Method for working face transportation crossheading to pass through overlying irregular coal pillar pressure area

Abstract

The invention relates to the technical field of coal mine safety mining, in particular to a method for a working face transportation crossheading to pass through an overlying irregular coal pillar pressure area. In order to solve the problem that roadway deformation is large when a transportation crossheading of a Xiayu coal mine 8206 working face passes through an overlying irregular coal pillar pressure area, the invention provides a novel method for enabling the transportation crossheading of the working face to pass through the overlying irregular coal pillar pressure area, and the method comprises the steps of drilling and pressure relief, roof grouting and reinforcement, and circular roof lifting. Through application of the pressure relief holes and selection of the reasonable depth of the pressure relief holes, the problems of large deformation of the crossheading roadway and sharp reduction of the section are effectively solved, the influence of advanced bearing pressure during stoping is relieved, and the deformation of the end of the working face and the surrounding rock of the roadway within the range of 50 m ahead is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of safe mining of coal mines, in particular to a method for a working face transport drift to pass through an overlying irregular coal pillar pressure zone. Background Art

[0002] When the 8206 fully mechanized caving working face in the 402 panel of the 22# layer of Xiaoyu Coal Industry Company was advanced to 1180m, the transport drift 2206 lane entered the coal pillar pressure zone of the 4803 working face in the East IV panel of the overlying 19# layer. The length of the coal pillar pressure zone is 120m, and the interlayer spacing is 10-15m. Affected by the superposition of the overlying coal pillar and the mining stress of the working face, the pressure in the influence range of the coal pillar pressure zone corresponding to the 2206 transport drift is obvious, and the deformation of the lane is large, that is, the roof of the lane is bent and sunk as a whole, and the movement of the two sides increases. If no measures are taken, it is expected that the transfer machine and the end frame will be difficult to move forward, and the safety of the working environment will be poor. Summary of the invention

[0003] In order to solve the problem of large tunnel deformation when the 8206 working face transport drift passes through the overlying irregular coal pillar pressure zone, the present invention provides a new method for the working face transport drift to pass through the overlying irregular coal pillar pressure zone.

[0004] The present invention is achieved by adopting the following technical solutions: A method for a working face transport chute to pass through an overlying irregular coal pillar pressure zone comprises the following steps: 1) Borehole pressure relief: In the irregular coal pillar pressure zone and the influence range of 20m before and after, pressure relief groups are set up on both sides of the tunnel. Each pressure relief group includes multiple pressure relief holes arranged in double rows up and down. The depth of each pressure relief hole is determined by FLAC3D numerical simulation method, that is, through FLAC 3D The influence of different pressure relief hole depths on the stress field and plastic zone distribution of the tunnel surrounding rock was analyzed by numerical simulation method, and finally the depth of each pressure relief hole was determined in combination with the construction cost. 2) Roof grouting reinforcement: Inject reinforcement materials into the irregular coal pillar pressure zone and within the 20m influence range before and after it; 3) Circular top lifting: For the range where the tunnel height cannot ensure the forward movement of the transfer machine and the end frame, the top is cyclically lifted and re-supported to ensure the smooth forward movement of the equipment.

[0005] Furthermore, in step 1), the depth of each pressure relief hole is 4m.

[0006] Furthermore, in step 1), the height of the pressure relief holes in the upper row of each pressure relief group from the tunnel floor is 1.2m, the height of the pressure relief holes in the lower row of each pressure relief group from the tunnel floor is 0.8m, and the distance between two adjacent pressure relief holes in each pressure relief group is 0.5m.

[0007] Furthermore, the advance support adopts three rows of hydraulic single pillars arranged on both sides of the tunnel and in the middle of the tunnel. The support range is the influence range of the pressure zone. The distance between two adjacent hydraulic single pillars in each row is changed from the original 1m to 0.3m. This kind of dense support method further improves the supporting force and ensures the stability of the roof.

[0008] Furthermore, in step 3), anchor rods, anchor cables, metal meshes, and W-steel belts are used for re-support to ensure the stability of the roof.

