Structural control method for preventing rock burst in coal mine tunnels

Abstract

The present invention provides a structural control method for preventing rock bursts in coal mine tunnels, which relates to the technical field of coal mining, including: determining the span of the overall artificial protective layer according to the designed tunnel width, the spacing between the designed tunnel and multiple hard rock layers, and the pressure relief angle of the artificial protective layer mining floor; determining the number of artificial protective layers according to the number of hard rock layers at the top of the designed tunnel; calculating the span of each artificial protective layer according to the uniaxial compressive strength of each artificial protective layer rock layer, the overburden load received, and the thickness of the corresponding rock layer; arranging and constructing each artificial protective layer according to the span of the overall artificial protective layer, the number of artificial protective layers, and the span of each artificial protective layer to transfer the high stress of the tunnel surrounding rock and avoid the risk of re-compaction. The present invention changes the coal rock structure through the combined action of multi-level and small-span artificial protective layers to achieve the effect of transferring high stress, which can effectively solve the problem of stress concentration in the tunnel surrounding rock.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, and in particular to a structural control method for preventing surrounding rock impact pressure in coal mine tunnels. Background Art

[0002] With the steady increase in coal demand, my country's coal mining has gradually entered the deep mining stage. At the same time, the application of coal mining modes such as wide mining width, fast mining speed and high mining height has increased the possibility and danger of rock burst in coal mines. According to statistics, most of the rock burst locations in my country's coal mines occur in tunnels.

[0003] The use of soft rock above the coal seam as an artificial protective layer is difficult to mine, and the mining range of the artificial protective layer is difficult to control. A large mining range has the risk of re-compaction and high stress transmission after landslides. A small mining range of the artificial protective layer has no protective effect and will increase the possibility and danger of rock burst. Summary of the invention

[0004] The present invention provides a structural control method for preventing rock impact in coal mine tunnel surrounding rocks, which can avoid the problem of using soft rock above the mined coal seam as an artificial protective layer, resulting in a difficult to control mining range. By constructing a multi-level, small-scale artificial protective layer above the coal seam tunnel, the bearing structure above the tunnel surrounding rock is changed, so as to achieve the purpose of transferring stress to protect the tunnel surrounding rock.

[0005] In order to achieve the above-mentioned invention object, the technical solution provided by the present invention is as follows:

[0006] A structural control method for preventing rock bursts in coal mine tunnels comprises: determining the span of an overall artificial protective layer according to a designed tunnel width, a distance between the designed tunnel and multiple hard rock layers, and a pressure relief angle of an artificial protective layer mining floor; determining the number of artificial protective layers according to the number of hard rock layers at the top of the designed tunnel; calculating the span of each artificial protective layer according to the uniaxial compressive strength of each artificial protective layer, the overlying load received, and the thickness of the corresponding rock layer; arranging and constructing each artificial protective layer according to the span of the overall artificial protective layer, the number of artificial protective layers, and the span of each artificial protective layer, adopting the principle of designing from the bottom to the top and constructing from the top to the bottom, so as to prevent the risk of re-compaction.

[0007] Exemplarily, the method of determining the span of the overall artificial protective layer based on the designed tunnel width, the distance between the designed tunnel and multiple layers of hard rock formations, and the pressure relief angle of the artificial protective layer mining floor also includes determining the height of the overall artificial protective layer, wherein the span and height of the overall artificial protective layer range from 0.3 meters to 3 meters.

[0008] Exemplarily, in determining the number of artificial protective layers according to the number of hard rock layers at the top of the designed tunnel, each layer of the artificial protective layer is a two-stage structure separated by a predetermined distance.

[0009] Exemplarily, in calculating the span of each artificial protective layer according to the uniaxial compressive strength of each artificial protective layer rock layer, the overburden load and the thickness of the corresponding rock layer, the span s of each artificial protective layer satisfies: Among them, R r is the uniaxial compressive strength, q i is the overlying load on the i-th rock layer, and h is the thickness of the i-th rock layer.

[0010] Exemplarily, in the arrangement and construction of each layer of artificial protective layer according to the span of the overall artificial protective layer, the number of layers of the artificial protective layer, and the span of each layer of artificial protective layer, the arrangement of each layer of artificial protective layer adopts the principle of designing from the bottom layer to the upper layer, and the construction of each layer of artificial protective layer adopts the principle of constructing from the upper layer to the lower layer, so as to avoid stress concentration and disturbance to the tunnel caused by direct construction on the bottom layer.

