Gob-side roadway accurate roof cutting method based on rock stratum geology detection while drilling

Abstract

The invention discloses a gob-side roadway accurate roof cutting method based on rock stratum geology detection while drilling, and belongs to the field of coal mine intelligent mining. Comprising the steps that S1, a while-drilling parameter measuring instrument installed on a drilling machine is used for collecting operation parameters of the drilling machine; s2, establishing a rock stratum strength identification model based on a comprehensive index by using the parameters collected in the S1 so as to determine the lithology and rock sequence distribution of the roof rock stratum; s3, establishing a coal face front advance bearing pressure distribution range calculation model to judge a gob-side roadway roof cutting range; s4, determining a gob-side roadway roof cutting layer position by utilizing the roof cutting height calculation equation and the rock stratum lithology distribution; and S5, the drilling angle is corrected in real time according to the monitoring result of the tilt angle sensor. The gob-side roadway roof cutting range and the roof cutting layer position are determined according to the roadway trend roof rock stratum geological conditions through the real-time operation data of the drilling machine, so that the roof cutting parameters are dynamically adjusted, the drilling angle is corrected in real time, and the purpose that the roof cutting effect is consistent with the design result is achieved.

Description

Technical Field

[0001] The present invention relates to the field of intelligent coal mining, and in particular to a method for accurately cutting the top of an empty tunnel based on rock stratum geological detection while drilling. Background Art

[0002] The recoverable coal resources in the mining areas in central and eastern my country are constantly decreasing. Leaving coal pillars between mining faces causes a huge waste of resources and is very likely to cause disasters such as impact ground pressure, fire in the empty area, and gas accumulation. One of the effective ways to solve the above problems is the technology of cutting the top to relieve pressure and leaving the lane along the empty area. This technology is of great significance to improving coal recovery rate, alleviating the downward pressure on the coal economy and the sustainable development of the mining industry.

[0003] The technology of retaining a roadway along the goaf is to pre-crack the roadway roof in front of the coal mining working face. The pre-cracked roof collapses under the pressure of the mine. After the collapsed roof is treated with gangue support, temporary support, and air leakage plugging technology, the roadway can be retained to serve the next working face. The core link of the technology of retaining a roadway along the goaf is top cutting and pressure relief. The traditional method uses a single top cutting parameter for the entire roadway along the goaf based on the geological information of the roof rock strata in the local area. It is impossible to dynamically adjust the top cutting parameter according to the geological conditions of the roof rock strata along the roadway. As a result, the roadways along the goaf generally have problems such as unreasonable top cutting position and timing, high stress concentration in the roadway, and large deformation of the surrounding rock.

[0004] In addition, anchor drilling rigs are commonly used on site for pre-cracking hole construction. However, due to the lack of effective monitoring methods, the inclination angles of the pre-cracking holes often deviate to varying degrees from the design angle during the pre-cracking hole construction, causing the pre-cracking holes to be not in the same plane, seriously affecting the blasting pre-cracking effect. Summary of the invention

[0005] In order to solve the problems that the traditional top cutting and pressure relief method cannot dynamically adjust the top cutting parameters according to the geological conditions of the top rock layer in the roadway direction, resulting in the common problems of unreasonable top cutting position and timing in the goaf-side roadway, high stress concentration in the roadway, and large deformation amplitude of the surrounding rock, and the inclination angles of each pre-crack hole often deviate from the design angle to varying degrees during the construction of the pre-crack hole, resulting in the pre-crack holes being not in the same plane, which seriously affects the blasting pre-crack top cutting effect, the present invention provides a precise top cutting method for goaf-side roadways based on rock stratum geological drilling detection, comprising the steps of:

[0006] S1: Install the drilling parameter measuring instrument on the single anchor drilling rig used for the top cutting construction of the goaf-side tunnel, use the drilling rig to drill holes on the top plate of the goaf-side tunnel, and use the drilling parameter measuring instrument to collect the drilling rig operation parameters such as thrust, torque, speed, displacement, vibration and inclination in real time;

