Method and method for determining the cascading instability of surrounding rocks in a coal mine chamber group.

Abstract

To provide a method and method for determining the cascading instability of surrounding rocks in a coal mine chamber group. [Solution] Based on the premise that fracture is unstable, mechanical criteria for each chamber instability are constructed from two angles: stress and energy. Then, the chamber group is traversed step by step based on the mechanical criteria for chamber instability, and the influence of stress / energy transfer of individual chamber instabilities on adjacent chambers is analyzed to determine whether the chamber group in the depths of the coal mine is in a chain reaction of instability. Based on the determination result, a method is created to control the stability of the surrounding rock of the chamber group. This invention not only avoids misjudgment based on a single mechanical indicator, but also improves the scientific accuracy of instability determination, reduces secondary disasters such as chain reaction of instability of the surrounding rock of a chamber group due to the instability of a single chamber, avoids problems such as ambiguity of support targets, excessive or insufficient control in the chamber group surrounding rock control process, and reduces safety risks to mine production.

Description

Technical Field

[0001] The present invention relates to the technical field of mine pressure, and particularly relates to a method for determining the chain instability of the surrounding rock of a chamber group in a coal mine.

Background Art

[0002] Coal mining in our country mainly relies on shaft mining, and chambers are the basic constituent units in the coal mine. To meet the requirements such as functions of power supply, drainage and separation, and transportation, installation and use of mechanical equipment, the chambers in coal mines are often densely arranged in groups. Under the influence of the complex environment of "three highs and one disturbance" in the deep part of the coal mine, such a chamber group has extremely high construction and maintenance difficulties, a large cross-sectional convergence rate, and accidents such as outbursts, floor heaves and dynamic failures often occur. The reasons mainly come from the following four aspects: 1. Significant changes have occurred in the mechanical properties of deep coal rocks and the characteristics of engineering responses; 2. The occurrence frequency, intensity and complexity of dynamic load disturbances and failure phenomena have increased significantly; 3. The chambers are enhanced under the influence of their own dimensional effects, the deformation and failure of the surrounding rock are intensified, and they are easily affected by the surrounding stress environment; 4. The influence of the interaction between chamber groups is intense, etc.

[0003] Extensive field practice and numerical simulations have shown that even if a certain area of ​​plastic fracture develops in a coal mine chamber, it can still remain relatively stable and meet normal usage requirements. This explains the essential difference between fracture and instability of the chamber's surrounding rock. Current methods for analyzing the stability of chamber's surrounding rock mainly include empirical methods, numerical simulations, and field monitoring methods. Among these, empirical methods rely on construction experience and statistical formulas, lacking adaptability to different geological conditions and external disturbances. Numerical simulations can analyze the stress and deformation characteristics of the surrounding rock relatively accurately, but the complexity of the calculations is high, making real-time use difficult. Field monitoring methods mainly rely on monitoring data to provide early warnings, but they usually only detect problems after obvious deformation or fracture has appeared in the surrounding rock, resulting in a delay. At the same time, mutual influence between chambers is unavoidable in a coal mine chamber group. Insight into the impact of instability in one chamber within a chamber group on surrounding chambers is key to controlling the surrounding rock in a chamber group.

[0004] Therefore, clarifying the relationship between the fracture and instability of the surrounding rocks, and establishing a scientific and rational method for determining the cascading instability of the chamber group, is of great importance in improving the stability of the surrounding rocks in the chamber group and preventing power-related accidents in coal mines. [Overview of the project]

[0005] The present invention provides a method for determining cascading instability of surrounding rocks in a coal mine chamber group in order to gain insight into the impact of instability in one chamber within a chamber group on other surrounding chambers and to provide technical support for low-cost, highly efficient safe support of the chamber group.

[0006] The present invention also provides the use of this determination method for controlling the stability of the surrounding rocks of a group of chambers.

[0007] To achieve the above objective, the technical aspects of the present invention are as follows.

