Method for inverting roof fracture position of gob-side entry retaining end

Abstract

The present application provides a kind of method for inverting roof fracture position of gob-side entry retaining end, and relates to the technical field of coal mining.The method comprises the following steps: drilling into the coal body of working face, installing anchor at different roof positions, monitoring the displacement change of deep foundation point of anchor, obtaining first change data; measuring the change of stress meter located behind support in goaf, obtaining second change data, thereby monitoring the fracture position along the strike and dip of working face; monitoring the stress change of multiple positions at different distances from roadway on the side of coal pillar, obtaining third change data; inverting the breaking rule of end roof by first change data, second change data and third change data.The present application inverts the breaking rule of end roof by the change of three kinds of data obtained by monitoring; the present application provides a determination method for fracture on both sides of end roof, and through the monitoring of stress change in goaf, the sub-stage breaking of roof can be monitored.

Description

Technical Field

[0001] This invention relates to the field of coal mining technology, and in particular to a method for inverting the location of the roof fracture at the end of a goaf-side roadway. Background Technology

[0002] like Figure 1 and Figure 2 As shown, after the working face is mined, the roof undergoes an "OX"-shaped fracture, forming three key blocks A, B, and C (hereinafter referred to as block A, block B, and block C). The end roof mainly refers to block B. The timing and location of the fracture of block B have little impact on traditional roadways, but for roadways left along the goaf, they greatly affect the strength of the roadway filling and the selection of the pressure relief method. Therefore, it is necessary to detect the timing and location of the fracture.

[0003] The structure of the roof cannot be directly probed. Some scholars have theoretically calculated the fracture span, suggesting that the span is close to the roof period to determine the step distance. Others have used borehole drilling, both underground and on the surface, to inspect the fracture location. However, this method has several problems. First, the borehole deforms after the roof collapses, making drilling difficult and hindering inspection. Second, drilling is somewhat unpredictable, as the drilling location may not be precisely at the fracture point, leading to higher costs.

[0004] Therefore, it is necessary to capture the locations of the leading and lagging fractures of the roof. Since the roof collapse is a phased collapse, it is also necessary to monitor the timing of the collapse in real time. Summary of the Invention

[0005] This invention provides a method for inverting the location of the fracture in the roof of the goaf-side roadway, in order to solve the defects in the prior art where the timing and location of "OX" type fractures are difficult to detect and grasp.

[0006] This invention provides a method for inverting the location of the roof fracture at the end of a goaf-side roadway, comprising:

[0007] By drilling holes into the coal seam of the working face and installing anchors on the roof at different layers, the displacement changes of the deep base points of the anchors are monitored to obtain the first change data.

[0008] The changes in stress gauges located in the goaf behind the support are measured to obtain second change data, thereby monitoring the fracture location along the strike and dip of the working face;

[0009] The stress changes at multiple locations at different distances from the roadway to the coal pillar were monitored to obtain the third set of change data;

[0010] The fracture pattern of the top plate is inverted using the first change data, the second change data, and the third change data.

[0011] According to the present invention, a method for inverting the location of the roof fracture at the end of a goaf-side roadway includes drilling holes into the coal seam of the working face, installing anchors in the roof at different strata, and monitoring the displacement changes of the deep base points of the anchors to obtain the first change data.

[0012] For capturing the locations of premature and delayed fractures, holes are drilled into the coal seam of the working face, and anchor claws are installed on the roof at different strata. One end of a steel wire rope is connected to the anchor claw, and the other end of the steel wire rope is connected to a deep base point displacement gauge at the hole opening. This allows the roof displacement at the anchor claw to be recorded, and the fracture and migration patterns of the roof can be determined by monitoring the deep base point displacement.

[0013] According to the present invention, a method for inverting the location of the roof fracture at the end of a goaf-retention roadway is provided. Specifically, drilling holes into the coal seam of the working face involves: arranging a first measuring station at a set distance from the working face cut and arranging a second measuring station at set intervals; drilling multiple holes into the roof in each measuring station and installing multiple deep baseline displacement gauges in each hole.

