Variable interlayer spacing hard roof partition control method

Abstract

This invention discloses a zonal control method for a hard roof with variable layer spacing, comprising: acquiring hard roof data with variable layer spacing; analyzing the energy of the hard rock layer during initial and periodic pressure events based on the hard roof data and in conjunction with the elastic foundation beam theory, to obtain the effective thickness of the disaster-causing hard rock layer; and performing zonal control based on the effective thickness. This invention proposes a novel roof control approach, and the zonal control method effectively reduces roof control costs and improves the impact risk in mines with variable layer spacing roofs.

Description

Technical Field

[0001] This invention belongs to the field of rigid roof control technology, and particularly relates to a method for zoned control of rigid roofs with variable layer spacing. Background Technology

[0002] In many mining areas of my country, coal seams are generally supported by hard roofs. During the mining process, the hard roofs may break and move, triggering dynamic disasters such as rock bursts, mine tremors, mine roof collapses, and coal and gas outbursts, which seriously threaten the safe production of coal mines.

[0003] Because the conditions of the coal seam roof have a significant impact on the occurrence of rockbursts, current research on the management and control of rockbursts caused by roof fracture with varying interlayer spacing typically employs simplification, assuming a uniform interlayer spacing and rarely addressing variations in the spacing between the hard roof and the coal seam. However, this approach does not align with the actual geological conditions of some coal mines. To ensure efficient and safe production in coal mines, it is urgent to study the disaster-causing mechanisms and control methods for hard roof fracture. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a method for controlling the partitioning of a rigid roof with variable layer spacing, which can ensure safe production in coal mines.

[0005] This invention provides a method for controlling the partitioning of a rigid roof with variable layer spacing, comprising:

[0006] Obtain data on rigid topslabs with variable layer spacing;

[0007] Based on the data of the variable-layer spacing hard top plate, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial and periodic pressure is analyzed to obtain the effective thickness of the disaster-causing hard rock layer.

[0008] Zoned control is performed based on the effective thickness.

[0009] Optionally, the data for the variable-layer spacing rigid top plate includes: the length of the fixed support beam, the thickness of the fixed support beam, the load on the fixed support beam, the length of the cantilever beam, the thickness of the cantilever beam, the cantilever beam suspension length, the load on the cantilever beam, the tensile strength and elastic modulus of the rock strata, and the foundation coefficient of the working face.

[0010] Optionally, based on the variable-layer spacing hard top plate data and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial and periodic pressure is analyzed to obtain the effective thickness of the disaster-causing hard rock layer, including:

[0011] Based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure period is analyzed to obtain the initial fracture step and its corresponding energy accumulation.

[0012] Based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the period of periodic pressure is analyzed to obtain the periodic fracture step and its corresponding energy accumulation.

[0013] The effective thickness of the hard rock layer causing the disaster is obtained based on the initial fracture step distance, the energy accumulation corresponding to the initial fracture step distance, the periodic fracture step distance, and the energy accumulation corresponding to the periodic fracture step distance.

[0014] Optionally, based on the data of the variable-layer spacing hard top plate and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure is analyzed to obtain the initial fracture step and its corresponding energy accumulation, including:

[0015] Obtain the deflection of the fixed beam. Based on the length, thickness, deflection, and load on the fixed beam, and in conjunction with the boundary conditions of the fixed beam, obtain the normal stress at each section of the fixed beam.

[0016] Based on the normal stress at each section of the fixed beam, and combined with the maximum tensile stress theory, the maximum tensile stress of the fixed beam is obtained.

[0017] Based on the maximum tensile stress of the fixed beam and the energy of the first hard rock layer, the initial fracture step distance and its corresponding energy accumulation are obtained.

[0018] Optionally, obtaining the maximum tensile stress of the fixed beam includes:

[0019]

[0020] Where, σ imax M is the maximum tensile stress of the fixed beam. imax β is the maximum bending moment of the fixed beam, h is the thickness of the fixed beam, and l is the length of the fixed beam.

