A large-diameter drilling parameter optimization and construction method based on a drilling pressure relief principle

Abstract

The application discloses a large-diameter drilling parameter optimization and construction method based on a drilling pressure relief principle, which comprises the following steps: firstly, determining the width of a reserved coal pillar and the width of a to-be-excavated roadway, then determining the layout mode of large-diameter pressure relief drilling, then evaluating the impact danger degree of the coal seam where the to-be-excavated working face is located, and determining the corresponding drilling diameter according to different impact danger degree grades; determining the horizontal interval of adjacent large-diameter pressure relief drilling according to the pressure relief zone radius of each large-diameter pressure relief drilling, ensuring that the pressure relief zones formed around all the drillings can be interconnected, so as to form a complete weakened zone; determining the length of the large-diameter pressure relief drilling according to the coal seam mining thickness of the to-be-excavated working face, ensuring that the effective length exceeds the position of the peak value of the coal wall support pressure, so as to effectively relieve the pressure of the to-be-excavated roadway and the to-be-excavated working face; finally, performing pressure relief construction according to the determined parameters, so that the drilling construction efficiency can be improved under the premise of ensuring the safety of the coal mine.

Description

TECHNICAL FIELD

[0001] The present application relates to a large-diameter drilling parameter optimization and construction method based on the principle of pressure relief by drilling, belonging to the technical field of coal mine safety production. BACKGROUND

[0002] With the development of coal resources gradually turning from shallow to deep, the stress of deep coal mining surrounding rock is rising, the stress environment of roadway is deteriorating, the risk of impact is rising, especially the driving roadway in coal seam has become a frequent area of dynamic disasters such as rock burst, coal and gas outburst, which seriously threatens the safety production and personnel life safety in deep mine.

[0003] According to the safety requirements of existing coal mines, the roadway is driven in the impact danger area, the coal body needs to be pre-unloaded, and at present, the construction of large-diameter drilling has become the main pressure relief technology for driving roadway in coal seam in impact danger area. Large-diameter drilling pressure relief is to make the drilling pressure relief zones connect with each other by reasonably constructing large-diameter drilling in the two sides of the roadway, to form a continuous weakening zone in the coal seam which is larger than the diameter of the drilling, to provide space for the release of internal high stress of coal body and the deformation and failure of coal body, so as to release the accumulated elastic energy in the coal seam and make the stress concentration area transfer to the deep part of the coal seam, finally play a certain pressure relief effect. However, the existing large-diameter drilling construction generally determines the parameters of drilling construction only by experience, which may lead to over-drilling, wasting construction cost and time, or insufficient drilling construction leading to poor pressure relief effect and affecting the safety of coal mine.

[0004] Therefore, how to provide a new method, which can reasonably design the parameters of large-diameter pressure relief drilling, and construct large-diameter drilling in the driven roadway before the driving construction of the to-be-driven roadway, to relieve pressure for the adjacent to-be-driven working face and its to-be-driven roadway, so as to improve the drilling construction efficiency under the premise of ensuring the safety of coal mine, is the technical problem to be solved by the present application. SUMMARY

[0005] In view of the problems existing in the prior art, the present application provides a large-diameter drilling parameter optimization and construction method based on the principle of pressure relief by drilling, which can reasonably determine the parameters of large-diameter pressure relief drilling, and construct large-diameter drilling in the driven roadway before the driving construction of the to-be-driven roadway, to relieve pressure for the adjacent to-be-driven working face and its to-be-driven roadway, so as to improve the drilling construction efficiency under the premise of ensuring the safety of coal mine.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is: a large-diameter drilling parameter optimization and construction method based on the principle of pressure relief by drilling, the specific steps are:

[0007] Step one, determining the width of the reserved coal pillar and the width of the roadway to be excavated: after the entire pressure relief work of the excavated roadway and its excavated working face is completed, the width of the reserved coal pillar and the width of the roadway to be excavated are determined, and the roadway to be excavated is parallel to the excavated roadway;