[0014] According to the method for inverting the location of the roof fracture at the end of the goaf, provided by the present invention, a first measuring station is set up 300 meters away from the working face cut, and a second measuring station is set up at a 50-meter interval.

[0015] According to a method for inverting the fracture location of the roof at the end of a goaf-side roadway provided by the present invention, seven boreholes are drilled into the roof at the first and second measuring stations respectively, and two to four deep baseline displacement gauges are installed in each of the boreholes.

[0016] According to the present invention, a method for inverting the location of the fracture in the top plate of the goaf-retention tunnel is provided, wherein the elevation angle of the borehole is in the range of 35° to 74°.

[0017] According to the method for inverting the fracture location of the roof at the end of a goaf-side roadway provided by the present invention, the step of measuring the change of stress gauges located in the goaf area behind the support to obtain second change data, thereby monitoring the fracture location along the strike and dip of the working face, specifically involves:

[0018] A first stress gauge is embedded in the middle of the support to monitor the direction and tendency of the fracture. When the top plate breaks, it will impact the first stress gauge. The time and location of the fracture can be monitored by the change in the reading of the first stress gauge.

[0019] The method for inverting the fracture location of the roof at the end of a goaf-side roadway according to the present invention further includes: setting a protective device on the outside of the first stress gauge to ensure stable monitoring and data transmission of the first stress gauge.

[0020] According to the method for inverting the location of the roof fracture at the end of a goaf-side roadway provided by the present invention, the third variation data obtained by monitoring the stress changes at multiple locations at different distances from the roadway to the coal pillar side is specifically as follows:

[0021] By drilling holes at distances of 2 meters, 4 meters, and 6 meters from the roadway on the side of the coal pillar and installing second stress gauges inside the holes, the fracture location of the roof can be obtained by inverting the data monitored by the second stress gauges.

[0022] The method for inverting the location of the fracture of the roof at the end of the goaf roadway provided by the present invention further includes: installing a borehole inspection instrument in the hole on the side of the coal pillar to inspect the roof on the side of the coal pillar.

[0023] This invention provides a method for inverting the location of roof fracture at the end of a goaf-side roadway. It monitors the displacement changes of deep foundation points above the roof, and the stress changes on the sides of the goaf and solid coal pillars. The fracture pattern of the end-point roof is inverted by monitoring the changes in these three types of data. This invention also provides a method for determining fractures on both sides of the end-point roof; by monitoring stress changes in the goaf, the staged fracture of the roof can be detected. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a plan view of the "OX" shaped fracture of the top slab;

[0026] Figure 2 It is a cross-sectional view of the "OX" shaped fracture of the top plate;

[0027] Figure 3 This is a schematic diagram of the drilling into the coal face and the installation position of the deep base point displacement meter provided by the present invention.

[0028] Figure 4 This is a schematic diagram of the installation position of the first stress gauge at the bracket provided by the present invention;

[0029] Figure 5 This is a schematic diagram of the installation position of the second stress gauge installed on the side of the coal pillar, as provided by the present invention. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0031] The following is combined with Figures 3-5 This invention describes a method for inverting the location of the roof fracture at the end of a goaf-side roadway. The method involves using three types of monitoring data to invert the fracture pattern of the roof at the end of the roadway, specifically including:

[0032] Firstly, by drilling holes into the coal seam of the working face and installing anchors on the roof at different layers, the displacement changes of the deep base points of the anchors are monitored to obtain the first change data, thereby determining the fracture height and the fracture location on the working face side.

[0033] Secondly, the changes in stress gauges located in the goaf behind the support are measured to obtain second change data, thereby monitoring the fracture location along the strike and dip of the working face, and thus determining the fracture strike and dip range.

[0034] Thirdly, stress changes at multiple locations at different distances from the roadway on the side of the coal pillar are monitored to obtain third change data, which is used to determine the stress on the side of the coal pillar.

[0035] The fracture pattern of the top plate was inverted using the first, second, and third change data.

