A constant resistance anchor rock beam stability control method for thick coal seam strike ultra-long working face

Abstract

The application provides a constant-resistance anchor rock beam stability control method for a thick coal seam strike super-long working face, which realizes constant-resistance reinforcement of a lower crossheading roof by excavating upper and lower crossheadings in the thick coal seam, reinforcing the lower crossheading roof by using constant-resistance anchors and W steel along the strike, and filling the mined-out side of the roadway with the cut-off gangue during the coal mining process to form a complete roadway; the roof support is realized by restraining the concrete retractable support, and the deformation requirement of the roadway roof is met by the retractability of the support, thus solving the support problem that the constant-resistance anchors cannot be hung in the stable rock stratum due to the limited length, enabling the top-cutting pressure-relief gob-side entry retaining technology to be successfully applied in the thick coal seam non-pillar mining, and being low in cost and not affecting the working face advancing and mining, and having incomparable advantages over the roadway-side filling gob-side entry retaining non-pillar mining, and being a more scientific and reasonable thick coal seam non-pillar mining method.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of coal seam mining thickness 2.5m~5.0m, working face strike length 2000m~5000m Condition is carried out along empty roadway, no coal pillar mining when, along empty roadway roof stability control A kind of method, specifically relates to a kind of thick coal seam strike length working face constant resistance anchor rock beam stability control method. BACKGROUND

[0002] Most of the mine relies on the arrangement method of one-face one-well large strip mining of super-long strike, realizes the goal of high efficiency and high yield, but the one-face two-lane, coal pillar layout system, causes the roadway excavation of working face, more coal pillar is set, low yield, low single, low resource recovery rate and other problems, among them, 3000m single super-long strike working face, roadway excavation reaches 6000m, discards coal pillar resource 351700 tons, worth 246 million.

[0003] The cutting and pressure-relief coal pillar-free mining technology developed in recent years has been widely applied, and this technology has also been successfully applied in thick coal seam along empty roadway coal pillar-free mining. The working face generally has a strike length of 600-1300m, and the time required for the stability of the along-empty roadway is generally about 1 year. However, when the working face strike length exceeds 3000m, due to the increase in working face length, the along-empty cutting and roadway service time reaches 2-3 years. The increase in service time leads to the change from short-term stability to long-term stability. Under the long-term pressure, the compression coefficient of the collapsed gangue will decrease with time, and the gangue will further compress with time, which leads to the gradual separation and instability of the surrounding rock strata of the along-empty cutting and roadway, and further leads to the deformation and damage of the along-empty cutting and roadway roof. Therefore, the along-empty cutting and roadway of the strike super-long working face requires higher long-term stability of the along-empty roadway roof, and the control of the long-term stability of the along-empty roadway roof becomes a technical problem. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provide a thick coal seam strike length working face constant resistance anchor rock beam stability control method to solve the technical problems raised in the above technical background.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] A thick coal seam strike length working face constant resistance anchor rock beam stability control method, comprising the following steps:

[0007] S1, excavate upper and lower crossheading on both sides of the first working face in thick coal seam, reinforce the roof of the lower crossheading with constant resistance anchor cable, high-strength anchor cable and W steel for strike, and realize constant resistance reinforcement of the roof of the lower crossheading roadway;

[0008] S2, a deep hole axial decoupling pre-splitting blasting is used to pre-split the roof hole in the downward crossheading top surface, so that the cracks are excited in the downward crossheading roof along the direction of the roof hole, thereby weakening the rock above the first working face;

[0009] S3, a gangue blocking structure and a strong support are erected on the left side of the downward crossheading to support the roadway roof of the downward crossheading;

[0010] S4, the first working face is mined to form a goaf, and as the goaf increases, the roof collapses along the cracks and falls into the goaf and is blocked in the goaf by the gangue blocking structure;

[0011] S5, after the first working face continues to advance to a certain distance, the roof collapse completely fills the goaf, the strong support beside the roadway is withdrawn and moved forward, a single column is erected in the downward crossheading, and the single column is used to resist the deformation pressure in the form of lifting the roof, and a constraint concrete retractable support is set beside the roadway;

