A method for dynamically measuring depth of plastic zone in roadway based on charge monitoring

Abstract

This invention discloses a method for dynamically measuring the depth of the plastic zone in a roadway based on charge monitoring, comprising the following steps: S1, obtaining the estimated depth L0m of the current plastic zone in the roadway; S2, drilling a borehole in the coal wall of the roadway to a depth of L1m; S3, sequentially placing several charge probes of a cluster-type charge monitor into the borehole, with a 0.5m interval between adjacent charge probes; S4, numbering the charge probes from the coal wall into the borehole as D1, D2, ..., Dk, where k is the number of probes; S5, monitoring and recording the instantaneous charge q of each charge probe, processing the monitoring data, and calculating the cumulative charge Q of each charge probe within the same time period; S6, plotting the relationship between the borehole depth and the cumulative charge Q, with the borehole depth corresponding to the maximum value of the cumulative charge Q being the precise depth of the plastic zone in the current roadway; the dynamic change process of the plastic zone depth in the roadway can be obtained through real-time monitoring.

Description

Technical Field

[0001] This invention relates to the field of coal mining, and in particular to a method for dynamically measuring the depth of the plastic zone in roadways based on charge monitoring. Background Technology

[0002] The extensive mining of underground coal mines necessitates the construction of roadways, which are vital lifelines for miners, making their safety paramount. Coal mine roadways are susceptible to various hazards, including rockbursts, coal and gas outbursts, and spontaneous combustion of coal. The management of these hazards all involves the plastic zone depth parameter of the roadway. For example, in rockburst prevention, roadway support can increase the critical stress of the roadway, thereby improving its safety; the plastic zone depth is a crucial parameter in roadway support design. Coal and gas outbursts are primarily managed through gas extraction, commonly using in-seam borehole extraction. However, the effectiveness of in-seam borehole extraction is affected by the quality of the sealing, which is related to the plastic zone depth. In easily spontaneously combustible coal seams, an excessively deep plastic zone leads to well-developed coal fissures, increasing the risk of spontaneous combustion due to oxygen ingress. Therefore, understanding the variations in the plastic zone depth of roadways is of significant importance and practical value.

[0003] Underground mining activities are constantly changing, and the stress state in the surrounding rock of the tunnel will change with the mining activities. This change in surrounding rock stress inevitably leads to a change in the depth of the plastic zone of the tunnel's surrounding rock; that is, the depth of the plastic zone is a quantity that changes with the stress in the surrounding rock. Currently, there are various methods for measuring the depth of the plastic zone, such as borehole inspection, testing while drilling, and ground-penetrating radar. However, these methods cannot achieve real-time monitoring of changes in the plastic zone depth. Therefore, it is necessary to study a dynamic measurement method for the plastic zone depth of tunnels based on charge monitoring to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to address the above-mentioned problems by providing a simple and real-time monitoring method for dynamically measuring the depth of the plastic zone in roadways based on charge monitoring.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows:

[0006] A dynamic measurement method for the depth of the plastic zone in roadways based on charge monitoring includes the following steps:

[0007] S1. Obtain the estimated depth L0m of the current plastic zone in the roadway;

[0008] S2. Drill a borehole in the coal wall of the roadway to a depth of L1m. L1 is calculated using the following formula:

[0009] L1 = L0 + 5;

[0010] S3. Place several charge probes of the cluster charge monitor into the borehole in sequence, with a 0.5m interval between adjacent charge probes;

[0011] S4. Number the charge probes from the coal wall of the roadway into the borehole as D1, D2, ..., Dk, where k is the number of probes.

[0012] S5. Monitor and record the instantaneous charge q of each charge probe, process the monitoring data, and calculate the cumulative charge Q of each charge probe within the same time period:

[0013]

[0014] In the formula q i To calculate the i-th charge quantity within the time period.

[0015] S6. Plot a graph showing the relationship between borehole depth and cumulative charge Q, with borehole depth as the horizontal axis and the cumulative charge Q of the charge probe corresponding to the borehole depth as the vertical axis. The borehole depth corresponding to the maximum value of cumulative charge Q is the current plastic zone depth of the roadway. The dynamic change process of the plastic zone depth of the roadway can be obtained through real-time monitoring.

[0016] Furthermore, in step S1, the estimated depth of the current plastic zone of the roadway is obtained by the drill cuttings method.

[0017] Furthermore, in step S2, the diameter of the drilled hole is 42-75 mm.

[0018] Furthermore, the clustered charge monitor consists of several charge probes and a charge monitor. The charge probes are arranged side by side in sequence, and adjacent charge probes and the foremost charge probe and the charge monitor are connected by signal transmission lines.

[0019] Furthermore, the number of charge probes is 2*L1.

