A method for leaving roadways along the goaf in pillarless mining

Abstract

This invention relates to the field of coal mining technology and discloses a method for pillarless mining with roadway retention along the goaf, comprising: installing an inclinometer inside the rock mass surrounding the roadway retention to monitor the inclination and displacement changes of the rock mass; installing a rock mass stress monitor inside the rock mass surrounding the roadway retention and connecting it to a monitoring system to monitor the stress state of the rock mass in real time; installing an acoustic emission sensor inside the rock mass surrounding the roadway retention to monitor the acoustic signals generated by the expansion of internal cracks and rock fracturing; calculating a comprehensive change index and a safety value by combining displacement, stress, acoustic emission monitoring data and calculation results; and then assessing the safety of the roadway retention area based on the safety value inside the roadway retention area. This method promptly reflects minute changes inside the rock mass surrounding the roadway retention area, ensures that the support measures are always in optimal condition, predicts the deformation trend of the surrounding rock, and helps to promptly detect potential safety hazards and avoid accidents.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, specifically to a method for pillarless mining with roadway retention along the goaf. Background Technology

[0002] In traditional coal mining, to ensure the stability of the working face and prevent disasters such as surface subsidence, coal pillars of a certain width are usually reserved between mining areas or on both sides of the working face as support structures. However, this practice not only occupies a large amount of mineable resources but also increases the difficulty and cost of subsequent processing. With the development of science and technology, people have begun to explore more efficient and reasonable mining models—the pillarless mining and gob-side roadway retention technology has emerged. Pillarless mining refers to a method in which, during underground coal mining, permanent coal pillars are not set up specifically to support the roof pressure, but other forms of temporary or semi-permanent support systems are used to maintain the stability of the roadway. Pillarless mining and gob-side roadway retention is an advanced coal mining technology that aims to improve resource utilization, reduce production costs, and improve mine safety conditions. By optimizing the roadway layout and support methods, it reduces or eliminates the coal pillars (i.e., the coal body supporting the roadway) that must be retained in traditional mining methods, thereby allowing more coal resources to be mined. Pillarless mining and gob-side roadway retention is a technological innovation project with great development potential. It can not only bring considerable economic benefits to enterprises but also promote the transformation and upgrading of the entire coal industry. With technological advancements and increasing social acceptance, this technology is expected to see wider application and development in the future.

[0003] The roadway along the goaf is located at the edge of the goaf area and is easily affected by the stress concentration and deformation of the surrounding rock mass, which leads to the instability of the surrounding rock. The roadway along the goaf will be damaged by deformation and collapse due to the instability of the surrounding rock mass, which increases the safety risk of the mine. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for pillarless mining with roadway retention along the goaf. This method features the ability to monitor displacement data, stress data, and acoustic emission data to promptly reflect minute changes within the rock mass surrounding the roadway, ensuring that support measures are always in optimal condition, predicting the deformation trend of the surrounding rock, providing a basis for rationally arranging production plans and mining succession, and helping to promptly identify potential safety hazards and prevent accidents.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for pillarless mining with roadway retention along the goaf, comprising the following steps:

[0008] Step 1: Install an inclinometer inside the rock mass surrounding the goaf-side tunnel, use the inclinometer to monitor the tilt and displacement changes of the rock mass, and record and save the monitoring data to form a displacement dataset.

[0009] Step 2: Install the rock mass stress monitor inside the rock mass surrounding the goaf-side roadway, connect it to the monitoring system to monitor the stress state of the rock mass in real time, and record and save the monitoring data to form a stress dataset.

[0010] Step 3: Install acoustic emission sensors inside the rock mass surrounding the goaf-keeping tunnel to monitor the acoustic signals generated by the propagation of internal cracks and rock fracturing, and record and save the monitoring data to form an acoustic emission dataset.

[0011] Step 4: Combine the displacement dataset, stress dataset, and acoustic emission dataset to calculate the displacement frequency change value WYbh, the stress frequency change value YYbh, and the acoustic emission frequency change value SFbh.

[0012] Step 5: Calculate the comprehensive change index ZHbh by combining the displacement frequency change value WYbh, the stress frequency change value YYbh, and the acoustic emission frequency change value SFbh.

[0013] Step 6: Calculate the internal safety value AQsz of the goaf retention roadway based on the comprehensive change index;

[0014] Step 7: Assess the internal safety of the goaf retainer based on the internal safety values.