[0012] S6, after the first working face continues to advance to a certain distance, the roof extrudes and compacts the gangue, the collapsed gangue forms a stable structure, the single column lifting the roof support in the roadway is withdrawn, and the constraint concrete retractable support beside the roadway is left;

[0013] S7, when the first working face is mined, the downward crossheading of the first working face is used as the upward crossheading of the second working face;

[0014] S8, steps S1-S7 are repeated until the entire thick coal seam is mined;

[0015] In step S1, the constant resistance anchor cable is a constant resistance large deformation cable, which comprises a multi-hole cable fitting, a stress dissipation pad, a tray and a constant resistance device, the constant resistance device is in a cylindrical structure, is sleeved at the tail of the cable body, the tray is sleeved at the tail of the constant resistance device, and the stress dissipation pad is sleeved at the tail of the cable body, wherein the middle part of the tray is provided with a hole for the constant resistance device to pass through;

[0016] In step S5, the constraint concrete retractable support comprises a lower sleeve rod and an upper sleeve rod sleeved on the lower sleeve rod, the lower sleeve rod is provided with a grouting port and a spherical valve, and the upper sleeve rod is provided with an exhaust port.

[0017] In the above invention content, further, in step S2, the angle between the roof hole crack and the horizontal plane is 60°.

[0018] In the above invention content, further, in step S5, after the strong support beside the roadway is withdrawn and moved forward, the constraint concrete retractable support is set beside the roadway every 4 meters.

[0019] The beneficial effects of the present application are:

[0020] The method provided by the application cancels the coal pillar, improves the utilization rate of coal resources, avoids the waste of resources caused by the coal pillar, and avoids the gas outburst and rock burst disasters caused by the coal pillar; the roof of the roadway and the roof of the mining area are disconnected by the deep and shallow hole top cutting and the strong support auxiliary top cutting, the dynamic pressure effect caused by the movement of the roof of the mining area is avoided, and the pressure of the roadway is reduced; the gangue cut off can fill the goaf side of the roadway to form a complete roadway; the roof support is realized by the restrained concrete retractable support, and the deformation requirement of the roof of the roadway is met by the retractability of the support, the support problem that the constant resistance anchor cable cannot be suspended in the stable stratum due to the limited length of the constant resistance anchor cable in the top cutting pressure relief gob-side entry retaining is solved, the top cutting pressure relief gob-side entry retaining technology can be successfully applied in the thick coal seam without coal pillar mining, meanwhile, the cost is low, the mining of the working face is not affected, and the technology has incomparable advantages over the roadway side filling gob-side entry retaining without coal pillar mining, and is a more scientific and reasonable thick coal seam without coal pillar mining method. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a schematic diagram of the first working face before recovery of the application;

[0022] Figure 2 It is a schematic diagram of the roof gangue falling and collapsing after recovery of the first working face of the application;

[0023] Figure 3 It is a schematic diagram of setting the restrained concrete retractable support in the roadway side of the application;

[0024] Figure 4 It is a schematic diagram of the constant resistance anchor cable structure of the application;

[0025] Figure 5 It is a schematic diagram of the structure of the restrained concrete retractable support of the application;

[0026] Figure 6 It is a schematic diagram of the structure of the constant resistance anchor beam of the roof of the coal pillar gob-side entry retaining;

[0027] Figure 7 It is a mechanical model diagram of the constant resistance anchor beam of the roof of the coal pillar gob-side entry retaining.

[0028] In the figure, 1 is a thick coal seam, 1.1 is a first working face, 1.2 is an upper crossheading, 1.3 is a lower crossheading, 1.4 is a second working face, 2 is a constant resistance anchor cable, 21 is a stress dissipation pad, 22 is a porous cable, 23 is a tray, 24 is a constant resistance device, 25 is a cable body, 3 is a high-strength anchor cable, 4 is a top cutting hole, 5 is a gangue blocking structure, 6 is a strong support, 7 is a single column, 8 is a restrained concrete retractable support, 8.1 is a lower sleeve rod, 8.2 is an upper sleeve rod, 8.3 is a grouting port, 8.4 is a spherical valve, and 8.5 is an exhaust port. DETAILED DESCRIPTION

[0029] The present application is herein described, by way of example only, with the comprehension that the advantages and utility thereof are apparent, and that modifications, of form, arrangement, proportions, and details of the herein described embodiments can be made by those skilled in the art without departing from the spirit of the application and without diminishing its intended advantages. It is to be understood that features of the various embodiments described herein can be combined with each other, where appropriate.

