Large-section gob-side entry driving coal pillar size optimization and asymmetric support method

Abstract

The invention discloses a large-section gob-side entry driving coal pillar size optimization and asymmetric support method. The method comprises the following steps: S10, establishing parameterized models of different coal pillar sizes; s20, related parameters are perfected, operation is performed, and a result is output; s30, analyzing an output result, and determining an optimal size; s40, the roadway is excavated to the design size, and a coal pillar with the optimal size is reserved; and S50, the roadway is supported. On the basis of comprehensively considering the roadway stability and the coal resource recovery rate, large-section gob-side entry driving coal pillar size optimization and asymmetric support are achieved, and safety and stability of large-section gob-side entry driving are guaranteed. Asymmetric support is carried out on the coal pillar side of the roadway according to the plastic zone distribution of the surrounding rock of the roadway, an asymmetric support system with anchor cable reinforcement and zoning grouting is provided, the integrity of the broken coal pillar is improved, and the bearing capacity of the surrounding rock of the roadway is improved. And different grouting materials are used according to different crushing degrees of the surrounding rock, so that the grouting cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of coal pillar size optimization and roadway support, and in particular to a method for optimizing the size of coal pillars and asymmetric support in a large-section gob-side roadway. Background Art

[0002] Gob-side tunneling is one of the effective ways to achieve efficient utilization of coal resources, that is, leaving coal pillars of different widths at the edge of the gob to ensure stable tunneling. At present, in order to maintain the stability of the tunnel, most mines leave too wide coal pillars in gob-side tunneling, resulting in a large amount of coal resources being wasted. The patent document with application number CN201810344351.2 discloses a finite element optimization method for the width of the protective coal pillar in the floor tunnel. Based on the ABAQUS platform, a dynamic parameterized model simulating different widths of protective coal pillars is established using Python language, and a finite element optimization analysis and calculation program based on Matlab language is compiled. The minimum deformation of the tunnel and the protective coal pillar is taken as the optimization target, and the established dynamic parameterized model is calculated to obtain a reasonable size of the protective coal pillar. This method takes the minimum deformation of the tunnel and the protective coal pillar as the optimization target, but in the actual design of the coal pillar size, the influence of the size of the coal pillar on the stability of the tunnel and the influence on the resource recovery rate are also very important influencing factors. At the same time, as coal mines enter deep mining, smaller coal pillars are left under high stress conditions. Due to the complex geomechanical environment, the tunnel will be in an asymmetric stress state. If only conventional support is used, the support strength will be insufficient. However, blindly carrying out full-section reinforcement support for the tunnel will lead to an increase in the tunnel support cost. Summary of the invention

[0003] In order to solve the technical problems existing in the above-mentioned background technology that the size of coal pillars should be set in comprehensive consideration of tunnel stability and coal resource recovery rate, as well as the asymmetric force on coal pillars, and targeted reinforcement and support are required, the present invention provides a method for optimizing the size of coal pillars and asymmetric support in large-section goaf-side roadway excavation.

[0004] The technical solution of the present invention is as follows:

[0005] A method for optimizing the size of coal pillars and asymmetric support in large-section gob-side roadway driving, comprising the following steps:

[0006] S10: Establish a parametric model of different coal pillar sizes;

[0007] Use Python language to write secondary development program based on ABAQUS to establish parametric dynamic finite element models of different coal pillar sizes;

[0008] S20: Improve relevant parameters, run and output results;

[0009] S201. Sample the surrounding rock of the tunnel, conduct uniaxial and triaxial compression tests, obtain relevant parameters of the surrounding rock samples and improve the numerical simulation program;

[0010] S202, run and output analysis files;

[0011] S30: Analyze the output results and determine the optimal size;

[0012] Score the distribution of the plastic zone and the size of the coal pillars in the roadway, and perform weight analysis according to the importance to determine the optimal size of the coal pillars in the roadway along the goaf;

[0013] S40: Excavate the tunnel to the designed size and leave the coal pillar of the optimal size;

[0014] S50: Support the tunnel;

[0015] The specific steps are:

[0016] S501, perform conventional support on the tunnel;

[0017] Anchor support is applied to the sides and roof of the tunnel, and steel mesh is hung on the roof, and diamond wire mesh is hung on the sides;

[0018] S502, provide asymmetric support for coal pillars in roadways;

[0019] The coal pillar is reinforced with grouting anchor cables, and the coal pillar is grouted in different areas according to the distribution characteristics of the plastic zone of the coal pillar.

