A method for arranging a borehole for advanced detection of a coal seam tunnel passing through a coal seam and a detection method

Abstract

This invention belongs to the field of advanced detection and prediction technology for tunnel engineering, and relates to a method for arranging and detecting advanced detection boreholes in a coal seam tunnel. The coal seam is a coal seam located on one side of the tunnel, and the coal seam gradually slopes towards the tunnel excavation face from back to front. The specific steps include: constructing five advanced detection boreholes sequentially at the center of the tunnel face with the same starting point. The five advanced detection boreholes are borehole 1, borehole 2, borehole 3, borehole 4, and borehole 5. The boreholes are then adjusted sequentially to have upward inclination angles α1, α2, α3, α4, and α5, and horizontal inclination angles β1, β2, β3, β4, and β5 towards the side where the coal seam is located, respectively. Wherein, α5>α4>α3=α1>α2, β1>β4>β5=β2>β3. This invention can accurately and efficiently detect the spatial distribution characteristics of the coal seam strike and dip angle along the coal seam ahead.

Description

Technical Field

[0001] This invention belongs to the field of tunnel engineering advanced detection and prediction technology, and relates to a method for arranging boreholes and a detection method for advanced detection of coal seam tunnels. Background Technology

[0002] Advanced drilling can detect changes in the coal seam ahead of the tunnel face, accurately predict coal seam parameters and gas parameters, and is a fundamental condition for pre-drainage and pre-venting of coal seam gas in coal-passing tunnels, ensuring production safety during excavation. Advanced drilling is currently a widely used technical measure for supplementing geological exploration and preventing gas outbursts during the construction phase of gas tunnels. The "Technical Specification for Design and Construction of Highway Gas Tunnels," Chinese patent application CN115126529A (specifically a construction method for predicting tunnel gas), and Chinese patent CN204299584U (an advanced detection drilling structure for tunnels crossing coal seams) all provide methods for advanced drilling layout at the tunnel face in coal-passing tunnels. However, this method is only applicable to coal-passing tunnels where the tunnel excavation direction has a large angle with the coal seam strike and the tunnel passes through the coal seam over a short distance. For tunnels that run parallel to the coal seam or pass through the coal seam over a long distance at a small angle, the existing advanced drilling method has the problem that some or all of the advanced drilling is parallel to the coal seam strike, making it impossible to accurately detect the coal seam occurrence state in front of the tunnel face. This leads to inadequate advanced treatment measures for coal seam gas during construction, which may eventually cause gas accidents during tunnel face excavation and threaten tunnel construction safety.

[0003] Therefore, based on the geological exploration of coal-bearing strata tunnels and the characteristics of the surrounding rock exposed at the tunnel face, a method for arranging and detecting fan-shaped advance detection boreholes along the coal seam for long-distance tunnels with the tunnel excavation direction parallel to or at a small angle to the coal seam strike is proposed, under the premise of following the advance drilling layout method required by relevant standards and specifications. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method for arranging and detecting advanced detection boreholes in coal seams for tunnels through coal seams. This method and method can accurately and efficiently detect the spatial distribution characteristics of the coal seam strike and dip angle ahead of the tunnel face, providing the necessary conditions for further gas pre-drainage and pre-discharge. It plays an important role in preventing gas disasters in coal seams and solves the problem that existing advanced borehole detection methods for coal seams lead to decreased accuracy and low efficiency in borehole detection, and cannot accurately detect the coal seam occurrence state ahead of the tunnel face, thus resulting in inadequate advanced gas treatment measures during construction.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] On one hand, the present invention provides a method for arranging advance detection boreholes for tunnels along a coal seam, wherein the coal seam is a coal seam located along one side of the tunnel, and the coal seam gradually slopes towards the tunnel excavation face from back to front, specifically including the following steps:

[0007] Five advance detection boreholes were constructed sequentially at the center of the tunnel face, starting from the same borehole. The five advance detection boreholes are borehole 1, borehole 2, borehole 3, borehole 4 and borehole 5.

[0008] First, conduct exploration in borehole No. 1: Adjust the borehole to start drilling with an upward inclination angle α1 and a horizontal inclination angle β1 towards the side where the coal seam is located, and record the borehole depth as R1 when coal slag appears in the drill cuttings.

