A method and system for judging the stability of bottom coal based on cusp mutation

Abstract

The present application relates to the field of coal mine safety technology, and provides a method and system for judging the stability of the bottom coal of the roadway under blasting disturbance conditions. The method is used to judge the stability of the bottom coal of the roadway under blasting disturbance conditions. Specifically, based on the constructed flexural failure model of the bottom coal of the roadway, a numerical model of the roadway coal seam beam is established; based on the cusp mutation theory, the threshold of the stability of the bottom coal of the roadway is determined according to the numerical model of the coal seam beam; based on the obtained mechanical parameters of the bottom coal of the roadway and the threshold of the stability of the bottom coal, a preliminary judgment is made on the stability of the bottom coal of the roadway under blasting disturbance conditions. The entire judgment process is simple, feasible and easy to operate, avoiding the limitations of the selection of on-site construction parameters, solving the drawbacks of waste of resources and unsatisfactory blasting effects caused by blind design, and can quickly, accurately and scientifically judge the stability of the bottom coal under blasting disturbance conditions, provide theoretical guidance for the design of on-site construction parameters, and ensure safe and efficient excavation of thick bottom coal roadways.

Description

Technical Field

[0001] The present application relates to the field of coal mine safety technology, and in particular to a method and system for judging bottom coal stability based on cusp mutation. Background Art

[0002] Bottom coal blasting is a common method for bottom coal treatment in thick bottom coal tunneling. The blasting disturbance effect generated during the unloading process is one of the main controlling factors affecting the stability of the bottom coal. The bottom coal with different thicknesses and hardness conditions has different degrees of response to the blasting disturbance during the unloading construction. However, there is a lack of relevant stability judgment methods in the specific construction process of bottom coal blasting, which leads to certain limitations in the selection of on-site construction parameters. Blind design based on traditional methods or engineering experience has the disadvantages of waste of resources and unsatisfactory blasting effects.

[0003] Therefore, there is an urgent need to provide a technical solution to the above-mentioned deficiencies in the prior art. Summary of the invention

[0004] The purpose of the present application is to provide a method and system for determining bottom coal stability based on cusp mutation, so as to solve or alleviate the problems existing in the above-mentioned prior art.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] The present application provides a method for distinguishing the stability of the bottom coal of a roadway based on cusp mutation, which is used to distinguish the stability of the bottom coal of a roadway under blasting disturbance conditions. The distinguishing method includes: step S101, establishing a numerical model of the roadway coal seam beam based on a constructed flexural failure model of the roadway bottom coal; step S102, determining the stability threshold of the bottom coal of the roadway according to the numerical model of the coal seam beam based on cusp mutation theory; step S103, making a preliminary judgment on the stability of the bottom coal of the roadway under blasting disturbance conditions according to the acquired mechanical parameters of the bottom coal of the roadway and the bottom coal stability threshold.

[0007] Preferably, the numerical model of the coal seam beam is:

[0008]

[0009] Wherein, E0 is the total potential energy of the coal seam beam; E1 is the bending strain energy of the coal seam beam; E2 is the increased potential energy of the coal seam beam; E3 is the work done by the outside world on the coal seam beam;

[0010] E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the width of the roadway; q0 is the original rock stress above the roadway; q is the force of the bottom plate surrounding rock; k is the stress attenuation coefficient of the crushing zone; ω is the central deflection of the coal seam beam; S is the horizontal stress of the coal seam beam; x is the horizontal coordinate of the coal seam beam when it is damaged by force; y is the vertical coordinate of the coal seam beam when it is damaged by force; p i is the energy transmitted to the coal seam beam by the blasting disturbance of the i-th blasthole, i∈n, and i and n are both positive integers.

