Online real-time monitoring device and method for movement of roof in coal mine goaf

Abstract

The invention provides a coal mine goaf roof motion online real-time monitoring device and method, and belongs to the technical field of goaf roof monitoring. The problem that an existing top plate vertical stress monitoring device or method is large in error is solved. Comprising pressure pillows arranged on a goaf roof in an array mode and used for collecting vertical stress of the roof, the pressure pillows are connected with a monitoring station through wires, the monitoring station is arranged in a roadway and connected with a signal processor through a passive cable, and the signal processor is connected with a computer network through a mining transmission optical cable; the height of the three zones is inversely calculated through the vertical stress of the top plate monitored by the pressure pillow and a drill hole histogram; the method is applied to coal mine goaf roof motion monitoring and is simple in principle, easy to operate, low in labor intensity and small in error.

Description

Technical Field

[0001] The invention provides an online real-time monitoring device and method for roof movement in a coal mine goaf area, belonging to the technical field of roof monitoring in goaf areas. Background Art

[0002] As a basic energy source and important industrial raw material, coal resources have played multiple roles in the national economy and social development. With the gradual depletion of shallow coal resources, the exploitation of deep coal resources has become an irreversible trend. However, this change has had a serious impact on the bending, sinking, fracture and collapse of the roof rock strata of the tunnel and working face. With the movement of the roof, the mine will cause surface collapse, seriously affecting the safety of equipment and personnel, and causing property losses. Therefore, studying the movement of the roof in the goaf is of great significance to further improve the safety of the roof of coal mines and the safe and sustainable production of my country's coal resources.

[0003] Under the existing technical equipment conditions, the main methods for monitoring the movement of the roof in the goaf area are to monitor the roof by drilling holes on site, to calculate the height of the three zones through empirical formulas to obtain the movement status of the roof, and numerical simulation. However, with the advancement of coal mining technology, the empirical formula has shown obvious limitations because it is based on past technical conditions, and the empirical calculation formula cannot meet current technical needs. Numerical simulation simplifies the underground overburden and mining technical conditions, cannot accurately reflect the actual situation on site, will have more human factors, and the results are unreliable and difficult to use to guide actual production. On-site drilling construction has the disadvantages of large workload, large number of personnel required, uneven data with errors, and relatively high cost.

[0004] Therefore, the Chinese patent (publication number CN108922363A) discloses a method of using a particle fixed on an object to track the motion state of the object, continuously monitor the vibration characteristics of the roof, and obtain the vertical velocity relationship of the roof vibration through analysis, so as to predict the motion state of the roof. The disadvantages of this method are: 1. It is necessary to use an anchor drill to drill holes in the roof and assemble anchor cables inside the boreholes, so it is necessary to have multiple underground workers for construction, which has high labor intensity and high equipment cost; 2. After the anchor cables are assembled, it is necessary to grout the boreholes and then tension the anchor cables, and finally perform secondary grouting, so the construction period is long, the construction process is cumbersome, and the labor intensity is high; 3. The anchor cable tensioning control stress is 0.70-0.80fp, which requires precise values, and due to on-site construction, it will also cause certain errors. Therefore, it is necessary to design a new device for obtaining the vertical stress of the roof to meet the needs of monitoring the motion state of the roof in the goaf area.

[0005] Another Chinese patent (publication number CN104405372A) discloses a method for testing the vertical three-zone height of the overburden in the mining area based on the high-level drilling flow rate. The method constructs an oblique high-level drilling from the solid coal in the coal lane of the working face to the pressure relief area on the side of the goaf, and uses the extraction data of the oblique high-level drilling to determine and test the vertical three-zone height of the overburden in the mining area. The disadvantages of this method are: 1. The method requires the drilling height to be about 13 to 15 times the coal mining height, so the equipment required for drilling is highly reliable, the drilling depth is also large, and the drilling cost and equipment cost increase accordingly; 2. This method is to construct an oblique high-level drilling from the solid coal in the coal lane of the working face to the coal rock entity in the goaf direction. The oblique orientation is difficult to judge, and the test results of the three-zone height are different for different oblique orientations, so this method has a certain error. Summary of the invention

[0006] In order to solve the above technical problems, the present invention proposes an online real-time monitoring device and method for roof movement in a coal mine goaf.

