A method for determining coal mine rock burst charge monitoring index and its critical warning initial value

Abstract

The present invention provides a method for determining a coal mine rock burst charge monitoring index and its critical warning initial value, including: on-site sampling and processing; installation and testing of a charge monitoring system, a loading system, and a shielding system; laboratory testing of charge induction law in the uniaxial compression failure process of coal samples; determining a charge monitoring index (average charge and charge variation coefficient) according to the test results of the charge induction law of coal samples; determining a charge critical coefficient according to the ratio of the average charge and the charge variation coefficient in the compaction elastic stage and the enhanced damage stage of the coal sample rupture process; conducting on-site charge monitoring in the coal seam tunnel of the rock burst mine without mining influence to obtain a standard value of the charge monitoring index; multiplying the standard value of the charge monitoring index by the critical charge coefficient to obtain the critical warning initial value of the corresponding mine rock burst charge monitoring index. The method can quickly and conveniently determine the initial warning value of the charge monitoring index, and can be used for quantitative and precise monitoring of rock burst disasters in deep mines by charge induction technology, which has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of safe mining of mines, and in particular relates to a method for determining a coal mine rock burst charge monitoring index and a critical early warning initial value thereof. Background Art

[0002] As my country's shallow coal resources decrease year by year, coal mining has gradually shifted to deep areas, which has significantly increased the frequency and intensity of rock bursts, seriously restricting the safe and efficient mining of deep coal resources. Therefore, the research on rock burst disaster monitoring methods and means has become an important scientific issue to ensure the safe and efficient mining of coal resources.

[0003] The deformation and destruction process of coal and rock mass generates electric charge due to factors such as piezoelectric effect, friction, and tip charge separation caused by microfracture. The charge signal generated in the deformation and fracture process of coal and rock is closely related to the dynamic process of coal and rock, which can be used as early warning information of changes in mechanical properties and dynamic manifestations in the fracture process of coal and rock, thus forming the charge induction monitoring technology of rock burst. However, most of the previous studies on charge induction studied the change law of coal and rock charge from the perspective of changes in sample failure stress under different loading modes or different types of coal and rock samples, or conducted qualitative research on the relationship between the charge induction law of rock burst mine tunnels and the distribution of advance support pressure. No charge monitoring indicators and critical warning values ​​of coal and rock dynamic disasters were given, so it is difficult to provide effective guidance for monitoring and early warning of rock burst on site.

[0004] Therefore, a method is needed to determine the charge monitoring index of coal mine rock burst and its critical warning initial value, which can be used for quantitative and precise monitoring and early warning of on-site rock burst using charge sensing technology in the future. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for determining coal mine rock burst charge monitoring indicators and their critical warning initial values, namely, the charge monitoring indicators and their critical warning initial values ​​are determined by combining laboratory tests on the charge law of coal sample load fracture with field tests on charge monitoring in underground tunnels, thereby providing quantitative and precise guidance for on-site rock burst charge monitoring and early warning.

[0006] The technical solution of the present invention is achieved in this way:

[0007] A method for determining a coal mine rock burst charge monitoring index and a critical warning initial value thereof comprises the following steps:

[0008] Step 1: Conduct laboratory tests on the charge induction law of coal sample uniaxial compression failure process; specifically include:

[0009] Step 1-1, on-site sampling and processing;

[0010] Step 1-2: Installation and testing of the charge monitoring system;

[0011] Step 1-3, load system installation test;

[0012] Step 1-4: Shielding system installation test;

[0013] Step 1-5: monitor the charge induction law during the uniaxial compression failure process of the coal sample.

[0014] Step 2: Determine the charge monitoring index based on the charge induction law test of the coal sample uniaxial compression failure process, including the average charge q mn and the charge variation coefficient q cv ; Specifically include:

[0015] Average charge q mn is the average value of the charge carried by all charge signals sensed within the Δt time, and the expression is (where q i is the charge amount of each charge signal induced within Δt time), which reflects the overall stress level of the coal body under the external load. mn As a charge monitoring indicator for coal instability and destruction.