[0009] After the exploration of borehole No. 1 is completed, the exploration of borehole No. 2 begins: the borehole is adjusted to start drilling with an upward inclination angle α2 and a horizontal inclination angle β2 towards the side where the coal seam is located, and the borehole depth is recorded as R2 when coal slag appears in the drill cuttings.

[0010] After the exploration of borehole No. 2 is completed, the exploration of borehole No. 3 begins: the borehole is adjusted to start drilling with an upward inclination angle α3 and a horizontal inclination angle β3 towards the side where the coal seam is located, and the borehole depth is recorded as R3 when coal slag appears in the drill cuttings.

[0011] After the exploration of borehole No. 3 is completed, the exploration of borehole No. 4 begins: the borehole is adjusted to start drilling at an upward inclination angle α4 and a horizontal inclination angle β4 towards the side where the coal seam is located, and the borehole depth is recorded as R4 when coal slag appears in the drill cuttings.

[0012] After the exploration of borehole No. 4 is completed, the exploration of borehole No. 5 begins: the borehole is adjusted to start drilling with an upward inclination angle of α5 and a horizontal inclination angle of β5 towards the side where the coal seam is located, and the borehole depth is recorded as R5 when coal slag appears in the drill cuttings.

[0013] Wherein, α5>α4>α3=α1>α2, and β1>β4>β5=β2>β3.

[0014] Furthermore, α1 is 10°~20°, β1 is 30°~40°; α2 is 0°~10°, β2 is 20°~30°; α3 is 10°~20°, β3 is 10°~20°; α4 is 20°~30°, β4 is 25°~30°; α5 is 30°~40°, β5 is 20°~30°.

[0015] Furthermore, the coal seam is a longitudinal coal seam located on the left side of the tunnel.

[0016] Furthermore, the coal seam is a longitudinal coal seam located on the right side of the tunnel.

[0017] Further, after recording the borehole depth as R1, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R1". Record the length of the borehole through the coal seam as B1 = R1" - R1. Then continue drilling. Stop drilling when the borehole depth is above R1" + 0.5m. The exploration of borehole No. 1 is completed.

[0018] After recording the borehole depth as R2, continue drilling. When the drill cuttings do not contain coal slag, record the borehole depth as R2". Record the length of the borehole through the coal seam as B2 = R2" - R2. Then continue drilling. Stop drilling when the borehole depth is above R2" + 0.5m. The exploration of borehole No. 2 is completed.

[0019] After recording the borehole depth as R3, continue drilling. When the drill cuttings do not contain coal slag, record the borehole depth as R3". Record the length of the borehole through the coal seam as B3 = R3" - R3. Then continue drilling. Stop drilling when the borehole depth is above R3" + 0.5m. The exploration of borehole No. 3 is completed.

[0020] After recording the borehole depth as R4, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R4". Record the length of the borehole through the coal seam as B4 = R4" - R4. Then continue drilling. Stop drilling when the borehole depth is above R4" + 0.5m. The exploration of borehole No. 4 is completed.

[0021] After recording the borehole depth as R5, continue drilling. When the drill cuttings no longer contain coal slag, record the borehole depth as R5". Record the length of the borehole crossing the coal seam as B5 = R5" - R5. Then continue drilling. Stop drilling when the borehole depth is above R5" + 0.5m. The exploration of borehole No. 5 is complete.

[0022] On the other hand, the present invention also provides a method for advance detection boreholes in coal seams tunnels, which employs the above-mentioned method for arranging advance detection boreholes in coal seams tunnels, and specifically includes the following steps:

[0023] A spatial rectangular coordinate system is established with the center of the tunnel face as the origin O. The excavation direction of the tunnel centerline is taken as the positive X-axis, the vertical upward direction as the positive Z-axis, and the direction perpendicular to the X-axis to the left on the horizontal plane as the positive Y-axis. The position of the advance detection borehole in contact with the coal seam is designated as point A. The coordinates of point A in the rectangular spatial coordinate system are (x...). A y A , z A The angle between the drilling direction and the XOY plane is the vertical inclination angle α of the drilling, and the angle between the drilling direction and the XOZ plane is the horizontal inclination angle β of the drilling. The straight-line distance from the drilling origin O to the coal seam contact point A is the drilling length R when coal slag appears in the drilling cuttings. Let the distance from point A to the tunnel centerline be S.