[0030] It is noted that the illustrations provided herein are solely for the purpose of illustrating the aspects of the present application and are not intended to limit the scope of the present application in any way. The drawings are only for the purpose of illustration and are not intended to limit the scope of the application in any way.

[0031] Embodiment:

[0032] A constant resistance anchor rock beam stability control method for a thick coal seam strike ultra-long working face, comprising the following steps:

[0033] Please refer to the accompanying Figure 1 -attached Figure 3 drawings;

[0034] S1, excavate an upper crossheading 1.2 and a lower crossheading 1.3 on both sides of a first working face 1.1 of a thick coal seam 1, reinforce the roof of the lower crossheading 1.3 with constant resistance anchor cables 2, high-strength anchor cables 3, and W steel for strike, and achieve constant resistance reinforcement of the roof of the lower crossheading 1.3;

[0035] S2, use deep hole axial uncoupling pre-splitting blasting to pre-split a roof breaking hole 4 obliquely upward along the top surface of the lower crossheading 1.3, so that cracks are generated in the direction of the roof breaking hole 4, thereby weakening the rock above the first working face 1.1;

[0036] S3, erect a gangue blocking structure 5 and a powerful support 6 on the left side of the lower crossheading 1.3 to support the roof of the lower crossheading 1.3;

[0037] S4, extract the first working face 1.1 to form a goaf, and as the goaf increases, the roof collapses along the cracks and falls into the goaf and is blocked by the gangue blocking structure 5 in the goaf;

[0038] S5, after the first working face 1.1 continues to advance to a certain distance, the roof collapse completely fills the goaf, the powerful support 6 is withdrawn and moved forward, a single column 7 is erected in the lower crossheading 1.3, the single column 7 is used to resist deformation pressure in a roof lifting manner, and a restrained concrete collapsible prop 8 is set in the roadside;

[0039] S6, the first working face 1.1 continues to advance to a certain distance, the roof will gangue compaction, the gangue collapse forms a stable structure, the anti-variation monomer column 7 in the withdrawal lane is lifted and supported, and the lane-side constraint concrete retractable support 8 is left;

[0040] S7, when the first working face 1.1 is mined, the lower crossheading 1.3 is continued to be excavated on the second working face 1.4, at this time, the lower crossheading 1.3 of the first working face 1.1 is used as the upper crossheading 1.2 of the second working face 1.4;

[0041] S8, repeat steps S1-S7 until the entire thick coal seam is mined.

[0042] Under the action of dynamic pressure and the pressure generated by the long-term creep compression of the gangue in the goaf, the roof of the gob-side entry retaining will be separated. The separation is mainly formed in the process of rotating and sinking after the rock stratum breaks. The main driving force comes from the load applied by the overburden and the creep pressure load of the gangue in the goaf, and the constraint force mainly comes from the anchoring load and the temporary support in and beside the lane. According to the movement characteristics of the lateral roof in the goaf, the following assumptions can be made about the roof activity of the gob-side entry retaining: 1) the roof deformation does not cause the instability of the rock stratum during the influence period of the tunneling, that is, the roof rock stratum still maintains its integrity; 2) the anchoring load of the gob-side entry retaining and the support strength in and beside the lane are sufficient, and have high resistance and pressure resistance characteristics; 3) the in-situ roof of the lane is complete and does not break above the gob-side entry retaining.

[0043] After the roof of the gob-side entry retaining is pre-cracked and pressure released, if a reasonable compensating stress is provided for the roof of the lane, the breaking position of the roof rock stratum will not be directly above the lane, but will be transferred to the roof within a certain distance on the side of the solid coal. At this time, the fracture is not as obvious as the fracture of the roof rock stratum in the goaf, but is completed by a large number of secondary cracks to release the elastic energy under the suspension arm driving. A structure model of the constant resistance anchor beam of the roof of the gob-side entry retaining without coal pillar is established as shown in the accompanying Figure 6

[0044] A mechanical model is established according to the constant resistance anchor rock beam structure model as shown in the accompanying Figure 7 The deformation of each layer after the roof is pre-cracked and cut can be calculated, and the separation value can be obtained.