[0011] Exemplarily, in determining the number of artificial protective layers according to the number of hard rock layers at the top of the designed tunnel, the number of artificial protective layers is at least three, and each layer of the artificial protective layer is a two-stage structure symmetrically distributed along the center line of the designed tunnel.

[0012] Exemplarily, the arrangement of each layer of artificial protective layer includes: designing a first layer of artificial protective layer from the edge of the overall artificial protective layer span, and arranging it along both sides of the tunnel; designing a second layer of artificial protective layer according to the span of the first layer of artificial protective layer, the span of the second layer of artificial protective layer, and the bottom plate pressure relief angle of the second layer of artificial protective layer; designing a third layer of protective layer according to the span of the second layer of artificial protective layer, the span of the third layer of artificial protective layer, and the bottom plate pressure relief angle of the third layer of artificial protective layer; and arranging in a cycle until the topmost protective layer.

[0013] Exemplarily, the construction of each layer of artificial protective layer includes: constructing the third layer of artificial protective layer to guide the stress to transfer to the opposite sides of the third layer of artificial protective layer, and the edge of the pressure relief range intersects with the edge of the second layer of artificial protective layer; constructing the second layer of artificial protective layer to guide the stress to continue to transfer and expand the pressure relief area, and the edge of the pressure relief range of the second layer of artificial protective layer intersects with the edge of the first layer of artificial protective layer; constructing the first layer of artificial protective layer, the tunnel is in the pressure relief area of ​​the overall artificial protective layer, so as to transfer high stress to a position away from the surrounding rock of the tunnel.

[0014] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0015] In the above technical solution, the range of the entire artificial protective layer is determined according to the distance between each hard rock layer and the coal seam, and then the range of a single protective layer is calculated according to the rock layer collapse step, rock layer spacing, and bottom plate pressure relief angle, and then the construction level and height are determined. The coal rock structure is changed by the combined action of multi-level, small-span artificial protective layers to achieve the effect of transferring high stress, which can effectively avoid the shortcomings of using soft rock above the coal seam to be mined as an artificial protective layer in preventing and controlling rock burst, and at the same time avoid rock layer collapse and re-compaction, effectively preventing rock burst problems in coal mine tunnel surrounding rocks.

[0016] In some of the above exemplary schemes, the artificial protective layer is designed from the bottom to the top and constructed from the top to the bottom. The top artificial protective layer is constructed first, and then constructed downwards in sequence. This can effectively avoid stress concentration and disturbance to the tunnel when constructing from the bottom. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a flow chart of the method of the present invention;

[0019] Figure 2 A schematic diagram of a three-level, small-scale artificial protective layer arrangement in an embodiment of the present invention;

[0020] Figure 3 for Figure 2 Schematic diagram of pressure relief regulation by artificial protective layer structure in the embodiment shown.

[0021] The accompanying drawings are described as follows:

[0022] 1—designed tunnel; 2—span of the entire artificial protective layer; 3—distance between the coal seam and the first artificial protective layer; 4—pressure relief angle of the first artificial protective layer mining floor; 5—span of the first artificial protective layer; 6—distance between the first and second artificial protective layers; 7—pressure relief angle of the second artificial protective layer mining floor; 8—span of the second artificial protective layer; 9—distance between the second and third artificial protective layers; 10—span of the third artificial protective layer; 11—pressure relief angle of the third artificial protective layer mining floor; 12—stress transfer zone of the third artificial protective layer; 13—edge of the pressure relief range of the third artificial protective layer; 14—stress transfer zone of the second artificial protective layer; 15—edge of the pressure relief range of the second artificial protective layer; 16—edge of the pressure relief range of the first artificial protective layer; 17—position of high stress concentration. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the common meanings understood by persons with ordinary skills in the field to which the present invention belongs. "Include" or "comprising" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0025] Combination Figure 1 As shown, an embodiment of the present invention provides a structural control method for preventing rock burst in coal mine tunnels, comprising the following steps:

[0026] S100: Determine the span of the overall artificial protective layer according to the designed tunnel width, the distance between the designed tunnel and multiple hard rock layers, and the pressure relief angle of the artificial protective layer mining floor;

[0027] S200: Determine the number of artificial protective layers according to the number of hard rock layers on the top of the designed tunnel;

[0028] S300: Calculate the span of each artificial protective layer according to the uniaxial compressive strength of each artificial protective layer rock layer, the overburden load and the thickness of the corresponding rock layer;

[0029] S400: Arranging and constructing each layer of the artificial protective layer according to the span of the entire artificial protective layer, the number of layers of the artificial protective layer, and the span of each layer of the artificial protective layer.