[0021] Optionally, the method for obtaining energy from the first hard rock layer is as follows:

[0022]

[0023] Where U represents the energy of the hard rock layer. The deformation potential energy is the length of the fixed beam on the rock strata. Let be the external potential energy of the gangue in the goaf on the length of the support beam of the rock strata, k be the subgrade coefficient, E be the elastic modulus of the rock strata, I be the moment of inertia of the rock beam section about the neutral axis, and l be the length of the support beam.

[0024] Optionally, based on the data of the variable-layer spacing hard top plate, and combined with the elastic foundation beam theory, the energy of the hard rock layer during periodic pressure is analyzed to obtain the periodic fracture step and its corresponding energy accumulation, including:

[0025] Based on the cantilever beam length, cantilever beam thickness, cantilever beam suspension length, and load on the cantilever beam, combined with the free end boundary conditions, the normal stress at each section of the cantilever beam is obtained.

[0026] Based on the normal stress at each section of the cantilever beam, and combined with the maximum tensile stress theory, the maximum tensile stress of the cantilever beam is obtained.

[0027] Based on the maximum tensile stress of the suspended beam and the energy of the second hard rock layer, the periodic fracture step and its corresponding energy accumulation are obtained.

[0028] Optionally, obtaining the maximum tensile stress of the cantilever beam includes:

[0029]

[0030] Where, σ max M is the maximum tensile stress of the cantilever beam. max φ1 is the maximum bending moment of the cantilever beam, φ2, φ3, and φ4 are Krylov functions, β is the characteristic coefficient of the foundation beam, l1 is the cantilever beam length, l2 is the cantilever beam length, and q is the load on the cantilever beam.

[0031] Optionally, the method for obtaining energy from the second hard rock layer is as follows:

[0032]

[0033] in, Let l1 be the deflection at point l1, l1 be the cantilever length of the cantilever beam, and l2 be the beam length of the cantilever beam. The deformation potential energy of the cantilever beam with five rock strata is the beam length. The external potential energy of the gangue in the goaf on the beam length of the cantilever beam of the five rock-bearing strata.

[0034] Compared with the prior art, the present invention has the following advantages and technical effects:

[0035] This invention provides a zoned control method for hard roofs with variable layer spacing. Based on theoretical analysis, it evaluates the impact hazard of initial and periodic pressure on hard roofs with variable layer spacing, proposes a novel roof control approach, and adopts a zoned control method to effectively reduce roof control costs and improve the impact hazard of mines with roofs with variable layer spacing. Attached Figure Description

[0036] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0037] Figure 1 This is a flowchart of a variable-layer-spacing rigid roof slab zoning control method according to an embodiment of the present invention;

[0038] Figure 2 This is the first pressure model in this embodiment of the invention;

[0039] Figure 3 This is a periodic pressure model according to an embodiment of the present invention. Detailed Implementation

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0042] This invention proposes a method for zoned control of rigid top slabs with variable layer spacing, such as... Figure 1 As shown, the specific steps include:

[0043] Obtain data on rigid topslabs with variable layer spacing;

[0044] Based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial and periodic pressure is analyzed to obtain the effective thickness of the hard rock layer that caused the disaster.

[0045] Zoned control is implemented based on the effective thickness.

[0046] Furthermore, the data for the rigid top slab with variable layer spacing includes: fixed beam length, fixed beam thickness, fixed beam deflection, fixed beam load, cantilever beam length, cantilever beam thickness, cantilever beam suspension length, and cantilever beam load.

[0047] Furthermore, based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial and periodic pressure events was analyzed to obtain the effective thickness of the disaster-causing hard rock layer, including:

[0048] Based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure period is analyzed to obtain the initial fracture step and its corresponding energy accumulation.

[0049] Based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the periodic pressure is analyzed to obtain the periodic fracture step and its corresponding energy accumulation.

[0050] The effective thickness of the hard rock layer causing the disaster is obtained based on the initial fracture step distance, the energy accumulation corresponding to the initial fracture step distance, the periodic fracture step distance, and the energy accumulation corresponding to the periodic fracture step distance.

