Method for monitoring auxiliary grouting operation in coal mine bed separation zone and reinforcing rod

Abstract

The application provides a kind of auxiliary coal mine off layer area grouting operation monitoring method and reinforcing rod, auxiliary coal mine off layer area grouting operation monitoring method includes: drawing the coal seam floor contour map of working face;The thickness of fracture zone is calculated, and according to the coal seam floor contour map of working face, the upper rock fracture zone bottom interface contour map of working face is drawn;According to the upper rock fracture zone bottom interface contour map of working face, a plurality of ground stress monitoring points are arranged in roadway;With each ground stress monitoring point as starting point, directional drilling is carried out;After each directional drilling is completed, the corresponding each drill hole stress sensor is sent into directional drilling respectively;According to the value detected by each drill hole stress sensor, it is judged whether the corresponding coal mine off layer area needs grouting or not.Through the technical scheme provided by the application, the problem of inaccurate grouting degree judgment in the prior art during coal mine off layer area grouting operation can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal mining, in particular to a monitoring method for assisting coal mine separation layer area grouting operation and a reinforcing rod. BACKGROUND

[0002] Coal mining is divided into open-pit mining and underground mining. Since coal resources are generally buried deep, most of the coal is mined by underground mining. In addition to the problem of surface subsidence, the large amount of coal gangue produced by underground mining is also the main solid waste. The separation layer area grouting technology can solve the problem of coal gangue disposal and surface subsidence. The injected slurry is mainly the slurry formed by coal gangue as raw material, which also realizes green mining of coal.

[0003] When coal mining is performed, the lower side of each key layer in the overburden will produce separation layer at a certain time. These separation layer spaces are the key positions for separation layer grouting. Each separation layer area experiences three stages of opening, development and closure as the mining working face advances. It is very critical to start grouting operation when the separation layer area is opened. However, since the separation layer space is deep underground, there is no suitable method to monitor the opening time of the separation layer area, which also restricts the scientific and efficient implementation of the separation layer area grouting work.

[0004] In the prior art, when grouting is performed, a small amount of grouting cannot effectively avoid surface subsidence, nor can it maximize the disposal of coal gangue. A large amount of grouting will cause the ground to swell or the slurry in the separation layer area to break through the safety protection layer into the mining space. Currently, the grouting degree is mainly judged indirectly through the hole grouting pressure. This method has the problem of inaccurate grouting amount judgment. SUMMARY

[0005] The present application provides a monitoring method for assisting coal mine separation layer area grouting operation and a reinforcing rod to solve the problem of inaccurate grouting degree judgment in the prior art when coal mine separation layer area grouting operation is performed.

[0006] In order to solve the above problems, according to one aspect of the present application, a monitoring method for assisting coal mine separation layer area grouting operation is provided, comprising: drawing a coal seam floor contour map of the working face; calculating the thickness of the fracture zone, and drawing an overburden rock fracture zone bottom interface contour map of the working face according to the coal seam floor contour map; arranging a plurality of ground stress monitoring points in the roadway according to the overburden rock fracture zone bottom interface contour map; performing directional drilling respectively with each ground stress monitoring point as a starting point; after the plurality of directional drilling is completed, a plurality of drilling stress sensors are respectively sent into the directional drilling; and judging whether the corresponding coal mine separation layer area needs grouting according to the value detected by each drilling stress sensor.

[0007] Further, the judgment of whether the corresponding coal mine separation layer area needs to be grouted comprises: starting to grout the coal mine separation layer area when the value detected by the borehole stress sensor reaches a first preset value; stopping to grout the coal mine separation layer area when the value detected by the borehole stress sensor rises from the first preset value to a second preset value; wherein the first preset value is the ground stress value after the coal mine separation layer area is mined, and the second preset value is the ground stress value when the coal mine separation layer area is not mined.

[0008] Further, the directional drilling from the ground stress monitoring point as the starting point comprises: drawing a perpendicular line from the ground stress monitoring point to the roadway arranged in the drilling field, and performing directional drilling along the perpendicular line; and flushing the rock debris in the directional drilling hole after the directional drilling is completed.

[0009] Further, the sending of the borehole stress sensor into the directional drilling hole comprises: installing the borehole stress sensor on a reinforcing rod; extending the reinforcing rod with the borehole stress sensor into the directional drilling hole after flushing is completed; and sequentially connecting the multiple reinforcing rods end to end and extending them into the directional drilling hole to send the borehole stress sensor to the bottom of the directional drilling hole.