[0008] Step two, determining the layout mode of the large-diameter pressure relief borehole: a plurality of large-diameter pressure relief boreholes are arranged in a row on the reserved coal pillar wall surface of the excavated roadway towards the working face to be excavated, and the distance from each large-diameter pressure relief borehole to the floor of the excavated roadway is the same;

[0009] Step three, determining the diameter of the large-diameter pressure relief borehole: the impact danger degree of the coal seam region where the roadway to be excavated and the working face to be excavated are located is evaluated by using an evaluation method and combining relevant data of the overall coal seam (including the excavated working face, the working face to be excavated and other parts), the impact danger degree grade of the working face to be excavated is determined, the impact danger degree grade is divided into three grades of weak, medium and strong, and the diameter of the large-diameter pressure relief borehole is determined according to the impact danger degree grade;

[0010] Step four, determining the horizontal spacing of the large-diameter pressure relief borehole: the horizontal spacing of adjacent large-diameter pressure relief boreholes is determined according to the pressure relief zone radius of a single large-diameter pressure relief borehole, to ensure that the pressure relief zones formed around all large-diameter pressure relief boreholes can be interconnected, thereby forming a complete weakened zone;

[0011] Step five, determining the length of the large-diameter pressure relief borehole: the length of the large-diameter pressure relief borehole is set, and the length needs to ensure that the effective length of the large-diameter pressure relief borehole in the working face to be excavated exceeds the position of the peak value of the coal wall abutment pressure, so as to effectively relieve the pressure of the roadway to be excavated and the working face to be excavated;

[0012] Step six, constructing large-diameter pressure relief boreholes for pressure relief: according to the layout mode, diameter, horizontal spacing and length of the large-diameter pressure relief borehole obtained in steps two to five, a row of large-diameter pressure relief boreholes perpendicular to the reserved coal pillar wall surface are constructed from the reserved coal pillar wall surface of the excavated roadway towards the roadway to be excavated and the working face to be excavated before the roadway to be excavated starts to be excavated, and the construction sequence of each large-diameter pressure relief borehole is consistent with the excavation direction of the roadway to be excavated, thereby completing the drilling and pressure relief process of the working face to be excavated.

[0013] Further, the evaluation method in step three is one or more of a combination of comprehensive index method, multi-factor coupling method, electromagnetic radiation method and seismic wave CT inversion method.

[0014] Further, the step three is to determine the diameter of the large-diameter pressure relief borehole according to the impact danger degree, specifically: when the working face to be excavated is a weak impact danger coal seam, the diameter R of the large-diameter pressure relief borehole is 110 mm; when the working face to be excavated is a medium impact danger coal seam, the diameter R of the large-diameter pressure relief borehole is 133 mm; when the working face to be excavated is a strong impact danger coal seam, the diameter R of the large-diameter pressure relief borehole is 153 mm.

[0015] Further, the step four is to determine the horizontal spacing of the adjacent large-diameter pressure relief borehole, specifically:

[0016]

[0017] wherein: D is the horizontal spacing of the large-diameter pressure relief borehole, m; R is the diameter of the large-diameter pressure relief borehole, m; p0 is the ground stress, MPa; C is the coal body cohesion, Mpa; and φ is the coal body internal friction angle.

[0018] Further, the step five is to determine the length of the large-diameter pressure relief borehole, L, and then:

[0019] L = L0 + a + b

[0020] wherein: a is the reserved coal pillar width, b is the width of the roadway to be excavated, and L0 is the effective length of the large-diameter pressure relief borehole in the working face to be excavated.

[0021] The effective length L0 is determined according to the coal seam mining thickness of the working face to be excavated, specifically: when the coal seam mining thickness H < 3.5 m, the effective length L0 ≥ 15 m; when the coal seam mining thickness 3.5 m ≤ H ≤ 8 m, the effective length L0 ≥ 20 m; and when the coal seam mining thickness H > 8 m, the effective length L0 ≥ 25 m; and the length L of the large-diameter pressure relief borehole is determined according to the effective length L0.