[0009] The beneficial effects of the present invention are as follows: 1) Through the above measures, the problem of large deformation of the transport chute tunnel is solved, the normal forward movement of the transfer machine and the end bracket is guaranteed, and the daily advancement and output of the working face are guaranteed to be normal; 2) Time is saved for the chute to quickly pass through the pressure zone; 3) The time that workers work in the dangerous area for a long time is reduced, the risk factor is reduced, and the labor intensity of workers is also reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0011] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0012] Figure 1 is a flow chart of the method of the present invention; Figure 2 Schematic diagram of tunnel surrounding rock stress distribution when the depth of the pressure relief hole is 0m, 3m, 4m, and 5m respectively; Figure 3 The schematic diagram of the distribution of plastic zone of tunnel surrounding rock when the depth of pressure relief hole is 0m, 3m, 4m and 5m respectively; Figure 4 This is a schematic diagram of the arrangement of pressure relief holes on both sides of the tunnel; Figure 5 This is a comparison chart of the working resistance of the hydraulic single support in the tunnel before and after the pressure relief hole is drilled. DETAILED DESCRIPTION

[0013] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0014] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0015] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0016] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0017] A method for conveying the working face through the pressure zone of the overlying irregular coal pillar, such as Figure 1 As shown, the following steps are included: 1) Borehole pressure relief: In the irregular coal pillar pressure area and the influence range of 20m before and after, such as Figure 4 As shown in the figure, pressure relief groups are provided on both sides of the tunnel. Each pressure relief group includes a plurality of pressure relief holes arranged in double rows up and down. The depth of each pressure relief hole is FLAC 3D The numerical simulation method is determined by FLAC 3D The influence of different pressure relief hole depths on the stress field and plastic zone distribution of the tunnel surrounding rock was analyzed by numerical simulation method. Finally, the depth of each pressure relief hole was determined based on the construction cost.

[0018] In order to ensure that the deformation of the tunnel and its two sides is controlled within a certain range and to prevent the serious reduction of the tunnel section, the method of drilling pressure-relieving holes is adopted to redistribute the stress. The principle is: the coal bodies on both sides of the tunnel are under extremely high loads and accumulate a large amount of deformation energy. The coal body, surrounding rock, initial support force of hydraulic support and mine pressure are in a critical equilibrium state. The pressure-relieving holes are precisely to alleviate this critical state, remove the lateral constraints of the coal seam, and disperse the already formed local high pressure to a wider area. The pressure-relieving holes cause local coal body rupture, reduce the strength of the coal body, redistribute the stress, release or reduce the elastic energy in the coal body, reduce the pressure on the support shed and the deformation of the tunnel, thereby achieving the purpose of protecting the tunnel.

[0019] By drilling to relieve pressure, the peak stress points on both sides of the tunnel are transferred to the deep coal body, avoiding the rapid movement of the two sides. 3DNumerical simulation analysis shows that drilling pressure relief can increase the fracture zone of the tunnel surrounding rock, change the stress field of the tunnel surrounding rock, and thus transfer the concentrated stress of the surrounding rock to the deep part of the coal wall and reduce the concentrated stress. Reasonable pressure relief hole depth can effectively reduce the deformation of the tunnel surrounding rock and ensure the stability of the tunnel.

[0020] 2) Roof grouting reinforcement: Inject reinforcement materials into the irregular coal pillar pressure zone and within the influence range of 20m before and after.

[0021] As the working face advances forward, when periodic pressure comes, the roof of the coal pillar pressure zone sinks gradually and obviously (especially within the advance support range). The stress state of the surrounding rock should be improved, the damaged parts should be repaired in time, and the support of the easily damaged areas should be strengthened, so the method of grouting reinforcement of the roof is adopted. Targeted injection of reinforcement materials into the broken area of ​​the roof ensures the integrity of the roof, eliminates roof leakage, and creates good conditions for the gradual and gradual top pick in front of the end frame, ensuring sufficient tunnel sections; it can effectively support the roof and avoid the blindness of injecting materials.

[0022] 3) Circular top lifting: For the range where the tunnel height cannot ensure the forward movement of the transfer machine and the end frame, the top is cyclically lifted and re-supported to ensure the smooth forward movement of the equipment.

[0023] During specific implementation, in step 1), the depth of each pressure relief hole is 4m.

[0024] like Figure 2 As shown in the figure, when the depth of the pressure relief hole is 3m, the influence on the stress field of the surrounding rock is not obvious; when the depth of the pressure relief hole is 4m, the pressure relief effect on the surrounding rock is significant, which plays a role in transferring the concentrated stress to the deep part of the coal wall; when the depth of the pressure relief hole is 5m, the pressure relief effect on the surrounding rock is basically similar to that when the depth of the pressure relief hole is 4m; Figure 2 It can be seen that in the absence of pressure relief holes, the plastic zone of the tunnel surrounding rock is mainly distributed on the two sides and the bottom plate of the tunnel. The depth of the crushed zone of the two sides surrounding rock is 3m, and the damage depth of the plastic zone of the bottom plate is about 3m. contrast Figure 3 From (b) to (d), it can be seen that with the increase of the depth of the pressure relief hole, the damage range of the roadway wall gradually increases, and the damage depths of the single-side plastic zone of the roadway wall are 3m, 4m and 5m respectively; the distribution range of the plastic zone of the top and bottom plates decreases with the increase of the depth of the pressure relief hole.