[0020] Based on the Python language, a secondary development optimization program for coal pillar size was compiled to achieve the establishment of parametric dynamic finite element models of different coal pillar sizes, which improved the efficiency of the optimal size analysis of coal pillars in large-section goaf-side tunneling. An asymmetric support system of anchor reinforcement and partition grouting was proposed to improve the integrity of the broken coal pillars and the bearing capacity of the tunnel surrounding rock. The distribution of the plastic zone on the side section of the tunnel coal pillar has a vital impact on the safety and stability of the tunnel. The size of the coal pillar is highly correlated with the utilization rate of coal resources. The larger the size of the coal pillar, the lower the utilization rate of coal resources. Based on the comprehensive consideration of tunnel stability and coal resource recovery rate, the optimization of the size of coal pillars and asymmetric support for large-section goaf-side tunneling were achieved, ensuring the safety and stability of large-section goaf-side tunneling.

[0021] In the above-mentioned large-section gob-side roadway coal pillar size optimization and asymmetric support method, step S30 is specifically as follows:

[0022] S301. Score the area of ​​the plastic zone of the coal pillar, including the following situations:

[0023] A. S NP ≤S P ;

[0024] B. S P NP ≤2S P ;

[0025] C.U S =0, S NP >2S P ;

[0026] Where U S is the plastic zone area score, S NP is the area of ​​non-plastic zone in the cross section of coal pillar, S P is the plastic zone area of ​​the coal pillar section;

[0027] S302, scoring the size of the coal pillar;

[0028] L≤L0;

[0029] Where U L is the coal pillar size score, L is the coal pillar size, and L0 is the maximum size of the coal pillar;

[0030] S303. Analyze the plastic zone area of ​​the roadway coal pillar and the size of the coal pillar in a ratio of 1:1 according to their importance, and determine the optimal size of the coal pillar.

[0031] The distribution of plastic zone in the side section of coal pillar in the tunnel has a vital impact on the safety and stability of the tunnel. The size of coal pillar is highly correlated with the utilization rate of coal resources. The larger the size of coal pillar, the lower the utilization rate of coal resources. The distribution of plastic zone, that is, the area of ​​plastic zone of coal pillar and the size of coal pillar are equally important.

[0032] Specifically, because different grouting materials have different diffusion ranges in surrounding rocks with different degrees of crushing, the zoning grouting in step S502 is specifically to inject granular grouting materials with poor diffusion efficiency into the plastic zone of the coal pillar under high pressure, and to inject chemical grouting materials with good diffusion efficiency into the non-plastic zone of the coal pillar under high pressure. The plastic zone of the coal pillar has poor homogeneity and many cracks, so the grouting material is selected as a granular slurry with poor diffusion efficiency but low cost, while the non-plastic zone of the coal pillar has good homogeneity and no obvious crack development, so the grouting material can be selected as a chemical slurry with good diffusion efficiency but high cost.

[0033] As a preferred implementation, the driving angle of the grouting anchor in step S502 is 15° upward from the horizontal direction, and the anchoring end of the anchor is ensured to be driven into a basically hard stable layer, ensuring that a length of more than 1.5 m can be anchored in the stable layer to ensure the support strength of the anchor.

[0034] ​Furthermore, during the zone grouting in step S502, the minimum diffusion diameter of the grouting material is used as the row spacing, and the coal pillars are zoned for grouting in a plum blossom arrangement, so that the rows are optimally overlapped and grouting blind areas are less likely to occur.

[0035] Preferably, the granular grouting material is cement water glass. Cement water glass slurry has the characteristics of rapid setting and controllable setting time, high slurry stone rate, high early strength of stone body, etc., and the slurry itself is non-toxic, non-polluting and low-cost.