[0016] Charge variation coefficient q cv is the discrete degree of charge quantity of all charge signals sensed within the time Δt, and the expression is (where q sd is the standard deviation of all charge signals sensed within Δt time), which reflects the degree of cracking of the coal body under the action of external load. cv As a charge monitoring indicator for coal instability and destruction.

[0017] Step 3: Determine the charge critical coefficient according to the ratio of the charge monitoring index in the strengthening damage stage and the compaction elastic stage of the uniaxial compression failure process of the coal sample; specifically including:

[0018] Step 3-1, the uniaxial compression failure process of the coal sample is divided into the compression elasticity, enhanced damage and post-peak failure stages;

[0019] Step 3-2: Count the average charge q of the compression elasticity and enhanced damage stages of each coal sample during the fracture process mn and the charge variation coefficient q cv The ratio of the average charge in the enhanced damage stage to the compact elastic stage is taken as the critical coefficient of the average charge k1; the ratio of the charge variation coefficient in the enhanced damage stage to the compact elastic stage is taken as the critical coefficient of charge variation k2.

[0020] Step 4: Conduct on-site charge monitoring in the coal seam tunnel of the rock burst mine without mining influence area to obtain the standard value of the charge monitoring index; specifically including:

[0021] Step 4-1, drill charge monitoring holes in the coal seam tunnel of the same rock burst mine as the sampling area without mining influence area, drill one monitoring hole every 10m, and drill 10 monitoring holes in total;

[0022] Step 4-2: Use a charge monitor to perform downhole monitoring on 10 charge monitoring holes every day, with a monitoring period of 15 days;

[0023] Step 4-3: Calculate the average charge of each charge monitoring point during the monitoring period, denoted as q mn1 ,q mn2 ……q mn10 ; and the coefficient of variation of the average charge, denoted as q cv1 ,q cv2 ……q cv10 ;

[0024] Step 4-4: Calculate the weighted average of the average charge of the 10 charge monitoring points to obtain the standard value of the average charge, recorded as The weighted average of the average charge variation coefficient of the 10 charge monitoring points is then used to obtain the standard value of the charge variation coefficient, which is recorded as

[0025] Step 5: Multiply the standard value of the charge monitoring index by the charge critical coefficient to obtain the critical warning initial value of the corresponding mine rock burst charge monitoring index; specifically including:

[0026] Step 5-1: Set the average charge standard value Multiplying by the average charge critical coefficient k1, we get the average charge critical warning initial value, recorded as Q;

[0027] Step 5-2: Set the charge variation coefficient standard value Multiplying it by the critical coefficient k2 of the charge variation coefficient gives the initial value of the critical warning of the charge variation coefficient, recorded as Q cv .

[0028] Beneficial effects of the invention: In order to improve the charge induction method for predicting and forecasting rock burst in coal mines, the invention proposes a method for determining a charge monitoring index and its critical warning initial value. This method can quickly and conveniently determine the charge monitoring index and its critical warning initial value, and can be used for quantitative and precise monitoring of rock burst disasters in deep mines using charge induction technology, which has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1The present invention is a flow chart of a method for determining a charge monitoring indicator and its critical warning initial value according to a specific implementation mode of the present invention.

[0030] Figure 2 This is a schematic diagram of monitoring the load fracture charge of a coal sample in step 1 of a specific implementation method of the present invention.

[0031] Figure 3 These are the test results of the charge induction law of uniaxial compression failure of coal samples in step 2 and step 3 of the specific implementation method of the present invention, and the division results of the compression elastic stage and the strengthening damage stage of the coal sample fracture process.

[0032] Figure 4 It is a schematic diagram of the arrangement of underground on-site charge monitoring points in step 4 of a specific implementation method of the present invention. DETAILED DESCRIPTION

[0033] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0034] A method for determining a charge monitoring index and its critical warning initial value, such as Figure 1 As shown, the following steps are included:

[0035] Step 1: Conduct laboratory tests on the charge induction law during the uniaxial compression failure process of coal samples.

