RU2312990C1 - Method to protect rock bump hazardous flat-lying seams against impacts - Google Patents

Abstract

FIELD: mining, particularly to prevent impacts during cutting of flat-lying seams with hardly caving roof.

SUBSTANCE: method involves exploring stratigraphic section and geological structure of seam sequence and enclosing rocks including bump hazardous seam to be excavated; determining spatial direction of endogenic fissures in roof of seam to be protected; selecting technological seam cutting scheme and breakage face advancing direction so that endogenic fissures in rock roof are oriented towards goaf and angle at breakage face line and said fissure system extension line meeting is 20°-40°.

EFFECT: increased safety of rock cutting.

3 dwg, 1 tbl

Description

The invention relates to the field of mining and can be used to prevent mountain strikes during the underground development of flat formations with hard-collapsing roofs.

A known method of combating mountain strikes (AS USSR No. 1578364, MKI E21F 5/00, publ. 15.07.90, bull. 26), which consists in the fact that of the longline drifts, which when conducting cleaning work subsequently will be in the area reference pressure, special discharge boreholes with a diameter of 150-390 mm, a length of 5-15 m and a distance between them of 1.5-5.0 m are drilled into the edge parts of the excavation column and the near-track pillar.

The disadvantages of this method are:

- the need to drill a large volume of wells in front of the stope (up to 5000-10000 m one bottom);

- significant costs for its implementation, increasing the cost of production of 1 ton of coal by 20-30%;

- low efficiency of the method (according to Kalinin S.I. Geomechanical support for the effective extraction of powerful flat formations with hard-to-break roofs by mechanized complexes. / S.I. Kalinin, V.M.Kolmogorov. - Kemerovo: Kuzbassvuzizdat, 2002. - 113 p.) : out of 20 mountain strikes on stratum 7-7a of the Raspadskaya mine, 12 occurred in the workings where it was used).

Closest to the invention is a method of preventing mountain impacts (AS USSR No. 1295005, MKI E21F 5/00, published 07.03.87, bull.9), which consists in studying the stratigraphic section and the geological structure of the formation and host formations rocks, including the shock-hazardous layer being developed, determine the underlying non-hazardous protective layer, which is subject to priority mining (the distance between the protective and protected layers should be at least three removable capacities of the latter and not more than 40-80 m, depending on the physical and mechanical FIR mezhduplastya properties and composition of rock); choose the technological scheme of advanced mining of the protective layer, providing impact-safe mining operations on the protected layer.

The disadvantages of this method are:

- the obligatory presence of a non-shock hazardous protective formation located below the protected at a distance of at least three removable capacities of the protective layer and not more than 40-80 m, depending on the physicomechanical properties and composition of the inter-layer rocks;

- compulsory advancing mining operations on the protective formation (by at least 1.5 excavation columns per fall), which in modern conditions and with long excavation columns can lead to a lag in development development time on the protected (possibly more productive) formation by 1 -2 years;

- an increase of 1.3-1.5 times the cost of coal mining, because the protective layer may be of low quality and occur in difficult mining and geological conditions;

- low reliability of the method due to the high variability of mining and geological conditions (thickness of beds and inter-layers, physico-mechanical properties and composition of the rock mass, etc.).

The objective of the invention is to increase the safety and efficiency of mining shock hazardous flat formations.

The solution to this problem is achieved by the fact that in the method of preventing mountain bumps on gently sloping formations with hard-to-collapse roofs, which consists in studying the stratigraphic section and the geological structure of the formation of formations and host rocks, including the impact-hazardous formation being developed, according to the invention, the spatial orientation of endogenous cracks in the roof of the protected formation, and the technological scheme of the excavation of the formation and the direction of movement of the working face are chosen so that endogenous cracks about novnoy roofing system in rocks falling into the goaf side and the meeting angle stope line and stretch of the fracture system was 20-40 °.

The invention is illustrated by drawings, which shows the formation of rock blocks of hard-to-collapse roofs when cracks fall in the main system "to the bottom" (figure 1) and "to the worked out space" (figure 2); figure 3 shows a copy of the mining plan for layer 6-6a mine "Raspadskaya".