[0030] Since rock burst prevention is a complex system engineering, from the perspective of system engineering, the structural form of the rock mechanics system is the basis for ensuring the function and overall effect of the rock mechanics system, and the system geometric structure information is a component of the system control variable. The change of the system structure will change its function and overall effect. Therefore, for the rock mechanics system in a critical or unstable state, by adjusting and optimizing its structural form, the system can be reinforced, the stability of the system can be improved, and the system instability can be prevented.

[0031] The above scheme determines the scope of the entire artificial protective layer according to the distance between each hard rock layer and the coal seam, and then calculates the scope of a single protective layer according to the rock layer collapse step, rock layer spacing, and bottom plate pressure relief angle, and then determines the construction level and height. The coal rock structure is changed by the combined action of multi-level, small-span artificial protective layers to achieve the effect of transferring high stress, which can effectively avoid the shortcomings of using soft rock above the coal seam to be mined as an artificial protective layer in preventing and controlling rock burst, and at the same time avoid rock layer collapse and re-compaction, effectively preventing rock burst problems in coal mine tunnel surrounding rocks.

[0032] It should be understood that, although the steps in the flowchart of the accompanying drawings are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

[0033] In some embodiments, exemplarily, in step S100: the span of the overall artificial protective layer is determined according to the designed tunnel width, the distance between the designed tunnel and multiple layers of hard rock formations, and the pressure relief angle of the artificial protective layer mining floor, and the height of the overall artificial protective layer is also determined, wherein the span and height of the overall artificial protective layer range from 0.3 meters to 3 meters.

[0034] It needs to be explained that the mining of artificial protective layers transfers stress, and the middle is mined out, causing stress on both ends. The pressure is transferred to both ends. If the roof collapses, it will cause stress recovery. Therefore, the artificial protective layers are arranged in layers to avoid the collapse of each liberation layer, thereby ensuring the pressure relief effect. In this way, it is necessary to calculate the collapse layout and arrange it in layers to ensure the pressure relief effect. Therefore, the specific number of liberation layers that need to be arranged must be determined through calculation. In addition, the pressure relief angle is generally monitored on-site. If necessary, the pressure relief angle can also be determined by stress monitoring of the mined working face.

[0035] In step S200: determining the number of layers of the artificial protective layer, each layer of the artificial protective layer is a two-stage structure separated by a predetermined distance. It should be pointed out here that the total pressure relief length of the artificial protective layer is calculated by the width of the tunnel to be protected and the distance of the first layer of hard roof (the purpose of selecting the hard roof is that it is not easy to collapse and ensure the pressure relief effect), and then the layout of the artificial protective layer can be calculated according to the roof distribution and the pressure relief angle.

[0036] In step S300, the span of each artificial protective layer is calculated according to the uniaxial compressive strength of each artificial protective layer rock layer, the overburden load and the thickness of the corresponding rock layer, and the span s of each artificial protective layer satisfies: Among them, d is the thickness of the rock layer corresponding to each artificial protective layer, p is the uniaxial compressive strength of each artificial protective layer rock layer, and f is the overlying load borne by each artificial protective layer rock layer.

[0037] In step S400: each layer of artificial protective layer is arranged and constructed according to the span of the overall artificial protective layer, the number of layers of the artificial protective layer and the span of each layer of artificial protective layer. The arrangement of each layer of artificial protective layer adopts the principle of designing from the bottom layer to the upper layer, and the construction of each layer of artificial protective layer adopts the principle of constructing from the upper layer to the lower layer, so as to avoid stress concentration and disturbance to the tunnel caused by direct construction on the bottom layer.

[0038] Following the above embodiment of step S300, the number of layers of the artificial protective layer is at least three, and each layer of the artificial protective layer is a two-stage structure symmetrically distributed along the center line of the designed lane.