[0036] Further preferably, the chemical grouting material is epoxy resin. Epoxy resin slurry has excellent mechanical properties, good permeability and adhesion, and a short curing time.

[0037] Specifically, for conventional support of the tunnel, in step S501, 5 anchor rods are arranged at the tunnel roof, the spacing between the anchor rods is 1000×1000mm, the spacing between the anchor rods is allowed to deviate by -100 to 100mm, and 4 anchor rods are arranged on each side, the spacing between the anchor rods is 1000×1000mm. This can ensure the stability of the anchor rods and avoid unnecessary cost increase or safety hazards caused by over-dense arrangement.

[0038] Through the above design, the beneficial effects of the large-section goaf-side roadway coal pillar size optimization and asymmetric support method of the present invention are:

[0039] (1) A secondary development optimization program for coal pillar size was compiled based on Python language, which realized the establishment of parametric dynamic finite element models of different coal pillar sizes and improved the efficiency of optimal size analysis of coal pillars in large-section goaf-side roadway excavation.

[0040] (2) The distribution of the plastic zone of the side section of the coal pillar in the tunnel has a crucial impact on the safety and stability of the tunnel. The size of the coal pillar is highly correlated with the utilization rate of coal resources. The larger the size of the coal pillar, the lower the utilization rate of coal resources. Based on comprehensive consideration of tunnel stability and coal resource recovery rate, the size optimization of the coal pillar and asymmetric support of the large-section goaf-side tunneling are achieved, ensuring the safety and stability of the large-section goaf-side tunneling.

[0041] (3) According to the distribution of plastic zones of the tunnel surrounding rock, asymmetric support was carried out on the side of the tunnel coal pillar, and an asymmetric support system of anchor reinforcement and zoned grouting was proposed, which improved the integrity of the broken coal pillar and the bearing capacity of the tunnel surrounding rock.

[0042] (4) Zone grouting not only improves the integrity of the coal pillar, but also uses different grouting materials according to the degree of surrounding rock fragmentation, saving grouting costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In the attached picture:

[0044] Figure 1It is a schematic diagram of a method for optimizing the size of coal pillars and asymmetric support in a large-section goaf-side roadway according to the present invention;

[0045] Figure 2 It is a secondary development program user graphical interface written in Python language in the embodiment;

[0046] Figure 3 Schematic diagram of different coal pillar size models in the embodiment;

[0047] Figure 4 Schematic diagram of the distribution of plastic zones of finite element models of different coal pillar sizes in the embodiment;

[0048] Figure 5 Schematic diagram of tunnel support in the embodiment;

[0049] The components represented by the reference numerals in the figure are:

[0050] 1. Anchor rod; 2. Anchor cable; 3. Plastic zone of coal pillar; 4. Non-plastic zone of coal pillar. DETAILED DESCRIPTION

[0051] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings.

[0052] Example

[0053] See also Figure 1 This embodiment provides a method for optimizing the size of coal pillars and asymmetric support in a large-section gob-side roadway, including the following steps:

[0054] S10: Establish a parametric model of different coal pillar sizes;

[0055] Use Python language to write secondary development program based on ABAQUS to establish parametric dynamic finite element models of different coal pillar sizes;

[0056] See also Figure 2 , and input different coal pillar sizes L in turn in the user graphical interface of the secondary development program written in Python. The secondary development program can be called in ABAQUS to automatically establish finite element models of different coal pillar sizes. By inputting relevant parameters through the user-defined window, the parametric modeling and meshing of models of different coal pillar sizes are completed. Figure 3 , a coal pillar size model is established with coal pillar sizes of L=1m, L=2m, L=3m, L=4m, L=5m and L=6m respectively.

[0057] S20: Improve relevant parameters, run and output results;

[0058] S201. Sample the surrounding rock of the tunnel, conduct uniaxial and triaxial compression tests, obtain relevant parameters of the surrounding rock samples and improve the numerical simulation program;

[0059] S202, run and output analysis files;

[0060] See also Figure 4 , output the plastic zone distribution map of the finite element model with different coal pillar sizes.