[0045] According to the principle of superposition method, the bearing capacity of the roof rock beam is divided into three situations of roof load q, anchor support load σ and single support load p, and the rock stratum deformation is the sum of the three. Under the action of q, the deflection curve equation of AB is:

[0046] (1-1)

[0047] ​Where wq(x) is the deflection of the rock beam under the load q; x is the distance from the rotation base point of the rock beam; q is the load on the rock beam; E is the elastic modulus of the rock; I is the moment of inertia of the cross section of the rock beam, and the value per unit length is h3 / 12; and L is the length from the rotation base point of the top rock beam to the end of the cantilever.

[0048] The lateral cantilever of the stope can remain relatively complete during the movement, and the curvature between the rock layers tends to be consistent. According to the formula (1-1) of the composite beam principle, q is:

[0049] (1-2)

[0050] Where Ei, γi, hi are the elastic modulus, volume force and thickness of the ith rock layer, respectively.

[0051] Under the action of the roadway roof anchor support load σ, the deflection equation of the rock beam is:

[0052] (1-3)

[0053] Where l, d are the distances from the rotation base point of the rock beam to the two sides of the roadway, respectively.

[0054] Similarly, the deflection equation of the rock beam under the action of the single support load p can also be calculated as:

[0055] (1-4)

[0056] Where b is the width of the single support.

[0057] (1) Separation within the anchoring area

[0058] The separation between the rock layers at different caving stages within the anchoring area is:

[0059] (1-5)

[0060] (2) Separation outside the anchoring area

[0061] (1-6)

[0062] (3) Roof support load and direct roof separation control

[0063] Practice shows that the direct roof separation is often the key factor determining the success or failure of the gob-side entry retaining, which is consistent with the above calculation and analysis results. Under the condition that the support structure has been formed and the roof occurrence structure cannot be changed, providing a reasonable roof support load becomes the main technical means to control the direct roof separation.

[0064] Let the direct roof and the upper separation be zero, and the formula (1-6) is derived as follows:

[0065] (1-7)

[0066] Formula (1-7) is the formula for controlling the minimum support load of the direct roof separation layer, which is called the critical support load. When the support load of the constant resistance large deformation anchor is less than the critical support load, the support structure is in a stable state; when the support load of the constant resistance large deformation anchor is equal to the critical support load, the support structure starts to yield, the constant resistance structure of the rod body starts to slide, and if the inner end of the constant resistance anchor penetrates the basic roof by a certain distance, the sliding yield will be converted into the separation amount between each rock layer. The constant resistance anchor may further develop under the appearance of the yield state of the rod body, and at this time the support structure is in a dynamic stable state; when the support load of the constant resistance large deformation anchor is less than the critical support load, the constant resistance anchor can start to yield, and when it slides to the maximum value, the structure is unstable.

[0067] The constant resistance anchor beam is a state after artificial intervention in the control of the roadway roof, aiming to form an anchored rock beam by actively controlling the roadway roof through high support resistance components before mining, and to realize yield by the sliding deformation of the constant resistance component on the constant resistance anchor cable when encountering great deformation during intense mining disturbance, so as to maintain the relative stability of the anchored rock beam and prevent it from being damaged. In the later period, the high resistance provided by the retractable steel pipe concrete column beside the roadway is relied on to realize long-term creep pressure support, and finally the stability of the constant resistance anchor rock beam is realized.

[0068] When thick coal seams are mined, the deformation amount of the roadway is large, and the roadway roof presents an inclined deformation state. The deformation in the roadway is small, and the deformation beside the roadway is large. Therefore, high-strength anchor cables are used in the roadway to reinforce the roof and form a composite beam to avoid roof separation instability; and constant resistance cables are used beside the roadway, because the constant resistance cables themselves have the property of elongation, and can adapt to the large deformation beside the roadway without breaking.

