Gob-side entry retaining method for coal pillar-free mining

Abstract

The invention relates to the technical field of coal mining, and discloses a coal-pillar-free mining gob-side entry retaining method which comprises the following steps: installing an inclinometer in a rock mass around a gob-side entry retaining, monitoring the inclination and displacement change of the rock mass by using the inclinometer, installing a rock mass stress monitor in the rock mass around the gob-side entry retaining, and monitoring the inclination and displacement change of the rock mass. The monitoring system is connected to monitor the stress state of the rock mass in real time, the acoustic emission sensor is installed in the rock mass around the gob-side entry retaining, acoustic signals generated by grain expansion and rock fracture in the rock mass are monitored, and a comprehensive change index and a safety value are calculated by combining displacement, stress, acoustic emission monitoring data and a calculation result. And then the internal safety of the gob-side entry retaining is evaluated according to the internal safety value of the gob-side entry retaining, tiny changes in the rock mass around the gob-side entry retaining are reflected in time, it is ensured that the supporting measures are always in the optimal state, the deformation trend of the surrounding rock of the roadway is predicted, potential safety hazards can be found in time, and accidents are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of coal mining, in particular to a method for coal pillar-free mining along gob-side lane retaining. Background Art

[0002] In the traditional coal mining process, in order to ensure the stability of the working face and prevent disasters such as surface collapse, coal pillars of a certain width are usually reserved between the mining areas or on both sides of the working face as supporting structures. However, this practice not only occupies a large amount of recoverable resources, but also increases the difficulty and cost of subsequent processing. With the development of science and technology, people have begun to explore a more efficient and reasonable mining model - the technology of leaving lanes along the goaf without coal pillars has emerged. Pillar-free mining refers to a method of maintaining the stability of the goaf without setting up permanent coal pillars specifically for supporting the roof pressure during underground coal mining, but using other forms of temporary or semi-permanent support systems. Pillar-free mining leaving lanes along the goaf is an advanced coal mining technology that aims to improve resource utilization, reduce production costs and improve mine safety conditions. By optimizing the layout and support methods of the goaf, the coal pillars (i.e. the coal body supporting the goaf) that must be retained in the traditional mining method are reduced or eliminated, so that more coal resources can be mined. Pillar-free mining leaving lanes along the goaf 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. In the future, with the advancement of technology and the continuous improvement of social recognition, I believe this technology will be more widely used and developed.

[0003] The goaf-retained tunnel is located at the edge of the goaf and is easily affected by the stress concentration and deformation of the surrounding rock mass, resulting in instability of the tunnel surrounding rock. The goaf-retained tunnel will be damaged by deformation and collapse due to the instability of the surrounding rock mass, increasing the safety risk of the mine. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the shortcomings of the prior art, the present invention provides a method for retaining a tunnel along the goaf in coal pillar-free mining. The method has the advantages of timely responding to slight changes in the rock mass around the tunnel along the goaf through monitoring of displacement data, stress data, and acoustic emission data, ensuring that support measures are always in the best condition, predicting the deformation trend of the tunnel surrounding rock, providing a basis for the reasonable arrangement of production plans and mining and excavation continuity, and helping to timely discover potential safety hazards and avoid accidents.

[0006] (II) Technical solution

[0007] To achieve the above object, the present invention provides the following technical solution: a method for coal pillar-free mining along the gob retaining road, comprising the following steps:

[0008] Step 1: Install an inclinometer inside the rock mass around the gob-side tunnel retaining, use the inclinometer to monitor the inclination and displacement changes of the rock mass, and record and save the monitoring data to form a displacement data set;

[0009] Step 2: Install the rock stress monitor inside the rock mass around the gob-side tunnel and 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 data set;

[0010] Step 3: Install the acoustic emission sensor inside the rock mass around the gob-side tunnel to monitor the acoustic wave signals generated by the expansion of the internal rock mass and the rock fracture, and record and save the monitoring data to form an acoustic emission data set;

[0011] Step 4: Combine the displacement data set, stress data set, and acoustic emission data set 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 gob-side entry according to the comprehensive change index;

[0014] Step 7: Assess the internal safety of the gob-retained tunnel in the mining area based on the internal safety values ​​of the gob-retained tunnel.

[0015] Preferably, in step 1, the record number of the displacement data set is: In this record number, is the first monitored displacement data, t corresponds to the monitoring time of the first monitored displacement data, is 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 recorded and numbered in the displacement data set.