[0011] Preferably, in step S102, based on the cusp catastrophe theory, the numerical model is converted into a cusp catastrophe model; wherein the cusp catastrophe model is:

[0012]

[0013] Among them, E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the roadway width; q0 is the original rock stress above the roadway; q is the force of the floor surrounding rock; ω is the central deflection of the coal seam beam; S is the horizontal stress on the coal seam beam; k is the stress attenuation coefficient of the crushing zone; and according to the formula:

[0014]

[0015] Determine the energy W transmitted to the coal seam beam by the blasting effect;

[0016] In the formula, p d is the peak value of the borehole wall pressure during blasting disturbance; r b is the radius of the blast hole during blasting disturbance; [r] is the effective blasting depth during blasting disturbance; λ is the lateral pressure coefficient;

[0017]

[0018] μ is the dynamic Poisson's ratio of the coal body.

[0019] Preferably, in step S102, according to the formula:

[0020]

[0021] Determine the bottom coal stability threshold δ of the tunnel; wherein q0 is the original rock stress above the tunnel; q is the force of the bottom plate surrounding rock; k is the stress attenuation coefficient of the crushing zone; E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; and B is the tunnel width.

[0022] Preferably, in step S103, the horizontal stress S on the coal seam beam is determined; in response to S≥δ, it is preliminarily determined that the bottom coal of the tunnel is unstable under the blasting disturbance condition; in response to S<δ, it is preliminarily determined that the bottom coal of the tunnel is stable under the blasting disturbance condition.

[0023] Preferably, it also includes: in response to S<δ, based on the geometric model of the roadway, simulating the blasting disturbance of the roadway, and establishing a correlation model between the vertical bottom drum height of the roadway and the thickness of the bottom coal in the roadway; based on the cusp mutation theory, converting the correlation model into a mutation mathematical model to make a secondary judgment on the stability of the bottom coal in the roadway under the blasting disturbance condition.

[0024] Preferably, in response to S<δ, based on the geometric model of the roadway, the blasting disturbance of the roadway is simulated to establish a correlation model between the vertical bottom drum height of the roadway and the bottom coal thickness of the roadway, including: in response to S<δ, the blasting disturbance of the geometric model of the roadway is simulated to respectively determine multiple average bottom drum values ​​of the midpoint of the roadway bottom, the first measuring point, and the second measuring point under different bottom coal thicknesses; wherein the first measuring point is a measuring point at a first preset distance from the midpoint of the bottom of the roadway along the roadway excavation direction; the second measuring point is a measuring point at a second preset distance from the midpoint of the bottom of the roadway perpendicular to the roadway excavation direction; multiple average bottom drum values ​​and corresponding bottom coal thicknesses are fitted to obtain a correlation model between the vertical bottom drum height of the roadway and the bottom coal thickness of the roadway.

[0025] Preferably, based on the cusp mutation theory, the association model is converted into a mutation mathematical model to perform a secondary judgment on the stability of the bottom coal of the roadway under blasting disturbance conditions, including: based on the cusp mutation theory, the association model is converted into a mutation mathematical model to calculate the value of the intersection set; according to the value of the intersection set, the range of the ultimate bottom coal thickness of the roadway is determined; in response to the actual bottom coal thickness of the roadway being greater than the minimum value of the ultimate bottom coal thickness, the bottom coal of the roadway under blasting disturbance conditions is stable; in response to the actual bottom coal thickness of the roadway being less than the minimum value of the ultimate bottom coal thickness, the bottom coal of the roadway under blasting disturbance conditions is unstable.

[0026] Preferably, according to the formula:

[0027]

[0028] Determine the value of the intersection set Δ; wherein a1, a2, a3, and a4 are respectively the fitting coefficients of the correlation model between the vertical floor drum height of the roadway and different roadway bottom coal thicknesses.

[0029] The embodiment of the present application also provides a bottom coal stability judgment system based on cusp mutation, which is used to judge the bottom coal stability of the roadway under blasting disturbance conditions. The judgment system includes: a numerical model establishment unit, configured to establish a numerical model of the roadway coal seam beam based on the constructed flexural failure model of the roadway bottom coal; a stability threshold unit, configured to determine the bottom coal stability threshold of the roadway according to the numerical model of the coal seam beam based on the cusp mutation theory; a preliminary judgment unit, configured to make a preliminary judgment on the bottom coal stability of the roadway under blasting disturbance conditions based on the acquired bottom coal mechanical parameters of the roadway and the bottom coal stability threshold.