[0010] Further, the arrangement of multiple ground stress monitoring points in the roadway comprises: arranging multiple ground stress monitoring points at intervals in the range of the fracture zone at the middle position of the working face, and the ground stress monitoring points are located at 2 / 3 of the height of the fracture zone in the height direction.

[0011] Further, the distance between two adjacent ground stress monitoring points is an integer multiple of the initial weighting distance of the main roof.

[0012] Further, the calculation of the thickness of the fracture zone comprises: calculating the height of the caving zone and the height of the water flowing fractured zone in the overburden strata of the goaf, and the thickness of the fracture zone is equal to the height of the water flowing fractured zone minus the height of the caving zone.

[0013] Further, the drawing of the coal seam floor contour map of the working face comprises: determining the change of the coal seam floor contour of the working face according to the elevations of the roadways around the working face, the internal exploration boreholes of the working face, and the previously exposed structures, to draw the coal seam floor contour map of the working face.

[0014] According to another aspect of the present application, a reinforcing rod is provided, which is applied in the above-mentioned monitoring method for assisting coal mine separation layer area grouting operation, and the reinforcing rod comprises a first sleeve and a second sleeve connected to each other, the diameter of the first sleeve is smaller than that of the second sleeve, the first sleeve has a limiting column at the end away from the second sleeve, the second sleeve has a limiting slot at the end away from the first sleeve, the limiting column on the first sleeve of one reinforcing rod and the limiting slot on the second sleeve of the adjacent reinforcing rod are in limiting fit, and the borehole stress sensor is installed at the end of the first sleeve or the end of the second sleeve.

[0015] Furthermore, the limiting groove includes a first groove and a second groove arranged sequentially in the circumferential direction of the second sleeve. One end of the first groove is located on the end face of the second sleeve, and the other end of the first groove is connected to the second groove. The limiting post and the inner wall of the second groove are mutually limiting and cooperating.

[0016] Furthermore, the first sleeve has a first notch that penetrates the side wall of the first sleeve, and the second sleeve has a second notch that penetrates the side wall of the second sleeve, and the first notch and the second notch are connected.

[0017] This invention provides a monitoring method for grouting operations in coal mine delamination zones, comprising: drawing a contour map of the coal seam floor of the working face; calculating the thickness of the fracture zone and, based on the contour map of the coal seam floor, drawing a contour map of the bottom interface of the overlying rock fracture zone of the working face; arranging multiple geostress monitoring points in the roadway based on the contour map of the bottom interface of the overlying rock fracture zone of the working face; drilling directional boreholes starting from each geostress monitoring point; after each directional borehole is completed, inserting a stress sensor into each borehole; and determining whether grouting is needed in the corresponding coal mine delamination zone based on the values ​​detected by each borehole stress sensor. This method, by inserting a stress sensor into each borehole, allows for the determination of whether grouting is needed in the coal mine delamination zone based on the values ​​detected by the stress sensors, effectively solving the problem of inaccurate judgment of the grouting degree during grouting operations in coal mine delamination zones in existing technologies. It also provides technical indicators for the timing of starting grouting and the standard for ending grouting in the coal mine delamination zone, thus improving the scientific nature and efficiency of grouting construction in the delamination zone. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0019] Figure 1 A flowchart of a monitoring method for auxiliary coal mine grouting operations provided in Embodiment 1 of the present invention is shown;

[0020] Figure 2 It shows Figure 1 Contour map of the coal seam floor in the working face;

[0021] Figure 3 It shows Figure 1 Contour map of the bottom interface of the overlying fracture zone in the middle working face;

[0022] Figure 4 It shows Figure 1 Layout diagram of directional drilling;

[0023] Figure 5 a sectional view of a directional drilling hole is shown; Figure 4 a sectional view of a directional drilling hole is shown;

[0024] Figure 6 a structural schematic diagram of a reinforcing rod provided by embodiment two of the present application is shown;

[0025] Figure 7 a sectional view of a directional drilling hole is shown; Figure 6 a schematic diagram of a first casing portion structure is shown;

[0026] Figure 8 a sectional view of a directional drilling hole is shown; Figure 6 a schematic diagram of a reinforcing rod portion structure is shown.