[0007] The technical solution adopted by the present invention is: an online real-time monitoring device for the movement of the roof of a coal mine goaf, including pressure pillows arranged in an array on the roof of the goaf for collecting the vertical stress of the roof, the pressure pillows are connected to a monitoring station through a wire, the monitoring station is set in a tunnel, the monitoring station is connected to a signal processor through a passive cable, and the signal processor is connected to a computer network through a mine transmission optical cable.

[0008] The pressure pillow comprises a pressure sensor and a wire, and the pressure sensor is connected to a monitoring station via the wire.

[0009] The pressure pillows are arranged in the vertical direction of the roof of the goaf, and the pressure pillows in the same row are evenly arranged, and as the coal mining working face advances a certain distance, another row of pressure pillows is arranged.

[0010] The pressure pillows arranged in the same row are spaced 5-15m apart.

[0011] The interval between the two rows of pressure pillows arranged front and back is 10-30m.

[0012] A method for online real-time monitoring of roof movement in a coal mine goaf area, using an online real-time monitoring device for roof movement in a coal mine goaf area, comprises the following steps:

[0013] The first step is to reasonably arrange the pressure pillows on the roof of the goaf;

[0014] The second step is to obtain the vertical stress of the roof of the goaf through the pressure pillow;

[0015] The third step is to calculate the height of the "three zones" above the roof based on the collected vertical stress of the roof. The calculation formula of the vertical stress of the roof is as follows:

[0016]

[0017] Where: σ is the vertical stress of the top plate detected by the pressure pillow, in MPa, F i / v i is the rock density of the i-th layer, in KN / m 3 , d i is the thickness of the i-th rock layer, in m;

[0018] The number of rock layers i is calculated according to the above formula, and then the height H of the "three zones" above the roof is calculated according to the known thickness of each rock layer. d , and its calculation formula is as follows:

[0019] H d =∑d i .

[0020] The numerical determination rule of the vertical stress of the top plate is as follows:

[0021] As the coal mining face advances forward, the pressure pillow is farther and farther away from the working face. The vertical stress σ of the goaf roof monitored by the pressure pillow will gradually increase and finally stabilize. When the vertical stress σ of the goaf roof is stable, read the value on the pressure pillow. The above value is the vertical stress of the roof used to calculate the number of rock layers.

[0022] The movement status of the goaf roof is evaluated based on the calculated “three-zone” heights above the roof.

[0023] According to the empirical formula of the maximum height of the caving zone and the fracture zone in the "Mine Hydrogeology Regulations", the caving zone height H is calculated respectively. c The height of the fracture zone H f , and the "three-band" height H calculated above d Compare and thus determine the movement state of the top plate.

[0024] The beneficial effects of the present invention compared with the prior art are as follows:

[0025] (1) The present invention uses a pressure pillow to monitor the vertical stress of the roof in real time. During this process, there is no need to drill holes and inject grout into the roof as in the patents related to the present invention. The present invention only needs to install multiple pressure pillows evenly arranged on the roof of the goaf, and the height of the "three zones" can be calculated by reverse calculation based on the vertical stress of the roof monitored by the pressure pillows. The principle is simple, the operation is simple, the labor intensity is low, and the error is small.

[0026] (2) The device for real-time monitoring of the movement state of the roof of the goaf proposed in the present invention can effectively reduce the workload of underground workers. It is reasonably designed and will not be damaged during use. The device is reusable. In addition, the device has a relatively simple composition and is easy to operate, thus having strong practicality.