[0030] Beneficial effects:

[0031] The bottom coal stability discrimination method based on cusp mutation provided in the embodiment of the present application is used to discriminate the bottom coal stability of the roadway under blasting disturbance conditions. First, based on the constructed flexural failure model of the bottom coal of the roadway, a numerical model of the roadway coal seam beam is established. Then, based on the cusp mutation theory and the numerical model of the coal seam beam, the bottom coal stability threshold of the roadway is determined, and based on the obtained mechanical parameters of the bottom coal of the roadway and the bottom coal stability threshold, a preliminary judgment is made on the bottom coal stability of the roadway under blasting disturbance conditions. The entire judgment process is simple, feasible, and easy to operate, and avoids the limitations of on-site construction parameter selection, effectively solving the drawbacks of waste of resources and unsatisfactory blasting effects caused by traditional methods or blind design based on engineering experience, and can quickly, accurately, and scientifically determine the stability of the bottom coal under blasting disturbance conditions, provide theoretical guidance for on-site construction parameter design, and ensure safe and efficient excavation of thick bottom coal roadways. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary 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. Among them:

[0033] Figure 1 A schematic flow chart of a method for determining bottom coal stability based on cusp mutation according to some embodiments of the present application;

[0034] Figure 2 A logic diagram of a method for judging bottom coal stability based on cusp mutation according to some embodiments of the present application;

[0035] Figure 3 A schematic diagram of flexural stress failure of a coal seam beam provided according to some embodiments of the present application;

[0036] Figure 4 A schematic diagram of the structure of a bottom coal stability determination system based on cusp mutation provided according to some embodiments of the present application. DETAILED DESCRIPTION

[0037] The present application will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments. Each example is provided by way of explanation of the present application and does not limit the present application. In fact, it will be clear to those skilled in the art that modifications and variations may be made in the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as a part of an embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desired that the present application includes such modifications and variations within the scope of the appended claims and their equivalents.

[0038] In the process of mining excavation and recovery, the most important and urgent key issue to be solved is to efficiently and accurately judge the stability of the bottom coal, which provides a theoretical basis for further impact prevention and control, and has a direct impact on ensuring the normal industrial production of coal mines. For this problem, if it can be solved scientifically, reasonably and qualitatively, it can improve production efficiency and improve the safety of workers' work.

[0039] At present, there is a lack of relevant stability judgment methods in the specific construction process of bottom coal blasting and decompression, which leads to certain limitations in the selection of on-site construction parameters. Most of them are determined by measuring the physical and mechanical parameters of coal and rock in the laboratory, density measurement, uniaxial compressive strength and dynamic failure time test, impact energy index test, elastic energy index test, and finally the coal seam impact tendency index analysis to judge the impact. On the one hand, judging by indoor tests has a long cycle and low efficiency, which greatly affects the mining progress and construction period of the mine; on the other hand, when relying on traditional methods or engineering experience for design, there is a lack of theoretical support and blind design, which may cause blasting decompression for mines that do not need blasting decompression, resulting in waste of resources and blasting effects that do not meet expectations.

[0040] Based on this, this application proposes a method for judging the stability of the bottom coal based on cusp mutation. According to the numerical model of the coal seam beam in the tunnel under blasting disturbance conditions and based on the cusp mutation theory, the bottom coal stability threshold of the tunnel is determined so as to make a preliminary judgment on the stability of the bottom coal in the tunnel under blasting disturbance conditions. The bottom coal stability under blasting disturbance conditions can be judged quickly, accurately and scientifically, providing corresponding theoretical guidance for the design of on-site construction parameters and ensuring safe and efficient excavation of thick bottom coal tunnels.

[0041] like Figures 1 to 3 As shown, the bottom coal stability determination method based on cusp mutation includes:

[0042] Step S101: Based on the constructed flexural failure model of the roadway bottom coal, a numerical model of the roadway coal seam beam is established.