[0061] A secondary development and optimization program for coal pillar size was compiled based on Python language, which realized the establishment of parametric dynamic finite element models of different coal pillar sizes and improved the efficiency of optimal size analysis of coal pillars in large-section goaf-side roadway excavation.

[0062] S30: Analyze the output results and determine the optimal size;

[0063] The distribution of the plastic zone 3 of the roadway coal pillar and the size of the coal pillar are scored, and a weight analysis is performed according to the importance to determine the optimal size of the coal pillar in the roadway along the goaf;

[0064] Specifically:

[0065] S301. Score the area of ​​the plastic zone 3 of the coal pillar, including the following situations:

[0066] A. S NP ≤S P ;

[0067] B. S P NP ≤2S P ;

[0068] C.U S =0, S NP >2S P ;

[0069] Where U S is the plastic zone area score, S NP is the area of ​​non-plastic zone in the cross section of coal pillar, S P is the plastic zone area of ​​the coal pillar section;

[0070] S302, scoring the size of the coal pillar;

[0071]

[0072] Where U L is the coal pillar size score, L is the coal pillar size, and L0 is the maximum size of the coal pillar;

[0073] S303. Analyze the area of ​​the plastic zone 3 of the roadway coal pillar and the size of the coal pillar in a ratio of 1:1 according to their importance, and determine the optimal size of the coal pillar.

[0074] ​After calculation, the optimal size of the coal pillar is when the coal pillar size L = 4m.

[0075] The distribution of the plastic zone of the side section of the coal pillar in the roadway has a vital impact on the safety and stability of the roadway. The size of the coal pillar is highly correlated with the utilization rate of coal resources. The larger the size of the coal pillar, the lower the utilization rate of coal resources. The distribution of the plastic zone, that is, the area of ​​the plastic zone 3 of the coal pillar and the size of the coal pillar are equally important. On the basis of comprehensive consideration of the roadway stability and the coal resource recovery rate, the optimization of the size of the coal pillar in the large-section goaf-side roadway is achieved, ensuring the safety and stability of the large-section goaf-side roadway.

[0076] S40: Excavate the tunnel to the designed size and leave coal pillars of optimal size.

[0077] S50: Support the tunnel;

[0078] The specific steps are:

[0079] S501, perform conventional support on the tunnel;

[0080] Anchor rods 1 are applied to the two sides and the top plate of the tunnel for support, and a steel mesh is hung on the top plate, and a diamond wire mesh is hung on the two sides; among them, metal meshes such as steel mesh and wire mesh can be used to protect the surrounding rock between the anchor rods 1 to prevent loose rocks from falling.

[0081] See also Figure 5 , the conventional support of the tunnel is as follows:

[0082] There are 5 anchor rods 1 at the tunnel roof, with a row spacing of 1000×1000mm, a length of 10-50mm exposed from the nut, and an allowable deviation of -100-100mm between the rows of anchor rods. The two outermost anchor rods 1 are tilted toward the two sides of the tunnel to provide shear resistance and prevent the roof from slipping and falling along the cracks at the corners. A steel mesh with a specification of length×width=4300×1100mm is hung on the roof, and the steel mesh is spliced ​​to improve the stability of the tunnel support.

[0083] Each side of the tunnel is equipped with 4 left-handed non-longitudinal rib threaded steel anchor rods 1 with specifications of Ф20×2400mm and diamond wire mesh. The left-handed non-longitudinal rib threaded steel anchor rods 1 have high strength, reasonable structure, large preload force, and can automatically adjust the force direction to increase the restraint force on the surrounding rock. The uppermost and lowermost anchor rods 1 are arranged tilted upward and downward respectively, with an angle of 75° with the side of the tunnel, and the middle anchor rod 1 is perpendicular to the side. The distance between the lowest anchor rod 1 of the side and the bottom plate of the tunnel is no more than 500mm. When the distance is greater than 500mm, the anchor rod 1 is promptly supplemented and the mesh is hung. The spacing between the anchor rods 1 is 1000×1000mm. It can not only ensure the stability of the anchor rods 1, but also avoid unnecessary cost increases or safety hazards caused by overly dense arrangements.