[0015] Preferably, in step one, the record number of the displacement dataset is: In this record number, This represents the first monitored displacement data, and t corresponds to the monitoring time for that first monitored displacement data. For the nth monitored displacement data, nt corresponds to the monitoring time of the nth monitored displacement data, and n represents the total number of n displacement data points recorded in the displacement dataset.

[0016] Preferably, in step two, the stress dataset record number is: In this record number, This represents the first stress data point monitored, and t corresponds to the monitoring time for that first stress data point. For the nth monitored stress data, nt corresponds to the monitoring time of the nth monitored stress data, and n represents the total number of stress data recorded in the stress dataset.

[0017] Preferably, in step three, the record number of the acoustic emission dataset is: In this record number, Let t represent the first monitored acoustic emission data, and t correspond to the monitoring time of the first monitored acoustic emission data. For the nth monitored acoustic emission data, nt corresponds to the monitoring time of the nth monitored acoustic emission data, and n represents the total number of recorded acoustic emission data in the stress dataset.

[0018] Preferably, in step four, the formula for calculating the displacement frequency change value WYbh is:

[0019]

[0020] Where it represents the i-th time point, This represents the displacement data monitored at time point 'it', where (i+1)t represents the (i+1)th time point. This represents the displacement data monitored at time point i+1, where (i+1)t-it represents the time interval between adjacent monitoring time points. This represents the change in displacement between adjacent monitoring time points. The value represents the rate of change of displacement over time, sin(θ). i ) represents the tilt angle θ measured at time point it. i The sine value is used to convert the tilt angle into displacement. λ is a constant or variable used to adjust the scale of the rate of change of displacement, representing the measurement interval, instrument constant, or other factors affecting displacement measurement. A scale used to adjust the rate of change of displacement.

[0021] Preferably, in step four, the formula for calculating the stress frequency change value YYbh is:

[0022]

[0023] in, Represents the i-th stress data. Represents the (i-1)th stress data. The difference in stress monitoring data at adjacent time points reflects the rate of change of stress over time. This represents the summation of differential data across all time points, incorporating stress variation information at all time points. This represents the transformation of time series data from the time domain to the frequency domain. Represents the k-th frequency component, and nt-(n-1)t represents the time interval between adjacent time points. It is a complex number expression where x is the imaginary unit, satisfying x 2 =-1.

[0024] Preferably, in step four, the formula for calculating the acoustic emission frequency change value SFbh is:

[0025]

[0026] in, This represents the acoustic emission data monitored at the time point it. This represents the acoustic emission data monitored at time point (i-1)t, where it represents the i-th time point and (i-1)t represents the (i-1)-th time point. It represents the change in acoustic emission data from adjacent time points it to (i-1)t, and it-(i-1)t represents the change in time from adjacent time points it to (i-1)t. This represents the rate of change of acoustic emission data from time point it to time point (i-1)t, where (i-2)t represents the (i-2)th time point. This represents the acoustic emission data monitored at time point (i-2)t. represents the change in acoustic emission data from adjacent time points (i-1)t to (i-2)t, and (i-1)t-(i-2)t represents the change in time from adjacent time points (i-1)t to (i-2)t. Let represent the rate of change of acoustic emission data from time point (i-1)t to time point (i-2)t, where i>2.

[0027] Preferably, in step five, the formula for calculating the comprehensive change index ZHbh is:

[0028]

[0029] Where α is the weighting factor of the displacement frequency change value WYbh, β is the weighting factor of the stress frequency change value YYbh, and γ is the weighting factor of the acoustic emission frequency change value SFbh, and α+β+γ=1.

[0030] Preferably, in step six, the formula for calculating the safety value AQsz is:

[0031]

[0032] Where ω is the threshold of the comprehensive change index ZHbh, and AQbh is the comprehensive safety change index.

[0033] Preferably, in step seven, the method for assessing the safety inside the goaf-side retaining roadway is as follows:

[0034] When the safety value AQsz is less than the safety value threshold, it indicates that there is a safety risk in the currently set goaf retention.

