Partition control method for hard roof with variable interlayer spacing

Abstract

The invention discloses a zoning control method for a variable-interlayer-spacing hard roof. The zoning control method comprises the following steps: acquiring data of the variable-interlayer-spacing hard roof; according to the variable interlayer spacing hard roof data, combining an elastic foundation beam theory to analyze the energy of the hard rock stratum during initial weighting and periodic weighting, and obtaining the effective thickness of the disaster-causing hard rock stratum; and performing partition control according to the effective thickness. The invention provides a novel roof control thought, the control cost of the roof is effectively reduced by adopting a zoning control method, and the mine impact risk of the roof with the variable interlayer spacing is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hard roof control, and in particular relates to a variable-layer spacing hard roof zoning control method. Background Art

[0002] There is generally a hard roof above the coal seams in many mining areas in my country. During the mining process, the hard roof breaks and causes dynamic disasters such as impact ground pressure, mine tremors, mining site frame crushing, coal and gas outbursts, etc., which seriously threaten the safe production of coal mines.

[0003] Since the coal seam roof conditions have a great influence on the occurrence of rock burst, the current research on the management and control of variable interlayer spacing roof break disasters usually adopts a simplified treatment, considering the interlayer spacing as consistent, and rarely involves the changes in the spacing between the hard roof and the coal seam, but this does not conform to the actual geological conditions of some coal mines. In order to ensure efficient and safe production in coal mines, it is urgent to study the disaster mechanism and prevention and control methods of hard roof break. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a variable layer spacing hard roof zoning control method, which can ensure the safe production of coal mines.

[0005] The present invention provides a variable-layer spacing hard roof partition control method, comprising:

[0006] Obtain data on hard roof with variable interlayer spacing;

[0007] According to the hard roof data with variable interlayer spacing, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure and periodic pressure is analyzed to obtain the effective thickness of the disaster-causing hard rock layer;

[0008] The partition control is performed according to the effective thickness.

[0009] Optionally, the variable layer spacing hard top plate data include: the length of the fixed beam, the thickness of the fixed beam, the load on the fixed beam, the length of the cantilever beam, the thickness of the cantilever beam, the hanging length of the cantilever beam, the load on the cantilever beam, the tensile strength of the rock formation, the elastic modulus, and the foundation coefficient of the working face.

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

[0011] According to the variable layer spacing hard roof data, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure is analyzed to obtain the initial breaking step and its corresponding energy accumulation size;

[0012] According to the variable interlayer spacing hard roof data, combined with the elastic foundation beam theory, the energy of the hard rock layer during the periodic pressure is analyzed to obtain the periodic breaking step and its corresponding energy accumulation size;

[0013] The effective thickness of the disaster-causing hard rock layer is obtained according to the initial breaking step, the energy accumulation size corresponding to the initial breaking step, the periodic breaking step and the energy accumulation size corresponding to the periodic breaking step.

[0014] Optionally, according to the variable layer spacing hard roof data, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure is analyzed to obtain the initial breaking step and its corresponding energy accumulation size, including:

[0015] Obtain the deflection of the fixed beam, and obtain the normal stress at each cross section of the fixed beam according to the length of the fixed beam, the thickness of the fixed beam, the deflection of the fixed beam and the load on the fixed beam, combined with the boundary conditions of the fixed beam;

[0016] According to the normal stress at each cross section of the clamped beam and in combination with the maximum tensile stress theory, the maximum tensile stress of the clamped beam is obtained;

[0017] Based on the maximum tensile stress of the clamped beam and combined with the energy of the first hard rock formation, the initial breaking step and the corresponding energy accumulation size are obtained.

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

[0019]

[0020] Among them, σ imax is the maximum tensile stress of the clamped beam, M imax is the maximum bending moment of the fixed-support beam, β is the characteristic coefficient of the foundation beam, h is the thickness of the fixed-support beam, and l is the length of the fixed-support beam.

[0021] Optionally, a method for obtaining the energy of the first hard rock formation is:

[0022]

[0023] Where U is the energy of hard rock formation, is the deformation potential energy of the fixed beam length on the rock layer, is the external force potential energy of the goaf waste rock on the length of the fixed-support beam of the rock stratum, k is the foundation coefficient, E is the elastic modulus of the rock stratum, I is the moment of inertia of the rock beam section about the neutral axis, and l is the length of the fixed-support beam.