[0007] S2: Use the collected drilling rig operating parameters to calculate the two comprehensive indicators of SEM and RDA; establish a rock formation strength identification model based on comprehensive indicators through the multivariate linear regression method; use the rock formation strength identification results and drilling displacement to determine the lithology and rock sequence distribution of the roof rock formation;

[0008] S3: Based on the information of coal mining face burial depth, height, mining height, roof lithology and rock sequence distribution, a calculation model for the distribution range of the advanced support pressure in front of the coal mining face is established;

[0009] S4: Substitute the parameters such as rock lithology, rock sequence and thickness into the top cutting height calculation equation to obtain the top cutting height at the drilling position;

[0010] S5: Based on the dynamic identification of the lithology and rock sequence of the roof strata by the detection while drilling technology, different top-cutting drilling hole spacings are designed according to the distribution of rock strata. When the top-cutting holes are drilled in the roof of the gob-side tunnel, the monitoring results of the inclination sensor are used to correct the drilling angle in real time to finally obtain the blasting hole.

[0011] Furthermore, in step S1, the device used includes a single anchor drilling rig, a drilling parameter measuring instrument, a signal wireless transmission module, a signal wireless receiving module, a multi-channel data acquisition module, a data storage and display terminal, a drill rod and a drill bit; the drilling parameter measuring instrument is internally installed with thrust, torque, speed, displacement and inclination sensors, the lower end of which is connected to the single anchor drilling rig with an external hexagonal shaft, and the upper end is connected to a B19 hexagonal drill rod.

[0012] Furthermore, the drilling rig operation parameters collected by each sensor first enter the signal wireless transmission module, and then are received by the signal wireless receiving module and transmitted to the multi-channel data acquisition module. The multi-channel data acquisition module is connected to the data storage and display terminal for storage and display.

[0013] Furthermore, in step S2, using the collected while-drilling parameters such as thrust, torque, rotation speed, drilling speed and vibration, two comprehensive indicators, namely, modulation specific energy SEM and rock drillability index RDA, can be calculated by the following formula:

[0014]

[0015] The multivariate linear regression model for predicting rock formation strength using SEM and RDA can be expressed as:

[0016] Rc=k1×SEM+k2×RDA.

[0017] Further, in step S3, the calculation model of the distribution range of the advance support pressure in front of the coal mining working face is:

[0018]

[0019] Furthermore, in step S4, the calculation formula for the top cutting height is:

[0020]

[0021] Furthermore, in step S5, the top cutting method adopts blasting top cutting, and according to different rock types, the spacing of blasting holes is designed as follows: ① hard top plate, the spacing is 500mm; ② soft rock top plate spacing is 550mm; ③ broken top plate spacing is 600mm.

[0022] Further, in step S5, the blast hole angle β is designed as follows: ① When H c ≤1m, β=20°;②When 1m<H c ≤3m, β=15°; ③When 3m<H c When ≤4.5m, β=10°.

[0023] Furthermore, in step S5, multiple blasting holes with the same inclination angle form cleavage cracks at the blasting position, and the cleavage cracks of each blasting hole are connected to form a regular structural weak surface on a plane. The roof rock layer is cut off and falls along the structural weak surface under the action of the advance support pressure of the working face.

[0024] In summary, the present invention has the following beneficial effects compared with the prior art:

[0025] The present invention obtains the parameters of the drilling rig during operation by means of a drilling parameter measuring instrument installed on a single anchor drill rig used for top cutting construction along the empty tunnel. The parameters of the drilling rig during operation are used to determine the lithology and rock sequence distribution of the top slab. Then, a calculation model for the distribution range of the advance support pressure in front of the coal mining face is established in combination with the buried depth, height, mining height, and top slab lithology and rock sequence distribution information, so that the distribution range of the advance support pressure is used as the advance top cutting area along the empty tunnel to achieve accurate while drilling judgment of the top cutting range along the empty tunnel. Parameters such as lithology, rock sequence, and thickness of the stratum are brought into the top cutting height calculation equation to achieve accurate while drilling judgment of the top cutting position along the empty tunnel. The inclination sensor monitoring results are used to correct the drilling angle in real time to ensure that each top cutting hole is in a straight line to the greatest extent possible to ensure the top cutting effect.