[0069] When thick coal seams are mined, the mining height of the coal seam is large, the height of the mined-out space is large, the roof caving height of the mining field is large, and the range of the rock layer of the roof movement is large. The hard roof is difficult to collapse due to its large strength, and cannot quickly fill the goaf, resulting in that the pressure of the overlying rock layer is transmitted to the hydraulic support on the working face through the hard roof, and to the roof of the gateway along the goaf. In addition, when the hard roof breaks, it has a sudden impact of destruction, and produces large deformation instantaneously. Under such action, the support of the roof of the gateway along the goaf requires not only a large support force, but also the ability to resist large deformation of instantaneous impact. The ordinary anchor cable currently used does not have the ability to resist large deformation of instantaneous impact, and the support force of the constant resistance large deformation cable is only 15-20 t, which is too low to support the roof pressure. Therefore, the constant resistance large deformation cable is used for reinforcement, and the large deformation cable has the ability to support 35-60 t, and has the ability to resist large deformation of instantaneous impact of 0.5-1.0 m.

[0070] As shown in the accompanying Figure 4 As shown in the accompanying The constant resistance anchor cable 2 is a constant resistance large deformation cable, which is different from the ordinary cable and is a constant resistance large deformation anchoring material. The constant resistance large deformation cable is specially designed for thick coal seam hard roof mining and can maintain constant resistance under the action of the huge pressure of thick coal seam hard roof stope and keep the extension amount by the mechanical sliding device. The constant resistance large deformation cable comprises a porous cable accessory 22, a stress dissipation pad 21, a tray 23 and a constant resistance device 24. The constant resistance device 24 is in a cylindrical structure and is sleeved at the tail of the cable body 25. The tray 23 is sleeved at the tail of the constant resistance device 24. The stress dissipation pad 21 is sleeved at the tail of the cable body 25. The middle part of the tray 23 is provided with a hole for the constant resistance device 24 to pass through. The cable body 25 passes through a plurality of holes in the porous cable accessory 22. The single steel strand on the cable is tensioned by a tensioning machine, and the porous cable accessory 22 is extruded, so that the constant resistance large deformation cable is tensioned.

[0071] In the above embodiment, preferably, the angle between the crack of the top breaking hole 4 and the horizontal plane is 60°.

[0072] In the above embodiment, preferably, after the roadside powerful support 6 is withdrawn and moved forward, a constraint concrete collapsible prop 8 is set every 4 meters in the roadside in step S5.

[0073] As shown in the accompanying Figure 5 As shown in the accompanying The constraint concrete collapsible prop 8 comprises a lower sleeve rod 8.1 and an upper sleeve rod 8.2 sleeved on the lower sleeve rod 8.1. The lower sleeve rod 8.1 is provided with a grouting port 8.3 and a spherical valve 8.4. The upper sleeve rod 8.2 is provided with an exhaust port 8.5. The constraint concrete prop 8 adopts a split sleeve design. The outer diameter of the upper sleeve rod 8.2 is 355.6 mm, the wall thickness is 6 mm, and the length is 1.5 m. The diameter of the lower sleeve rod 8.1 is 377 mm, the wall thickness is 6 mm, and the length is 2.0 m. The lap length is 0.5 m. The size of the steel pipe is reasonably matched. Foam concrete is injected into the lower sleeve rod 8.1 through the grouting port 8.3 to form a constraint concrete prop with internal foam concrete and external steel. Because the foam concrete is compressible concrete with internal air hole structure, the upper sleeve rod 8.2 and the lower sleeve rod 8.1 can extrude the foam concrete injected inside under the action of pressure to realize collapsibility.

[0074] Experimental example:

[0075] The ground elevation of Shanbula coal mine 36203 working face is generally between +1254~+1327, the working face elevation is between +1105~+1125m, the coal seam is 149~202m deep from the ground, the ground is typical eroded hilly landform, the corresponding surface is high density natural forest, there is no old mine and other buildings, so the ground building has no influence on the mining; the thickest coal seam in this area is 3.8m, the thinnest is 3.2m, and the average thickness is 3.5m; the working face inclination length is 175.5m, the inclination angle is 0~3°, and the recoverable length is 1752m.

[0076] Gas condition: the relative gas emission of the mine is 1.10m³ / t, the absolute gas emission is 3.01m³ / min; the absolute carbon dioxide emission of the mine is 4.51m³ / min, the relative carbon dioxide emission of the mine is 1.64m³ / t, which belongs to low gas mine, and there is no coal and gas outburst phenomenon.