[0008] A method for determining the cascading instability of the surrounding rocks of a coal mine chamber group, Based on the premise that fracture is unstable, we constructed instability mechanics criteria for each chamber from two angles: stress and energy, and expressed them as the instability stress index Sσ and the instability energy index Su of the surrounding rock, respectively. The mechanics criteria constructed within these criteria are:

[0009]

number

[0010] In this process, the instability stress index of the surrounding rock is the ratio of the dynamic and static superimposed stress within the surrounding rock of the chamber to the load strength of the anchor surrounding rock, and the instability energy index of the surrounding rock is the ratio of the dynamic and static superimposed energy within the surrounding rock of the chamber to the maximum absorbed energy of the anchor surrounding rock, step 1, Step 2 involves evaluating each chamber in a chamber group containing n chambers according to the mechanical criteria of Step 1. If all chambers are stable, the chamber group is considered stable; if one chamber is unstable, the evaluation is stopped and the next step is initiated. Step 3 involves constructing an unstable mechanical criterion for the remaining chambers according to the method of Step 1, continuing to assess the remaining chambers according to the method of Step 2, and so on by analogy until assessment and identification are completed for all remaining chambers. Methods that include...

[0011] Furthermore, the unstable stress index of the surrounding rock of the chamber is expressed as the ratio of the dynamic and static superimposed stress within the plastic zone of the surrounding rock of the chamber to the load strength of the anchor surrounding rock.

[0012] Furthermore, the method for determining the unstable stress index of the surrounding rock of the chamber involves making the cross-sectional shape of the chamber equivalent to a circle using a correction coefficient to determine its equivalent radius, determining the radius of the plastic zone of the surrounding rock of the chamber from the equivalent radius of the surrounding rock of the chamber, and then determining the dynamic and static superimposed stress within the range of the plastic zone and the load strength of the anchor surrounding rock.

[0013] Furthermore, the instability energy index of the surrounding rock is expressed as the ratio of the static load energy at the plastic-loosening boundary of the surrounding rock of the chamber, the external disturbance energy acting on the plastic-loosening boundary of the surrounding rock, and the energy consumed by the fracture of the anchor surrounding rock. In this, the loosening boundary refers to the boundary of the loosening area formed when the plastic area of ​​the chamber is fractured when the instability stress index of the surrounding rock of the chamber is greater than 1.

[0014] Furthermore, the method for determining the instability energy index of the surrounding rock involves considering the loosened area as a newly excavated chamber, and determining the equivalent radius of the newly excavated chamber, i.e., the radius at the loosening boundary, by equivalentizing the cross-sectional shape of this newly excavated chamber to a circle using a correction coefficient. Next, the sum of the static load energy and the external disturbance energy acting on the plastic-loosening boundary of the surrounding rock, and the energy consumed by the fracture of the anchor surrounding rock can be obtained.

[0015] Furthermore, the detailed method for step 3 is as follows: 3.1: Since the unstable chamber identified in step 2 generates new stress and energy increases in the surrounding chambers, the unstable stress index and unstable energy index of the surrounding rocks of the remaining n-1 chambers are recalculated based on this, a new instability mechanical criterion is constructed for the remaining n-1 chambers, and the unstable conditions of each of the remaining n-1 chambers are identified based on the new instability mechanical criterion. If all of the remaining n-1 chambers are stable, it indicates that no cascading instability has occurred. If another chamber is unstable, the determination is stopped and the next step is initiated, and it is explained that a cascading instability has occurred in the group of chambers. 3.2: Recalculate the unstable stress index and unstable energy index of the surrounding rocks for the remaining n-2 chambers, construct a new instability mechanics criterion for the remaining n-2 chambers, identify the unstable conditions for each of the remaining n-2 chambers based on the new instability mechanics criterion, and if no instability occurs in any of the remaining n-2 chambers, the chain of instability ends. If any of the remaining n-2 chambers are unstable, stop the determination and proceed to the next step. 3.3: Reconstruct new instability mechanics criteria for the remaining n-3 chambers and determine the instability of the remaining n-3 chambers based on these criteria, and continue in this manner until the determination for all chambers is complete.