[0027] Among them, the above drawings include the following reference signs:

[0028] 10, a ground stress monitoring point;

[0029] 20, a plumb line;

[0030] 31, a first casing; 311, a limiting column; 312, a first notch; 32, a second casing; 321, a limiting groove; 3211, a first notch; 3212, a second notch; 322, a second notch. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] As Figures 1 to 5 shown, embodiment one of the present application provides a monitoring method for assisting coal mine separation layer area grouting operation, comprising: drawing a coal seam floor contour map of a working face; calculating the thickness of a fracture zone, and drawing an overburden rock fracture zone bottom interface contour map of the working face according to the coal seam floor contour map; arranging a plurality of ground stress monitoring points 10 in a roadway according to the overburden rock fracture zone bottom interface contour map; respectively performing directional drilling with each ground stress monitoring point 10 as a starting point; after the plurality of directional drilling holes are completed, respectively sending a plurality of drilling stress sensors into the directional drilling holes; judging whether the corresponding coal mine separation layer area needs grouting according to the values detected by each drilling stress sensor.

[0033] With the scheme, the corresponding each borehole stress sensor is respectively sent into the directional borehole, so that whether the coal mine separation layer area needs to be grouted can be judged through the value detected by the borehole stress sensor, effectively solving the problem that the grouting degree is not accurately judged in the grouting operation of the coal mine separation layer area in the prior art. Meanwhile, the technical indexes of the starting grouting time and the grouting end standard for the grouting construction of the coal mine separation layer area are provided, and the scientificity and efficiency of the grouting construction of the separation layer area are improved.

[0034] Specifically, the borehole stress sensor can be selected from YHY25 mine intrinsic safety type borehole stress meter.

[0035] It should be noted that: when the coal is mined, the "upper three zones" (not all mines can develop complete upper three zones, but the mines that can use the separation layer grouting technology must develop complete upper three zones) will be formed in the overburden strata of the goaf, which are respectively the caving zone, the fractured zone and the curved subsidence zone.

[0036] Explanation and characteristics of caving zone: the immediate roof is crushed and caved due to the lower part of the coal being mined, and the immediate roof is crushed and caved under the pressure of the upper rock strata. The rocks in the caving zone are randomly stacked in the goaf.

[0037] Explanation and characteristics of fractured zone: after the immediate roof is crushed and caved, the main roof produces cracks under the pressure of the overburden strata. The rock strata in the fractured zone mainly develop longitudinal cracks and have regular layer-by-layer distribution characteristics.

[0038] Explanation and characteristics of curved subsidence zone: after the main roof produces cracks and subsides, part of the rock strata above the main roof produces curved subsidence under the pressure of the overburden strata. The curved subsidence zone is the main position of the separation layer grouting.

[0039] The development height calculation of the caving zone and the water flowing fractured zone is divided into theoretical formula method, measurement method and analogy method.

[0040] The measurement method is to determine the development range of the caving zone and the water flowing fractured zone through hole inspection, drilling fluid loss and other means by constructing a borehole in the overburden strata of the goaf.

[0041] The analogy method is to determine the development range of the caving zone and the water flowing fractured zone by analogy and inference based on the measured data of the similar surrounding mines or the adjacent working faces in the mine field.

[0042] The judgment of whether the coal mine separation layer area needs to be grouted includes: starting to grout the coal mine separation layer area when the value detected by the borehole stress sensor reaches the first preset value; stopping to grout the coal mine separation layer area when the value detected by the borehole stress sensor rises from the first preset value to the second preset value; wherein the first preset value is the ground stress value after the coal mine separation layer area is mined, and the second preset value is the ground stress value when the coal mine separation layer area is not mined. After the borehole stress sensor is installed, after the directional drilling hole is deformed and fully contacts with the borehole stress sensor, the initial ground stress value of the coal mine separation layer area is recorded at this time. With the continuous progress of the working face mining operation, the value detected by the borehole stress sensor will have a process of first falling and then rising and recovering. Specifically, when the value detected by the borehole stress sensor reaches the first preset value, the value of the first preset value is less than the initial ground stress value, at which time the coal mine separation layer area is started to be grouted; then the change of the value detected by the borehole stress sensor is continuously observed, when the value detected by the borehole stress sensor rises from the first preset value to the second preset value, the value of the second preset value is greater than or equal to the initial ground stress value, at which time the coal mine separation layer area is stopped to be grouted, which indicates that the coal mine separation layer area has been completely filled, and the grout of the coal mine separation layer area has sufficient strength to support the overlying strata.