[0036] Test system such as Figure 2 As shown, it includes a loading system 1, a charge monitoring system 2, a shielding system 3 and a coal sample 4. The specific test process is as follows:

[0037] Step 1-1, on-site sampling and processing;

[0038] Step 1-2: Installation and testing of the charge monitoring system;

[0039] Step 1-3, load system installation test;

[0040] Step 1-4: Shielding system installation test;

[0041] Step 1-5: Monitor the charge induction law of the coal sample during uniaxial compression failure, record the load and charge signal data of the coal sample during the fracture process, and obtain the Figure 3 The test results are shown. Figure 3 The curves showing the stress and induced charge signal changes with time during the coal sample fracture process can reflect the change law of the induced charge signal with load at different stages of the coal sample fracture process. The charge signal is relatively stable at the initial loading stage, and the charge signal is significantly enhanced before the failure.

[0042] Step 2: According to the laboratory test results of the charge induction law in the uniaxial compression failure process of coal samples (see Figure 3), the charge signal amplitude (charge amount) is closely related to the stress level of the coal sample; the abnormal change of the charge signal is consistent with the stress mutation. Therefore, the charge monitoring index is determined as the average charge amount q mn and the charge variation coefficient q cv The specific process is as follows:

[0043] Step 2-1: After statistical analysis, the average charge q mn is the average value of the charge carried by all charge signals sensed within the Δt time, and the expression is (where q i is the charge amount of each charge signal induced within Δt time), which reflects the overall stress level of the coal body under the external load. mn As a charge monitoring indicator for coal body instability and destruction;

[0044] Step 2-2, charge variation coefficient q cv is the discrete degree of charge quantity of all charge signals sensed within the time Δt, and the expression is (where q sd is the standard deviation of all charge signals sensed within Δt time), which reflects the degree of cracking of the coal body under the action of external load. cv As a charge monitoring indicator for coal body instability and destruction;

[0045] Step 3: According to the fact that the front of the underground coal mining face is divided into the original rock stress zone and the stress increase zone, the coal sample fracture process is divided into the compaction elastic stage and the enhanced damage stage, such as Figure 3 As shown, the critical charge coefficient is determined by combining the compaction elasticity and the charge induction law in the enhanced damage stage. The specific process is as follows:

[0046] Step 3-1: The uniaxial compression failure process of the coal sample is divided into compression elasticity (0~70%σ c , σ c is the uniaxial compressive strength of the coal sample), strengthening damage (70% to 100% σ c ) and post-peak destruction phase;

[0047] Step 3-2: Count the average charge q of the compression elasticity and enhanced damage stages of each coal sample during the fracture process mn and the charge variation coefficient q cv The ratio of the average charge in the enhanced damage stage to the compact elastic stage is taken as the critical coefficient of average charge k1; the ratio of the charge variation coefficient in the enhanced damage stage to the compact elastic stage is taken as the critical coefficient of charge variation k2;

[0048] Step 4: Conduct on-site charge monitoring in the coal seam tunnel of the rock burst mine without mining influence. The charge monitoring points are arranged as follows: Figure 4 As shown, the standard value of the charge index is obtained through statistical analysis.

[0049] The specific process is as follows:

[0050] Step 4-1, drill charge monitoring holes in the coal seam of the same rock burst mine as the sampling area without mining influence area, drill one monitoring hole every 10m, and drill 10 monitoring holes in total;

[0051] Step 4-2: Use a charge monitor to perform downhole monitoring on 10 charge monitoring holes every day, with a monitoring period of 15 days;

[0052] Step 4-3: Calculate the average charge of each charge monitoring point during the monitoring period, denoted as q mn1 ,q mn2 ……q mn10 ; and the coefficient of variation of the average charge, denoted as q cv1 ,q cv2 ……q cv10 ;

[0053] Step 4-4: Calculate the weighted average of the average charge of the 10 charge monitoring points to obtain the standard value of the average charge, recorded as The weighted average of the average charge variation coefficient of the 10 charge monitoring points is then used to obtain the standard value of the charge variation coefficient, which is recorded as

[0054] Step 5: Multiply the standard value of the charge monitoring index by the critical charge coefficient to obtain the initial value of the corresponding mine rock burst charge index warning. The specific process is as follows:

[0055] Step 5-1: Set the average charge standard value Multiplying by the average charge critical coefficient k1, we get the average charge critical warning initial value, recorded as Q;

[0056] Step 5-2: Set the charge variation coefficient standard value Multiplying it by the critical coefficient k2 of the charge variation coefficient gives the initial value of the critical warning of the charge variation coefficient, recorded as Q cv .