[0024] Optionally, according to the variable interlayer spacing hard roof data, 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 size, including:

[0025] According to the cantilever beam length, cantilever beam thickness, cantilever beam hanging length and cantilever beam load, combined with the free end boundary conditions, obtain the normal stress at each cross section of the cantilever beam;

[0026] According to the normal stress at each cross section of the cantilever beam and in combination 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 cantilever beam and combined with the energy of the second hard rock formation, the periodic fracture step and the corresponding energy accumulation size are obtained.

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

[0029]

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

[0031] Optionally, a method for obtaining the energy of the second hard rock formation is:

[0032]

[0033] in, is the deflection at l1, l1 is the cantilever beam suspension length, l2 is the cantilever beam length, is the deformation potential energy of the beam length of the five-layer cantilever beam, It is the external force potential energy of the goaf waste rock on the beam length of the cantilever beam containing five rock layers.

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

[0035] The present invention provides a zoning control method for a hard roof with variable interlayer spacing. Based on theoretical analysis, the impact hazard of the hard roof with variable interlayer spacing during the initial pressure and periodic pressure is evaluated, and a new roof control idea is proposed. The zoning control method is adopted to effectively reduce the roof control cost and improve the impact hazard of the roof in mines with variable interlayer spacing. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0037] Figure 1 It is a flow chart of a variable-layer spacing hard roof partition control method according to an embodiment of the present invention;

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

[0039] Figure 3 It is a periodic pressure model of an embodiment of the present invention. DETAILED DESCRIPTION

[0040] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

[0042] The present invention proposes a variable layer spacing hard roof partition control method, such as Figure 1 As shown, the specific steps include:

[0043] Obtain data on hard roof with variable interlayer spacing;

[0044] According to the hard roof data with variable interlayer spacing, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure and periodic pressure is analyzed to obtain the effective thickness of the disaster-causing hard rock layer;

[0045] Partition control is carried out according to effective thickness.

[0046] Furthermore, the variable interlayer spacing rigid top plate data include: fixed beam length, fixed beam thickness, fixed beam deflection, load on the fixed beam, cantilever beam length, cantilever beam thickness, cantilever beam suspension length and cantilever beam load.

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

[0048] According to the data of hard roof with variable interlayer spacing, combined with the elastic foundation beam theory, the energy of hard rock layer during the initial pressure is analyzed to obtain the initial breaking step and its corresponding energy accumulation size;

[0049] According to the hard roof data with variable interlayer spacing, 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 size;

[0050] The effective thickness of the disaster-causing hard rock stratum is obtained according to the initial breaking step, the energy accumulation size corresponding to the initial breaking step, the periodic breaking step and the energy accumulation size corresponding to the periodic breaking step.

[0051] Furthermore, based on the data of hard roof with variable interlayer spacing, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure is analyzed to obtain the initial breaking step and its corresponding energy accumulation size, including:

[0052] According to the length of the fixed beam, the thickness of the fixed beam, the deflection of the fixed beam and the load on the fixed beam, combined with the boundary conditions of the fixed beam, the normal stress at each cross section of the fixed beam is obtained;

[0053] According to the normal stress at each cross section of the clamped beam and the maximum tensile stress theory, the maximum tensile stress of the clamped beam is obtained;

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

[0055] Specifically, the energy accumulation of hard rock during the initial pressure is studied based on the elastic foundation beam theory. The specific process is as follows:

[0056] Establish an elastic foundation beam model with two ends fixed, where l and h are the length and thickness of the fixed beam respectively; ω is the deflection of the fixed beam; q is the load on the fixed beam, according to the formula: Calculation is performed, where γ0 is the bulk density of the five-bearing rock layer, h0 is the thickness of the five-bearing rock layer, and γ i is the bulk density of the top plate of the i-th layer, h i is the thickness of the top plate of the i-th layer.

[0057] According to the initial parameter method, the deflection equation of a finite length beam is: Where ω0, θ0, M0, 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 foundation coefficient, EI is the bending stiffness of the foundation beam section; ω* is the deflection correction term of the loading section of the foundation beam.

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

[0059]

[0060] According to the boundary conditions of the fixed end of the fixed beam: ω0 = 0, θ0 = 0, the deflection equation of the fixed beam is:

[0061] According to the relationship between the rock beam deflection ω, deflection angle θ, bending moment M and shear force Q:

[0062] By the fixed beam boundary condition: ω l =0,θ l =0, we can know that:

[0063] Then the normal stress σ at each cross section of the clamped beam is:

[0064] According to the maximum tensile stress theory, when the normal stress σ>σ T When the hard rock layer breaks for the first time.