[0043] In this application, by conducting mechanical analysis on the coal at the bottom of the tunnel, a flexural failure model (mechanical model) of the coal at the bottom of the tunnel is established to realize the potential energy analysis of the coal at the bottom of the tunnel. By analyzing the influence of the blasting disturbance effect on the potential energy of the coal at the bottom of the tunnel, a numerical model of the coal seam beam in the tunnel is established. Specifically, the numerical model of the coal seam beam is:

[0044]

[0045] Wherein, E0 is the total potential energy of the coal seam beam; E1 is the bending strain energy of the coal seam beam; E2 is the increased potential energy of the coal seam beam; E3 is the work done by the outside world on the coal seam beam;

[0046] E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the width of the roadway; q0 is the original rock stress above the roadway; q is the force of the bottom plate surrounding rock; k is the stress attenuation coefficient of the crushing zone; ω is the central deflection of the coal seam beam; S is the horizontal stress on the coal seam beam; x is the horizontal coordinate of the coal seam beam when it is damaged by force; y is the vertical coordinate of the coal seam beam when it is damaged by force; W i is the energy transmitted to the coal seam beam by the blasting disturbance of the i-th blasthole, i∈n, and i and n are both positive integers.

[0047] Step S102: Based on the cusp catastrophe theory and the numerical model of the coal seam beam, determine the bottom coal stability threshold of the roadway.

[0048] Specifically, based on the cusp mutation theory, the numerical model of the coal seam beam is transformed into a cusp mutation model. Specifically, the cusp mutation model obtained is:

[0049]

[0050] Among them, E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the width of the roadway; q0 is the original rock stress above the roadway; q is the force of the bottom plate surrounding rock; ω is the central deflection of the coal seam beam; S is the horizontal stress on the coal seam beam; k is the stress attenuation coefficient of the crushing zone; W is the energy transmitted to the coal seam beam by the blasting effect.

[0051] In this application, when blasting and unloading, a blast hole is arranged at 90 degrees in the middle of the tunnel, and a blast hole is constructed at 45 degrees at each of the two bottom corners of the tunnel. The depth of the blast hole reaches the bottom rock. The length of the charging section is 1 meter, and the length of the sealing section is 4 to 7 meters. Specifically, according to the formula:

[0052]

[0053] Determine the energy W transmitted to the coal seam beam by the blasting effect of the three blastholes.d is the peak value of the borehole wall pressure during blasting disturbance; r b is the radius of the blast hole during blasting disturbance; [r] is the effective blasting depth during blasting disturbance; λ is the lateral pressure coefficient;

[0054]

[0055] μ is the dynamic Poisson's ratio of the coal body.

[0056] In the cusp catastrophe model, we have:

[0057]

[0058] Also because is always greater than zero, so,

[0059]

[0060] Then, we get:

[0061]

[0062] Then, according to the obtained bottom coal mechanical parameters of the tunnel, the formula is:

[0063]

[0064] Determine the bottom coal stability threshold δ of the tunnel. Among them, q0 is the original rock stress above the tunnel; q is the force of the bottom plate surrounding rock; k is the stress attenuation coefficient of the crushing zone; E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the width of the tunnel. Among them, k has different values ​​in different mines according to actual geological differences. Specifically, data is obtained through field blasting vibration tests in mines, and the relationship between the vibration velocity of the measuring point and the distance from the explosion center and the maximum single-shot charge is obtained by using Sadovsky's empirical formula. Through linear regression analysis, the coefficient k value related to the propagation geological conditions can be obtained.

[0065] Step S103: Based on the acquired bottom coal mechanical parameters and bottom coal stability threshold of the roadway, a preliminary judgment is made on the bottom coal stability of the roadway under blasting disturbance conditions.