[0020] Compared with the prior art, the advantages and positive effects of this invention are:

[0021] This invention utilizes the charge signal generated by coal and rock fracture and the relationship between the charge signal intensity and the degree of coal and rock fracture to propose a method for measuring the depth of the plastic zone in a roadway using a charge monitoring instrument. This method obtains the change in the depth of the plastic zone caused by the change in the stress state of the surrounding rock in the roadway in real time by monitoring the change in the charge signal intensity. It effectively realizes the real-time monitoring of the depth of the plastic zone and the dynamic change process of the depth of the plastic zone. This measurement method is simple and flexible, and provides timely and reliable data for mine disaster management. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of a cluster-type charge monitor.

[0024] Figure 2 A schematic diagram showing the setup for measuring the depth of the plastic zone using a charge monitor;

[0025] Figure 3 This is a graph showing the relationship between borehole depth and cumulative charge. Detailed Implementation

[0026] 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, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art to all other embodiments obtained without creative effort should be included within the protection scope of the present invention.

[0027] This embodiment describes the rockburst monitoring and prevention measures adopted in a rockburst-prone mine during the mining process. The specific steps are as follows:

[0028] Step 1: Use the drill cuttings method to obtain an estimated depth of 2m in the current plastic zone of the roadway;

[0029] Step 2: Drill a 45mm diameter hole in the coal wall of the roadway. According to the calculation, the drilling depth is 7m.

[0030] Step 3: Place the charge probe of the clustered charge monitor into the borehole; the clustered charge monitor mainly consists of a charge monitor and a clustered probe (such as...). Figure 1 As shown, the cluster probe consists of multiple charge probes connected by signal transmission lines, with each charge probe performing independent monitoring.

[0031] Step 4: There are 14 charge probes, numbered from closest to farthest from the charge monitor as D1, D2…, D14. After the charge probes are placed in the borehole, probe D1 should be 0.5m from the coal face. Figure 2 As shown;

[0032] Step 5: Monitor and record the charge q value of each charge probe, process the monitoring data, and calculate the cumulative charge Q of each charge probe within a certain time period.

[0033] In the formula q i To calculate the amount of charge at a certain moment within a time period;

[0034] Step 6: A graph showing the relationship between borehole depth and cumulative charge was plotted with borehole depth on the x-axis and the cumulative charge of the charge probe corresponding to the borehole depth on the y-axis, as shown below. Figure 3 As shown; by Figure 3 The calculated depth of the plastic zone in the roadway was 3m.

[0035] This invention utilizes the charge signal generated by coal and rock fracture and the relationship between the charge signal intensity and the degree of coal and rock fracture to propose a method for measuring the depth of the plastic zone in a roadway using a charge monitoring instrument. This method obtains the change in the depth of the plastic zone caused by the change in the stress state of the surrounding rock in the roadway in real time by monitoring the change in the charge signal intensity. It effectively realizes the real-time monitoring of the depth of the plastic zone and the dynamic change process of the depth of the plastic zone. This measurement method is simple and flexible, and provides timely and reliable data for mine disaster management.

Claims

1. A method for dynamic measurement of the plastic zone depth in roadways based on charge monitoring, characterized in that: Includes the following steps: S1. Obtain the estimated depth L0m of the current plastic zone in the roadway; S2. Drill a borehole in the coal wall of the roadway to a depth of L1m. L1 is calculated using the following formula: L1 = L0 + 5; S3. Place several charge probes of the cluster charge monitor into the borehole in sequence, with a 0.5m interval between adjacent charge probes; S4. Number the charge probes from the coal wall of the roadway into the borehole as D1, D2, ..., Dk, where k is the number of probes. S5. Monitor and record the instantaneous charge q of each charge probe, process the monitoring data, and calculate the cumulative charge Q of each charge probe within the same time period: where q i Qi is the amount of charge at the i-th time period; S6. Plot a graph showing the relationship between borehole depth and cumulative charge Q, with borehole depth as the horizontal axis and the cumulative charge Q of the charge probe corresponding to the borehole depth as the vertical axis. The borehole depth corresponding to the maximum value of cumulative charge Q is the precise depth of the plastic zone of the current roadway. The dynamic change process of the plastic zone depth of the roadway can be obtained through real-time monitoring.

2. The method for dynamic measurement of the plastic zone depth in roadways based on charge monitoring as described in claim 1, characterized in that: In step S1, the estimated depth of the current plastic zone of the roadway is obtained by the drill cuttings method.

3. The method for dynamic measurement of the plastic zone depth in roadways based on charge monitoring as described in claim 2, characterized in that: In step S2, the diameter of the drilled hole is 42-75 mm.

4. The method for dynamic measurement of the plastic zone depth in roadways based on charge monitoring as described in claim 3, characterized in that: The clustered charge monitor consists of several charge probes and a charge monitor. The charge probes are arranged side by side in sequence, and adjacent charge probes and the frontmost charge probe and the charge monitor are connected by signal transmission lines.

5. The method for dynamic measurement of the plastic zone depth in roadways based on charge monitoring as described in claim 4, characterized in that: The number of charge probes is 2*L1.

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