[0065] The energy of hard rock formation is mainly composed of two parts: the deformation potential energy of rock formation and the external force potential energy of gangue. The calculation formula is:

[0066] according to and The initial fracture step distances and energy accumulation of five rock-bearing strata under different foundation coefficients can be obtained.

[0067] When the rock mass energy level is 1MJ, the risk of rock burst is relatively high. The foundation coefficient is calculated when U=1MJ. When the foundation coefficient is between 10 and 15MN / m 3 , only pre-cracked bedrock is needed, when the foundation coefficient k>15MN / m 3 , it is necessary to consider the hard stratum that causes fracture and determine the thickness of the required hard rock stratum.

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

[0069] According to the cantilever beam length, cantilever beam thickness, cantilever beam hanging length and cantilever beam load, combined with the free end boundary conditions, obtain the normal stress at each cross section of the cantilever beam;

[0070] According to the normal stress at each cross section of the cantilever beam and 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 combined with the energy of the second hard rock formation, the periodic fracture step and its corresponding energy accumulation size are obtained.

[0072] Specifically, the energy accumulation of hard rock during periodic compression is studied based on the elastic foundation beam theory. The specific process is as follows:

[0073] As the working face advances, the periodic fracture of the hard rock strata goes through three stages: complete contact with the rock → partial contact with the rock → complete suspension. A cantilever elastic foundation beam model is established, where l2 and h are the 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 basic differential equation for a beam on elastic foundation is:

[0075] The foundation coefficient k of the part of the hard rock layer that does not touch the gangue is 0. According to the boundary conditions of the fixed support end ω0 = 0, θ0 = 0, the relationship between the deflection, deflection angle, bending moment and shear force of the rock beam can be obtained:

[0076] Q1=-qx-EIa;

[0077] The deflection, deflection angle, bending moment and shear force of the part of the hard rock layer that touches the gangue can be determined according to 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 the maximum. According to the maximum tensile stress theory (same as the initial pressure):

[0081]

[0082] The energy calculation formula for hard rock formation is:

[0083] When the rock is completely touched, l1 = 0;

[0084] When part of the rock is in contact with the rock, l1≠l2;

[0085] When completely suspended, l1=l2;

[0086] Analyze the degree of energy accumulation in the three stages of hard rock formations. If there is no impact risk and the risk is low, no control is required. If there is an impact risk, it is necessary to control the effective thickness and achieve the effect of zoning control overall.

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

[0088] Based on the theoretical calculation of the impact risk of the hard roof in different situations, the effective thickness and target layer that need to be weakened in different parts are zoned and controlled. For example, in areas with higher impact risk, the hard roof of a certain thickness needs to be weakened, while in areas with lower impact risk, only the bedrock area needs to be weakened.

[0089] The present invention will be described in detail below in conjunction with the accompanying drawings:

[0090] Taking Zhuxianzhuang Coal Mine as an example, the five rock-bearing strata were controlled in different areas. After blasting measures were taken on the hard roof, the middle support of the working face was further analyzed. The working support experienced 28 cycles of pressure during the advancement process. The initial pressure step was about 37m, and the periodic pressure step was about 12 to 30m, which was consistent with the pre-cracking step 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 phenomenon in the 883-1 working face, and the mine pressure was not obvious. This shows that the deep hole blasting weakening technology adopted for the roof of the 883-1 working face is effective, which ensures the safe and efficient production of the working face.

[0091] The displacement of the top and bottom plates of the tunnel and the displacement of the two sides were measured respectively. On-site observations showed that as the working face advanced, the deformation of the tunnel gradually increased. When the measuring point was about 40m away from the working face, the measuring point entered the influence range of the advanced support pressure of the working face, and the deformation of the tunnel began to increase significantly. Taking station 1 as an example, the maximum deformation of its roof, floor, coal pillar side and solid coal side were 14.6, 18.9, 14.7 and 13.5mm respectively, and the corresponding maximum deformation speeds were 2.63, 3.51, 3.61 and 1.92mm / d respectively. It can be seen that after the deep hole blasting pre-cracking measures in the roof mining area, the cumulative deformation and sinking speed of the tunnel were very small, reducing the impact of mining on the mining tunnel.

[0092] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A variable-layer spacing hard roof partition control method, characterized in that: include: Obtain data on hard roof with variable interlayer spacing; According to the variable interlayer spacing hard roof data, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure and periodic pressure is analyzed to obtain the effective thickness of the disaster-causing hard rock layer; The partition control is performed according to the effective thickness.