[0066] Specifically, the horizontal stress S received by the coal seam beam is determined. The horizontal stress S received by the coal seam beam can be determined by field measurement through stress strain gauges. In response to S≥δ, it is preliminarily judged that the bottom coal of the roadway is unstable under the condition of blasting disturbance, that is, the stability of the bottom coal of the roadway is poor, and there is a risk of failure of active pressure relief of the bottom coal, and pressure relief treatment is required; in response to S<δ, it is preliminarily judged that the bottom coal of the roadway is stable under the condition of blasting disturbance.

[0067] And when it is preliminarily judged that the bottom coal stability of the roadway is good under the blasting disturbance condition, that is, S<δ, in this application, the stability of the roadway is further verified by roadway simulation and combined with the cusp mutation theory. Specifically, in response to S<δ, based on the geometric model of the roadway, the blasting disturbance of the roadway is simulated, and a correlation model between the vertical bottom drum height of the roadway and the thickness of the bottom coal of the roadway is established; then, based on the cusp mutation theory, the correlation model is transformed into a mutation mathematical model to make a secondary judgment on the stability of the bottom coal of the roadway under the blasting disturbance condition.

[0068] Among them, when S<δ, based on the geometric model of the roadway, the blasting disturbance of the roadway is simulated, in response to S<δ, the blasting disturbance of the geometric model of the roadway is simulated, and multiple average bottom drum values ​​of the midpoint of the bottom of the roadway, the first measuring point, and the second measuring point of the roadway under different bottom coal thicknesses are determined respectively; wherein, the first measuring point is a measuring point at a first preset distance from the midpoint of the bottom of the roadway along the direction of roadway excavation; the second measuring point is a measuring point at a second preset distance from the midpoint of the bottom of the roadway perpendicular to the direction of roadway excavation.

[0069] Specifically, based on the physical and mechanical parameters of the tunnel, a collective model of the coal mine tunnel is established, and boundary conditions, model mechanical parameters, and model grids are set. The thickness of the bottom coal in the coal mine tunnel collective model is continuously increased to obtain different bottom coal thicknesses h. i Under the condition, the average bottom heave value L of the midpoint of the bottom of the coal mine roadway and the corresponding distance measurement points from the midpoint along the roadway excavation direction and perpendicular to the roadway excavation direction i Among them, the first measuring point is 3m away from the midpoint of the bottom of the tunnel along the excavation direction, and the second measuring point is close to the two sides of the tunnel along the vertical direction from the midpoint of the bottom of the tunnel.

[0070] Then, multiple average floor heave values ​​and corresponding bottom coal thicknesses are fitted to obtain a correlation model between the vertical floor heave height of the roadway and the bottom coal thickness of the roadway. i , L i ) data points were fitted with a fourth-order function curve, and the vertical floor drum height L was obtained as a function of the bottom coal thickness h of the coal mine roadway. i The model of change, that is, the correlation model between the vertical floor drum height of the roadway and the coal thickness at the bottom of the roadway is:

[0071]

[0072] Among them, a0, a1, a2, a3, and a4 are all fitting coefficients.

[0073] Next, based on the cusp catastrophe theory, the association model is transformed into a catastrophe mathematical model to make a secondary judgment on the stability of the bottom coal of the tunnel under blasting disturbance conditions. Specifically, based on the cusp catastrophe theory, the association model is transformed into a catastrophe mathematical model to calculate the value of the intersection set. That is, the calculation model of the intersection set can be obtained by taking the first and second derivatives of the cusp catastrophe standard function respectively.

[0074] Specifically, order:

[0075]

[0076] Then the association model can be obtained through the matrix:

[0077]

[0078] Translates to:

[0079] β=t0+t1u+t2u 2 +t4u 4

[0080] make:

[0081]

[0082] The association model can be further transformed into:

[0083] M=N+cu+bu 2 +u 4

[0084] Then, we take the first-order derivative and the second-order derivative of the above formula and get:

[0085]

[0086] Furthermore, the standard function of the cusp mutation after the bottom coal is:

[0087] R(u)=cu+bu 2 +u 4

[0088] By taking the first and second order derivatives of the cusp mutation standard function and eliminating u simultaneously, we can get the calculation model of the crossover set Δ. Specifically, according to the formula:

[0089]

[0090] Determine the value of the cross set Δ. Wherein, a1, a2, a3, and a4 are the fitting coefficients of the correlation model between the vertical floor drum height of the roadway and different roadway bottom coal thicknesses.