[0039] In the above embodiment, the arrangement of each artificial protective layer includes:

[0040] S411: designing a first layer of artificial protective layer from the edge of the span of the overall artificial protective layer, and arranging it along both sides of the tunnel; S412: designing a second layer of artificial protective layer according to the span of the first layer of artificial protective layer, the span of the second layer of artificial protective layer, and the bottom plate pressure relief angle of the second layer of artificial protective layer;

[0041] S413: designing the third protective layer according to the span of the second artificial protective layer, the span of the third artificial protective layer, and the bottom plate pressure relief angle of the third artificial protective layer;

[0042] S414: Loop the arrangement until the topmost protective layer.

[0043] In addition, the construction of each artificial protective layer includes:

[0044] S421: constructing the third artificial protective layer to guide the stress to transfer to the opposite sides of the third artificial protective layer, and the edge of the pressure relief range intersects with the edge of the second artificial protective layer;

[0045] S422: construct the second artificial protective layer to guide the continuous transfer of stress and expand the pressure relief area. The edge of the pressure relief range of the second artificial protective layer intersects with the edge of the first artificial protective layer;

[0046] S423: Construct the first layer of artificial protective layer. The tunnel is in the pressure relief area of ​​the overall artificial protective layer to transfer high stress to a position far away from the tunnel surrounding rock.

[0047] In summary, according to the embodiment provided by the present invention, a three-level, small-span artificial protective layer can be designed, and a specific structural control method for preventing rock burst pressure in coal mine tunnels can be combined with Figure 2 and Figure 3 , which can be shown as the following steps.

[0048] S1: Determine the span 2 and height of the overall artificial protective layer (the thickness of each layer of artificial protective layer can be 1m) based on the designed tunnel width 1, the distance between the coal seam and the first layer of artificial protective layer 3, the distance between the first layer of artificial protective layer and the second layer of artificial protective layer 6, the distance between the second layer of artificial protective layer and the third layer of artificial protective layer 9, the pressure relief angle of the mining floor of the first layer of artificial protective layer 4, the pressure relief angle of the mining floor of the second layer of artificial protective layer 7, and the pressure relief angle of the mining floor of the third layer of artificial protective layer 11.

[0049] S2: The span of the first artificial protective layer is 5, the span of the second artificial protective layer is 8, and the span of the third artificial protective layer is 10 according to the uniaxial compressive strength of each artificial protective layer rock layer, the overburden load, and the thickness of the rock layer.

[0050] S3: Design the first artificial protective layer from the edge of span 2 of the overall artificial protective layer, and arrange it on both sides of the tunnel. Design the second artificial protective layer according to the span 5 of the first artificial protective layer, the span 8 of the second protective layer, and the unloading angle 7 of the second artificial protective layer mining floor;

[0051] S4: According to the arrangement method of the second protective layer, the third protective layer is designed, that is, according to the span 8 of the second artificial protective layer, the span 10 of the third artificial protective layer, and the unloading angle 11 of the mining floor of the third artificial protective layer, the third artificial protective layer is designed.

[0052] S5: Design from the bottom to the top, and construct from the top to the bottom. First, construct the top third protective layer with a span of 10, and then go down in sequence. Avoid stress concentration and disturbance to the roadway when constructing from the bottom.

[0053] When constructing the third artificial protective layer, the stress is transferred to both sides to the stress transfer area 12 of the third artificial protective layer; the edge 13 of the pressure relief range of the third artificial protective layer intersects with the second artificial protective layer;

[0054] Then, the second artificial protective layer is constructed, and the stress is continuously transferred to both sides to the stress transfer area 14 of the second artificial protective layer, and the pressure relief area is expanded at the same time, and the pressure relief range edge 15 of the second artificial protective layer intersects with the first artificial protective layer;

[0055] During the construction of the first artificial protective layer, the tunnel is located in the pressure relief zone around the edge 16 of the pressure relief range of the first artificial protective layer of the overall artificial protective layer, and the high stress is transferred to a position away from the surrounding rock of the tunnel.

[0056] The high stress concentration position 17 where the stress is transferred can be designed as required. Here, the high stress concentration position 17 can be determined by coal body stress monitoring.

[0057] The overall artificial protective layer can change the overall structure of the tunnel surrounding rock, transfer the high stress of the tunnel surrounding rock without collapsing the liberation layer, avoid the risk of re-compaction, and effectively prevent impact ground pressure disasters in the surrounding rock of coal mine tunnels.