[0077] Spontaneous combustion: the coal flame length of 6-2 coal seam is >120mm, the rock powder filling amount is 60%, the coal dust is explosive, the coal belongs to class I easy spontaneous combustion coal seam, and the shortest natural fire period of the coal seam is 45 days.

[0078] The thick coal seam strike super-long working face constant resistance anchor rock beam stability control method provided by the method is applied to mining, and the application effect is:

[0079] The gob-side entry retaining of 36203 working face is 980m; the one-beam five-column retreat mileage is 680m, the pouring of steel pipe concrete column is 702m, the spraying is 650m, the high strength anchor cable is 1270m, the constant resistance anchor cable+steel belt is 1240m, the slot hole is 1320m, and the slot hole blasting is 1175m! The maximum roof subsidence of the entry retaining section is 30mm (at 250m), the maximum rib spalling depth is 300mm, locally 500mm, and there is basically no floor heave.

[0080] The above-described embodiments only express the specific implementation of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of the present application.

Claims

1. A constant resistance anchor beam stability control method for a thick coal seam strike ultra-long working face, characterized in that, The method comprises the following steps: S1, excavating an upper crossheading and a lower crossheading on both sides of a first working face of a thick coal seam, reinforcing a roof of the lower crossheading by using a constant resistance anchor cable, a high-strength anchor cable and a W steel for a strike direction, and realizing constant resistance reinforcement of the roof of the lower crossheading; S2, using deep hole axial uncoupling pre-splitting blasting to pre-split a roof breaking hole along the roof of the lower crossheading, making the roof of the lower crossheading generate cracks along the direction of the roof breaking hole, and thus weakening the rock above the first working face; S3, erecting a gangue blocking structure and a strong support on the left side of the lower crossheading to support the roof of the lower crossheading; S4, mining the first working face to form a goaf, as the goaf increases, the roof collapses along the cracks and falls into the goaf and is blocked in the goaf by the gangue blocking structure; S5, after the first working face continues to advance to a certain distance, the roof collapse completely fills the goaf, the strong support beside the roadway is withdrawn and moved forward, a single column is erected in the lower crossheading, the single column is used to resist deformation pressure in a lifting shed mode, and a restrained concrete collapsible prop is arranged beside the roadway; S6, after the first working face continues to advance to a certain distance, the roof extrudes and compacts the gangue, the collapsed gangue forms a stable structure, the single column lifting shed support in the roadway is withdrawn, and the restrained concrete collapsible prop beside the roadway is left; S7, after the first working face is mined, the lower crossheading of the first working face is used as an upper crossheading of a second working face when the lower crossheading of the second working face is excavated; S8, repeating steps S1-S7 until the entire thick coal seam is mined; In step S1, the constant resistance anchor cable is a constant resistance large deformation cable, the constant resistance large deformation cable comprises a multi-hole cable fitting, a stress dissipation pad, a tray and a constant resistance device, the constant resistance device is in a cylindrical structure, is sleeved at a tail of a cable body, the tray is sleeved at the tail of the constant resistance device, and the stress dissipation pad is sleeved at the tail of the cable body, wherein a middle part of the tray is provided with a hole for the constant resistance device to pass through; In step S5, the restrained concrete collapsible prop comprises a lower sleeve rod and an upper sleeve rod sleeved on the lower sleeve rod, the lower sleeve rod is provided with a grouting port and a spherical valve, and the upper sleeve rod is provided with a vent.

2. The constant resistance rock beam stability control method for strike ultra-long working face in thick coal seam according to claim 1, characterized in that, In step S2, an angle between the roof breaking hole crack and a horizontal plane is 60°.

3. The constant resistance rock beam stability control method for strike ultra-long working face in thick coal seam according to claim 1, characterized in that, In step S5, after the strong support beside the roadway is withdrawn and moved forward, the restrained concrete collapsible prop is arranged every 4 meters beside the roadway. In step S5, after the strong support beside the roadway is withdrawn and moved forward, the restrained concrete collapsible prop is arranged every 4 meters beside the roadway.

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