[0024] Among them, the vertical inclination angle α, the horizontal inclination angle β, and the borehole length R when coal slag appears in the borehole are all known data. The coordinates (x, y, y) of point A can be deduced from α, β, and R using the following formula. A y A , z A The values ​​of ) and the distance S from point A to the centerline of the tunnel;

[0025]

[0026] The S values ​​of the five advanced detection boreholes are respectively , , , as well as ;

[0027] The minimum value S among S1~S5 min ={S1, S2, S3, S4, S5}, if S min When the distance between the coal seam and the tunnel is less than the specified safety limit, tunnel excavation should be stopped and coal seam gas emission measures should be implemented. If S min No coal seam gas emission is required when the distance between the coal seam and the tunnel exceeds the specified safety limit.

[0028] Furthermore, based on the coordinates of the contact points between boreholes No. 1, No. 2, No. 4, and No. 5 and the coal seam, the dip angle and strike of the coal seam can be detected. Let the angle between the coal seam and the XOZ plane be θ, and the angle between the coal seam and the XOY plane be ω. The specific steps include:

[0029] A vector on the coal seam contact surface is determined by the coordinates (x1, y1, z1) of the contact point between borehole No. 1 and the coal seam, and the coordinates (x2, y2, z2) of the contact point between borehole No. 2 and the coal seam. =(x1-x2,y1-y2,z1-z2)=(u1,u2,u3);

[0030] Another vector on the coal seam contact surface is determined by the coordinates (x4, y4, z4) of the contact point between borehole No. 4 and the coal seam, and the coordinates (x5, y5, z5) of the contact point between borehole No. 5 and the coal seam. =(x4-x5,y4-y5,z4-z5)=(v1,v2,v3);

[0031] Two non-collinear vectors , The cross product determines a normal vector perpendicular to the coal seam contact surface. :

[0032]

[0033] Based on the normal vector of the coal seam contact surface and a normal vector of the XOZ surface The angle θ between the coal seam contact surface and the XOZ plane can be calculated using the formula (0,1,0).

[0034]

[0035]

[0036] Based on the normal vector of the coal seam contact surface and a normal vector of the XOY plane The angle ω between the coal seam contact surface and the XOY plane can be calculated using the formula (0,0,1).

[0037]

[0038]

[0039] The angle θ between the coal seam and the XOZ plane is the angle between the coal seam strike line and the tunnel strike line, and the angle ω between the coal seam and the XOY plane is the dip angle of the coal seam. min When the distance between the coal seam and the tunnel is less than the specified limit of safety, tunnel excavation should be stopped and coal seam gas emission measures should be taken. The subsequent drainage borehole layout plan should be based on the dip angle and direction of the coal seam mentioned above.

[0040] Further, after recording the borehole depth as R1, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R1". Record the length of the borehole through the coal seam as B1 = R1" - R1. Then continue drilling. Stop drilling when the borehole depth is above R1" + 0.5m. The exploration of borehole No. 1 is completed.

[0041] After recording the borehole depth as R2, continue drilling. When the drill cuttings do not contain coal slag, record the borehole depth as R2". Record the length of the borehole through the coal seam as B2 = R2" - R2. Then continue drilling. Stop drilling when the borehole depth is above R2" + 0.5m. The exploration of borehole No. 2 is completed.

[0042] After recording the borehole depth as R3, continue drilling. When the drill cuttings do not contain coal slag, record the borehole depth as R3". Record the length of the borehole through the coal seam as B3 = R3" - R3. Then continue drilling. Stop drilling when the borehole depth is above R3" + 0.5m. The exploration of borehole No. 3 is completed.

[0043] After recording the borehole depth as R4, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R4". Record the length of the borehole through the coal seam as B4 = R4" - R4. Then continue drilling. Stop drilling when the borehole depth is above R4" + 0.5m. The exploration of borehole No. 4 is completed.