[0026] The precise top cutting method for goaf-side tunnels based on rock stratum geological detection while drilling provided by the present invention dynamically adjusts the top cutting parameters according to the geological conditions of the top rock stratum along the tunnel direction through the real-time operation data of the drilling rig, thereby achieving the purpose of accurately judging the top cutting range and top cutting position of goaf-side tunnels. In addition, the present invention uses the monitoring results of the inclination sensor to correct the drilling angle in real time, which can ensure that the top cutting effect is consistent with the design result during the construction process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 This is a flow chart of the precise top cutting method of goaf-side tunnel based on rock geology detection while drilling;

[0029] Figure 2 This is a schematic diagram of the overall structure of the equipment for detection while drilling;

[0030] Figure 3 To collect and transmit the drilling parameters;

[0031] Figure 4 is the collected data curve;

[0032] Figure 5 It is the relationship curve between SEM, RDA and rock formation strength;

[0033] Figure 6 It is the multivariate linear regression model process;

[0034] Figure 7 Schematic diagram of the cutting height of the composite roof.

[0035] The above drawings include the following reference numerals:

[0036] 1. Single anchor drilling rig; 2. Drilling parameter measuring instrument; 3. Signal wireless transmission module; 4. Signal wireless receiving module; 5. Multi-channel data acquisition module; 6. Data storage and display terminal; 7. B19 hexagonal drill rod; 8. Top rock layer. DETAILED DESCRIPTION

[0037] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form can also include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0040] See also Figure 1 As shown, the present invention provides a method for accurately cutting the top of a goaf-side tunnel based on rock stratum geological detection while drilling, comprising the steps of:

[0041] S1: Install the intelligent drilling detection equipment for rock formation geological information on the drilling rig used for blasting pre-cracking construction, and use the drilling rig to carry out the 8-strength drilling experiment of the tunnel roof rock formation. Collect the drilling rig operating parameters such as thrust, torque, speed, vibration and inclination during the drilling process in real time to provide original data for establishing a rock formation strength drilling identification model suitable for the on-site geological conditions.

[0042] like Figure 2 As shown, the device used includes a single anchor drilling rig 1, a drilling parameter measuring instrument 2, a signal wireless transmission module 3, a signal wireless receiving module 4, a multi-channel data acquisition module 5, a data storage and display terminal 6, and a B19 hexagonal drill rod 7. Among them, thrust, torque, speed, displacement and inclination sensors are installed inside the drilling parameter measuring instrument 2. The lower end of the drilling parameter measuring instrument 2 is connected to the single anchor drilling rig 1 by an external hexagonal shaft, and the upper end is connected to the B19 hexagonal drill rod 7. The drilling rig operation parameters collected by each sensor first enter the signal wireless transmission module 3, and then are received by the signal wireless receiving module 4 and transmitted to the multi-channel data acquisition module 5. The multi-channel data acquisition module 5 is connected to the data storage and display terminal 6 for storage and display. The drilling parameter collection and transmission process in step S1 is as follows. Figure 3 shown.

[0043] During the test, the drilling parameter measuring instrument 2 is first debugged to ensure that data collection and transmission are correct. Then the outer hexagonal shaft at the lower end of the drilling parameter measuring instrument is inserted into the drill rod interface of the drilling rig, and the drilling parameter measuring instrument is fixed to the single anchor drilling rig 1. The B19 hexagonal drill rod 7 is installed on the upper end of the drilling parameter measuring instrument, the data acquisition device switch is turned on, and finally the water source and gas source are connected to drill the top plate rock layer 8. During the drilling, the drilling parameter measuring instrument 2 is used to collect the drilling rig operation data such as thrust, torque, speed, displacement, inclination and vibration in real time. The data curve collected by step S1 is as follows: Figure 4 S2: As shown. Figure 5 and Figure 6 As shown, the two comprehensive indicators of SEM and RDA are calculated using the drilling rig operating parameters (thrust, torque, rotation speed, drilling speed and vibration, etc.) collected on site; a rock formation strength identification model based on the comprehensive indicators is established through the multivariate linear regression method; the rock formation strength identification results and drilling displacement are used to determine the lithology and rock sequence distribution in the top plate rock layer 8.