[0035] Compared with the prior art, the present invention provides a method for pillarless mining with roadway retention along the goaf, which has the following beneficial effects:

[0036] 1. This invention monitors displacement data, stress data, and acoustic emission data to promptly reflect minute changes within the rock mass surrounding the goaf-retention tunnel. The dataset ensures the timeliness and accuracy of the data, providing a reliable basis for subsequent analysis and decision-making. It facilitates the identification of potential displacement trends and abnormal changes, helps to promptly detect and address safety hazards, and prevents accidents from occurring.

[0037] 2. This invention calculates a comprehensive change index by combining the changes in displacement frequency, stress frequency, and acoustic emission frequency. Then, it calculates a safety value based on this comprehensive change index. Safety assessments based on these safety values ​​allow for timely adjustments to support schemes to adapt to changes in roadway surrounding rock stress, ensuring support measures are always in optimal condition. It also predicts the deformation trend of the roadway surrounding rock, providing a basis for rationally arranging production plans and mining succession, alleviating the tension in mining succession. Through the assessment of the comprehensive change index and safety values, potential risks in the coal mine production process can be comprehensively assessed and effectively controlled, ensuring the safety and stability of coal mine production. Attached Figure Description

[0038] Figure 1 This is a diagram illustrating the steps of the method of the present invention; Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figure 1 A method for pillarless mining with roadway retention along the goaf, comprising the following steps:

[0041] Step 1: Install an inclinometer inside the rock mass surrounding the goaf-side tunnel, use the inclinometer to monitor the tilt and displacement changes of the rock mass, and record and save the monitoring data to form a displacement dataset.

[0042] The record numbers in the displacement dataset are: In this record number, This represents the first monitored displacement data, and t corresponds to the monitoring time for that first monitored displacement data. For the nth monitored displacement data, nt corresponds to the monitoring time of the nth monitored displacement data, and n represents that there are a total of n displacement data in the displacement dataset that are recorded and numbered.

[0043] Displacement data monitoring is crucial for assessing roadway stability, monitoring rock movement and the development and changes in mine pressure. Data sets ensure the timeliness and accuracy of data, providing a reliable basis for subsequent analysis and decision-making. They facilitate the identification of potential displacement trends and abnormal changes, helping to promptly detect and address safety hazards and prevent accidents.

[0044] Step 2: Install the rock mass stress monitor inside the rock mass surrounding the goaf-side roadway, connect it to the monitoring system to monitor the stress state of the rock mass in real time, and record and save the monitoring data to form a stress dataset.

[0045] The stress dataset record number is: In this record number, This represents the first stress data point monitored, and t corresponds to the monitoring time for that first stress data point. For the nth monitored stress data, nt corresponds to the monitoring time of the nth monitored stress data, and n represents that there are a total of n stress data in the stress dataset that are recorded and numbered.

[0046] Real-time monitoring of the stress state of the surrounding rock helps to promptly detect potential safety hazards, such as rock deformation and crack propagation, thereby enabling preventive measures to be taken to avoid accidents. It can also assess the stability of the roadway, providing a basis for developing reasonable support schemes and ensuring the safety and stability of the roadway during use.

[0047] Step 3: Install acoustic emission sensors inside the rock mass surrounding the goaf-keeping tunnel to monitor the acoustic signals generated by the propagation of internal cracks and rock fracturing, and record and save the monitoring data to form an acoustic emission dataset.

[0048] The record numbers in the acoustic emission dataset are: In this record number, Let t represent the first monitored acoustic emission data, and t correspond to the monitoring time of the first monitored acoustic emission data. For the nth monitored acoustic emission data, nt corresponds to the monitoring time of the nth monitored acoustic emission data, and n represents that there are a total of n acoustic emission data in the stress dataset for recording and numbering;

[0049] Acoustic emission data reflects minute changes within the rock mass. Real-time analysis of acoustic emission data can provide early warnings before significant deformation or failure of the rock mass occurs, allowing for timely measures to prevent accidents. Acoustic emission data can also reflect stress concentration and release within the rock mass, helping to assess the stress state of the rock mass, predict its stability and potential failure risks, effectively reduce mine accident risks, and improve mine efficiency and safety.

[0050] Step 4: Combine the displacement dataset, stress dataset, and acoustic emission dataset to calculate the displacement frequency change value WYbh, the stress frequency change value YYbh, and the acoustic emission frequency change value SFbh.