[0016] A method for controlling the long-term stability of a group of chambers in a coal mine using a method for determining the cascading instability of the surrounding rocks of the chambers, wherein, based on the determination result, it is determined whether or not cascading instability has occurred in the chambers, and if cascading instability has occurred, the product of the instability stress index and the instability energy index is defined as the chamber key coefficient, all unstable chambers are ranked according to the magnitude of the chamber key coefficient, the chamber with a larger key coefficient has a higher keyness within the chambers, and thereafter, corresponding support measures are established based on the keyness of each unstable chamber within the chambers, the chamber with a higher keyness is given higher support measures to control its stability, and it is also necessary to take timely measures for chambers that have slowly fractured to prevent further fracture.

[0017] The present invention has the following features and advantages compared to the prior art. 1. This method determines the cascading instability of the surrounding rock in a coal mine chamber group. This method clarifies the relationship between fracture and instability of the surrounding rock, meaning that fracture is not instability, but rather a prerequisite for instability. Instability determination criteria were constructed from two angles: mechanics and energy. Not only was the effect of static-dynamic superposition stress on the load-bearing capacity of the surrounding rock considered, but the relationship between static-dynamic superposition energy and the energy consumed by the fracture of the surrounding rock was comprehensively evaluated. If fracture occurs in the surrounding rock, and it is still in a critical equilibrium state, and the external disturbance is not sufficient to break this equilibrium, the surrounding rock of the chamber can still maintain stability, and only stable deformation occurs. Instability of the surrounding rock only occurs when an external disturbance causes stress overload on the surrounding rock, and the energy storage exceeds the critical value of the energy consumed by fracture. This not only avoids misjudgments that can occur with a single mechanical indicator, but also enhances the scientific accuracy of the instability determination. 2. This method highlights the interrelationships between chamber groups, specifically how stress and energy changes caused by instability in any chamber within a chamber group containing n chambers affect other surrounding chambers, allowing for a stepwise assessment of the propagation paths and extent of cascading instability. This helps identify the location of dangerous chambers within a chamber group containing n chambers, enabling the development of appropriate support optimization strategies and reinforcement measures for the surrounding rock. This reduces secondary disasters such as cascading instability of the surrounding rock of a chamber group due to the instability of a single chamber, avoids problems such as unclear support targets, excessive or insufficient control, and reduces the safety risks to mining production. 3. This method can be applied not only to theoretical analysis but also to monitoring data from coal mine sites (e.g., stress monitoring, micro-seismic monitoring, surrounding rock deformation monitoring, etc.) to dynamically evaluate the instability tendencies of surrounding rock, giving it relatively strong process adaptability and practical value. [Brief explanation of the drawing]

[0018] [Figure 1] This is the stage where the chamber deforms stably. [Figure 2] This is the stage where the chamber is slowly destroyed. [Figure 3] This is the stage where the chamber becomes increasingly unstable. [Figure 4] This is a flowchart for identifying the occurrence of a chain reaction of instability in a group of chambers containing n chambers. [Modes for carrying out the invention]

[0019] To more clearly illustrate the technical aspects of the embodiments of the present invention, the drawings necessary for describing the embodiments will be briefly described below. However, the drawings in the following description represent only some of the embodiments of the present invention, and those skilled in the art can obtain other drawings based on these without expending any creative effort. Hereinafter, for the preferred embodiments of the present invention, in order for those skilled in the art to more easily understand the advantages and features of the present invention and to more clearly and precisely define the protection scope of the present invention, a detailed description will be given with reference to the accompanying drawings.

[0020] Hereinafter, referring to FIGS. 1-3, the process of constructing the mechanical criteria of the present invention will be described.

[0021] Step 1. Calculate the equivalent radius of the chamber The cross-sectional shape of chamber 1 is made equal to a circle by a correction factor, and the equivalent radius R is as follows:

[0022]

Equation

[0023] Here, R is the equivalent radius of the chamber, in m, Sc is the cross-sectional area of the chamber, in m2, Kc is the correction factor of the cross-section of the chamber, and the values are shown in Table 1.