[0044] (1) Specific energy modulation (SEM)

[0045] The mutual information and statistical analysis methods were used to study the recognition effect of modulation energy on coal-rock boundary. The results showed that modulation energy (SEM) can distinguish coal and non-coal rock with significant consistency. Modulation energy SEM is expressed by the following formula:

[0046]

[0047] In the formula, the logarithmic function helps to amplify weak signals in SEM and sharpen the difference characteristics of different lithologies. w is used to enhance weak signals in the drilling specific energy sequence, and c specifies the transition point of the logistic function, whose physical meaning is the characteristic point of the SEM curve when the lithology changes, and its value is 0.65. In this paper, a is fixed to 2, and its value controls the transition interval of the SEM curve when the lithology changes. In addition, the constant k a and C are 1000 and 2 respectively.

[0048] (2) Rock drillability index (RDA)

[0049] Dimensional analysis can be used to determine the specific functional relationship between various variables that affect each other and express it as a simple mathematical or physical model. In the present invention, the drilling parameters include thrust, torque, rotation speed, drilling speed and vibration. Since there is an obvious functional relationship between rock strength and drilling parameters, it is assumed that the functional relationship between drilling parameters and rock strength is:

[0050] f(F,v,T,ω,g)=0

[0051] According to the π theorem, the three basic dimensions of M, L and T are selected to form the dimensional formula of six dimensional variables, and then three dimensionless quantities (π1, π2 and π3) are formed based on the dimensional analysis theory to characterize the relationship between the drilling parameters and rock strength. Each dimensionless quantity can be expressed as:

[0052]

[0053] Since π1, π2 and π3 are independent of each other, there exists π3=λπ1 α π2 β , where λ, α and β are important parameters for controlling the functional relationship between rock strength and drilling parameters. In this paper, λ is set to 0.01, and u and t are 2 and -0.5 respectively. The present invention uses rock drillability index to reflect rock strength, and the relationship between RDA and drilling parameters can be expressed as:

[0054] RDA=λv u+2t ω u / F 3-u-t T u+t-2 .

[0055] (3) Multivariate linear regression model of rock formation strength

[0056] For a set of data, let the independent variable be x i (i=1…m), the dependent variable is y, ε is the nonlinear error, and the regression coefficient is a i (i=0…m), then the functional relationship between the independent variable and the dependent variable can be expressed as a multiple regression equation:

[0057] y=a0+a1x1+…+a m x m +ε

[0058] Finally, the multivariate linear regression model for predicting rock formation strength using SEM and RDA can be expressed as:

[0059] R c =k1×SEM+k2×RDA.

[0060] S3: Based on the information of coal mining working face burial depth, height, mining height, roof lithology and rock sequence distribution, a calculation model for the advance support pressure distribution range in front of the coal mining working face is established, so that the advance support pressure distribution range is used as the advance top cutting area of ​​the gob-side tunnel to achieve accurate while-drilling judgment of the top cutting range of the gob-side tunnel.

[0061] like Figure 7As shown, according to the rock sequence and rock sequence distribution, the top cutting position should be arranged at the interface of the rock layer or thin and soft rock layer as much as possible, and the weak surface of the roof soft layer, rock layer surface and other weak surfaces should be used as the cutting interface as much as possible, which can be conducive to the collapse of the roof after the cutting. On the basis of meeting the top cutting height, if thick and hard rock layers are encountered, the top cutting height should be increased. In addition, based on full consideration of the rock layer distribution, the top cutting height design must meet the requirements that the rock mass within the top cutting range can effectively fill the goaf within a certain range beside the tunnel after collapse and expansion, and then form a gravel wall to play a necessary supporting role for the overlying rock layer of the goaf, and slow down the sinking and rotation deformation of the overlying rock in the tunnel. On the basis of understanding the lithology, thickness and expansion coefficient of the top rock layer 8, the top cutting height is calculated in detail according to the following method. Assuming that there are m layers of rock layers in the top cutting range, the top cutting height should meet the following formula:

[0062]

[0063] Where: H F is the cutting height, m; H c is the thickness of the coal seam, m; K P It is the average expansion coefficient of the rock formation, usually 1.3-1.5.