[0043] Specifically, taking the ground stress monitoring point 10 as the starting point, the directional drilling includes: taking the ground stress monitoring point 10 as the starting point, making a perpendicular line 20 to the roadway arranged in the drilling field, and drilling along the perpendicular line 20; after the directional drilling is completed, the drillings in the directional drilling hole are flushed. By using the above method, the perpendicular line 20 is made to the roadway arranged in the drilling field, and the directional drilling is performed along the perpendicular line 20, so that the accuracy of the directional drilling can be ensured. After the roadway around the working face is formed, all directional drilling holes for installing borehole stress sensors are constructed before mining, and the drillings in each directional drilling hole are carefully flushed after the directional drilling hole is constructed to the designed depth, so that the borehole stress sensor can be smoothly sent to the bottom of the hole.

[0044] It should be noted that: the angle of the directional drilling hole from the hole opening to the hole bottom is a positive angle, so that the drillings in the directional drilling hole can be flushed clean in the later period.

[0045] Optionally, the position of each drilling field is arranged in the roadway below the working face, so that the hole opening and the hole bottom have a greater height difference. And as shown in Figure 5 , the directional drilling trajectory design cannot pass through the caving zone boundary formed by the future working face mining; the roadway where the drilling field is located requires personnel to normally enter and exit during the mining operation in order to monitor the data, therefore, the roadway arranged by the drilling field should not be adjacent to the roadway of the working face.

[0046] Optionally, the outer diameter of the drill bit during the directional drilling construction is required to match the borehole stress sensor, so as to ensure that the borehole stress sensor can fully contact with the hole wall.

[0047] In the embodiment, the sending the borehole stress sensor into the directional borehole comprises: installing the borehole stress sensor on a reinforcing rod; extending the reinforcing rod with the borehole stress sensor into the directional borehole after the flushing; and connecting the reinforcing rods with the borehole stress sensors in sequence and extending them into the directional borehole to send the borehole stress sensor to the bottom of the directional borehole. By using the method, the borehole stress sensor can be sent to the bottom of the directional borehole smoothly, and the communication cable can be prevented from being damaged.

[0048] The communication cable is left outside the directional borehole with a certain length to compensate for the length deformation of the directional borehole during the mining operation.

[0049] Specifically, the arrangement of the multiple ground stress monitoring points 10 in the roadway comprises: arranging the multiple ground stress monitoring points 10 in the range of the fracture zone at the middle position of the working face, and the ground stress monitoring points 10 are located at 2 / 3 of the height of the fracture zone in the height direction. By arranging the multiple ground stress monitoring points 10, the coal mine separation zone can be better monitored, and the subsequent grouting operation of the coal mine separation zone is facilitated.

[0050] The distance between two adjacent ground stress monitoring points 10 is an integer multiple of the initial weighting distance of the main roof. The data of the ground stress monitoring points 10 monitored by the borehole stress sensor can be more accurate. The initial weighting of the main roof refers to the first fracture and rotation of the main roof after the direct roof collapses, which leads to the sharp subsidence of the working face roof and the general weighting phenomenon of the working face roof.

[0051] In the embodiment, the calculation of the thickness of the fracture zone comprises: calculating the height of the caving zone and the height of the water flowing fractured zone in the overburden strata of the goaf, and the thickness of the fracture zone is equal to the height of the water flowing fractured zone minus the height of the caving zone. Since the height of the water flowing fractured zone and the height of the caving zone can be calculated by the existing formula, the thickness of the fracture zone can be calculated by the height of the water flowing fractured zone and the height of the caving zone, thereby preparing for drawing the contour line graph of the fracture zone bottom interface of the overburden strata of the working face. The goaf refers to the "cavity" produced by human excavation or natural geological movement under the ground surface, and the goaf formed by the full filling or partial filling method of the working face, and the working face roof only partially subsides.

[0052] Specifically, the drawing of the coal seam floor contour line graph of the working face comprises: determining the change of the coal seam floor contour line of the working face according to the elevations of the roadways around the working face, the internal exploration boreholes of the working face, and the previously exposed structures, so as to draw the coal seam floor contour line graph of the working face. Before drawing the coal seam floor contour line graph of the working face, the relevant geological data (the elevations of the roadways around the working face, the internal exploration boreholes of the working face, and the previously exposed structures) of the region can be consulted to draw the graph.