[0084] S502, provide asymmetric support for coal pillars in roadways;

[0085] The coal pillar is reinforced with grouting anchor cables 2, and the coal pillar is grouted in different areas according to the distribution characteristics of the plastic zone 3 of the coal pillar;

[0086] Among them, the reinforcement support of the coal pillar with grouting anchor cable 2 is specifically as follows: two grouting anchor cables 2 with a specification of Ф17.8×5000mm are added to the side of the coal pillar, and the spacing between the anchor cables 2 is 2000×2000mm. In order to ensure the support strength of the anchor cable 2, the driving angle is 15° upward from the horizontal direction, and the anchoring end of the anchor cable 2 is ensured to be driven into the basically hard stable layer, ensuring that it can be anchored in the stable layer with a length of more than 1.5m. The initial tensioning of the anchor cable 2 has a preload force of not less than 135kN and a pull-out resistance of not less than 224kN. After the anchor cable 2 is installed, it is subjected to high-pressure grouting. The grouting material is cement mortar, and the grouting pressure is 3MPa. Compared with the anchor rod 1, the anchor cable 2 is longer and can be anchored into deep stable rocks. It can also apply prestress to limit the development of harmful deformation of the rock mass, thereby maintaining the stability of the rock mass.

[0087] Because different grouting materials have different diffusion ranges in surrounding rocks with different degrees of crushing, the specific zoning grouting of the coal pillar is as follows: the granular grouting material with poor diffusion efficiency is injected into the plastic zone 3 of the coal pillar under high pressure, and the chemical grouting material with good diffusion efficiency is injected into the non-plastic zone 4 of the coal pillar under high pressure. The plastic zone 3 of the coal pillar has poor homogeneity and many cracks, so the grouting material is a granular slurry with poor diffusion efficiency but low cost, while the non-plastic zone 4 of the coal pillar has good homogeneity and no obvious crack development, so the grouting material can be a chemical slurry with good diffusion efficiency but high cost.

[0088] Preferably, the granular grouting material is cement water glass. Cement water glass slurry has the characteristics of rapid setting and controllable setting time, high slurry stone rate, high early strength of stone body, etc., and the slurry itself is non-toxic, non-polluting and low-cost.

[0089] Further preferably, the chemical grouting material is epoxy resin. Epoxy resin slurry has excellent mechanical properties, good permeability and adhesion, and a short curing time.

[0090] Furthermore, when performing zone grouting, the minimum diffusion diameter of the grouting material is used as the row spacing, and the coal pillars are zoned for grouting in a plum blossom shape arrangement, so that the optimal overlap is achieved between the rows and grouting blind areas are less likely to occur.

[0091] An asymmetric support system of anchor cable 2 reinforcement and zoned grouting was proposed to improve the integrity of the broken coal pillar and the bearing capacity of the tunnel surrounding rock.

[0092] The method for optimizing the size of coal pillars and asymmetric support for large-section goaf-side roadway excavation in the present invention is based on the Python language to compile a secondary development optimization program for coal pillar size, realizes the establishment of a parametric dynamic finite element model of different coal pillar sizes, and improves the efficiency of analyzing the optimal size of coal pillars for large-section goaf-side roadway excavation. At the same time, since the distribution of the plastic zone of the side section of the roadway coal pillar has a vital impact on the safety and stability of the roadway, the size of the coal pillar is highly correlated with the utilization rate of coal resources. The larger the size of the coal pillar, the lower the utilization rate of coal resources. Therefore, on the basis of comprehensive consideration of the roadway stability and the coal resource recovery rate, the size of the coal pillars for large-section goaf-side roadway excavation is optimized, ensuring the safety and stability of large-section goaf-side roadway excavation. According to the distribution of the plastic zone of the roadway surrounding rock, the side of the roadway coal pillar is asymmetricly supported, and an asymmetric support system of anchor cable 2 reinforcement plus zoned grouting is proposed, which improves the integrity of the broken coal pillars and the bearing capacity of the roadway surrounding rock. While improving the integrity of the coal pillars, the zoned grouting uses different grouting materials according to the different degrees of surrounding rock crushing, saving the grouting cost.