[0064] S4: Substitute the parameters such as rock lithology, rock sequence and thickness into the top cutting height calculation equation to obtain the reasonable top cutting height of the drilling position. On the basis of meeting the top cutting height, the top cutting terminal is arranged at the rock layer interface or soft rock layer as much as possible. The top cutting height should be increased for thick and hard rock layers, and finally the top cutting height of the goaf tunnel can be accurately judged while drilling.

[0065] The intersection of the limit equilibrium zone and the elastic zone is the stress peak. The distance from the peak of the advance support pressure to the coal wall is:

[0066]

[0067] Where, m is the coal seam mining height, m; f is the friction factor between coal seams; C is the cohesion of coal body, MPa; σ is the vertical stress, MPa; is the internal friction angle of the coal body, °; K is the stress concentration coefficient; γ is the average bulk density of the overlying strata on the working face, 25kNN / m3; H is the buried depth of the coal seam on the working face, m.

[0068] The intersection of the elastic zone and the original rock stress zone can be approximately taken as the original rock stress, and the width of the elastic zone can be obtained as:

[0069]

[0070] β is the inverse of the lateral pressure coefficient.

[0071] Influence range of advance support pressure:

[0072] x=x0+x1

[0073] In the calculation model of the advance support pressure range, the lithology and rock sequence distribution of the top rock layer 8 along the tunnel strike can be more accurately measured by using the detection while drilling technology, so as to more accurately solve the vertical stress of the tunnel and make the calculation of the influence range of the advance support pressure more accurate.

[0074] S5: Based on the dynamic and accurate identification of the lithology and rock sequence of the roof rock layer 8 by using the drilling detection technology, different cutting top drilling hole spacings are designed according to the distribution of rock layers. When drilling cutting top holes on the top plate of the gob-side tunnel, the drilling angle is corrected in real time using the monitoring results of the inclination sensor to ensure that each cutting top hole is in a straight line to the greatest extent possible to ensure the cutting top effect.

[0075] The top cutting method adopts blasting. According to different rock types, the spacing of blasting holes can be designed as follows: ① Hard top plate, spacing is 500mm; ② Soft rock top plate spacing is 550mm; ③ Broken top plate spacing is 600mm. The design of blasting hole angle β is: ① When H c ≤1m, β=20°;②When 1m<H c ≤3m, β=15°; ③When 3m<H c When ≤4.5m, β=10°. Multiple blasting holes with the same inclination angle form splitting cracks at the blasting position, and the splitting cracks of each blasting hole are connected to form a regular structural weak surface on the plane. The top rock layer 8 is cut off and falls along the structural weak surface under the action of the advanced support pressure of the working face.

[0076] Anchor drilling rigs are commonly used on site for pre-crack hole construction. However, due to the lack of effective monitoring methods, the inclination angles of the pre-crack holes often deviate from the design angles to varying degrees during the construction of the pre-crack holes, causing the pre-crack holes to be not in the same plane, which seriously affects the blasting pre-crack effect. The use of drilling detection technology can monitor the construction angle of the pre-crack holes in real time. When the deviation between the construction angle and the design angle exceeds 2°, the drilling angle can be corrected in time to ensure that the pre-crack holes are in the same plane as much as possible.