[0051] Furthermore, based on the data of the hard top plate with varying layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock strata during the initial pressure event was analyzed to obtain the initial fracture step and its corresponding energy accumulation, including:

[0052] Based on the length, thickness, deflection, and load on the fixed beam, and in conjunction with the boundary conditions of the fixed beam, the normal stress at each section of the fixed beam is obtained.

[0053] Based on the normal stress at each section of the fixed beam, and combined with the maximum tensile stress theory, the maximum tensile stress of the fixed beam is obtained.

[0054] Based on the maximum tensile stress of the fixed beam and combined with the energy of the first hard rock layer, the initial fracture step and its corresponding energy accumulation are obtained.

[0055] Specifically, the study on energy accumulation in hard rock strata during the initial pressure event, based on the elastic foundation beam theory, proceeds as follows:

[0056] Establish a model of an elastic foundation beam fixed at both ends, where l and h are the beam length and thickness, respectively; ω is the beam deflection; and q is the load on the beam, based on the formula: The calculation is performed, where γ0 is the unit weight of the fifth-bearing rock stratum, h0 is the thickness of the fifth-bearing rock stratum, and γ i Let h be the unit weight of the i-th floor slab. i Let be the thickness of the i-th layer top plate.

[0057] According to the initial parameter method, the deflection equation for a finite-length beam is: Where ω0, θ0, M0, and Q0 are the deflection, deflection angle, bending moment, and shear force of the fixed beam at x = 0, respectively; β is the characteristic coefficient of the foundation beam, β = (k / EI). 1 / 4 , where k is the subgrade coefficient, EI is the bending stiffness of the subgrade beam section; ω* is the deflection correction term for the loaded subgrade beam.

[0058] Under the action of a uniformly distributed load q, ω * =q(1-φ1) / k; φ1, φ2, φ3, φ4 are Krylov functions.

[0059]

[0060] From the boundary conditions at the fixed ends of the fixed beam: ω0=0, θ0=0, the deflection equation of the fixed beam is:

[0061] Based on the relationship between the deflection ω, deflection angle θ, bending moment M, and shear force Q of the rock beam, it can be concluded that:

[0062] Boundary conditions for a fixed beam: ω l =0, θ l =0, therefore:

[0063] The normal stress σ at each section of the fixed beam is:

[0064] According to the maximum tensile stress theory, when the normal stress σ at the top of the fixed support is greater than σ... T At that time, the hard rock strata underwent their first fracture.

[0065] The energy of hard rock strata mainly consists of two parts: the deformation potential energy of the rock strata and the external force potential energy of the gangue. The calculation formula is as follows:

[0066] according to and It is possible to obtain the initial fracture step distance and energy accumulation of the five rock strata under different foundation coefficients.

[0067] When the rock mass energy level is 1 MJ, the risk of rockburst is relatively high. The subgrade coefficient is calculated when U = 1 MJ, and when the subgrade coefficient is between 10 and 15 MN / m... 3 Only pre-fractured bedrock is required, when the subgrade coefficient k > 15MN / m 3 If so, it is necessary to consider the hard strata that cause fracturing and determine the thickness of the hard rock layer.

[0068] Furthermore, based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during periodic pressure is analyzed to obtain the periodic fracture step and its corresponding energy accumulation, including:

[0069] Based on the cantilever beam length, cantilever beam thickness, cantilever beam suspension length, and load on the cantilever beam, combined with the free end boundary conditions, the normal stress at each section of the cantilever beam is obtained.

[0070] Based on the normal stress at each section of the cantilever beam, and combined with the maximum tensile stress theory, the maximum tensile stress of the cantilever beam is obtained.

[0071] Based on the maximum tensile stress of the cantilever beam and the energy of the second hard rock layer, the periodic fracture step and its corresponding energy accumulation are obtained.