2. A variable-spacing rigid roof partition control method according to claim 1, characterized in that: The variable interlayer spacing hard top plate data include: fixed beam length, fixed beam thickness, load on fixed beam, cantilever beam length, cantilever beam thickness, cantilever beam hanging length, load on cantilever beam, tensile strength of rock formation, elastic modulus, and foundation coefficient of working surface.

3. A variable-layer spacing rigid roof partition control method according to claim 2, characterized in that: According to the hard roof data with variable interlayer spacing, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure and periodic pressure is analyzed to obtain the effective thickness of the disaster-causing hard rock layer, including: According to the variable layer spacing hard roof data, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure is analyzed to obtain the initial breaking step and its corresponding energy accumulation size; According to the variable interlayer spacing hard roof data, combined with the elastic foundation beam theory, the energy of the hard rock layer during the periodic pressure is analyzed to obtain the periodic breaking step and its corresponding energy accumulation size; The effective thickness of the disaster-causing hard rock layer is obtained according to the initial breaking step, the energy accumulation size corresponding to the initial breaking step, the periodic breaking step and the energy accumulation size corresponding to the periodic breaking step.

4. A variable-interval hard roof partition control method according to claim 3, characterized in that: According to the variable interlayer spacing hard roof data, combined with the elastic foundation beam theory, the energy of the hard rock layer during the initial pressure is analyzed to obtain the initial breaking step and its corresponding energy accumulation size, including: Obtain the deflection of the fixed beam, and obtain the normal stress at each cross section of the fixed beam according to the length of the fixed beam, the thickness of the fixed beam, the deflection of the fixed beam and the load on the fixed beam, combined with the boundary conditions of the fixed beam; According to the normal stress at each cross section of the clamped beam and in combination with the maximum tensile stress theory, the maximum tensile stress of the clamped beam is obtained; Based on the maximum tensile stress of the clamped beam and combined with the energy of the first hard rock formation, the initial breaking step and the corresponding energy accumulation size are obtained.

5. A variable-layer spacing rigid roof partition control method according to claim 4, characterized in that: Obtaining the maximum tensile stress of the clamped beam includes: Among them, σ imax is the maximum tensile stress of the clamped beam, M imax is the maximum bending moment of the fixed-support beam, β is the characteristic coefficient of the foundation beam, h is the thickness of the fixed-support beam, and l is the length of the fixed-support beam.

6. A variable-interval hard roof partition control method according to claim 5, characterized in that: The method for obtaining the energy of the first hard rock formation is: Where U is the energy of hard rock formation, is the deformation potential energy of the fixed beam length on the rock layer, is the external force potential energy of the goaf waste rock on the length of the fixed-support beam of the rock stratum, k is the foundation coefficient, E is the elastic modulus of the rock stratum, I is the moment of inertia of the rock beam section about the neutral axis, and l is the length of the fixed-support beam.

7. A variable-layer spacing rigid roof partition control method according to claim 6, characterized in that: According to the variable interlayer spacing hard roof data, 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 size, including: According to the cantilever beam length, cantilever beam thickness, cantilever beam hanging length and cantilever beam load, combined with the free end boundary conditions, obtain the normal stress at each cross section of the cantilever beam; According to the normal stress at each cross section of the cantilever beam and in combination with the maximum tensile stress theory, the maximum tensile stress of the cantilever beam is obtained; Based on the maximum tensile stress of the cantilever beam and combined with the energy of the second hard rock formation, the periodic fracture step and the corresponding energy accumulation size are obtained.

8. A variable-interval hard roof partition control method according to claim 7, characterized in that: Obtaining the maximum tensile stress of the cantilever beam includes: Among them, σ max is the maximum tensile stress of the cantilever beam, M max is the maximum bending moment of the cantilever beam, φ1, φ2, φ3, φ4 are Krylov functions, β is the characteristic coefficient of the foundation beam, l1 is the suspended length of the cantilever beam, l2 is the beam length of the cantilever beam, and q is the load on the cantilever beam.

9. The variable-interval hard roof partition control method according to claim 7 is characterized in that: The method for obtaining the energy of the second hard rock formation is: in, is the deflection at l1, l1 is the cantilever beam suspension length, l2 is the cantilever beam length, is the deformation potential energy of the beam length of the five-layer cantilever beam, It is the external force potential energy of the goaf gangue on the beam length of the cantilever beam containing five rock layers.

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