[0044] After recording the borehole depth as R5, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R5". Record the length of the borehole through the coal seam as B5 = R5" - R5. Then continue drilling. Stop drilling when the borehole depth is above R5" + 0.5m. The exploration of borehole No. 5 is completed.

[0045] The thickness h of the coal seam can be calculated based on the arrangement angles α and β of any borehole, the length B of the borehole traversing the coal seam, and the angles θ and ω between the coal seam contact surface and the coordinate system plane:

[0046]

[0047] The thickness of the coal seam is detected to provide a basis for the subsequent layout of drainage boreholes.

[0048] The beneficial effects of this invention are as follows:

[0049] This invention provides a method for arranging and detecting gas exploration boreholes in long-distance coal-passing tunnels along coal seams. The fan-shaped borehole arrangement method can accurately and efficiently detect the spatial distribution characteristics of the coal seam strike, thickness, and dip angle ahead. It can avoid the time wasted by blind drilling, enabling more effective discharge of coal seam gas in the tunnel and improving the efficiency and safety of tunnel gas control.

[0050] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0051] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein:

[0052] Figure 1 This is a schematic diagram of the drilling arrangement in this invention;

[0053] Figure 2 This is a schematic diagram of the drilling arrangement angle in this invention;

[0054] Figure 3 for Figure 1 Schematic diagram of the drilling arrangement on the XOZ surface;

[0055] Figure 4 for Figure 1 A schematic diagram of the drilling arrangement on the XOY plane;

[0056] Figure 5 for Figure 1 A schematic diagram of the drilling arrangement on the YOZ plane.

[0057] Attached diagram labels: 1-Drill hole No. 1, 2-Drill hole No. 2, 3-Drill hole No. 3, 4-Drill hole No. 4, 5-Drill hole No. 5, 6-Tunnel, 7-Coal seam. Detailed Implementation

[0058] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0059] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0060] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0061] Please see Figures 1-5 This is a method for arranging boreholes for advance detection in a coal seam tunnel. In this embodiment, the coal seam 7 is located on the left side of the excavated tunnel 6, and the direction of the coal seam 7 is almost parallel to the excavation direction of the tunnel 6, and gradually slopes towards the excavation face of the tunnel 6 from back to front. That is, the coal seam 7 is a coal seam along the tunnel.

[0062] Five advance detection boreholes were constructed in batches at the center of the tunnel face, starting from the same borehole. The diameter of each of the five advance detection boreholes was Φ75mm~Φ90mm. The drilling direction of each of the five advance detection boreholes was to the left and upwards of the tunnel face. Each of the five advance detection boreholes had to penetrate into the coal seam 7 to be detected, and drilling had to be stopped only after penetrating the coal seam by at least 0.5m. In the end, the five boreholes were distributed in a fan shape.

[0063] First, conduct exploration in borehole 1: Adjust the borehole to start drilling with an upward inclination angle α1 (α1 controls the angle 10°~20°) and a leftward inclination angle β1 (β1 controls the angle 30°~40°). When coal slag appears in the drill cuttings, record the borehole depth as R1, and then continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R1" and the length of the borehole penetrating the coal seam as B1 = R1" - R1, and then continue drilling. Stop drilling when the borehole penetrates the coal seam by 0.5m, that is, stop drilling when the borehole depth is R1" + 0.5m.

[0064] After borehole 1 exploration is completed, borehole 2 exploration begins: Adjust the borehole to an upward inclination angle α2 (α2 controls the angle 0°~10°) and a leftward inclination angle β2 (β2 controls the angle 20°~30°). When coal slag is found in the drill cuttings, record the borehole depth as R2, and continue drilling. When no coal slag is found in the drill cuttings, record the borehole depth as R2", and record the length of the borehole penetrating the coal seam as B2 = R2" - R2, and continue drilling. Stop drilling when the borehole penetrates 0.5m into the coal seam.

[0065] After the exploration of borehole 2 is completed, exploration of borehole 3 begins: The borehole is adjusted to an upward inclination angle α3 (α3 controlled by an angle of 10°~20°) and a leftward inclination angle β3 (β3 controlled by an angle of 10°~20°) to begin drilling. When coal slag is found in the drill cuttings, the borehole depth is recorded as R3, and drilling continues. When no coal slag is found in the drill cuttings, the borehole depth is recorded as R3", and the length of the borehole penetrating the coal seam is recorded as B3 = R3" - R3, and drilling continues. Drilling is stopped when the borehole penetrates 0.5m into the coal seam.