[0091] The sudden change of the positive and negative values ​​of the intersection set indicates that the bottom coal has impacted. Therefore, according to the value of the intersection set, the range of the limit bottom coal thickness of the roadway can be determined, that is, when Δ changes from a positive value to a negative value, h i range. When the actual bottom coal thickness of the roadway is greater than the minimum value of the limit bottom coal thickness, the bottom coal of the roadway is stable under the blasting disturbance condition; when the actual bottom coal thickness of the roadway is less than the minimum value of the limit bottom coal thickness, the bottom coal of the roadway is unstable under the blasting disturbance condition, that is, the stability of the bottom coal of the roadway is poor and pressure relief treatment is required. Among them, the actual bottom coal thickness of the roadway is obtained by drilling sampling. Here, it should be noted that when the actual bottom coal thickness of the roadway is equal to the minimum value of the limit bottom coal thickness, the bottom coal of the roadway is just stable under the blasting disturbance condition, but with a cautious attitude, pressure relief treatment is still carried out at this time.

[0092] Therefore, based on the threshold of roadway bottom coal stability determined by the numerical model of coal seam beam, a preliminary judgment is made on the stability of roadway bottom coal under blasting disturbance conditions. Then, a secondary judgment is made on the stability of roadway bottom coal through the combination of roadway geometric simulation and cusp catastrophe theory. The stability of roadway bottom coal is finally determined by combining the initial judgment with the secondary judgment. Only when the results of the two judgments show that the roadway bottom coal is stable can it be finally determined that the stability of bottom coal is good. Otherwise, if the secondary verification fails, it is determined that the stability of roadway bottom coal is poor and pressure relief treatment is required.

[0093] In a specific example, when the above-mentioned roadway bottom coal stability determination method is used for initial determination, it can be known from the obtained roadway mechanical parameters that:

[0094]

[0095] The horizontal stress S<δ of the coal seam beam measured by the stress strain gauge is preliminarily judged to be stable under the blasting disturbance condition. Then, the stability of the bottom coal of the roadway is further verified by simulating the roadway geometry model and combining the cusp catastrophe theory. i =2.0m, 2.5m, 3.0m, 3.5m, 4.0m, 4.5m working conditions, simulation was carried out to obtain the average bottom heave value L of the midpoint of the bottom of the coal mine tunnel and the corresponding distance measurement points from the midpoint along the tunnel excavation direction and perpendicular to the tunnel excavation direction i , all (h i , L i ) data points are fitted with a 4-fold function curve, and the value of the crossover set Δ is calculated. As shown in Table 1:

[0096] Table 1 Prediction results

[0097]

[0098] in,

[0099]

[0100]

[0101] Then, according to the value of the intersection set, the range of the limit bottom coal thickness of the roadway can be determined, that is, when Δ changes from a positive value to a negative value, h i The range is: [h] = [2.5,3]m; and the actual measured bottom coal thickness is 2.1m, which is smaller than the range of the limit bottom coal thickness. Therefore, through the initial judgment and the secondary judgment, it is proved that the bottom coal stability of the tunnel is good.

[0102] When judging the stability of the bottom coal in the tunnel by this judgment method, the whole process is simple and easy to operate, avoiding the limitations of the selection of on-site construction parameters, and effectively solving the drawbacks of waste of resources and unsatisfactory blasting effects caused by traditional methods or blind design based on engineering experience. It can quickly, accurately and scientifically judge the stability of the bottom coal under blasting disturbance conditions, provide theoretical guidance for the design of on-site construction parameters, and ensure safe and efficient excavation of thick bottom coal tunnels.