[0051] The formula for calculating the displacement frequency change value WYbh is:

[0052]

[0053] Where it represents the i-th time point, This represents the displacement data monitored at time point 'it', where (i+1)t represents the (i+1)th time point. This represents the displacement data monitored at time point i+1, where (i+1)t-it represents the time interval between adjacent monitoring time points. This represents the change in displacement between adjacent monitoring time points. The value represents the rate of change of displacement over time, sin(θ). i ) represents the tilt angle θ measured at time point it. i The sine value is used to convert the tilt angle into displacement. λ is a constant or variable used to adjust the scale of the rate of change of displacement, representing the measurement interval, instrument constant, or other factors affecting displacement measurement. A scale used to adjust the rate of displacement change;

[0054] The formula for calculating the stress frequency variation value YYbh is:

[0055]

[0056] in, Represents the i-th stress data. Represents the (i-1)th stress data. The difference in stress monitoring data at adjacent time points reflects the rate of change of stress over time. This represents the summation of differential data across all time points, incorporating stress variation information at all time points. This represents the transformation of time series data from the time domain to the frequency domain. Represents the k-th frequency component, and nt-(n-1)t represents the time interval between adjacent time points. It is a complex number expression where x is the imaginary unit, satisfying x 2 =-1;

[0057] The formula for calculating the acoustic emission frequency variation SFbh is:

[0058]

[0059] in, This represents the acoustic emission data monitored at the time point it. This represents the acoustic emission data monitored at time point (i-1)t, where it represents the i-th time point and (i-1)t represents the (i-1)-th time point. It represents the change in acoustic emission data from adjacent time points it to (i-1)t, and it-(i-1)t represents the change in time from adjacent time points it to (i-1)t. This represents the rate of change of acoustic emission data from time point it to time point (i-1)t, where (i-2)t represents the (i-2)th time point. This represents the acoustic emission data monitored at time point (i-2)t. represents the change in acoustic emission data from adjacent time points (i-1)t to (i-2)t, and (i-1)t-(i-2)t represents the change in time from adjacent time points (i-1)t to (i-2)t. Let represent the rate of change of acoustic emission data from time point (i-1)t to time point (i-2)t, where i>2;

[0060] Step 5: Calculate the comprehensive change index ZHbh by combining the displacement frequency change value WYbh, the stress frequency change value YYbh, and the acoustic emission frequency change value SFbh.

[0061] The formula for calculating the comprehensive change index ZHbh is:

[0062]

[0063] Where α is the weighting factor of the displacement frequency change value WYbh, β is the weighting factor of the stress frequency change value YYbh, and γ is the weighting factor of the acoustic emission frequency change value SFbh, and α+β+γ=1;

[0064] Step 6: Calculate the internal safety value AQsz of the goaf retention roadway based on the comprehensive change index;

[0065] The formula for calculating the safety value AQsz is:

[0066]

[0067] Where ω is the threshold of the comprehensive change index ZHbh, and AQbh is the comprehensive safety change index;

[0068] Step 7: Assess the internal safety of the goaf retainer based on the internal safety values.

[0069] When the safety value AQsz is less than the safety value threshold, it means that there is a safety risk in the currently set goaf retention.