[0066] After exploration of borehole 3 is completed, exploration of borehole 4 begins: Adjust the borehole to begin drilling with an upward inclination angle α4 (α4 controlled at 20°~30°) and a leftward inclination angle β4 (β4 controlled at 25°~30°). When coal slag is found in the drill cuttings, record the borehole depth as R4, and continue drilling. When no coal slag is found in the drill cuttings, record the borehole depth as R4", and record the length of the borehole penetrating the coal seam as B4 = R4" - R4, and continue drilling. Stop drilling when the borehole penetrates 0.5m into the coal seam.

[0067] After drilling borehole 4 is completed, drilling borehole 5 begins: Adjust the borehole to an upward inclination angle α5 (α5 controls the angle 30°~40°) and a leftward inclination angle β5 (β5 controls the angle 20°~30°). When coal slag is found in the drill cuttings, record the borehole depth as R5, and continue drilling. When no coal slag is found in the drill cuttings, record the borehole depth as R5", and record the length of the borehole penetrating the coal seam as B5 = R5" - R5, and continue drilling. Stop drilling when the borehole penetrates 0.5m into the coal seam.

[0068] The vertical upward inclination angle α of the boreholes is as follows: Borehole 5 > Borehole 4 > Borehole 3 = Borehole 1 > Borehole 2; the horizontal leftward inclination angle β is as follows: Borehole 1 > Borehole 4 > Borehole 2 = Borehole 5 > Borehole 3. That is, α5 > α4 > α3 = α1 > α2; β1 > β4 > β5 = β2 > β3.

[0069] A spatial rectangular coordinate system is established with the center of the tunnel face as the origin O. The excavation direction of the tunnel centerline is the positive X-axis, the vertical upward direction is the positive Z-axis, and the direction perpendicular to the X-axis to the left on the horizontal plane is the positive Y-axis. The angle between the strike line of coal seam 7 and the strike line of tunnel 6 is θ, and the dip angle of the coal seam is ω. That is, the angle between coal seam 7 and the XOZ plane is θ, and the angle between coal seam 7 and the XOY plane is ω.

[0070] The borehole is drilled at a certain angle from the origin O of the rectangular coordinate system to probe coal seam 7. The position where the borehole contacts coal seam 7 is point A, and the coordinates of point A in the rectangular coordinate system are (x, y, y). A y A , z A The angle between the drilling direction and the XOY plane is the vertical inclination angle α of the borehole, and the angle between the drilling direction and the XOZ plane is the horizontal inclination angle β of the borehole. The straight-line distance from the borehole origin O to the contact point A of coal seam 7 is the borehole length R when coal slag appears in the borehole. The distance from point A to the tunnel centerline is S, and the distance from point A to the XOY plane is H. The projection point of point A on the XOY plane is A1, and the distance from point A1 to the origin O is L.

[0071] The vertical inclination angle α, the horizontal inclination angle β, and the borehole length R when coal slag appears in the borehole are all known data. The coordinates (x, y) of point A can be deduced from α, β, and R using the following formula. A y A , z A The values ​​of ) and the distance S from point A to the tunnel centerline (x-axis).

[0072] (1)

[0073] (2)

[0074] Formula (3) can be derived from formulas (1) and (2).

[0075] (3)

[0076] (4)

[0077] (5)

[0078] Formula (6) can be derived from formulas (4) and (5).

[0079] (6)

[0080] (7)

[0081] (8)

[0082] Based on the data recorded in borehole 1, α1, β1, and R1, combined with formulas (1) to (8), the coordinates (x1, y1, z1) of the contact point between borehole 1 and coal seam 7 can be determined, and the distance from the contact point of coal seam 7 to the tunnel centerline (x-axis) can be calculated. .

[0083] Based on the data recorded in borehole 2, α2, β2, and R2, combined with formulas (1) to (8), the coordinates (x2, y2, z2) of the contact point between borehole 2 and coal seam 7 can be determined, and the distance from the contact point of coal seam 7 to the tunnel centerline (x-axis) can be calculated. .