[0022] Further, the step six is to determine the distance between the large-diameter pressure relief borehole and the floor of the excavated roadway, which should be less than or equal to half of the coal seam mining thickness of the working face to be excavated.

[0023] ​Compared with the prior art, the present application firstly determines the width of the reserved coal pillar and the width of the to-be-excavated roadway, then determines the approximate position and arrangement mode of the large-diameter pressure relief borehole arranged in the excavated roadway, then evaluates the impact risk degree of the coal seam region of the to-be-excavated working face, and determines the diameter of the corresponding large-diameter pressure relief borehole according to the determined different impact risk degree grades, so that the diameter meets the needs of pressure relief corresponding to different impact risk degree grades; the horizontal spacing of the adjacent large-diameter pressure relief borehole is determined according to the pressure relief zone radius of each large-diameter pressure relief borehole, so as to ensure that the pressure relief zones formed around all the large-diameter pressure relief boreholes can be mutually penetrated, thereby forming a complete weakened zone; the length of the large-diameter pressure relief borehole is determined according to the coal seam mining thickness of the to-be-excavated working face, so as to ensure that the effective length exceeds the position of the peak value of the coal wall abutment pressure, thereby being capable of effectively relieving the pressure of the to-be-excavated roadway and the to-be-excavated working face; finally, the pressure relief construction is carried out according to the above determined parameters of the large-diameter pressure relief borehole; the present application determines the parameters of the large-diameter pressure relief borehole reasonably, and constructs the large-diameter borehole in the excavated roadway before the to-be-excavated roadway construction, thereby relieving the pressure of the adjacent to-be-excavated working face and the to-be-excavated roadway, so as to improve the drilling construction efficiency under the premise of ensuring the safety of the coal mine. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the overall arrangement schematic diagram of the present application;

[0025] Figure 2 is Figure 1 the sectional view of A-A direction in

[0026] In the figure: 1, excavated working face; 2, to-be-excavated working face; 3, excavated roadway; 4, reserved coal pillar; 5, to-be-excavated roadway; 6, goaf; a, width of the reserved coal pillar; b, width of the to-be-excavated roadway; L0, effective length; L, length of the large-diameter pressure relief borehole; D, horizontal spacing of the large-diameter pressure relief borehole; R, diameter of the large-diameter pressure relief borehole; H, coal seam mining thickness of the to-be-excavated working face. DETAILED DESCRIPTION

[0027] The present application will be further described below.

[0028] As Figure 1 and 2 shown, the specific steps of the present application are as follows:

[0029] Step one, determine the width of the reserved coal pillar and the width of the to-be-excavated roadway: after the complete pressure relief work of the excavated roadway 3 and the excavated working face 1 is completed, the width of the reserved coal pillar 4 and the width of the to-be-excavated roadway 5 are determined, and the to-be-excavated roadway 5 is parallel to the excavated roadway 3;

[0030] Step two, determine the layout of large diameter pressure relief borehole: a plurality of equal interval large diameter pressure relief boreholes are arranged on the wall of the reserved coal pillar 4 of the excavated roadway 3 towards the to-be-excavated working face 2, and the distance between each large diameter pressure relief borehole and the floor of the excavated roadway 3 is the same;

[0031] Step three, determine the diameter of the large diameter pressure relief borehole: adopt an evaluation method, which is one or more of the following: comprehensive index method, multi-factor coupling method, electromagnetic radiation method and vibration wave CT inversion method; and evaluate the impact danger degree of the coal seam region of the to-be-excavated roadway 5 and the to-be-excavated working face 2 in combination with the overall coal seam related data, determine the impact danger degree grade of the to-be-excavated working face 2 coal seam, the impact danger degree grade is divided into three grades: weak, medium and strong, and the diameter of the large diameter pressure relief borehole is determined according to the impact danger degree grade, specifically: when the to-be-excavated working face 2 is a weak impact danger coal seam, the diameter R of the large diameter pressure relief borehole is 110mm; when the to-be-excavated working face 2 is a medium impact danger coal seam, the diameter R of the large diameter pressure relief borehole is 133mm; when the to-be-excavated working face 2 is a strong impact danger coal seam, the diameter R of the large diameter pressure relief borehole is 153mm, which can be adjusted slightly according to the actual situation and construction technical conditions in the actual process, but the diameter R of the large diameter pressure relief borehole must be within the range of 100-200mm.