[0070] By combining the changes in displacement frequency, stress frequency, and acoustic emission frequency, a comprehensive change index is calculated. Then, a safety value is calculated based on this comprehensive change index. Safety assessments based on these safety values ​​allow for timely adjustments to support schemes to adapt to changes in the stress of the surrounding rock in the roadway, ensuring that support measures are always in optimal condition. This also helps predict the deformation trend of the surrounding rock, providing a basis for rationally arranging production plans and mining succession, alleviating the tension in mining succession. Through the assessment of the comprehensive change index and safety values, potential risks in the coal mine production process can be comprehensively assessed and effectively controlled, ensuring the safety and stability of coal mine production.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for pillarless mining with roadway retention along the goaf, characterized in that, Includes the following steps: Step 1: Install an inclinometer inside the rock mass surrounding the goaf-side tunnel, use the inclinometer to monitor the tilt and displacement changes of the rock mass, and record and save the monitoring data to form a displacement dataset. In step one, the record numbers of the displacement dataset are: In the record number, This is the first monitored displacement data. The monitoring time corresponding to the first monitored displacement data, For the first Displacement data from monitoring, Corresponding to the The monitoring time of each monitored displacement data. The displacement dataset contains a total of Each displacement data point is recorded and numbered; Step 2: Install the rock mass stress monitor inside the rock mass surrounding the goaf-side roadway, connect it to the monitoring system to monitor the stress state of the rock mass in real time, and record and save the monitoring data to form a stress dataset. Step 3: Install acoustic emission sensors inside the rock mass surrounding the goaf-keeping tunnel to monitor the acoustic signals generated by the propagation of internal cracks and rock fracturing, and record and save the monitoring data to form an acoustic emission dataset. Step 4: Calculate the displacement frequency change value by combining the displacement dataset, stress dataset, and acoustic emission dataset. Stress frequency variation value and the change in acoustic emission frequency ; In step four, the displacement frequency change value The calculation formula is: in, Representing the At a certain point in time, Representative at Displacement data monitored at specific time points, Representing the At a certain point in time, represent Displacement data monitored at specific time points, This represents the time interval between adjacent monitoring time points. This represents the change in displacement between adjacent monitoring time points. The symbol represents the rate of change of displacement over time. Represents a point in time Measured tilt angle The sine value is used to convert the tilt angle into displacement. It is a constant or variable used to adjust the scale of the rate of change of displacement, representing the measurement interval, instrument constant, or other factors that affect displacement measurement. A scale used to adjust the rate of displacement change; Step 5: Combine the displacement frequency change value Stress frequency variation value and the change in acoustic emission frequency Calculate the comprehensive change index ; Step Six: Based on the comprehensive change index Calculate the internal safety values ​​of the goaf-retaining roadway. ; Step 7: Based on the safety values ​​inside the goaf-side retaining roadway. An assessment of the internal safety of the goaf-retaining roadway was conducted.

2. The method for pillarless mining with roadway retention according to claim 1, characterized in that: In step two, the stress dataset record number is: In the record number, This is the first stress data monitored. The monitoring time corresponding to the first monitored stress data, For the first The stress data monitored, Corresponding to the The monitoring time of each monitored stress data, The representative stress dataset contains a total of Each stress data point is recorded and numbered.

3. The method for pillarless mining with roadway retention according to claim 1, characterized in that: In step three, the record numbers of the acoustic emission dataset are: In the record number, This is the first monitored acoustic emission data. The monitoring time corresponding to the first monitored acoustic emission data, For the first One monitored acoustic emission data, Corresponding to the The monitoring time of each monitored acoustic emission data, The representative stress dataset contains a total of Each acoustic emission data point is recorded and numbered.

4. The method for leaving a roadway along the goaf in pillarless mining according to claim 2, characterized in that: In step four, the stress frequency change value The calculation formula is: in, Representing the One stress data point, Representing the One stress data point, The difference in stress monitoring data at adjacent time points reflects the rate of change of stress over time. This represents the summation of differential data across all time points, incorporating stress variation information at all time points. This represents the transformation of time series data from the time domain to the frequency domain. Representing the One frequency component, Represents the time interval between adjacent time points. It is a complex expression, where It is the imaginary unit, satisfying .

5. The method for pillarless mining with roadway retention according to claim 3, characterized in that: In step four, the change value of acoustic emission frequency The calculation formula is: in, Representative at Acoustic emission data monitored at specific time points, Representative at Acoustic emission data monitored at specific time points, Representing the At a certain point in time, Representing the At a certain point in time, Representing adjacent time points arrive The change in acoustic emission data, Representing adjacent time points arrive The amount of change over time Indicates from Time's up Rate of change of acoustic emission data at time points Representing the At a certain point in time, Representative at Acoustic emission data monitored at specific time points, Representing adjacent time points arrive The change in acoustic emission data, Representing adjacent time points arrive The amount of change over time Indicates from Time's up The rate of change of acoustic emission data at time points, and, .

6. The method for pillarless mining with roadway retention according to claim 5, characterized in that: In step five, the comprehensive change index The calculation formula is: in, The displacement frequency change value Weighting factors The stress frequency variation value Weighting factors The change in acoustic emission frequency The weighting factors, and .

7. The method for pillarless mining with roadway retention according to claim 6, characterized in that: In step six, the safety value The calculation formula is: in, Comprehensive change index The threshold, The comprehensive safety change index.

8. The method for pillarless mining with roadway retention according to claim 7, characterized in that: In step seven, the method for assessing the internal safety of the goaf-side retaining roadway is as follows: When the security value If the value is less than the safety threshold, it means that the currently set goaf retention method poses a safety risk.

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