[0024]

Table 1

[0025] Step 2. Determine the instability stress index 2.1: Determine the radius Rp of the plastic zone of the surrounding rock of the chamber from the equivalent radius R of chamber 1, that is

[0026]

Equation

[0029] φ is the internal friction angle of the surrounding rock of the chamber. σc is the rock mass strength of the surrounding rock of the chamber, in MPa,

[0030]

Number

[0031] Where c is the cohesion of the rock of the chamber, and all are obtained by mechanical tests on the rock in the laboratory.

[0032] 2.2: According to the rock mass mechanics theory, when the static and dynamic superimposed stress of the surrounding rock is less than the loading strength of the anchor surrounding rock of the chamber, it can be seen that only stable deformation occurs in the surrounding rock of Chamber 1 and no new failure occurs. As can be seen from Figure 1, the surrounding area where Chamber 1 deforms stably forms a plastic zone 2 and an elastic zone 3. When the static and dynamic superimposed stress of the surrounding rock exceeds the loading strength of the anchor surrounding rock of the chamber, the limit stress equilibrium state of the rock mass in the plastic zone 3 is broken, the cracks further expand and penetrate, and a loosening zone 4 is further formed (see Figure 2). The failure of the surrounding rock in the loosening zone 4 is serious and presents a granular state (see Figure 3), and it has basically lost its loading capacity and can be regarded as a newly excavated chamber with an equivalent radius Rs (R < Rs ≦ Rp) (see the newly added plastic zone 5 in Figure 3), which can cause a redistribution of the stress of the surrounding rock and further deformation and failure of the surrounding rock. Based on the above principle, the ratio of the sum of the static load stress σj in the plastic zone of the surrounding rock of the chamber and the external disturbance stress σd acting in the plastic zone to the loading strength σmc of the anchor surrounding rock is defined as the instability stress index Sσ. That is:

[0033]

Number

[0034] Here, the calculation formula for the static load stress σj in the plastic zone is as follows:

[0035]

number

[0036] During the ceremony: σc is the rock mass strength of the surrounding rock of the chamber, in MPa. r is the distance m from any point within the plastic region to the center of the chamber. σm is the supporting reaction force of the surrounding rocks of the chamber, in MPa, obtained through on-site monitoring. Rp is the radius of the plastic zone of the surrounding rock of the chamber. R is the equivalent radius of the chamber, in meters.

[0037] The formula for calculating dynamic load stress within the plastic region is as follows:

[0038]

number

[0039] During the ceremony: σD is the dynamic load intensity at the earthquake source, expressed in MPa, and can be obtained through micro-seismic monitoring at the site. ηe is the wave impedance, MPa / m, at which vibration waves propagate in the elastic region. S is the distance between the epicenter and the chamber, in meters, and is obtained through micro-seismic monitoring at the site. ηp is the wave impedance of vibration wave propagation in the plastic region, MPa / m. Kp is the transmittance of vibrational waves as they propagate through the plastic region, and is in the range of 0 to 1. The load strength σmc of the anchor surrounding rock is as follows:

[0040]

number

[0041] During the ceremony: b is the length of the supporting structure of the surrounding rocks of the chamber, and m is the length of the supporting structure of the surrounding rocks.

[0042] 2.3: According to rock mechanics theory, when the superimposed static-dynamic energy of the surrounding rock is less than the energy consumed by the fracture of the anchor surrounding rock, the rock body in the loosening zone of the surrounding rock is in an energy-stable state, and the energy consumed by the fracture of the anchor surrounding rock cancels out the external dynamic load energy, so that the surrounding rock of the chamber will only fracture in the short term. However, if timely and effective reinforcement is not performed, the surrounding rock of the chamber will develop fatigue-loosening instability under long-term alternating static-dynamic loads. When the superimposed static-dynamic energy of the surrounding rock exceeds the energy consumed by the fracture of the anchor surrounding rock, the excess energy present at the plastic-loosening boundary continues to act on the loosening zone in the form of kinetic or mechanical energy, causing the loosening rock body to instantaneously activate, gain initial velocity, and be thrown into free space, resulting in accelerated instability of the surrounding rock of the chamber. Based on the above principles, the instability energy index Su is defined as the ratio of the sum of the static load energy Uj at the plastic-loosening boundary (r=Rs) of the surrounding rock of the chamber, the external disturbance energy Ud acting on the plastic-loosening boundary of the surrounding rock, and the energy Umc consumed by the fracture of the anchor surrounding rock.