[0053] As Figures 6 to 8As shown, the second embodiment of the present application provides a reinforcing rod, which is applied in the above-mentioned monitoring method for auxiliary coal mine separation zone grouting operation, and the reinforcing rod comprises a first sleeve 31 and a second sleeve 32 connected with each other, the diameter of the first sleeve 31 is smaller than that of the second sleeve 32, the end of the first sleeve 31 away from the second sleeve 32 is provided with a limiting column 311, the end of the second sleeve 32 away from the first sleeve 31 is provided with a limiting groove 321, the limiting column 311 on the first sleeve 31 of one reinforcing rod is limitedly matched with the limiting groove 321 on the second sleeve 32 of the adjacent reinforcing rod, and a borehole stress sensor is installed at the end of the first sleeve 31 or the end of the second sleeve 32. The diameter of the first sleeve 31 is smaller than that of the second sleeve 32, so that when the adjacent two reinforcing rods are assembled, it can be ensured that the first sleeve 31 can be inserted into the second sleeve 32, and the connection strength is improved; the limiting column 311 and the limiting groove 321 are arranged, and the mutual connection of the adjacent two reinforcing rods can be realized. The borehole stress sensor is installed at the end of the first sleeve 31 or the end of the second sleeve 32, and the installation mode can be bonding or other fixing modes.

[0054] The limiting groove 321 comprises a first slot 3211 and a second slot 3212 arranged in sequence in the circumferential direction of the second sleeve 32, one end of the first slot 3211 is located at the end face of the second sleeve 32, the other end of the first slot 3211 and the second slot 3212 are communicated, and the limiting column 311 and the inner wall of the second slot 3212 are limitedly matched. When installing, the limiting column 311 on the first sleeve 31 of one reinforcing rod can be sequentially inserted into the first slot 3211 and the second slot 3212, and the inner wall of the second slot 3212 and the limiting column 311 are limitedly matched. Specifically, the second slot 3212 has a first side wall, a second side wall and a third side wall connected in sequence, the first side wall and the third side wall are arranged in parallel, the second side wall is perpendicular to the first side wall and the third side wall, and the limiting column 311 abuts against the first side wall, the second side wall and the third side wall.

[0055] Specifically, the first sleeve 31 has a first notch 312 penetrating the side wall of the first sleeve 31, the second sleeve 32 has a second notch 322 penetrating the side wall of the second sleeve 32, and the first notch 312 and the second notch 322 are communicated. The first notch 312 and the second notch 322 are arranged, and the first notch 312 and the second notch 322 are communicated, so that when the borehole sensor is transported, the communication cable is placed, and the operation is simple and convenient.

[0056] The specific implementation of the monitoring method for auxiliary coal mine separation zone grouting operation and the reinforcing rod of the present application is as follows:

[0057] A coal mine production capacity of 5.5 million tons / year, annual waste amount of 1 million tons, a year because of the waste field expiration can not lead to the production of waste, to solve the problem of restricting production of waste, the mine built a set of production capacity of 1.2 million tons / year of separation zone grouting system.

[0058] The working face with separation zone grouting has a buried depth of 460-520 meters, a working face width of 210 meters, a advancing length of 1770 meters, an average coal thickness of 3.6 meters, and an average inclination of 2°. It adopts a longwall retreat mining method with a mining height of 3.6 meters. It is a monocline structure and no faults and folds are found.

[0059] Combined with a large number of exploration drill holes and rock mechanics properties measurement in the working face, it is concluded that a thick layer of fine-grained sandstone is developed at a position of 280-320 meters above the coal seam. The lower side of the layer of fine-grained sandstone is a thin layer of sandstone and mudstone interbedded. The thick layer of fine-grained sandstone will become a key layer during the recovery operation and separate the sand and mud interbedded layer below to form a separation zone. The separation grouting operation takes the separation zone as the main filling object.

[0060] 1. Determine the structure change of the coal seam in the working face

[0061] Combined with the roadway floor traverse point elevation of the rubberized transportation gate, return air gate, open-off cut and withdrawal channel in the working face, and the coal elevation of the exploration drill hole in the working face, the coal seam floor contour of the working face is drawn, as shown in Figure 2 .

[0062] 2. Determine the development position of the "fractured zone" in the overburden strata of the working face

[0063] The "upper three zones" exploration has not been done in the mine, and there is no reference data from the surrounding mines. Therefore, the theoretical method is used to calculate the height of each zone.