Claims

1. A method for determining coal mine rock burst charge monitoring indicators and their critical warning initial values, characterized in that: The following steps are involved: Step 1: Conduct laboratory tests on the charge induction law during the compression and failure process of coal samples; Step 2: Determine the charge monitoring index according to the charge induction law test during the compression and destruction process of the coal sample; Step 3, determining the charge critical coefficient according to the ratio of the charge monitoring index in the strengthening damage stage and the compaction elastic stage of the coal sample compression failure process; Step 4: Conduct on-site charge monitoring in the coal seam tunnel of the rock burst mine without mining influence area to obtain the standard value of the charge monitoring index; Step 5: Multiply the standard value of the charge monitoring index by the charge critical coefficient to obtain the critical warning initial value of the corresponding mine rock burst charge monitoring index; The charge monitoring index in step 2 includes the average charge q mn and charge variation coefficient q cv ; The average charge q mn For The average value of the charge carried by all charge signals sensed within a certain period of time is expressed as ,in q i for The charge amount of each charge signal induced within a certain period of time reflects the overall stress level of the coal body under the action of external loads; The charge variation coefficient q cv For The discrete degree of charge quantity of all charge signals sensed within a certain time period is expressed as ,in q sd for The standard deviation of the charge of all charge signals sensed within a certain period of time reflects the degree of cracking of the coal body under the action of external loads. The step 3 comprises the following steps: Step 3-1, the uniaxial compression failure process of the coal sample is divided into the compression elasticity, enhanced damage and post-peak failure stages; Step 3-2: Count the average charge of each coal sample during the compression elasticity and enhanced damage stages q mn and charge variation coefficient q cv ; The ratio of the average charge in the enhanced damage stage to the average charge in the compacted elastic stage is taken as the critical coefficient of the average charge k 1; The ratio of the charge variation coefficient in the enhanced damage stage to that in the compacted elastic stage is taken as the critical coefficient of charge variation coefficient k 2 .

2. The method for determining a coal mine rock burst charge monitoring index and its critical warning initial value according to claim 1, characterized in that: The step 1 comprises the following steps: Step 1-1, on-site sampling and processing; Step 1-2: Installation and testing of the charge monitoring system; Step 1-3, load system installation test; Step 1-4: Shielding system installation test; Step 1-5: monitor the charge induction law during the uniaxial compression failure process of the coal sample.

3. The method for determining the coal mine rock burst charge monitoring index and its critical warning initial value according to claim 1, characterized in that: The step 4 comprises the following steps: Step 4-1, drill charge monitoring holes in the coal seam tunnel of the same rock burst mine as the sampling area without mining influence area, drill one monitoring hole every 10m, and drill 10 monitoring holes in total; Step 4-2, use a charge monitor to perform downhole monitoring on 10 charge monitoring holes every day, with a monitoring period of 15 days; Step 4-3: Calculate the average charge of each charge monitoring point during the monitoring period, recorded as ; and the coefficient of variation of the average charge, denoted as ; Step 4-4: Calculate the weighted average of the average charge at each charge monitoring point to obtain the standard value of the average charge, recorded as ; The weighted average of the average coefficient of variation of each charge monitoring point is calculated to obtain the standard value of the charge coefficient of variation, which is recorded as .

4. A method for determining a coal mine rock burst charge monitoring index and its critical warning initial value according to claim 3, characterized in that: The step 5 comprises the following steps: Step 5-1: Set the average charge standard value Critical coefficient of average charge k 1 to obtain the initial value of the critical warning of the average charge quantity, which is recorded as ; Step 5-2: Set the charge variation coefficient standard value Critical coefficient of charge variation coefficient k 2 Multiply them to get the initial value of critical warning of charge variation coefficient, which is recorded as .

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