[0043]

number

[0044] In the equation, the static load energy Uj at the plastic-loosening boundary (r=Rs) of the surrounding rock of the chamber, the external disturbance energy Ud acting on the plastic-loosening boundary of the surrounding rock, and the energy Umc consumed by the fracture of the anchor surrounding rock are all calculated according to the minimum energy criterion. This is common knowledge in this field and will not be explained in detail here.

[0045] 2.3 Since fracture of the surrounding rock is a prerequisite for instability, the fractured surrounding rock is in a critical equilibrium state and only when subjected to external disturbances does it further induce fracture and instability of the surrounding rock. Based on this mechanism, the mechanical criteria for chamber instability were constructed as follows:

[0046]

number

[0047] The above criteria embody the forms of fracture and instability of the chamber's surrounding rock structure and can better reflect the instability process of the chamber's anchoring surrounding rock.

[0048] The following explains, with reference to Figure 4 and an example, how the present invention determines the unstable state of a chamber group (1,2,3…i…k…x…n) consisting of n chambers using the above criteria.

[0049] Step 1: Based on the method for constructing the mechanical criteria for chamber instability described above, obtain the corresponding parameters for each chamber and construct the mechanical instability criteria for each chamber. Step 2: Each of the n chambers in the chamber group is evaluated one by one according to the mechanical criteria of Step 1. If all chambers are stable, the chamber group is stable. If a chamber slowly breaks, it indicates that it may be unstable. Continue the evaluation until one chamber (assuming chamber i) becomes unstable, then stop evaluating and proceed to the next step. Step 3: The instability of chamber i generates new stress and energy increases for the surrounding chambers. Under these conditions, the instability mechanical criteria for the remaining chambers are again constructed according to the method of Step 1, and the determination is continued for the remaining chambers according to the method of Step 2, this time by analogy, until determination and identification are completed for all remaining chambers.

[0050] The detailed method is as follows: 3.1: The instability of chamber i generated new static load stresses and energy increases for the surrounding chambers; in other words, the instability of chamber i altered the mechanical environment in which the other chambers are situated, and therefore the instability mechanical criteria for the remaining n-1 chambers must be reconstructed. After chamber i becomes unstable, the superimposed increment of static load stress in the surrounding chambers is as follows:

[0051]

number

[0052] In the formula, L is the distance, m, from any point in the elastic region of chamber i to the center of chamber i.

[0053] Simultaneously, the superimposed energy increment of the surrounding chambers after chamber i becomes unstable is calculated according to the minimum energy criterion. Based on the superimposed increments of static load stress and energy, the unstable stress coefficients and energy coefficients of the remaining n-1 chambers are recalculated to form a new instability mechanics criterion. Based on the new instability mechanics criterion, the unstable conditions of each of the remaining n-1 chambers are identified one by one. If all of the remaining n-1 chambers are stable, it explains that no chain instability has occurred. If another chamber (assuming it is chamber k) is unstable, the determination is stopped and the next step is taken, explaining that a chain instability has occurred in the group of chambers containing n chambers.

[0054] 3.2: Similarly, since the instabilities in chambers i and k have generated new stress and energy increases in the surrounding chambers, recalculate the instability stress index and instability energy index of the surrounding rocks for the remaining n-2 chambers, and construct a new instability mechanical criterion for the remaining n-2 chambers. Based on the new instability mechanical criterion, identify the unstable conditions of each of the remaining n-2 chambers one by one. If no instability occurs in any of the remaining n-2 chambers, the chain of instabilities ends. If any of the remaining n-2 chambers (assuming chamber x) is unstable, stop the determination and proceed to the next step.