[0036] This invention provides a method for inverting the location of roof fracture at the end of a goaf-side roadway. It monitors the displacement changes of deep foundation points above the roof, and the stress changes on the sides of the goaf and solid coal pillars. The fracture pattern of the end-point roof is inverted by monitoring the changes in these three types of data. This invention also provides a method for determining fractures on both sides of the end-point roof; by monitoring stress changes in the goaf, the staged fracture of the roof can be detected.

[0037] In one embodiment of the present invention, the specific construction method for determining the fracture height in the first aspect is as follows: For capturing the premature and delayed fracture locations, holes are drilled into the coal seam of the working face, and anchor claws are installed in the roof at different strata. One end of a steel wire rope is connected to the anchor claw, and the other end of the steel wire rope is connected to a deep base point displacement gauge at the hole opening, thereby recording the roof displacement at the anchor claw. The roof fracture and migration patterns are determined by monitoring the deep base point displacement. Specifically, when the roof undergoes an "OX"-shaped fracture, the position of the anchor claw changes. This position change is monitored by the deep base point displacement gauge. The location of the roof fracture and the migration pattern are determined by the amount of displacement change before and after the fracture is detected by the deep base point displacement gauge.

[0038] In one embodiment of the present invention, drilling holes into the coal seam of the working face specifically involves: arranging a first measuring station at a predetermined distance from the working face cut, and arranging second measuring stations at predetermined intervals; drilling multiple holes into the roof within each measuring station, and installing multiple deep-base displacement gauges within each hole. Specifically, as... Figure 3 As shown, the first monitoring station is set up 300 meters from the cut of the working face, and the second monitoring station is set up at 50-meter intervals. Seven boreholes are drilled into the roof at each monitoring station, and 2 to 4 deep foundation displacement gauges are installed in each borehole. The elevation angle of the boreholes ranges from 35° to 74°, and all boreholes are arranged within a single vertical section with no horizontal sway. Based on experience, the height and horizontal distance of the expected fracture location should not exceed 20 meters. A total of 20 deep foundation detection positions are set up at each monitoring station, with one anchor and one deep foundation displacement gauge at each detection position. When the roof fractures and rotates, the anchor moves, causing deformation. This displacement change is monitored by the deep foundation displacement gauges. The changes in the monitoring results of the deep foundation displacement gauges at different locations are compared. The one or several with the most obvious or least obvious changes can be used to preliminarily determine the approximate location of the roof fracture. The timing of the roof fracture is also determined based on the timing of the deep foundation displacement changes.

[0039] In one embodiment of the present invention, in the second aspect of determining the fracture direction and tendency range, the specific construction method is as follows: a first stress gauge is embedded in the middle of the support to monitor the fracture direction and tendency; when the top plate breaks, it will impact the first stress gauge, and the time and location of the fracture are monitored by the change in the reading of the first stress gauge. Specifically, the installation position of the first stress gauge is as follows: Figure 4 As shown, when the top plate breaks, it will impact the first stress gauge on the support. The time and location of the fracture are monitored based on the changes in the reading of the first stress gauge. Further, an installation trench is excavated in the bottom rock strata on the side of the support closest to the working face's advancing direction; the first stress gauge is placed in the installation trench; and a covering material is filled into the gaps above and around the first stress gauge in the installation trench.

[0040] In one embodiment of the present invention, a protective device is provided on the outside of the first stress gauge to ensure stable monitoring and data transmission of the first stress gauge. Since the collapse of the roof in the goaf will cause stress damage, it needs to be protected to ensure stable monitoring and data transmission of the stress gauge. Specifically, this can be achieved by filling the area above and around the first stress gauge with a covering material as described in the above embodiment; alternatively, a box with good support and protection functions can be used to protect the first stress gauge and connecting cables; or wireless transmission can be employed.