[0016] Preferably, in step 2, the stress data set record number is: In this record number, is the first monitored stress data, t corresponds to the monitoring time of the first monitored stress data, is 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 recorded and numbered in the stress data set.

[0017] Preferably, in step 3, the record number of the acoustic emission data set is: In this record number, is the first monitored acoustic emission data, t corresponds to the monitoring time of the first monitored acoustic emission data, is 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 recorded and numbered in the stress data set.

[0018] Preferably, in step 4, the calculation formula of the displacement frequency change value WYbh is:

[0019]

[0020] Among them, it represents the i-th time point, represents the displacement data monitored at the it time point, (i+1)t represents the i+1th time point, represents the displacement data monitored at time point i+1, (i+1)t-it represents the time interval between adjacent monitoring time points, Represents the displacement change between adjacent monitoring time points, 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 of is used to convert the tilt angle into displacement. λ is a constant or variable used to adjust the scale of the displacement change rate. It represents the measurement spacing, instrument constant or other factors that affect the displacement measurement. The scale used to adjust the rate of change of displacement.

[0021] Preferably, in step 4, the calculation formula of the stress frequency change value YYbh is:

[0022]

[0023] in, represents the i-th stress data, represents the i-1th stress data, Represents the difference between stress monitoring data at adjacent time points, reflecting the rate of change of stress over time. It represents the sum of the differential data at all time points, combining the stress change information at all time points. Represents the conversion of time series data from the time domain to the frequency domain. represents the kth frequency component, nt-(n-1)t represents the time interval between adjacent time points, is a complex expression where x is the imaginary unit such that x 2 =-1.

[0024] Preferably, in step 4, the calculation formula of the acoustic emission frequency change value SFbh is:

[0025]

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

[0027] Preferably, in step 5, the calculation formula of the comprehensive change index ZHbh is:

[0028]

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

[0030] Preferably, in step 6, the calculation formula of the safety value AQsz is:

[0031]

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

[0033] Preferably, in step 7, the method for evaluating the internal safety of the gob-side entry is as follows:

[0034] 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-side tunnel retention.

[0035] Compared with the prior art, the present invention provides a method for coal pillar-free mining along the gob and retaining lanes, which has the following beneficial effects:

[0036] 1. The present invention monitors displacement data, stress data, and acoustic emission data to timely respond to small changes in the rock mass around the gob-side tunnel. The data set can ensure the timeliness and accuracy of the data, provide a reliable basis for subsequent analysis and decision-making, facilitate the identification of potential displacement trends and abnormal changes, and help to promptly discover and deal with safety hazards and avoid accidents.

[0037] 2. The present invention calculates a comprehensive change index by combining the displacement frequency change value, the stress frequency change value and the acoustic emission frequency change value, and then calculates a safety value based on the comprehensive change index. The support plan can be adjusted in time according to the safety assessment based on the safety value to adapt to the changes in the stress of the tunnel surrounding rock, ensure that the support measures are always in the best state, predict the deformation trend of the tunnel surrounding rock, provide a basis for the reasonable arrangement of production plans and mining and excavation succession, and alleviate the tense situation of mining and excavation succession. Through the evaluation of the comprehensive change index and the safety value, the potential risks in the coal mine production process can be comprehensively evaluated and effectively controlled to ensure the safety and stability of coal mine production. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a step diagram of the method of the present invention; DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] See also Figure 1 A method for retaining a lane along the goaf in a non-pillar mining process comprises the following steps:

[0041] Step 1: Install an inclinometer inside the rock mass around the gob-side tunnel retaining, use the inclinometer to monitor the inclination and displacement changes of the rock mass, and record and save the monitoring data to form a displacement data set;

[0042] The record numbers of the displacement dataset are: In this record number, is the first monitored displacement data, t corresponds to the monitoring time of the first monitored displacement data, is 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 recorded and numbered in the displacement data set;

[0043] Displacement data monitoring is essential for evaluating the stability of tunnels, monitoring the movement of rock formations, and the development and change of mine pressure. The data set can ensure the timeliness and accuracy of the data, provide a reliable basis for subsequent analysis and decision-making, and facilitate the identification of potential displacement trends and abnormal changes, which helps to timely discover and deal with safety hazards and avoid accidents.

[0044] Step 2: Install the rock stress monitor inside the rock mass around the gob-side tunnel and 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 data set;

[0045] The stress data set record numbers are: In this record number, is the first monitored stress data, t corresponds to the monitoring time of the first monitored stress data, is 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 recorded and numbered in the stress data set;

[0046] Real-time monitoring of surrounding rock stress status helps to timely discover potential safety hazards, such as rock deformation and crack expansion, so as to take preventive measures to avoid accidents. It can also evaluate the stability of the tunnel and provide a basis for formulating reasonable support plans to ensure the safety and stability of the tunnel during use.