[0055] 3.3: Reconstruct new instability dynamics criteria for the remaining n-3 chambers and determine the instability of the remaining n-3 chambers based on these criteria, continuing in this manner until the determination of all chambers is complete. Furthermore, in the determination process of steps 2 and 3 of this invention, the chambers that are slowly destroyed are recorded, which is convenient for scientifically controlling the stability of the chamber group in the later stages.

[0056] If the assessment results indicate a chain reaction of instability, the stability of the chamber group needs to be controlled. The control method involves first calculating the product of the instability stress index and the instability energy index (i.e., the chamber key coefficient) for all chambers. This chamber key coefficient is used as an index reflecting the keyness of each chamber in the chamber group; a larger chamber key coefficient indicates a higher keyness. Based on this principle, all chambers are ordered in a sequence where their keyness decreases sequentially. Then, based on the principle of priority, i.e., based on the keyness of each chamber, the stability of the surrounding rock is controlled in order from highest to lowest keyness. Simultaneously, timely measures are taken for chambers that have slowly fractured to prevent further fracture. This provides a feasible approach to interrupting chain reactions of instability. At the same time, targeted support designs are implemented based on the specific conditions of the important chambers, laying the foundation for long-term stability control of the surrounding rock of the chamber group. To illustrate the importance of the determination method of the present invention in controlling the stability of the surrounding rock of chamber groups, the method of the present invention was used to determine the stability of a group of coal waste sorting chambers at the Shandong Xinjulong Coal Mine. Based on the determination results, the use and analysis of the support scheme were developed, and long-term monitoring was conducted on the fracture surface and deep displacement of the chamber's surrounding rock, as well as the load-bearing characteristics of the anchors / cables. The results of the field monitoring showed that the integrity of the surrounding rock was relatively good, the maximum fracture depth was 2.5m, the chamber cross-sectional convergence rate was a maximum of 6.2%, meeting the deformation control requirements, the load-bearing characteristics of the anchors / cables were relatively stable, there was no obvious abscission within the surrounding rock, the chamber group remained stable for a long period during its service life, the support scheme was successful in field, and the surrounding rock control effect was good.

[0057] Of course, the above description does not limit the patent of the present invention, nor is the patent of the present invention limited to the above examples. Any modifications, alterations, additions, or substitutions made by an articulator in the art within the substantial scope of the patent of the present invention also fall within the scope of protection of the patent of the present invention. [Explanation of Symbols]

[0058] 1-chamber, 2-plastic zone, 3-Elastic zone, 4. Loosening area, 5. Newly added plastic zone.

Claims

1. A method for determining the cascading instability of the surrounding rocks of a coal mine chamber group, Based on the premise that fracture is unstable, we constructed mechanical criteria for chamber instability from two angles: stress and energy. These criteria are expressed as the instability stress index Sσ and the instability energy index Su of the surrounding rock, respectively. The mechanical criteria constructed within these criteria are: [Math 1] Step 1 is as follows: (The instability stress index of the surrounding rock is the ratio of the dynamic and static superimposed stress within the surrounding rock of the chamber to the load strength of the anchor surrounding rock, and the instability energy index of the surrounding rock is the ratio of the dynamic and static superimposed energy within the surrounding rock of the chamber to the maximum absorbed energy of the anchor surrounding rock) Step 2 involves evaluating each chamber in a chamber group containing n chambers according to the mechanical criteria of Step 1. If all chambers are stable, the chamber group is stable. If a chamber slowly breaks, it indicates a potential instability. The evaluation continues until one chamber becomes unstable, at which point the evaluation stops and the next step is initiated. Step 3 involves constructing an unstable mechanical criterion for the remaining chambers according to the method of Step 1, continuing to assess the remaining chambers according to the method of Step 2, and so on by analogy until assessment and identification are completed for all remaining chambers. including A method for determining the cascading instability of surrounding rocks in a coal mine chamber group, characterized by the following features.