[0072] Specifically, the study on energy accumulation in hard rock strata during periodic pressure based on the elastic foundation beam theory is as follows:

[0073] As the working face advances, the periodic fracturing of the hard rock strata goes through three stages: complete rock contact, partial rock contact, and complete suspension. A cantilever elastic foundation beam model is established, where l2 and h are the beam length and thickness of the cantilever beam, respectively; l1 is the suspension length of the cantilever beam; and q is the load on the beam.

[0074] The fundamental differential equation for a beam on an elastic foundation is:

[0075] For the portion of the hard rock strata not touching the rock mass, the subgrade coefficient k = 0. Based on the fixed-end boundary conditions ω0 = 0 and θ0 = 0, the relationship between the rock beam deflection, deflection angle, bending moment, and shear force can be obtained as follows:

[0076] Q1 = -qx - EIa;

[0077] The deflection, deflection angle, bending moment, and shear force of the hard rock strata at the contact point with the rock mass can be determined using the initial parameter method.

[0078]

[0079] Consider the free end boundary condition M l2 =0, Q l2 =0, we can get

[0080] When y = -h / 2 and x = 0, the tensile stress is at its maximum, according to the maximum tensile stress theory (same as the initial compression case):

[0081]

[0082] The formula for calculating the energy of hard rock strata is:

[0083] When the rock is fully fused, l1 = 0;

[0084] When there is partial contact with the rock, l1≠l2;

[0085] When completely suspended, l1 = l2;

[0086] The energy accumulation degree in the three stages of hard rock strata was analyzed. If there was no impact risk and the risk was low, no control was required. If there was an impact risk, the effective thickness needed to be controlled, so as to achieve the effect of zoned control in general.

[0087] Furthermore, the specific analysis process of the roof slab zoning weakening control method is as follows:

[0088] Based on theoretical calculations of the impact risk of the hard roof under different conditions, the optimal thickness and target layer to be weakened in different parts are controlled by zoning. For example, in areas with high impact risk, a certain thickness of the hard roof needs to be completely weakened, while in areas with low impact risk, only the bedrock area needs to be weakened.

[0089] The invention will now be described in detail with reference to the accompanying drawings:

[0090] Taking Zhuxianzhuang Coal Mine as an example, its five rock strata were zoned for control. After blasting measures were taken on the hard roof, further analysis was conducted using the support in the middle of the working face as an example. The support underwent 28 cycles of pressure during its advancement. The initial pressure step distance was about 37m, and the cycle pressure step distance was about 12-30m, which is consistent with the pre-splitting step distance of the roof. The average working resistance of the working face support was 5269.87KN, accounting for 69.33% of the rated working resistance of the support. There was basically no coal wall spalling in the 883-1 working face, and the mine pressure was not obvious. This indicates that the deep-hole blasting weakening technology adopted for the roof of the 883-1 working face is effective, ensuring the safe and efficient production of the working face.

[0091] The approach of the roof and floor plates, as well as the approach of the sidewalls, were measured separately. Field observations showed that as the working face advanced, the roadway deformation gradually increased. When the measuring point was approximately 40m from the working face, it entered the influence range of the working face's advance support pressure, and the roadway deformation began to increase significantly. Taking measuring station 1 as an example, the maximum deformation of its roof, floor, coal pillar, and solid coal sidewalls were 14.6, 18.9, 14.7, and 13.5 mm, respectively, corresponding to maximum deformation rates of 2.63, 3.51, 3.61, and 1.92 mm / d. It can be seen that after the deep-hole blasting pre-splitting measures in the roof mining area, the cumulative deformation and subsidence rate of the roadway were very small, reducing the impact of mining on the recovery roadway.