[0058] In addition, according to the embodiments provided by the present invention, there may be two, four or more layers of artificial protective layers with a small span, or the overall artificial protective layer area may not be symmetrically distributed along the center of the tunnel. Alternatively, in some embodiments, each layer of artificial protective layer in the overall artificial protective layer area contains a different number of segment structures. For example, the first layer of artificial protective layer includes three mutually spaced liberation layer areas, the second layer of artificial protective layer includes two mutually spaced liberation layer areas, the third layer of artificial protective layer includes only one liberation layer area, and the fourth layer of artificial protective layer includes six mutually liberated layer areas, which are not listed one by one here.

[0059] There are a few points to note:

[0060] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention, and other structures may refer to the general design.

[0061] (2) For the sake of clarity, in the drawings used to describe the embodiments of the present invention, the thickness of layers or regions is exaggerated or reduced, that is, these drawings are not drawn according to the actual scale.

[0062] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to obtain new embodiments.

[0063] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A structural control method for preventing rock burst in coal mine tunnels, characterized in that: include: The span of the overall artificial protective layer is determined based on the designed tunnel width, the distance between the designed tunnel and multiple hard rock layers, and the pressure relief angle of the artificial protective layer mining floor; Determine the number of layers of artificial protective cover; The span of each artificial protective layer is calculated according to the uniaxial compressive strength of the rock layer of each artificial protective layer, the overburden load and the thickness of the corresponding rock layer; Arrange and construct each layer of artificial protective layer according to the span of the overall artificial protective layer, the number of layers of the artificial protective layer, and the span of each layer of artificial protective layer to transfer the high stress of the surrounding rock of the tunnel, and adopt the principle of designing from the bottom layer to the upper layer and constructing from the upper layer to the lower layer to avoid the risk of re-compaction; In the step of determining the number of artificial protective layers according to the number of hard rock layers at the top of the designed tunnel, the number of artificial protective layers is at least three, and each layer of the artificial protective layer is a two-stage structure symmetrically distributed along the center line of the designed tunnel; The construction of each artificial protective layer includes: The third artificial protective layer is constructed to guide the stress to transfer to the opposite sides of the third artificial protective layer, and the edge of the pressure relief range intersects with the edge of the second artificial protective layer; The second artificial protective layer is constructed to guide the continuous transfer of stress and expand the pressure relief area. The edge of the pressure relief range of the second artificial protective layer intersects with the edge of the first artificial protective layer. The first layer of artificial protective layer is constructed, and the tunnel is located in the pressure relief area of ​​the overall artificial protective layer to transfer high stress to a position far away from the surrounding rock of the tunnel.

2. The structural control method for preventing rock burst in coal mine tunnels according to claim 1 is characterized in that: The method of determining the span of the overall artificial protective layer based on the designed tunnel width, the distance between the designed tunnel and multiple hard rock formations, and the pressure relief angle of the artificial protective layer mining floor also includes determining the height of the overall artificial protective layer, wherein the span and height of the overall artificial protective layer range from 0.3 meters to 3 meters.

3. The structural control method for preventing rock burst in coal mine tunnels according to claim 1 is characterized in that: In the method of determining the number of artificial protective layers according to the number of hard rock layers on the top of the designed tunnel, each layer of the artificial protective layer is a two-stage structure with a predetermined distance between them.

4. The structural control method for preventing rock burst in coal mine tunnels according to claim 1 is characterized in that: In calculating the span of each artificial protective layer according to the uniaxial compressive strength of each artificial protective layer rock layer, the overburden load and the thickness of the corresponding rock layer, the span s of each artificial protective layer satisfies: Among them, R r is the uniaxial compressive strength, q i is the overlying load on the i-th rock layer, and h is the thickness of the i-th rock layer.

5. The structural control method for preventing rock burst in coal mine tunnels according to claim 1 is characterized in that: The arrangement of each artificial protective layer includes: Design the first layer of artificial protection layer from the edge of the overall artificial protection layer span and arrange it along both sides of the roadway; designing the second artificial protective layer according to the span of the first artificial protective layer, the span of the second artificial protective layer, and the bottom plate pressure relief angle of the second artificial protective layer; Design the third protective layer according to the span of the second artificial protective layer, the span of the third artificial protective layer, and the bottom plate pressure relief angle of the third artificial protective layer; Repeat the process until you reach the top protective layer.

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