2. The unstable stress index of the surrounding rock of the chamber is expressed as the ratio of the dynamic and static superimposed stress within the plastic zone of the surrounding rock of the chamber to the load strength of the anchor surrounding rock. A method for determining the cascading instability of the surrounding rocks of a coal mine chamber group as described in claim 1.

3. The method for determining the unstable stress index of the surrounding rock of the chamber involves making the cross-sectional shape of the chamber equivalent to a circle using a correction factor to determine its equivalent radius, determining the radius of the plastic zone of the surrounding rock of the chamber from the equivalent radius of the surrounding rock of the chamber, and then determining the dynamic and static superimposed stress within the range of the plastic zone and the load strength of the anchor surrounding rock. A method for determining the cascading instability of the surrounding rocks of a coal mine chamber group as described in claim 1.

4. The instability energy index of the surrounding rock is expressed as the ratio of the sum of the static load energy at the plastic-loosening boundary of the surrounding rock of the chamber, the external disturbance energy acting on the plastic-loosening boundary of the surrounding rock, and the energy consumed by the fracture of the anchor surrounding rock, wherein the loosening boundary refers to the boundary of the loosening region formed when the plastic region of the chamber is fractured when the instability stress index of the surrounding rock of the chamber is greater than 1. A method for determining the cascading instability of the surrounding rocks of a coal mine chamber group as described in claim 1.

5. The method for determining the instability energy index of the surrounding rock involves considering the loosening area as a newly excavated chamber, and determining the equivalent radius of the newly excavated chamber, i.e., the radius at the loosening boundary, by equivalentizing the cross-sectional shape of this newly excavated chamber to a circle using a correction factor. Next, the sum of the static load energy and the external disturbance energy acting on the plastic-loosening boundary of the surrounding rock, and the energy consumed by the fracture of the anchor surrounding rock can be obtained. A method for determining the cascading instability of the surrounding rocks of a coal mine chamber group as described in claim 1.

6. Step 3 above is, 3.1: Since the unstable chamber identified in step 2 generates new stress and energy increases in the surrounding chambers, based on this, the unstable stress index and unstable energy index of the surrounding rock of the remaining n-1 chambers are recalculated, a new instability mechanical criterion is constructed for the remaining n-1 chambers, and the unstable conditions of each of the remaining n-1 chambers are identified based on the new instability mechanical criterion. If all of the remaining n-1 chambers are stable, it indicates that no cascading instability has occurred. If another chamber is unstable, the determination is stopped and the next step is initiated, and at this point, it is explained that a cascading instability has occurred in the group of chambers. 3.2: Recalculate the unstable stress index and unstable energy index of the surrounding rocks for the remaining n-2 chambers, construct a new instability mechanics criterion for the remaining n-2 chambers, identify the unstable conditions of each of the remaining n-2 chambers based on the new instability mechanics criterion, and if no instability occurs in any of the remaining n-2 chambers, the chain of instability ends. If any of the remaining n-2 chambers are unstable, stop the determination and proceed to the next step. 3.3: Reconstruct new instability dynamics criteria for the remaining n-3 chambers, and determine the instability of the remaining n-3 chambers based on these criteria, continuing in this manner until the determination for all chambers is complete. A method for determining the cascading instability of surrounding rocks in a coal mine chamber group according to claim 1.

7. A method for controlling the long-term stability of a group of chambers in a coal mine, using a method for determining the cascading instability of the surrounding rocks of the chamber group, Based on the assessment results, it is determined whether or not a chain reaction of instability has occurred in the chamber group. If a chain reaction of instability has occurred, the product of the unstable stress index and the unstable energy index is defined as the chamber key coefficient. All unstable chambers are ranked according to the magnitude of their chamber key coefficients. Chambers with larger key coefficients have a higher key degree within the chamber group. Subsequently, corresponding support measures are determined based on the key degree of each unstable chamber within the chamber group. Chambers with higher key degrees require higher support measures to control their stability, and timely measures are needed to prevent further failure in chambers that have slowly failed. A method for controlling the long-term stability of a group of chambers in a coal mine using a method for determining the cascading instability of the surrounding rocks of the chamber group, characterized by the above.

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