[0027] (3) The method for real-time monitoring of the movement state of the roof of the goaf proposed in the present invention calculates the height of the "three zones" based on the magnitude of the vertical stress of the roof. It avoids the limitations brought by empirical formula calculations and has strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be further described below in conjunction with the accompanying drawings:

[0029] Figure 1 Flow chart for online real-time monitoring of roof movement status in goaf area

[0030] Figure 2 This is a diagram of the online real-time monitoring device for the movement status of the roof in the goaf area;

[0031] Figure 3 A schematic diagram of the reasonable arrangement of pressure pillows on the roof of the goaf;

[0032] Figure 4 is a schematic diagram of a drilling histogram;

[0033] Figure 5 This is a schematic diagram of the height of the "three belts";

[0034] Figure 6 Schematic diagram of vertical stress variation of the roof;

[0035] In the figure: 1-pressure pillow, 2-pressure sensor, 3-conductor, 4-monitoring station, 5-passive cable, 6-signal processor, 7-mine transmission optical cable, 8-computer network. DETAILED DESCRIPTION

[0036] like Figure 2 As shown, the present invention provides an online real-time monitoring device for the movement of the roof of a coal mine goaf, comprising a pressure pillow 1 arranged with a pressure sensor 2 and a wire 3, the pressure pillow 1 is connected to a monitoring station 4 through the wire 3, and the monitored vertical stress σ of the roof of the goaf is transmitted to the monitoring station 4, the monitoring station 4 transmits the vertical stress signal to the signal processor 6 through a passive cable 5, the signal processor 6 pre-processes the vertical stress signal of the roof and transmits it to a ground computer network 8 through a mine transmission optical cable 7, finally realizing real-time monitoring of the vertical stress of the roof of the goaf.

[0037] like Figure 1 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, the present invention also introduces a method for online real-time monitoring of roof movement in a coal mine goaf, using the device as described above, comprising the following steps:

[0038] The first step is to arrange the pressure pillow reasonably

[0039] First, in the vertical direction of the goaf, a pressure pillow 1 is arranged every 5-15m, and the pressure pillows 1 are evenly arranged in the same row. When the coal mining working face advances forward every 10 to 30m, the above pressure pillows 1 are repeatedly arranged. By analogy, the goaf will be filled with pressure pillows 1 neatly arranged like a matrix.

[0040] The second step is to obtain the vertical stress σ of the roof of the goaf through the pressure pillow.

[0041] The vertical stress of the goaf roof monitored by the pressure pillow 1 is transmitted to the monitoring station 4 through the wire 3 connected to the pressure sensor 2. The monitoring station 4 is connected to the signal processor 6 through the passive cable 5. The signal processor 6 pre-processes the signal of the vertical stress of the roof and transmits the stress signal to the ground computer network 8 through the mining transmission optical cable 7. Finally, we obtain the size of the vertical stress σ of the goaf roof through the computer network 8.

[0042] The third step is to calculate the height H of the "three belts" according to the vertical stress σ d

[0043] As the working face advances forward, the vertical stress on the roof monitored by the pressure pillow 1 will slowly increase and finally reach a state of equilibrium. At this time, the vertical stress on the pressure pillow 1 is the value we need for calculation.

[0044] Specifically, as the coal mining face advances forward, the distance between the pressure pillow 1 and the working face becomes farther and farther, and the vertical stress σ of the goaf roof monitored by the pressure pillow 1 will gradually increase and finally stabilize. When the vertical stress σ of the goaf roof is stable, the value on the pressure pillow 1 is read. The value at this time is as follows: Figure 6 Point A on the top plate, use the value of point A to calculate the height H of the "three belts" above the top plate d .