[0084] Based on the data obtained from borehole 3, α3, β3, and R3, combined with formulas (1) to (8), the coordinates (x3, y3, z3) of the contact point between borehole 3 and coal seam 7 can be determined, and the distance from the contact point of coal seam 7 to the tunnel centerline (x-axis) can be calculated. .

[0085] Based on the data recorded in borehole 4, α4, β4, and R4, combined with formulas (1) to (8), the coordinates (x4, y4, z4) of the contact point between borehole 4 and coal seam 7 can be determined, and the distance from the coal seam contact point to the tunnel centerline (x-axis) can be calculated. .

[0086] Based on the data recorded in borehole 5, α5, β5, and R5, combined with formulas (1) to (8), the coordinates (x5, y5, z5) of the contact point between borehole 5 and coal seam 7 can be determined, and the distance from the contact point of the coal seam to the tunnel centerline (x-axis) can be calculated. .

[0087] Based on the coordinates of the contact points between boreholes 1, 2, 4, and 5 and coal seam 7, the dip angle ω of coal seam 7 and the angle θ between the strike line of coal seam 7 and the strike line of tunnel 6 can be calculated. The specific calculation steps are as follows:

[0088] A vector is determined on the coal seam contact surface by (x1, y1, z1) and (x2, y2, z2). =(x1-x2,y1-y2,z1-z2)=(u1,u2,u3);

[0089] Another vector on the coal seam contact surface is determined by (x4, y4, z4) and (x5, y5, z5). =(x4-x5,y4-y5,z4-z5)=(v1,v2,v3);

[0090] Two non-collinear vectors , The cross product can determine a normal vector perpendicular to the coal seam contact surface. :

[0091] (9)

[0092] Based on the contact surface normal vector of coal seam 7 and a normal vector of the XOZ surface The angle θ between the coal seam contact surface and the XOZ plane can be calculated using the formula (0,1,0).

[0093] (10)

[0094] (11)

[0095] Based on the normal vector of the contact surface of coal seam 7 and a normal vector of the XOY plane The angle ω between the coal seam contact surface and the XOY plane can be calculated using the formula (0,0,1).

[0096] (12)

[0097] (13)

[0098] The thickness h of the coal seam can be calculated based on the borehole layout angles α and β, the length B of the borehole traversing the coal seam, and the angles θ and ω between the coal seam contact surface and the coordinate system plane:

[0099] (14)

[0100] Specifically, when calculating the thickness h of a coal seam, if the h values ​​of the five boreholes are different, the median or average of the h values ​​can be selected.

[0101] The line where the coal seam face intersects the horizontal plane is called the strike line. The directions pointed to by the two ends of the strike line are called the strike direction.

[0102] Based on the established spatial rectangular coordinate system, the excavation direction of tunnel 6 is parallel to the XOZ plane. That is, the angle between the direction line of coal seam 7 and the direction line of tunnel 6 is the angle θ between the contact surface of coal seam 7 and the XOZ plane. During actual excavation, the direction of coal seam 7 can be determined by combining the calculated angle between coal seam 7 and tunnel 6 with the excavation direction of tunnel 6.

[0103] A straight line drawn downwards along a plane perpendicular to the strike line is called an inclination line. The angle between the inclination line and its projection onto the horizontal plane is called the dip angle.

[0104] Based on the established spatial rectangular coordinate system, the dip angle of coal seam 7 is the angle ω between the contact surface of coal seam 7 and the XOY plane. The minimum value S among S1~S5 is... min ={S1, S2, S3, S4, S5}, if S min When the distance between coal seam 7 and tunnel 6 is less than the specified safety limit, excavation of tunnel 6 should be stopped and coal seam 7 gas emission measures should be implemented. Based on the calculated dip angle, strike, and thickness of coal seam 7, a reasonable basis can be provided for the subsequent drainage borehole layout plan.