[0025] From the analysis of the stress distribution and plastic zone distribution of the tunnel, it can be seen that the 3m deep pressure relief hole has no obvious effect on the improvement of the stability of the tunnel surrounding rock and the surrounding rock stress field; the 4m deep pressure relief hole can effectively reduce the concentrated stress of the surrounding rock and improve the surrounding rock stability of the tunnel; the effect of the 5m deep pressure relief hole is similar to that of the 4m deep pressure relief hole. Therefore, considering the pressure relief effect and construction cost factors comprehensively, it is finally determined that the 4m deep pressure relief hole is the most suitable.

[0026] Compare the deformation of the tunnel with and without pressure relief holes: a measuring point is arranged every 4m in the pressure relief hole section, a total of 8 points, to measure the displacement of the top and bottom plates and the displacement of the two sides, once a week, for 10 consecutive days, and keep records. The measuring points are arranged normally and the displacement of the top and bottom plates and the two sides is observed. Finally, the measured data for two months are compared, and the results are shown in Table 1. Table 1 Comparison of tunnel deformation

[0027] It can be seen from Table 1 that, through the pressure relief holes, the movement of the top and bottom plates can be reduced by 410mm, and the movement of the two sides can be reduced by 300mm.

[0028] like Figure 5 As shown, the resistance of drilling pressure relief holes is obviously much smaller than that of not drilling pressure relief holes. Therefore, the application of pressure relief holes in the 2806 drift effectively solves a series of problems such as severe deformation of the drift tunnel, rapid reduction of cross-section, and high wind speed, thereby improving the safety of the working environment.

[0029] In the specific implementation, in step 1), the pressure relief holes in the upper row of each pressure relief group are 1.2m high from the tunnel floor, the pressure relief holes in the lower row of each pressure relief group are 0.8m high from the tunnel floor, and the spacing between two adjacent pressure relief holes in each pressure relief group is 0.5m.

[0030] During the specific implementation, the advance support adopts three rows of hydraulic single pillars arranged on both sides of the tunnel and in the middle of the tunnel. The support range is the influence range of the pressure zone. The distance between two adjacent hydraulic single pillars in each row is changed from the original 1m to 0.3m. This kind of dense support method further improves the supporting force and ensures the stability of the roof.

[0031] In this specific implementation, in step 3), anchor rods, anchor cables, metal meshes, and W-steel belts are used for re-support to ensure the stability of the top plate.

[0032] The method described in the present invention saves construction time (about 24 days) and construction costs for the drift to quickly pass through the pressure zone, and at the same time reduces the time that workers work in the dangerous area for a long time, reduces the risk factor, and reduces the labor intensity of workers.

[0033] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A method for transporting coal from a working face through an overlying irregular coal pillar pressure zone, characterized in that: The following steps are included: 1) Drilling pressure relief: In the irregular coal pillar pressure zone and the 20m influence range before and after it, pressure relief groups are set up on both sides of the tunnel. Each pressure relief group includes multiple pressure relief holes arranged in double rows up and down. The depth of each pressure relief hole adopts FLAC 3D The numerical simulation method is determined by FLAC 3D The numerical simulation method is used to analyze the influence of different pressure relief hole depths on the stress field and plastic zone distribution of the tunnel surrounding rock, and finally the depth of each pressure relief hole is determined based on the construction cost; 2) Roof grouting reinforcement: Reinforcement materials are injected into the irregular coal pillar pressure zone and the influence range of 20m before and after it; 3) Cyclic roof lifting: Cyclic roof lifting and re-support are carried out in the range where the tunnel height cannot ensure the forward movement of the transfer machine and the end frame.

2. A method for a working face transport drift to pass through an overlying irregular coal pillar pressure zone according to claim 1, characterized in that: In step 1), the depth of each pressure relief hole is 4m.

3. The method for transporting coal from a working face through an overlying irregular coal pillar pressure zone according to claim 2, characterized in that: In step 1), the height of the pressure relief holes in the upper row of each pressure relief group from the tunnel floor is 1.2m, the height of the pressure relief holes in the lower row of each pressure relief group from the tunnel floor is 0.8m, and the distance between two adjacent pressure relief holes in each pressure relief group is 0.5m.

4. A method for a working face transport drift to pass through an overlying irregular coal pillar pressure zone according to claim 3, characterized in that: The advance support adopts three rows of hydraulic single pillars arranged on both sides of the tunnel and in the middle of the tunnel. The support range is the influence range of the pressure zone. The distance between two adjacent hydraulic single pillars in each row is 0.3m.

5. A method for a working face transport drift to pass through an overlying irregular coal pillar pressure zone according to claim 4, characterized in that: In step 3), anchor rods, anchor cables, metal mesh and W steel belts are used for re-support.

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