[0064] ① Calculate the height of the caving zone

[0065] According to the exploration drill hole, it is obtained that the overburden strata of the working face belong to "medium hard". Therefore, the corresponding formula is used for calculation. The mining height is 3.6 meters. The calculation can obtain the height of the caving zone of 7.8-12.2 meters, and the maximum value is 12.2 meters.

[0066] Special note: If the coal thickness and mining height of a working face change greatly, or there is a structure influence, then it needs to be calculated in different zones. The calculation of other parameters is the same.

[0067] ② Calculate the height of the water flowing fractured zone

[0068] According to the exploration drill hole, it is obtained that the overburden strata of the working face belong to "medium hard". Therefore, formula one and formula two are used for calculation. The mining height is 3.6 meters. The calculation can obtain the height of the water flowing fractured zone of 44-47.9 meters, and the maximum value is 47.9 meters.

[0069] ③Calculate fracture zone parameters

[0070] Fracture zone thickness = height of water flowing fractured zone - height of caving zone, the calculated fracture zone thickness is 35.7 meters.

[0071] In order to reduce the influence of "fracture zone" cracks on the borehole, the borehole is arranged in the middle and upper position of the "fracture zone", that is, 24 meters away from the bottom interface of the "fracture zone".

[0072] The height of the fracture zone bottom interface from the goaf floor is equal to the thickness of the mined coal + the height of the caving zone, which is calculated to be 15.8 meters.

[0073] ④Draw the contour map of the bottom interface of the overburden "fracture zone"

[0074] Combined with the floor contour of the working face and the fracture zone parameters calculated in step ③, the contour map of the bottom interface of the overburden "fracture zone" is drawn. In this example, because the mining height and coal thickness are fixed and not affected by the structure, the thickness of the overburden "fracture zone" is constant, so there is no need to draw the isoperimetric line map of the overburden "fracture zone", as shown in Figure 3 .

[0075] 3, Determine the position of the ground stress monitoring point in the working face

[0076] The initial pressure distance of the surrounding working face of the mine is 40 meters, and the analogy method is used to infer that the initial pressure distance of the working face is 40 meters. In order to ensure the richness and reliability of the data of the separation grouting monitoring, the interval of the ground stress monitoring points is 2 times the initial pressure step distance of the main roof, that is, 80 meters. All ground stress monitoring points are located in the "fracture zone" of the overburden in the middle of the working face. The elevation data of each ground stress monitoring point is determined in combination with the contour map of the bottom interface of the overburden "fracture zone".

[0077] 4, Directional drilling design and construction

[0078] From the coal floor contour, it can be known that the rubber transport gate of the working face is significantly lower than the air return gate of the working face, and the rubber transport gate of the working face will be damaged during mining operation. In order to avoid the borehole passing through the caving zone, and the personnel can normally enter and exit the roadway for data monitoring during the separation grouting operation, therefore, the drilling field is arranged in the air return gate of the working face. As shown in Figure 4 and Figure 5 .

[0079] (Every ground stress monitoring point has different heights, which needs to be determined one by one in combination with the data)

[0080] In this example, the ground stress monitoring points are arranged in the overburden above the middle of the working face. According to the "masonry beam" theory, in the goaf, except for the stress recovery of the roadway edge supported by the overburden triangular hinge, the other areas will gradually recover to the original rock stress state before mining as time goes on. Therefore, when selecting the position, the triangular hinge at the edge of the goaf should be avoided, and the closer to the middle position, the better, but the engineering quantity will increase accordingly.

[0081] In this case, directional drilling is used to drill holes equipped with 75mm outer diameter drill bits. The mine intrinsically safe type drill hole stress sensor has an outer diameter of 50mm, and the communication cable length is 150 meters, which is longer than the drill hole trajectory length by a certain distance.

[0082] After the directional drilling is in place, the drill hole is flushed with a large pump capacity of clean water and the drill is kept rotating at a low speed. After the water in the hole returns without coal and rock debris, the drill is withdrawn a certain distance. The drill hole is again flushed with a large pump capacity of clean water and the drill is kept rotating at a low speed. After the water in the hole returns without coal and rock debris, the drill is withdrawn a certain distance. This process is repeated until all the drills are withdrawn from the drill hole.