[0077] Table 1 Evaluation of the application effect of the precise top cutting method along the goaf based on the rock geology while drilling detection

[0078]

[0079]

[0080] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for accurate top cutting of goaf-side tunnels based on rock stratum geological detection while drilling, characterized in that: The specific steps include: S1: installing a drilling parameter measuring instrument (2) on a single anchor drilling rig (1) used for top cutting construction of a goaf-side tunnel, using the drilling rig to drill a rock layer (8) on the top of the goaf-side tunnel, and collecting the drilling rig operating parameters in real time through the drilling parameter measuring instrument (2); the drilling rig operating parameters include: thrust, torque, rotation speed, displacement, inclination and vibration; S2: using the collected drilling rig operating parameters to calculate two comprehensive indicators, SEM and RDA; using the multivariate linear regression method, establishing a rock formation strength identification model based on the comprehensive indicators; using the rock formation strength identification results and drilling displacement, determining the lithology and rock sequence distribution of the top rock layer (8); S3: Combined with the burial depth, height, mining height, roof lithology and rock sequence distribution information of the coal mining face, a calculation model for the distribution range of the advanced support pressure in front of the coal mining face is established; S4: Substitute the lithology, rock sequence and rock thickness into the cut-off height calculation equation to obtain the cut-off height at the drilling position; S5: Based on the dynamic identification of the lithology and rock sequence of the roof rock layer (8) by the drilling detection technology, different top-cutting drilling hole spacings are designed according to the distribution of the rock layers; when drilling the top-cutting holes in the top plate of the gob-side tunnel, the drilling angle is corrected in real time using the monitoring results of the inclination sensor, and finally the top-cutting holes are obtained.

2. The precise top cutting method for goaf-side tunnel based on rock stratum geological detection while drilling according to claim 1 is characterized in that: In step S1, the device used includes a single anchor drilling rig (1), a drilling parameter measuring instrument (2), a signal wireless transmission module (3), a signal wireless receiving module (4), a multi-channel data acquisition module (5), a data storage and display terminal (6) and a B19 hexagonal drill rod (7); thrust, torque, rotation speed, displacement, vibration and inclination sensors are installed inside the drilling parameter measuring instrument (2), the lower end of which is connected to the single anchor drilling rig (1) using an external hexagonal shaft, and the upper end is connected to the B19 hexagonal drill rod (7).

3. The precise top cutting method for goaf-side tunnel based on rock stratum geological detection while drilling according to claim 2 is characterized in that: The drilling rig operating parameters collected by the sensor first enter the signal wireless transmission module (3), and then are received by the signal wireless receiving module (4) and transmitted to the multi-channel data acquisition module (5). The multi-channel data acquisition module (5) is connected to the data storage and display terminal (6) for storage and display.

4. The method for precise top cutting of goaf-side tunnels based on rock stratum geological detection while drilling according to claim 1 is characterized in that: In step S2, the modulation specific energy SEM and the rock drillability index RDA are expressed by the following formula: The multivariate linear regression model for predicting rock formation strength using SEM and RDA can be expressed as: Rc=k1×SEM+k2×RDA.

5. The method for precise top cutting of goaf-side tunnel based on rock stratum geological detection while drilling according to claim 1 is characterized in that: In step S3, the calculation model of the distribution range of the advance support pressure in front of the coal mining face is:

6. The method for precise top cutting of goaf-side tunnels based on rock stratum geological detection while drilling according to claim 1 is characterized in that: In step S4, the top cutting height calculation formula is:

7. The method for precise top cutting of goaf-side tunnels based on rock stratum geological detection while drilling according to claim 1 is characterized in that: In step S5, the roof cutting method adopts blasting cutting. According to different rock types, the spacing between blasting holes is designed as follows: ① hard roof, the spacing is 500mm; ② soft rock roof spacing is 550mm; ③ broken roof spacing is 600mm.

8. The method for precise top cutting of goaf-side tunnels based on rock stratum geological detection while drilling according to claim 1 is characterized in that: In step S5, the blast hole angle β is designed as follows: ① When H c ≤1m, β=20°;②When 1m<H c ≤3m, β=15°; ③When 3m<H c When ≤4.5m, β=10°.

9. The method for precise top cutting of goaf-side tunnels based on rock stratum geological detection while drilling according to claim 1 is characterized in that: In step S5, multiple blasting holes with the same inclination angle form splitting cracks at the blasting position, and the splitting cracks of each blasting hole are connected to form a regular structural weak surface on a plane. The roof rock layer (8) is cut off and falls along the structural weak surface under the action of the advanced support pressure of the working face.

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