif using cable anchors inserted into the fans of the wells drilled from a previously passed annular drilling located along the perimeter of the pit in its lower part, and from it the outer side using a wire-mesh curtain placed on the local slopes of the slopes of the quarry using its elements placed in previously created through wells.

To solve this problem, the method of strengthening the pit ledge, including underground mining along the perimeter of the pit in its instrument part outside the rock displacement zone, drilling fan holes, placing anchors in the wells that are fixed with a hardening solution, differs in that the upper and lower edges in the fan the wells are drilled in the plane perpendicular to the longitudinal axis of the underground mine and are made through, with the upper bore crossing the ledge between the boundary of its safety berm and the lower the edge of the escarpment of the overlying ledge, and the lower well intersects the escarpment of the reinforced ledge above its lower edge, while a cable is passed through the said wells, the ends of which are led into the underground mine, the cable is tensioned, after which both of these wells are filled with concrete, while maintaining the cable tension to hardening of concrete, in addition, a portion of the cable located outside the wells is passed over a metal mesh placed at least on the slope of the ledge, in addition, the remaining wells are fan-shaped they are drilled at an angle to the plane passing through the extreme upper and lower wells of the fan, with the intersection of the contact planes of at least two neighboring rock blocks, and at least the holes of the fans closest to these sections are sent to areas with increased fracturing of the array. In addition, anchor locks are installed at the mouths of through holes, for example, in the form of support shoes with a diameter corresponding to 3-5 well diameters.

A comparative analysis of the features of the claimed solution with the features of the prototype and analogues indicates the compliance of the claimed solution with the criterion of "novelty."

In the proposed method, the new features are:

- use of the new principle of strengthening local sections of the fractured massif, both from the side of its internal and external parts;

- the use of a new technological scheme for the integrated use of each of the fan wells drilled from an underground mine to accommodate individual elements of anchoring from both the internal and external parts of the array;

- the use of a new layout of wells in the fan and rows of fans of wells depending on the fracture parameters of the strengthened local section of the array.

All of these new features eliminate the disadvantages of existing methods of fixing local sections of fractured massifs and provide the following positive properties:

- long-term preservation of the most unstable part of the fractured massif;

- more reliable fastening of anchor locks when using the entire length of through underground wells using locking plates for fastening cable anchors at their mouths;

- reducing the cost and laboriousness of work due to the use of underground fan holes to place cable elements of a wire mesh curtain in them, instead of a significant number of wells drilled from the surface of the berm;

- a high degree of mechanization in the production of reinforcement work.

The method is illustrated by drawings, in which Fig. 1 shows a diagram of the drilling of rows of fan holes from underground drillings and the placement of a wire mesh curtain, Fig. 2 schematically shows a section along the line A-A, Fig. 3 - a section along the line B-B , Fig. 4 is a diagram of an arrangement of through holes in a drift drift (node 1), Fig. 5 is a diagram of an arrangement of a through hole with a fastening lock in the form of a shoe at its mouth (node 2), Fig. 6 is a diagram of a cable anchor in a through hole well extending to the surface of the slope for the entire length of the fixed section of the tro ow-mesh curtain, Fig.7 is a General view of the fortified local sections along the contour of the quarry.

The method of strengthening local sections of the fractured massif of the quarry is as follows.

From the preliminary underground quarries 1, passed along the perimeter of the quarry in its instrument part outside the zone of rock displacement, the fans of the wells 2 are drilled for the subsequent introduction of wire anchors 3 into them and secured with a hardening solution in the wells 4. Drilled through and through upper and lower wells 5 are intended for passing through it the fastening ropes 7 for subsequent mounting and mounting on them elements of a cable-mesh curtain. In this case, the berm of the ledge between the boundary of its safety berm and the lower edge of the slope of the overlying ledge cross the upper well, and the slope of the reinforced ledge crosses the lower well above its lower edge. Stable fastening of the fastening ropes in the wells is ensured by anchor locks (metal shoes) 10 located at their mouths, which, when the fastening ropes are tensioned while hanging and attaching the cable-curtain, are tightly attached to the surface of the underground mine working arch at the base of the through holes, acting as an anchor lock . For fixing the cable beginning anchor shoe diameter is 3-5 borehole diameter (d _BH). Extreme fans of through holes are placed along the boundaries of local sections of the fractured massif.

Underground mine workings are carried out by traditional methods using drilling and blasting operations in a tunnel, or using a combine method using tunneling combines. An annular underground mining takes place outside the boundary of the zone of movement of rocks of the pit 11.