[0083] 5. Installing the drill hole stress sensor

[0084] After each directional drilling is completed and the drill is withdrawn from the drill hole, the drill hole stress sensor is sent into the hole as soon as possible. The specific operation steps are as follows:

[0085] The drill hole stress sensor is fixed at the end of the reinforcing rod, and the tape is firmly adhered to prevent it from falling off. The communication cable is embedded in the reinforcing rod after being smeared with butter. The connection between each adjacent reinforcing rod is fixed with tape to prevent the reinforcing rod connection from coming off. The device is sent into the hole one section at a time until the designed depth is reached.

[0086] 6. Dynamic monitoring of the values detected by the drill hole stress sensor and assisting the coal separation zone grouting operation

[0087] After all the drill hole stress sensors are installed, the values of each stress sensor are continuously monitored. When the values of each stress sensor rise steadily, they are recorded as the initial ground stress values (assuming A).

[0088] During the working face mining operation, the data of each drill hole stress sensor is continuously observed.

[0089] According to theoretical calculations, numerical simulations and similar simulation tests, when the drill hole stress sensor value recovers to 0.7A, the designed grouting separation zone separation begins to develop. When the drill hole stress sensor value recovers to 1.05A, the designed grouting separation zone separation is completely filled.

[0090] After the working face pushes through the borehole stress sensor projection point by a certain distance, the borehole stress sensor value will have a process of first falling and then rising and recovering. When the borehole stress sensor value rises to 0.7A, the grouting operation is started; during the grouting operation, the change of the borehole stress sensor value is continuously paid attention to, and when the borehole stress sensor value rises to 1.05A, the grouting is stopped. The grouting pipeline is moved to the next grouting hole, and the cycle is repeated until all the separation layer areas are filled.

[0091] The advantages of the scheme are as follows:

[0092] 1. The coal separation layer grouting technology plays a great technical support for green coal mining, but there is no ready-made scheme to assist in determining the starting grouting time and the grouting end standard of the coal separation layer. The scheme provides technical indexes of the starting grouting time and the grouting end standard for the coal separation layer grouting construction through the recovery monitoring of the ground stress of the "fracture zone" in the goaf. The scientificity and efficiency of the coal separation layer grouting construction are improved.

[0093] 2. The main method of ground stress monitoring cannot provide monitoring services for coal separation layer grouting, and the scheme can set the borehole stress sensor to a specific position through directional drilling, overcoming the defects of the prior art.

[0094] 3. The scheme sets the borehole stress sensor in the "fracture zone", which has the characteristics of layer-by-layer regular distribution after mining, and only a small amount of longitudinal cracks are developed, which will not cause damage to the equipment in the borehole. The rock in the "caving zone" is chaotic, which is not conducive to the reliable bearing of the ground stress by the borehole stress sensor, and there is a probability problem of taking chances, and the equipment cable is easily damaged. The "complete subsidence zone" is the main separation grouting space, and if the drilling is constructed, the "string grouting" phenomenon is easily caused, and production accidents are easily caused.

[0095] 4. The reinforcing rod is provided with a first notch and a second notch, which facilitates the rapid embedding of the communication cable; through the assembly mode of the limiting column and the limiting groove, the rapid assembly of the adjacent reinforcing rods is facilitated; at the same time, butter can also be smeared during construction to reduce the resistance of the length compensation of the communication cable when the formation deforms.