[0092] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for zoned control of a rigid roof slab with variable layer spacing, characterized in that, include: Obtain data on rigid topslabs with variable layer spacing; Based on the data of the variable-layer spacing hard top plate, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial and periodic pressure is analyzed to obtain the effective thickness of the disaster-causing hard rock layer. Zoned control is performed based on the effective thickness; The data for the variable-layer spacing hard top plate includes: fixed beam length, fixed beam thickness, fixed beam load, cantilever beam length, cantilever beam thickness, cantilever beam suspension length, cantilever beam load, tensile strength of the rock strata, elastic modulus, and foundation coefficient of the working face. Based on the data of the variable-layer spacing hard top plate, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial and periodic pressure events is analyzed to obtain the effective thickness of the disaster-causing hard rock layer, including: Based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure period is analyzed to obtain the initial fracture step and its corresponding energy accumulation. Based on the data of the hard top plate with variable layer spacing, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the period of periodic pressure is analyzed to obtain the periodic fracture step and its corresponding energy accumulation. The effective thickness of the disaster-causing hard rock layer is obtained based on the initial fracture step distance, the energy accumulation size corresponding to the initial fracture step distance, the periodic fracture step distance, and the energy accumulation size corresponding to the periodic fracture step distance. Based on the data of the variable-layer spacing hard top plate, and combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure period is analyzed to obtain the initial fracture step and its corresponding energy accumulation, including: Obtain the deflection of the fixed beam. Based on the length, thickness, deflection, and load on the fixed beam, and in conjunction with the boundary conditions of the fixed beam, obtain the normal stress at each section of the fixed beam. Based on the normal stress at each section of the fixed beam, and combined with the maximum tensile stress theory, the maximum tensile stress of the fixed beam is obtained. Based on the maximum tensile stress of the fixed beam and the energy of the first hard rock layer, the initial fracture step distance and its corresponding energy accumulation are obtained.

2. The method for zoned control of a rigid top slab with variable layer spacing according to claim 1, characterized in that, Obtaining the maximum tensile stress of the fixed beam includes: in, For the maximum tensile stress of the fixed beam, The maximum bending moment of the fixed beam. β The characteristic coefficient of the foundation beam. h To support the thickness of the beam, l The length of the fixed support beam.

3. The method for zoned control of a rigid roof slab with variable layer spacing according to claim 2, characterized in that, The method for obtaining energy from the first hard rock layer is as follows: Where U represents the energy of the hard rock layer. The deformation potential energy is the length of the fixed beam on the rock strata. The external potential energy of the gangue in the goaf on the length of the rock strata support beam is given. k Let E be the subgrade coefficient, E be the elastic modulus of the rock strata, and I be the moment of inertia of the rock beam section about the neutral axis. l This is the length of the fixed beam.

4. The method for zoned control of a rigid top slab with variable layer spacing according to claim 3, characterized in that, Based on the data of the variable-layer spacing hard top plate, and combined with the elastic foundation beam theory, the energy of the hard rock layer during periodic pressure is analyzed to obtain the periodic fracture step and its corresponding energy accumulation, including: Based on the cantilever beam length, cantilever beam thickness, cantilever beam suspension length, and load on the cantilever beam, combined with the free end boundary conditions, the normal stress at each section of the cantilever beam is obtained. Based on the normal stress at each section of the cantilever beam, and combined with the maximum tensile stress theory, the maximum tensile stress of the cantilever beam is obtained. Based on the maximum tensile stress of the suspended beam and the energy of the second hard rock layer, the periodic fracture step and its corresponding energy accumulation are obtained.

5. The method for zoned control of a rigid top slab with variable layer spacing according to claim 4, characterized in that, Obtaining the maximum tensile stress of the cantilever beam includes: in, This represents the maximum tensile stress of the cantilever beam. This represents the maximum bending moment of the cantilever beam. ϕ 1. ϕ 2. ϕ 3. ϕ 4 is the Krylov function. β The characteristic coefficient of the foundation beam. l 1 represents the cantilever beam's length in the air. l 2 represents the length of the cantilever beam. q This refers to the load on the cantilever beam.

6. The method for zoned control of a rigid top slab with variable layer spacing according to claim 4, characterized in that, The method for obtaining energy from the second hard rock layer is as follows: in, In order to be in l 1 Deflection at the point, l 1 represents the cantilever beam's length in the air. l 2 represents the length of the cantilever beam. The deformation potential energy of the cantilever beam with five rock strata is the beam length. The external potential energy of the gangue in the goaf on the beam length of the cantilever beam of the five rock-bearing strata.

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