[0045] After obtaining the vertical stress σ of the goaf roof, according to Figure 4 The drill hole column diagram shown in the figure uses the rock bulk density F / v and rock thickness d of each rock layer above the coal seam to calculate how many layers of rock the "three zones" contain through the formula. Finally, the thickness d of these rocks is accumulated to obtain the height H of the "three zones" above the roof. d :

[0046]

[0047] Where: σ is the vertical stress of the top plate detected by the pressure pillow, in MPa, F i / v i is the rock density of the i-th layer, in KN / m 3 , d i is the thickness of the i-th rock layer, in m;

[0048] From this we get:

[0049] H d =∑d i ;

[0050] Where: H d It is the height of the “three zones” above the top plate, in meters.

[0051] Specifically, Figure 4 The drill hole histogram shown belongs to a known part of each mined coal mine, namely F i / v i , and d i are all known. The unknown number required by this formula is the number of rock layers i. According to the borehole column chart, by accumulating the values ​​of multiple rock layers, when this value is the same as or close to the vertical stress σ of the top plate detected by the pressure pillow 1, the number of corresponding rock layers can be obtained.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An online real-time monitoring device for roof movement in coal mine goaf, characterized in that: The invention comprises pressure pillows (1) arranged in an array on the roof of a goaf for collecting vertical stress of the roof, wherein the pressure pillows (1) are connected to a monitoring station (4) via a wire (3), the monitoring station (4) is arranged in a tunnel, the monitoring station (4) is connected to a signal processor (6) via a passive cable (5), and the signal processor (6) is connected to a computer network (8) via a mine transmission optical cable (7).

2. The device for online real-time monitoring of roof movement in coal mine goaf according to claim 1, characterized in that: The pressure pillow (1) comprises a pressure sensor (2) and a wire (3); the pressure sensor (2) is connected to a monitoring station (4) via the wire (3).

3. The device for online real-time monitoring of roof movement in coal mine goaf according to claim 1, characterized in that: The pressure pillows (1) are arranged in the vertical direction of the roof of the goaf, and the pressure pillows (1) in the same row are evenly arranged, and as the coal mining working face advances a certain distance, another row of pressure pillows (1) is arranged.

4. The device for online real-time monitoring of roof movement in coal mine goaf according to claim 3 is characterized by: The pressure pillows (1) arranged in the same row are spaced 5-15m apart from each other.

5. The device for online real-time monitoring of roof movement in coal mine goaf according to claim 3 is characterized by: The interval between the two rows of pressure pillows (1) arranged front and back is 10-30m.

6. A method for online real-time monitoring of roof movement in a coal mine goaf, using the device for online real-time monitoring of roof movement in a coal mine goaf as claimed in any one of claims 1 to 5, characterized in that: The following steps are involved: The first step is to reasonably arrange pressure pillows on the roof of the goaf (1); The second step is to obtain the vertical stress of the roof of the goaf through the pressure pillow (1); The third step is to calculate the height of the "three zones" above the roof based on the collected vertical stress of the roof. The calculation formula of the vertical stress of the roof is as follows: Where: σ is the vertical stress of the top plate detected by the pressure pillow, in MPa, F i / v i is the rock density of the i-th layer, in KN / m 3 , d i is the thickness of the i-th rock layer, in m; The number of rock layers i is calculated according to the above formula, and then the height H of the "three zones" above the roof is calculated according to the known thickness of each rock layer. d , and its calculation formula is as follows: Hd=∑d i 。 7. A method for online real-time monitoring of roof movement in a coal mine goaf according to claim 6, characterized in that: The numerical determination rule of the vertical stress of the top plate is as follows: As the coal mining face advances forward, the distance between the pressure pillow (1) and the working face becomes farther and farther, and the vertical stress σ of the roof of the goaf monitored by the pressure pillow (1) will gradually increase and finally stabilize. When the vertical stress σ of the roof of the goaf is stable, read the value on the pressure pillow (1). The above value is the vertical stress of the roof used to calculate the number of rock layers.

8. A method for online real-time monitoring of roof movement in a coal mine goaf according to claim 6, characterized in that: The movement state of the goaf roof is evaluated based on the calculated "three-zone" height above the roof.

Images