[0105] If S min If the distance between coal seam 7 and tunnel 6 exceeds the specified safety limit, it indicates that gas emission from coal seam 7 is not required. Based on the calculated dip angle and strike of coal seam 7, after tunnel 6 continues to be excavated a certain safe distance, five advance boreholes are drilled again following the steps described above to check whether gas emission from coal seam 7 is necessary.

[0106] This embodiment only takes the coal seam 7 being located on the left side of the excavated tunnel 6 as an example. When the coal seam 7 is located on the right side of the tunnel 6, the drilling angle can be adjusted to the right side according to the drilling arrangement method.

[0107] Example 1

[0108] Based on preliminary geological surveys and the specific conditions on site, construction of Tunnel 6 was halted 10 meters from the excavation face of Tunnel 6 in an area with unfavorable geological conditions. Advanced drilling exploration was then carried out to predict coal and gas outbursts and determine the location of the coal seam 7 ahead.

[0109] Five advance boreholes with a diameter of 76mm were drilled with the center of the tunnel face 6 as the origin.

[0110] Exploration of Borehole 1. Starting from the origin, the borehole was adjusted to a horizontal angle of 41° to the left and a vertical angle of 16° upwards. Based on the borehole length when coal slag was present in the drill cuttings, the distance from the starting point of Borehole 1 to the contact point with coal seam 7 was determined to be 43.94m. When no coal slag was present in the drill cuttings, the borehole length was 49.07m. The length of Borehole 1 traversing the coal seam was 5.13m.

[0111] According to formulas (1) to (8), the coordinates of the contact point between borehole 1 and coal seam 7 are determined as (31.88, 27.71, 12.11). The distance from the contact point of coal seam 7 to the centerline of tunnel 6 is S1 = 30.24m. Exploration of borehole 2. With the origin as the starting point of the borehole, the borehole is adjusted to start drilling in a direction of 27° to the left horizontally and 8° to the top vertically. The distance from the starting point of borehole 2 to the contact point of coal seam 7 is determined to be 48.24 m based on the borehole length when coal slag is present in the drill cuttings. The borehole length is 55.44 m when there is no coal slag in the drill cuttings. The length of borehole 2 that crosses the coal seam is 7.20 m.

[0112] According to formulas (1) to (8), the coordinates of the contact point between borehole 2 and coal seam 7 are determined as (45.56, 21.69, 6.7). The distance from the contact point of coal seam 7 to the center line of tunnel 6 is S2 = 22.70m.

[0113] Exploration was conducted in borehole 3. Starting from the origin, the borehole was adjusted to a horizontal angle of 5° to the left and a vertical angle of 16° upwards. Based on the borehole length when coal slag was present in the drill cuttings, the distance from the starting point of borehole 3 to the contact point with coal seam 7 was determined to be 70.64m. When no coal slag was present in the drill cuttings, the borehole length was 109.26m. The length of borehole 3 traversing the coal seam was 38.62m.

[0114] According to formulas (1) to (8), the coordinates of the contact point between borehole 3 and coal seam 7 are determined as (67.64, 5.92, 19.47). The distance from the contact point of coal seam 7 to the center line of tunnel 6 is S3 = 20.35m.

[0115] Exploration of Borehole 4. Starting from the origin, the borehole was adjusted to a horizontal angle of 33° to the left and a vertical angle of 27° upwards. Based on the borehole length when coal slag was present in the drill cuttings, the distance from the starting point of Borehole 4 to the contact point with coal seam 7 was determined to be 49.48m. When no coal slag was present in the drill cuttings, the borehole length was 56.15m. The length of Borehole 4 traversing the coal seam was 6.67m.

[0116] According to formulas (1) to (8), the coordinates of the contact point between borehole 4 and coal seam 7 are determined as (36.97, 24.01, 22.46). The distance from the contact point of coal seam 7 to the center line of tunnel 6 is S4 = 32.88m.

[0117] Exploration of Borehole 5. Starting from the origin, the borehole was adjusted to a horizontal angle of 27° to the left and a vertical angle of 34° upwards. Based on the borehole length when coal slag was present in the drill cuttings, the distance from the starting point of Borehole 5 to the contact point with coal seam 7 was determined to be 55.71m. When no coal slag was present in the drill cuttings, the borehole length was 64.3m. The length of Borehole 5 traversing the coal seam was 8.59m.