[0103] like Figure 4 As shown, the embodiment of the present application also provides a bottom coal stability discrimination system based on cusp mutation, which is used to discriminate the bottom coal stability of the roadway under blasting disturbance conditions. The discrimination system includes: a numerical model establishment unit 401, a stability threshold unit 402, and a preliminary judgment unit 403. Among them, the numerical model establishment unit 401 is configured to establish a numerical model of the roadway coal seam beam based on the constructed flexural failure model of the roadway bottom coal; the stability threshold unit 402 is configured to determine the bottom coal stability threshold of the roadway according to the numerical model of the coal seam beam based on the cusp mutation theory; the preliminary judgment unit 403 is configured to make a preliminary judgment on the bottom coal stability of the roadway under blasting disturbance conditions according to the acquired bottom coal mechanical parameters and bottom coal stability threshold of the roadway.

[0104] The bottom coal stability judgment system based on cusp mutation provided in the embodiment of the present application can implement the steps and processes of the bottom coal stability judgment method based on cusp mutation described in any of the above embodiments, and achieve the same technical effects, which will not be described one by one here.

[0105] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for judging the stability of bottom coal based on cusp mutation, characterized in that: Used to judge the stability of bottom coal in tunnel under blasting disturbance conditions, the judging method includes: Step S101, establishing a numerical model of the coal seam beam in the roadway based on the constructed flexural failure model of the roadway bottom coal; Step S102: Based on the cusp catastrophe theory and the numerical model of the coal seam beam, according to the formula: Determine the bottom coal stability threshold δ of the roadway; where q0 is the original rock stress above the roadway; q is the force of the bottom plate surrounding rock; k is the stress attenuation coefficient of the crushing zone; E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the roadway width; Based on the cusp catastrophe theory, the numerical model is transformed into a cusp catastrophe model; wherein the cusp catastrophe model is: Among them, E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the roadway width; q0 is the original rock stress above the roadway; q is the force of the floor surrounding rock; ω is the central deflection of the coal seam beam; S is the horizontal stress on the coal seam beam; k is the stress attenuation coefficient of the crushing zone; and according to the formula: Determine the energy W transmitted to the coal seam beam by the blasting effect; In the formula, p d is the peak value of the borehole wall pressure during blasting disturbance; r b is the radius of the blast hole during blasting disturbance; [r] is the effective blasting depth during blasting disturbance; λ is the lateral pressure coefficient; μ is the dynamic Poisson's ratio of the coal body; Step S103: Preliminary judgment is made on the stability of the bottom coal in the roadway under blasting disturbance conditions according to the acquired bottom coal mechanical parameters and the bottom coal stability threshold.

2. The method for determining bottom coal stability based on cusp mutation according to claim 1, characterized in that: The numerical model of the coal seam beam is: Wherein, E0 is the total potential energy of the coal seam beam; E1 is the bending strain energy of the coal seam beam; E2 is the increased potential energy of the coal seam beam; E3 is the work done by the outside world on the coal seam beam; E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the width of the roadway; q0 is the original rock stress above the roadway; q is the force of the bottom plate surrounding rock; k is the stress attenuation coefficient of the crushing zone; ω is the central deflection of the coal seam beam; S is the horizontal stress of the coal seam beam; x is the horizontal coordinate of the coal seam beam when it is damaged by force; y is the vertical coordinate of the coal seam beam when it is damaged by force; p i is the energy transmitted to the coal seam beam by the blasting disturbance of the i-th blasthole, i∈n, and i and n are both positive integers.

3. The method for determining bottom coal stability based on cusp mutation according to claim 1, characterized in that: In step S103, Determine the horizontal stress S on the coal seam beam; in response to S≥δ, preliminarily judge that the bottom coal of the roadway is unstable under the blasting disturbance condition; in response to S<δ, preliminarily judge that the bottom coal of the roadway is stable under the blasting disturbance condition.

4. The method for determining bottom coal stability based on cusp mutation according to claim 3 is characterized in that: Also includes: In response to S<δ, based on the geometric model of the roadway, the blasting disturbance of the roadway is simulated, and a correlation model between the vertical floor drum height of the roadway and the thickness of the coal at the bottom of the roadway is established; Based on the cusp catastrophe theory, the association model is transformed into a catastrophe mathematical model to make a secondary judgment on the bottom coal stability of the tunnel under blasting disturbance conditions.