[0032] Step four, determine the horizontal spacing of the large diameter pressure relief borehole: determine the horizontal spacing of adjacent large diameter pressure relief boreholes according to the pressure relief zone radius of a single large diameter pressure relief borehole, specifically:

[0033]

[0034] Wherein: D is the horizontal spacing of the large diameter pressure relief borehole, m; R is the diameter of the large diameter pressure relief borehole, m; p0 is the ground stress, MPa; C is the coal body cohesion, Mpa; is the coal body internal friction angle.

[0035] The horizontal spacing of the large diameter pressure relief borehole is determined in the above manner, which ensures that the pressure relief zones formed around all large diameter pressure relief boreholes can be interconnected, thereby forming a complete weakened zone;

[0036] Step five, determine the length of the large diameter pressure relief borehole: set the length of the large diameter pressure relief borehole as L, then:

[0037] L=L0+a+b

[0038] In the formula, a is the width of the reserved coal pillar, b is the width of the to-be-excavated roadway, and L0 is the effective length of the large diameter borehole in the to-be-excavated working face 2;

[0039] According to the coal seam mining thickness of the to-be-excavated working face, the effective length L0 value is determined, specifically: when the coal seam mining thickness H < 3.5 m, the effective length L0 ≥ 15 m; when the coal seam mining thickness 3.5 m ≤ H ≤ 8 m, the effective length L0 ≥ 20 m; when the coal seam mining thickness H > 8 m, the effective length L0 ≥ 25 m; according to the determined effective length L0 value, the length L value of the large-diameter pressure relief borehole is obtained;

[0040] The length L of the large-diameter pressure relief borehole is determined in the above manner, so as to ensure that the effective length L0 of the large-diameter pressure relief borehole in the to-be-excavated working face 2 exceeds the position of the coal wall abutment pressure peak value, thereby being capable of effectively relieving pressure on the adjacent to-be-excavated roadway 5 and the to-be-excavated working face 2;

[0041] Step six, construction of the large-diameter pressure relief borehole for pressure relief: according to the layout mode, diameter, horizontal spacing and length of the large-diameter pressure relief borehole obtained in steps two to five, before the to-be-excavated roadway 5 starts to be excavated, a row of large-diameter pressure relief boreholes perpendicular to the wall surface of the reserved coal pillar 4 of the excavated roadway 3 is constructed in the direction of the to-be-excavated roadway 5 and the to-be-excavated working face 2, and the distance between the large-diameter pressure relief borehole and the floor of the excavated roadway 3 should be less than or equal to half of the coal seam mining thickness of the to-be-excavated working face 2, generally 1.0 m to 1.5 m; the construction sequence of each large-diameter pressure relief borehole is consistent with the excavation direction of the to-be-excavated roadway 5, thereby completing the drilling pressure relief process of the to-be-excavated working face 2.