Drilling of fans of wells is carried out from a drilling hole using a drilling rig, which allows fastening a fractured massif with cable anchors from 1.0 to 25.0-40.0 m long, for example, Tamrock Cabolt, Cabolt is a fully mechanized electro-hydraulic drilling rig, which conducts drilling, manipulates rods, delivers a hardening mortar (for example, based on cement) and cables. This fully autonomous and mechanized unit is operated by one person. A high degree of mechanization means improved working conditions and greater safety for the operator. The undercarriage is specially designed for use in underground conditions; its centrally articulated connection promotes additional maneuverability. In this case, the mixing of the solution takes place in a mortar mixer located on the drilling rig. During operation, the Cabolt installation is in a stable position with hydraulic jacks. The hardening solution is supplied to the end of the well through a rigid nylon hose. The unit has its own high-pressure water supply system, which facilitates the operator the process of cleaning the mixer and the working device. For placement of cable anchors, drill rods with a diameter of 32 mm are used. The control of the rods is fully mechanized and carried out remotely. On the drum is 900 m of cable. Steel cables with a diameter of 15.2 mm with a breaking strength of 250 kN are used as cable anchors. In the well, the cable is fixed with a hardening solution. If necessary, an increase in breaking strength is possible to place two cables in the well, with a breaking strength of up to 500 kN.

Wells with a diameter of 51 mm are drilled for cables. After the well is drilled to the required depth, the rods are removed. To supply a hardening solution, the hose is introduced into the bottom of the well. As the solution is pumped into the well, the hose is removed. At the same time, the well is overloaded with a solution of about 20% to prevent the formation of air pockets.

Feeding and trimming of cables is fully mechanized. The cable length can be observed by a digital depth gauge. When the cable is installed, it is cut off by a hydraulic cutter. If the cable is installed in through-holes, it can be automatically bent to prevent slipping.

To achieve the required quality of strengthening the internal part of the fractured massif, the distance between the ends of the wells (cable anchors) in the fan and the horizontal distance between the fans take no more than the average size of the rock structural block. In addition, the remaining non-through holes of the fan are drilled at an angle to the plane passing through the upper and lower through holes of the fan, with the intersection of the contact planes of at least two adjacent rock blocks, and at least the fan holes closest to the areas with increased fracturing of the array are directed to these sites.

The distance between the rows of fans of the wells (figure 3, 7), where the mounting ropes 7 are installed in the through holes 5, is determined by the length of the local disturbance section, but not more than 5 meters, based on the bearing capacity of the fixing ropes. To increase the reliability of fastening of the fastening ropes in through holes, anchor locks (metal shoes) are located at their mouths. The base of the fixing rope is fixed in it, the diameter of the shoe is not less than 3-5 well diameters (see Figs. 4-6).

To install wire mesh curtains on local sections of the surface of the berm, the following list of works is performed:

- layout of the safety berm 6, which provides for the location of the fastening ropes and individual short surface anchors under the wire mesh curtain;

- a thorough frill of the slopes of the ledges in the areas of placement of the cable-mesh curtain;

- drilling through upper and lower wells 5 from underground workings 1 and drilling of individual short wells 11 from the surface under short anchors to secure the crosshead;

- installation of anchors using means of mechanization;

- construction and installation of the traverse using bulldozers located on the horizon of laying anchors and the horizon of lifting the curtain;

- the formation of sections of the curtain from a metal mesh "netting", their binding;

- connection with a traverse, lifting the traverse with the net to the required height.

The calculation of the strength of the ropes is established from the condition that the steel ropes work in tension and bending. When calculating the ropes, in this case, it is customary not to take into account the effect of bending. Thus, the ropes are calculated only by tensile strength in accordance with the following formula:

S = R / k,

where S is the permissible force on the rope in kg; R is the tensile strength of the rope in kg, obtained from reference data, from a technical specification or empirically in a laboratory; k is the safety factor of the rope.

Long experience in the use of metal ropes for the construction of wire mesh curtains in deep quarries in the North allows accepting with a sufficient margin of safety metal ropes with a maximum diameter of 32-37 mm with a breaking strength of at least 139 kg / mm.

Claims (2)

1. The method of strengthening the ledge of the quarry, including the sinking of underground excavation along the perimeter of the quarry in its instrument part outside the zone of displacement of rocks, drilling of fans of wells, placement of anchors in the wells, which are fixed with a hardening solution, characterized in that the upper and lower wells are extreme in the fan they are drilled in a plane perpendicular to the longitudinal axis of the underground excavation, and are made through, with the upper bore crossing the ledge between the boundary of its safety berm and the lower edge of the slope overlying its ledge, and the lower well intersects the slope of the reinforced ledge above its lower edge, while a cable is passed through the said wells, the ends of which are led into the underground mine, the cable is tensioned, after which both of these wells are filled with concrete, while maintaining the cable tension until the concrete hardens, except in addition, a portion of the cable located outside the wells is passed over a metal mesh placed at least on the slope of the ledge, in addition, the remaining holes of the fan are drilled at an angle to the plane, passing through the extreme upper and lower through holes of the fan, with the intersection of the contact planes of at least two neighboring rock blocks, and at least the wells of fans closest to these sections are sent to areas with increased fracturing of the array. 2. The method according to claim 1, characterized in that the anchors are installed at the mouths of the through holes, for example, in the form of support shoes, with a diameter corresponding to 3-5 well diameters.

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