[0041] In one embodiment of the present invention, the specific construction method for determining the stress on the coal pillar side in the third aspect is as follows: Holes are drilled at three locations on the coal pillar side, 2 meters, 4 meters, and 6 meters from the roadway, and second stress gauges are installed in each hole. The fracture location of the roof is obtained by inverting the data monitored by the second stress gauges. When blocks A and B break, according to the cantilever beam theory, the moment is 0 at the cantilever hinge joint, and the pressure on the coal pillar below is the lowest at this point. Therefore, the location where the second stress gauge reading at the drilled hole decreases is used as the basis for determining the fracture location; the location with the largest decrease in reading can be preliminarily judged as the location of the most obvious fracture. Based on field experience, the fracture location does not exceed 6 meters; therefore, second stress gauges are installed at 2 meters, 4 meters, and 6 meters respectively.

[0042] In one embodiment of the present invention, in a third aspect, it further includes: installing a borehole inspection device in a hole on the side of the coal pillar to inspect the roof of the coal pillar side. Since the roof of the coal pillar side is relatively intact, the borehole inspection device can be used in conjunction with this method to inspect the roof.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for inverting the location of the roof fracture at the end of a goaf-side roadway, characterized in that, include: By drilling holes into the coal seam of the working face and installing anchors on the roof at different layers, the displacement changes of the deep base points of the anchors are monitored to obtain the first change data. The changes in stress gauges located in the goaf behind the support are measured to obtain second change data, thereby monitoring the fracture location along the strike and dip of the working face. Specifically, a first stress gauge is embedded in the middle of the support to monitor the strike and dip of the fracture. When the roof breaks, it will impact the first stress gauge. The time and location of the fracture are monitored by the change in the reading of the first stress gauge. The stress changes at multiple locations at different distances from the roadway on the side of the coal pillar are monitored to obtain the third change data. Specifically, holes are drilled at 2 meters, 4 meters and 6 meters from the roadway on the side of the coal pillar and a second stress gauge is installed in the hole. The fracture location of the roof is obtained by inverting the data obtained by monitoring the second stress gauge. The fracture pattern of the top plate is inverted using the first change data, the second change data, and the third change data.

2. The method for inverting the location of the roof fracture at the end of a goaf-side roadway according to claim 1, characterized in that, The method involves drilling holes into the coal seam at the working face, installing anchors in the roof at different strata, and monitoring the displacement changes of the deep base points of the anchors to obtain the first change data. For capturing the locations of premature and delayed fractures, holes are drilled into the coal seam of the working face, and anchor claws are installed on the roof at different strata. One end of a steel wire rope is connected to the anchor claw, and the other end of the steel wire rope is connected to a deep base point displacement gauge at the hole opening. This allows the roof displacement at the anchor claw to be recorded, and the fracture and migration patterns of the roof can be determined by monitoring the deep base point displacement.

3. The method for inverting the location of the fracture in the roof at the end of a goaf-side roadway according to claim 2, characterized in that, Specifically, drilling holes into the coal face involves: setting up a first measuring station at a set distance from the working face cut, and setting up a second measuring station at set intervals; drilling multiple holes into the roof at each measuring station, and installing multiple deep base point displacement gauges in each hole.

4. The method for inverting the location of the fracture in the roof at the end of a goaf-side roadway according to claim 3, characterized in that, The first measuring station is set up 300 meters away from the working face cut, and the second measuring station is set up at a 50-meter interval.

5. The method for inverting the location of the roof fracture at the end of a goaf-side roadway according to claim 3, characterized in that, Seven holes are drilled into the top plate in the first and second measuring stations respectively, and two to four deep base point displacement gauges are installed in each of the holes.

6. The method for inverting the location of the roof fracture at the end of a goaf-side roadway according to claim 3, characterized in that, The elevation angle of the borehole is between 35° and 74°.

7. The method for inverting the location of the roof fracture at the end of a goaf-side roadway according to claim 1, characterized in that, Also includes: A protective device is installed on the outside of the first stress gauge to ensure stable monitoring and data transmission of the first stress gauge.

8. The method for inverting the location of the fracture in the roof at the end of a goaf-side roadway according to claim 1, characterized in that, Also includes: A borehole inspection instrument is installed in the hole on the side of the coal pillar to inspect the roof of the coal pillar.

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