[0042] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for optimizing large-diameter borehole parameters and constructing a borehole based on the principle of borehole pressure relief, characterized in that, The specific steps are as follows: Step 1: Determine the width of the reserved coal pillar and the width of the roadway to be excavated: After all the depressurization work is completed in the excavated roadway and the mined working face, determine the width of the reserved coal pillar and the width of the roadway to be excavated, and the roadway to be excavated is parallel to the excavated roadway; Step 2: Determine the layout of large-diameter pressure relief boreholes: Multiple large-diameter pressure relief boreholes are arranged in a row at equal intervals on the pre-reserved coal pillar wall of the excavated roadway, facing the working face to be mined. Each large-diameter pressure relief borehole is equidistant from the floor of the excavated roadway. Step 3: Determine the diameter of the large-diameter pressure relief borehole: Using evaluation methods and combining relevant data of the overall coal seam, assess the impact hazard level of the roadway to be excavated and the coal seam area where the working face to be mined is located. Determine the impact hazard level of the coal seam in the working face to be mined. The impact hazard level is divided into three levels: weak, medium, and strong. The diameter of the large-diameter pressure relief borehole is determined based on the impact hazard level. The evaluation method is one or more of the following: comprehensive index method, multi-factor coupling method, electromagnetic radiation method, and seismic wave CT inversion method. Step 4: Determine the horizontal spacing of large-diameter pressure relief boreholes: Based on the radius of the pressure relief zone of a single large-diameter pressure relief borehole, determine the horizontal spacing between adjacent large-diameter pressure relief boreholes, specifically as follows: ； Where: D is the horizontal spacing of large-diameter pressure relief boreholes, in meters; The diameter of the large-diameter pressure relief borehole is in meters (m). C is the in-situ stress, MPa; C is the coal body cohesion, MPa. The friction angle within the coal seam; ensuring that the pressure relief zones formed around all large-diameter pressure relief boreholes can be interconnected, thereby forming a complete weakening zone; Step 5: Determine the length of the large-diameter pressure relief borehole: Set the length of the large-diameter pressure relief borehole, and this length must ensure that the effective length of the large-diameter pressure relief borehole in the working face to be mined exceeds the position of the peak value of the coal wall support pressure, so as to effectively relieve pressure on the roadway to be excavated and the working face to be mined. Step Six: Decompression by constructing large-diameter pressure relief boreholes: Following the layout, diameter, horizontal spacing, and length of the large-diameter pressure relief boreholes obtained in Steps Two to Five, before the roadway to be excavated begins to be excavated, construct a row of large-diameter pressure relief boreholes perpendicular to the reserved coal pillar wall from the wall of the reserved coal pillar in the already excavated roadway toward the roadway to be excavated and the working face to be mined. The construction sequence of each large-diameter pressure relief borehole is consistent with the excavation direction of the roadway to be excavated, thereby completing the drilling and pressure relief process of the working face to be mined.

2. The method for optimizing large-diameter borehole parameters and construction based on the borehole pressure relief principle according to claim 1, characterized in that, In step three, the diameter of the large-diameter pressure relief borehole is determined according to the degree of impact hazard. Specifically, when the working face to be mined is a coal seam with weak impact hazard, the diameter R of the large-diameter pressure relief borehole is 110 mm; when the working face to be mined is a coal seam with medium impact hazard, the diameter R of the large-diameter pressure relief borehole is 133 mm; and when the working face to be mined is a coal seam with strong impact hazard, the diameter R of the large-diameter pressure relief borehole is 153 mm.

3. The method for optimizing large-diameter borehole parameters and construction based on the borehole pressure relief principle according to claim 1, characterized in that, If the length of the large-diameter pressure relief borehole in step five is L, then: L = L0 + a + b In the formula, a is the width of the reserved coal pillar, b is the width of the roadway to be excavated, and L0 is the effective length of the large-diameter borehole in the working face to be mined; The effective length L0 is determined based on the coal seam thickness of the working face to be mined. Specifically: when the coal seam thickness H < 3.5m, the effective length L0 ≥ 15m; when the coal seam thickness 3.5m ≤ H ≤ 8m, the effective length L0 ≥ 20m; when the coal seam thickness H > 8m, the effective length L0 ≥ 25m. The length L of the large-diameter pressure relief borehole is then derived based on the determined effective length L0.

4. The method for optimizing large-diameter borehole parameters and construction based on the borehole pressure relief principle according to claim 1, characterized in that, In step six, the distance between the large-diameter pressure relief borehole and the floor of the excavated roadway should be less than or equal to half the mining thickness of the coal seam in the working face to be mined.

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