Claims

1. A method for optimizing the size of coal pillars and asymmetric support in large-section gob-side roadway driving, characterized in that: The steps include: S10: Establishing parameterized models for different coal pillar sizes; Use Python language to write secondary development program based on ABAQUS to establish parametric dynamic finite element models of different coal pillar sizes; S20: Improve relevant parameters, run and output results; S201. Sample the surrounding rock of the tunnel, conduct uniaxial and triaxial compression tests, obtain relevant parameters of the surrounding rock samples and improve the numerical simulation program; S202, run and output analysis files; S30: Analyze the output results and determine the optimal size; The distribution of the plastic zone (3) and the size of the coal pillar in the roadway are scored, and a weight analysis is performed according to the importance to determine the optimal size of the coal pillar (6) in the roadway along the goaf; S40: Excavate the tunnel to the designed size and leave the coal pillar of the optimal size; S50: Support the tunnel; The specific steps are: S501, perform conventional support on the tunnel; Anchor rods (1) are applied to the sides and top of the tunnel for support, and a steel mesh is hung on the top, and diamond wire mesh is hung on the sides; S502, provide asymmetric support for coal pillars in roadways; The coal pillar is reinforced with grouting anchor cables (2), and grouting is performed in different areas of the coal pillar according to the distribution characteristics of the plastic zone (3) of the coal pillar.

2. A method for optimizing coal pillar size and asymmetric support in large-section gob-side roadway driving according to claim 1, characterized in that: Step S30 is specifically as follows: S301. Score the area of ​​the plastic zone (3) of the coal pillar, specifically including the following situations: C、U S =0,S NP >2S P ; Where U S is the plastic zone area score, S NP is the area of ​​non-plastic zone in the cross section of coal pillar, S P is the plastic zone area of ​​the coal pillar section; S302, scoring the size of the coal pillar; Where U L is the coal pillar size score, L is the coal pillar size, and L0 is the maximum size of the coal pillar; S303, analyzing the area of ​​the roadway coal pillar plastic zone (3) and the size of the coal pillar in a ratio of 1:1 according to the importance, and determining the optimal size of the coal pillar.

3. The method for optimizing the size of coal pillars and asymmetric support in large-section gob-side roadway driving according to claim 1 is characterized in that: The zoned grouting in step S502 specifically includes injecting a granular grouting material with poor diffusion efficiency into the plastic zone (3) of the coal pillar under high pressure, and injecting a chemical grouting material with good diffusion efficiency into the non-plastic zone (4) of the coal pillar under high pressure.

4. A method for optimizing coal pillar size and asymmetric support in large-section gob-side roadway driving according to claim 1, characterized in that: In step S502, the driving angle of the grouting anchor cable (2) is 15° upward from the horizontal direction, and it is ensured that the anchoring end of the anchor cable (2) is driven into a basically hard and stable layer.

5. The method for optimizing the size of coal pillars and asymmetric support in large-section gob-side roadway driving according to claim 1 is characterized in that: During the zone grouting in step S502, the minimum diffusion diameter of the grouting material is used as the row spacing, and the coal pillars are zoned grouting is performed in a plum blossom shape.

6. A method for optimizing coal pillar size and asymmetric support in large-section gob-side roadway driving according to claim 3, characterized in that: The granular grouting material is cement water glass.

7. A method for optimizing coal pillar size and asymmetric support in large-section gob-side roadway driving according to claim 3, characterized in that: The chemical grouting material is epoxy resin.

8. The method for optimizing coal pillar size and asymmetric support in large-section gob-side roadway driving according to claim 1, characterized in that: In step S501, 5 anchor rods (1) are provided at the tunnel roof, with a spacing of 1000×1000 mm between the anchor rods, and 4 anchor rods (1) are provided on each of the two sides, with a spacing of 1000×1000 mm between the anchor rods.

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