[0096] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A monitoring method for assisting grouting operation in a coal mine separation layer area, characterized in that, The application relates to a coal seam floor contour drawing method for a working face. The method comprises the following steps: drawing a coal seam floor contour map of a working face; calculating the thickness of a fractured zone and drawing an overburden rock fractured zone bottom interface contour map of the working face according to the coal seam floor contour map; arranging a plurality of ground stress monitoring points (10) in a roadway according to the overburden rock fractured zone bottom interface contour map; performing directional drilling respectively from each ground stress monitoring point (10) as a starting point; sending a plurality of borehole stress sensors into the directional drilling holes respectively after the directional drilling is completed; continuously monitoring the values of the borehole stress sensors after the borehole stress sensors are installed; recording the initial ground stress value A when the values of the borehole stress sensors are stable; judging whether the corresponding coal mine separation layer area needs to be grouted according to the values detected by the borehole stress sensors; judging whether the corresponding coal mine separation layer area needs to be grouted, which comprises the following steps: starting grouting of the coal mine separation layer area when the value detected by the borehole stress sensor reaches a first preset value; stopping grouting of the coal mine separation layer area when the value detected by the borehole stress sensor rises from the first preset value to a second preset value; wherein the value of the borehole stress sensor first decreases and then rises after the working face pushes through the projection point of the borehole stress sensor by a certain distance, and the grouting operation is started when the value of the borehole stress sensor rises to 0.7A; the value change of the borehole stress sensor is continuously paid attention to during the grouting operation, and the grouting operation is stopped when the value of the borehole stress sensor rises to 1.05A; performing the directional drilling from the ground stress monitoring point (10) as a starting point, which comprises the following steps: arranging a perpendicular line (20) from the ground stress monitoring point (10) to the roadway arranged in a drilling field, and performing the directional drilling along the perpendicular line (20); and flushing the rock debris in the directional drilling hole after the directional drilling is completed. The method comprises the following steps: sending the borehole stress sensor into the directional drilling hole, which comprises the following steps: installing the borehole stress sensor on a reinforcing rod; extending the reinforcing rod with the borehole stress sensor into the directional drilling hole after flushing is completed; and sequentially connecting the reinforcing rods with the borehole stress sensors to extend into the directional drilling hole to send the borehole stress sensors into the bottom of the directional drilling hole. The method comprises the following steps: arranging a plurality of ground stress monitoring points (10) in the range of the fractured zone at the middle position of the working face, and arranging the ground stress monitoring points (10) at 2 / 3 of the height of the fractured zone in the height direction. The distance between two adjacent ground stress monitoring points (10) is an integer multiple of the primary roof pressure distance. The method comprises the following steps: calculating the height of a caving zone and the height of a water flowing fractured zone in the overburden rock layer of a goaf, and the thickness of the fractured zone is equal to the height of the water flowing fractured zone minus the height of the caving zone. The method comprises the following steps: drawing a coal seam floor contour map of a working face; calculating the thickness of a fractured zone and drawing an overburden rock fractured zone bottom interface contour map of the working face according to the coal seam floor contour map; arranging a plurality of ground stress monitoring points (10) in a roadway according to the overburden rock fractured zone bottom interface contour map; performing directional drilling respectively from each ground stress monitoring point (10) as a starting point; sending a plurality of borehole stress sensors into the directional drilling holes respectively after the directional drilling is completed; continuously monitoring the values of the borehole stress sensors after the borehole stress sensors are installed; recording the initial ground stress value A when the values of the borehole stress sensors are stable; judging whether the corresponding coal mine separation layer area needs to be grouted according to the values detected by the borehole stress sensors; judging whether the corresponding coal mine separation layer area needs to be grouted, which comprises the following steps: starting grouting of the coal mine separation layer area when the value detected by the borehole stress sensor reaches a first preset value; stopping grouting of the coal mine separation layer area when the value detected by the borehole stress sensor rises from the first preset value to a second preset value; wherein the value of the borehole stress sensor first decreases and then rises after the working face pushes through the projection point of the borehole stress sensor by a certain distance, and the grouting operation is started when the value of the borehole stress sensor rises to 0.7A; the value change of the borehole stress sensor is continuously paid attention to during the grouting operation, and the grouting operation is stopped when the value of the borehole stress sensor rises to 1.05A; performing the directional drilling from the ground stress monitoring point (10) as a starting point, which comprises the following steps: arranging a perpendicular line (20) from the ground stress monitoring point (10) to the roadway arranged in a drilling field, and performing the directional drilling along the perpendicular line (20); and flushing the rock debris in the directional drilling hole after the directional drilling is completed. ​ ​ 2. The method for monitoring the grouting operation in the separation zone of the coal mine according to claim 1, characterized in that, ​ ​ ​ ​ 3. The method for monitoring the grouting operation in the separation zone of the coal mine according to claim 1, characterized in that, ​ ​ 4. The method for monitoring the grouting operation in the separation zone of the coal mine according to claim 3, characterized in that, ​ 5. The method for monitoring the grouting operation in the separation zone of the coal mine according to claim 1, characterized in that, ​ ​ 6. The method for monitoring the grouting operation in the separation zone of the coal mine according to claim 1, characterized in that, ​ According to the elevation of the roadway around the working face, the internal exploration borehole of the working face and the structure determined in the early stage, the coal seam floor contour line variation of the working face is determined to draw the coal seam floor contour line map of the working face.

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