The method is as follows. In the case when cracks fall "to the bottom", the formation of blocks occurs according to the traditional scheme, i.e. in the process of excavating formation 1 and moving the working face at a distance multiple of the width of the combine harvester, rock pressure cracks 2 form in the rocks of the roof, which, as energy accumulates, grow more and more in the layer of hard-breaking rock. However, none of them has enough accumulated energy to reach layer-by-layer crack 3 (weakened mechanical contact). When subsequent coal shavings are removed in the working face, the next rock pressure crack 2, coinciding with the endogenous (inborn) crack 4, which is also a weakened contact, quickly grows to a layer-by-layer crack 3, completing the process of formation of a breaking block. Having lost contact with the massif of rocks located in front of the stope along the strike and with the massif located above it, the block sets in motion, forming high levels of static and dynamic load on the edge parts of the excavation column, pillars and support of the stope (Fig. 1 ) This is the reason for the manifestation of a rock strike in the presence of other related factors.

With the fall of endogenous cracks 4 "on the worked-out space" the mechanism of destruction of the roof rocks is completely different. The formation of the next block also begins with periodically generated and growing as pressure energy cracks rock pressure 2 (line AC in figure 2). However, when one of these cracks reaches the endogenous crack 4 (point C in FIG. 2), the further contouring of the future block changes its direction and continues along the line of the mass weakened by the endogenous crack (CB line in FIG. 2). As a result of this, a complex configuration block ACBB'C'A 'is formed with hinges at points C and C'. The rock enclosed in the ASD triangle, after destruction in the process of turning the block, provides partial re-training of its front console. The presence of support and connections at the forming block along the lines CB and A'C 'and in the hinges at points C and C' ensures a smooth turn and lowering of the blocks on the soil or on collapsed rocks of the lower layers of the roof, without creating dangerous levels of concentration and load on the edge of the excavation column and adjacent pillars.

In addition to the above, it should be noted that mining of excavation columns in the direction against the fall of endogenous cracks 4 (cracks fall "on the worked-out space") is 1.4-1.8 times more effective, and the accident rate of treatment equipment is 1.4-1.8 times less than when working in the opposite direction (Nabokov A.I. Improving the cutting and mining of mine fields. // Bulletin of the Kuzbass State Technical University. - 2004. No. 1, - p. 38-39.) .

In the above descriptions of the mechanisms of formation of collapsing blocks of sedimentary (fractured) rocks, new principles (hypothesis) for the destruction of a hard-to-collapse roof are described taking into account its dislocation by rock pressure cracks, endogenous cracks and layered weakened mechanical contacts.

The proposed method of preventing rock blows during the development of formations with hard-to-collapse roofs has the following advantages:

- ensuring higher levels of impact safety and mining efficiency due to redistribution and reduction of load on the edge parts of the excavation column, adjacent pillars and workings;

- the absence of significant additional costs for bringing the mountain massif into an unstressed state due to the lack of the need to perform special work (activities) for this purpose;

- reducing accident rate and increasing the productivity of treatment equipment by reducing the load on the lining of the face by 2.5-3.5 times.

The table shows the results of the analysis of 32 cases of manifestations of mountain impacts in four layers, and Fig. 3 shows a copy from the actual mining plan for layer 6-6a of the Raspadskaya mine, which shows the direction of movement of the working faces 5, strike line 6 and the direction of fall 7 main system of endogenous cracks.

As can be seen from the table and figure 3, all 32 mountain impacts recorded on the strata 6-6a, 7-7a, 9-10, and 9, occurred in lavas with odd numbers, i.e. where the fall of endogenous cracks was “downhole”.

It should be noted that the orientation of the face movement in space with respect to the bedding elements of the main system of endogenous fracturing and in other layers where rock shocks are recorded are similar to those discussed above. This is evidenced by the odd numbers of lavas in all strata (see table). It follows that all rock strikes and other severe forms of manifestation of rock pressure occurred only in those cases when the cracks fell "to the bottom."

Therefore, to prevent mountain impacts during mining of formations with hard-to-collapse roofs, the working faces must be oriented so that the cracks of the main system fall "on the worked out space".

This fact is explained by the different mechanism of destruction and the nature of the collapse of roof rocks with different directions of movement of the working faces relative to the direction of incidence of endogenous cracks.

Claims (1)

A method for preventing mountain impacts on shallow shock hazardous formations, which consists in studying the stratigraphic section and geological structure of a formation of formations and host rocks, including the developed shock hazardous formation, characterized in that the spatial orientation of endogenous cracks in the roof of the protected formation is determined, and its technological scheme the notches and the direction of movement of the working face are chosen so that endogenous cracks in the roof rocks fall towards the worked out space and the angle trechi stope line stretch and line cracking of the system amounted to 20-40 °.

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