5. The method for determining bottom coal stability based on cusp mutation according to claim 4 is characterized in that: In response to S<δ, based on the geometric model of the roadway, the blasting disturbance of the roadway is simulated to establish a correlation model between the vertical floor drum height of the roadway and the thickness of the coal at the bottom of the roadway, including: In response to S<δ, the blasting disturbance of the geometric model of the roadway is simulated to determine multiple average bottom drum values ​​of the midpoint of the roadway bottom, the first measuring point, and the second measuring point under different bottom coal thicknesses; wherein the first measuring point is a measuring point at a first preset distance from the midpoint of the roadway bottom along the roadway excavation direction; the second measuring point is a measuring point at a second preset distance from the midpoint of the roadway bottom in the direction perpendicular to the roadway excavation direction; A plurality of the average floor heave values ​​and the corresponding bottom coal thicknesses are fitted to obtain a correlation model between the vertical floor heave height of the roadway and the bottom coal thickness of the roadway.

6. The method for determining bottom coal stability based on cusp mutation according to claim 4, characterized in that: Based on the cusp catastrophe theory, the association model is transformed into a catastrophe mathematical model to make a secondary judgment on the bottom coal stability of the tunnel under blasting disturbance conditions, including: Based on the cusp mutation theory, the association model is transformed into a mutation mathematical model to calculate the value of the crossover set; Determining the range of the limit bottom coal thickness of the roadway according to the value of the intersection set; In response to the actual bottom coal thickness of the roadway being greater than the minimum value of the limit bottom coal thickness, the bottom coal of the roadway under the blasting disturbance condition is stable; In response to the actual bottom coal thickness of the tunnel being less than the minimum value of the limit bottom coal thickness, the bottom coal of the tunnel is unstable under the blasting disturbance condition.

7. The method for determining bottom coal stability based on cusp mutation according to claim 6, characterized in that: According to the formula: determining a value of the intersection set Δ; Among them, a1, a2, a3, and a4 are the fitting coefficients of the correlation model between the vertical floor drum height of the tunnel and different tunnel bottom coal thicknesses.

8. A bottom coal stability judgment system based on cusp mutation, characterized in that: Used to judge the stability of bottom coal in tunnel under blasting disturbance conditions, the judging system includes: a numerical model building unit configured to build a numerical model of the roadway coal seam beam based on the constructed flexural failure model of the roadway bottom coal; The stability threshold unit is configured based on the cusp catastrophe theory, according to the numerical model of the coal seam beam, according to the formula: Determine the bottom coal stability threshold δ of the roadway; where q0 is the original rock stress above the roadway; q is the force of the bottom plate surrounding rock; k is the stress attenuation coefficient of the crushing zone; E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the roadway width; Based on the cusp catastrophe theory, the numerical model is transformed into a cusp catastrophe model; wherein the cusp catastrophe model is: Among them, E is the elastic model of the coal body; I is the cross-sectional inertia moment of the coal seam beam; β is the influence range coefficient of the support load; B is the roadway width; q0 is the original rock stress above the roadway; q is the force of the floor surrounding rock; ω is the central deflection of the coal seam beam; S is the horizontal stress on the coal seam beam; k is the stress attenuation coefficient of the crushing zone; and according to the formula: Determine the energy W transmitted to the coal seam beam by the blasting effect; In the formula, p d is the peak value of the borehole wall pressure during blasting disturbance; r b is the radius of the blast hole during blasting disturbance; [r] is the effective blasting depth during blasting disturbance; λ is the lateral pressure coefficient; μ is the dynamic Poisson's ratio of the coal body; The preliminary judgment unit is configured to make a preliminary judgment on the stability of the bottom coal of the roadway under blasting disturbance conditions according to the acquired mechanical parameters of the bottom coal of the roadway and the bottom coal stability threshold.

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