[0047] Step 3: Install the acoustic emission sensor inside the rock mass around the gob-side tunnel to monitor the acoustic wave signals generated by the expansion of the internal rock mass and the rock fracture, and record and save the monitoring data to form an acoustic emission data set;

[0048] The record numbers of the acoustic emission dataset are: In this record number, is the first monitored acoustic emission data, t corresponds to the monitoring time of the first monitored acoustic emission data, is 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 recorded and numbered in the stress data set;

[0049] Acoustic emission data reflects the slight changes inside the rock mass. Through real-time analysis of acoustic emission data, early warning can be issued before the rock mass undergoes significant deformation or damage, and timely measures can be taken to prevent accidents. Acoustic emission data can reflect the stress concentration and release inside the rock mass, help evaluate the stress state of the rock mass, predict the stability of the rock mass and potential damage risks, effectively reduce the risk of mine accidents, and improve mine mining efficiency and safety;

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

[0051] The calculation formula of displacement frequency change value WYbh is:

[0052]

[0053] Among them, it represents the i-th time point, represents the displacement data monitored at the it time point, (i+1)t represents the i+1th time point, represents the displacement data monitored at time point i+1, (i+1)t-it represents the time interval between adjacent monitoring time points, Represents the displacement change between adjacent monitoring time points, 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 of is used to convert the tilt angle into displacement. λ is a constant or variable used to adjust the scale of the displacement change rate. It represents the measurement spacing, instrument constant or other factors that affect the displacement measurement. A scale for adjusting the rate of change of displacement;

[0054] The calculation formula of stress frequency change value YYbh is:

[0055]

[0056] in, represents the i-th stress data, represents the i-1th stress data, Represents the difference between stress monitoring data at adjacent time points, reflecting the rate of change of stress over time. It represents the sum of the differential data at all time points, combining the stress change information at all time points. Represents the conversion of time series data from the time domain to the frequency domain. represents the kth frequency component, nt-(n-1)t represents the time interval between adjacent time points, is a complex expression where x is the imaginary unit such that x 2 = -1;

[0057] The calculation formula of acoustic emission frequency change value SFbh is:

[0058]

[0059] in, represents the acoustic emission data monitored at the it time point, represents the acoustic emission data monitored at the (i-1)t time point, it represents the i-th time point, (i-1)t represents the i-1th time point, represents the change in acoustic emission data from the adjacent time point it to (i-1)t, it-(i-1)t represents the change in the adjacent time point it to (i-1)t, represents the rate of change of acoustic emission data from time point it to time point (i-1)t, (i-2)t represents the i-2th time point, 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, (i-1)t-(i-2)t represents the change in time from adjacent time points (i-1)t to (i-2)t, represents the rate of change of acoustic emission data from time point (i-1)t to time point (i-2)t, and 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 calculation formula of the comprehensive change index ZHbh is:

[0062]

[0063] Among them, α is the weight factor of the displacement frequency change value WYbh, β is the weight factor of the stress frequency change value YYbh, γ is the weight 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 gob-side entry according to the comprehensive change index;

[0065] The calculation formula of the safety value AQsz is:

[0066]

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

[0068] Step 7: Evaluate the internal safety of the gob-side tunnel according to the internal safety value of the gob-side tunnel;

[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 gob-side lane retention.

[0070] The comprehensive change index is calculated by combining the displacement frequency change value, stress frequency change value and acoustic emission frequency change value, and then the safety value is calculated based on the comprehensive change index. Safety assessment based on the safety value can adjust the support plan in time to adapt to the changes in the tunnel surrounding rock stress, ensure that the support measures are always in the best state, predict the deformation trend of the tunnel surrounding rock, provide a basis for the reasonable arrangement of production plans and mining and excavation succession, and alleviate the tense situation of mining and excavation succession. Through the evaluation of the comprehensive change index and safety value, the potential risks in the coal mine production process can be comprehensively evaluated and effectively controlled to ensure the safety and stability of coal mine production.

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

Claims

1. A method for coal pillar-free mining with gob-side entry retention, characterized in that: The following steps are involved: Step 1: Install an inclinometer inside the rock mass around the gob-side tunnel retaining, use the inclinometer to monitor the inclination and displacement changes of the rock mass, and record and save the monitoring data to form a displacement data set; Step 2: Install the rock stress monitor inside the rock mass around the gob-side tunnel and 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 data set; Step 3: Install the acoustic emission sensor inside the rock mass around the gob-side tunnel to monitor the acoustic wave signals generated by the expansion of the internal rock mass and the rock fracture, and record and save the monitoring data to form an acoustic emission data set; Step 4: Combine the displacement data set, stress data set, and acoustic emission data set to calculate the displacement frequency change value WYbh, the stress frequency change value YYbh, and the acoustic emission frequency change value SFbh; 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; Step 6: Calculate the internal safety value AQsz of the gob-side entry according to the comprehensive change index; Step 7: Assess the internal safety of the gob-retained tunnel in the mining area based on the internal safety values ​​of the gob-retained tunnel.

2. A method for retaining gob-side entry in coal-pillar-free mining according to claim 1, characterized in that: In step 1, the record number of the displacement data set is: In this record number, is the first monitored displacement data, t corresponds to the monitoring time of the first monitored displacement data, is 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 recorded and numbered in the displacement data set.

3. A method for coal pillar-free mining and gob-side entry retention according to claim 1, characterized in that: In step 2, the stress data set record number is: In this record number, is the first monitored stress data, t corresponds to the monitoring time of the first monitored stress data, is 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 recorded and numbered in the stress data set.

4. The method for retaining gob-side entry in coal-pillar-free mining according to claim 1, characterized in that: In step 3, the record number of the acoustic emission data set is: In this record number, is the first monitored acoustic emission data, t corresponds to the monitoring time of the first monitored acoustic emission data, is 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 recorded and numbered in the stress data set.

5. The method for retaining gob-side entry in coal-pillar-free mining according to claim 2, characterized in that: In step 4, the calculation formula of the displacement frequency change value WYbh is: Among them, it represents the i-th time point, represents the displacement data monitored at the it time point, (i+1)t represents the i+1th time point, represents the displacement data monitored at time point i+1, (i+1)t-it represents the time interval between adjacent monitoring time points, Represents the displacement change between adjacent monitoring time points, 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 of is used to convert the tilt angle into displacement. λ is a constant or variable used to adjust the scale of the displacement change rate. It represents the measurement spacing, instrument constant or other factors that affect the displacement measurement. The scale used to adjust the rate of change of displacement.

6. A method for retaining gob-side entry in coal pillar-free mining according to claim 3, characterized in that: In step 4, the calculation formula of the stress frequency change value YYbh is: in, represents the i-th stress data, represents the i-1th stress data, Represents the difference between stress monitoring data at adjacent time points, reflecting the rate of change of stress over time. It represents the sum of the differential data at all time points, combining the stress change information at all time points. Represents the conversion of time series data from the time domain to the frequency domain. represents the kth frequency component, nt-(n-1)t represents the time interval between adjacent time points, is a complex expression where x is the imaginary unit such that x 2 =-1.

7. A method for coal pillar-free mining and gob-side entry retention according to claim 4, characterized in that: In step 4, the calculation formula of the acoustic emission frequency change value SFbh is: in, represents the acoustic emission data monitored at the it time point, represents the acoustic emission data monitored at the (i-1)t time point, it represents the i-th time point, (i-1)t represents the i-1th time point, represents the change in acoustic emission data from the adjacent time point it to (i-1)t, it-(i-1)t represents the change in the adjacent time point it to (i-1)t, represents the rate of change of acoustic emission data from time point it to time point (i-1)t, (i-2)t represents the i-2th time point, 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, (i-1)t-(i-2)t represents the change in time from adjacent time points (i-1)t to (i-2)t, It represents the rate of change of acoustic emission data from time point (i-1)t to time point (i-2)t, and i>

2.

8. A method for retaining gob-side entry in coal-pillar-free mining according to claim 7, characterized in that: In step 5, the calculation formula of the comprehensive change index ZHbh is: Among them, α is the weight factor of the displacement frequency change value WYbh, β is the weight factor of the stress frequency change value YYbh, γ is the weight factor of the acoustic emission frequency change value SFbh, and α+β+γ=1.

9. A method for retaining gob-side entry in coal pillar-free mining according to claim 8, characterized in that: In step 6, the calculation formula of the safety value AQsz is: Among them, ω is the threshold of the comprehensive change index ZHbh, and AQbh is the safety comprehensive change index.

10. A method for retaining gob-side entry in coal-pillar-free mining according to claim 9, characterized in that: In step 7, the method for evaluating the internal safety of the gob-side tunnel is as follows: 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-side tunnel retention.

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