[0118] According to formulas (1) to (8), the coordinates of the contact point between borehole 5 and coal seam 7 are determined as (41.45, 20.97, 31.15). The distance from the contact point of coal seam 7 to the center line of tunnel 6 is S5 = 37.55m.

[0119] Based on the coordinates of the contact point of coal seam 7 and formulas (9) to (14), the angle between the strike line of coal seam 7 and the strike line of tunnel 6 is calculated to be 30.95°, the dip angle ω of coal seam 7 is 86.86°, and the thickness h of coal seam is 3.78m. By determining the strike, dip angle, and thickness of coal seam 7, and combining this with the minimum distance from the contact point of coal seam 7 to the center line of tunnel 6 (S3=20.35m, which is the minimum distance from the contact point of coal seam to the center line of tunnel), it is possible to quickly determine whether coal seam gas emission is required.

[0120] This invention provides a method for arranging and detecting gas exploration boreholes in long-distance coal-passing tunnels along coal seams. The fan-shaped borehole arrangement method can accurately and efficiently detect the spatial distribution characteristics of the coal seam strike, thickness, and dip angle ahead. It can avoid the time wasted by blind drilling, enabling more effective discharge of coal seam gas in the tunnel and improving the efficiency and safety of tunnel gas control.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for arranging advance detection boreholes for tunnels along coal seams, characterized in that, The coal seam (7) is a coal seam located along one side of the tunnel (6), and the coal seam gradually slopes towards the excavation face of the tunnel (6) from back to front, specifically including the following steps: Five advance detection boreholes were constructed sequentially at the center of the tunnel face, starting from the same borehole. The five advance detection boreholes are borehole 1 (1), borehole 2 (2), borehole 3 (3), borehole 4 (4), and borehole 5 (5). First, conduct exploration in borehole (1): Adjust the borehole to start drilling with an upward tilt angle α1 and a horizontal tilt angle β1 towards the side where the coal seam (7) is located, and record the borehole depth as R1 when coal slag appears in the drill cuttings; After the exploration of borehole 1 (1) is completed, the exploration of borehole 2 (2) begins: the borehole is adjusted to start drilling at an upward tilt angle α2 and a horizontal tilt angle β2 towards the side where the coal seam (7) is located, and the borehole depth is recorded as R2 when coal slag appears in the drill cuttings. After the exploration of borehole No. 2 (2) is completed, the exploration of borehole No. 3 (3) begins: the borehole is adjusted to start drilling at an upward tilt angle α3 and a horizontal tilt angle β3 towards the side where the coal seam (7) is located, and the borehole depth is recorded as R3 when coal slag appears in the drill cuttings; After the exploration of borehole No. 3 (3) is completed, the exploration of borehole No. 4 (4) begins: the borehole is adjusted to start drilling in the direction of upward inclination angle α4 and horizontal inclination angle β4 on the side where the coal seam (7) is located, and the borehole depth is recorded as R4 when coal slag appears in the drill cuttings; After the exploration of borehole No. 4 (4) is completed, the exploration of borehole No. 5 (5) begins: the borehole is adjusted to start drilling at an upward tilt angle α5 and a horizontal tilt angle β5 towards the side where the coal seam (7) is located, and the borehole depth is recorded as R5 when coal slag appears in the drill cuttings; Wherein, α5>α4>α3=α1>α2, β1>β4>β5=β2>β3, α1 is 10°~20°, β1 is 30°~40°; α2 is 0°~10°, β2 is 20°~30°; α3 is 10°~20°, β3 is 10°~20°; α4 is 20°~30°, β4 is 25°~30°; α5 is 30°~40°, β5 is 20°~30°; After recording the borehole depth as R1, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R1". Record the length of the borehole through the coal seam as B1 = R1" - R1. Then continue drilling. Stop drilling when the borehole depth is above R1" + 0.5m. The exploration of borehole No. 1 (1) is completed. After recording the borehole depth as R2, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R2". Record the length of the borehole through the coal seam as B2 = R2" - R2. Then continue drilling. Stop drilling when the borehole depth is above R2" + 0.5m. The exploration of borehole No. 2 (2) is completed. After recording the borehole depth as R3, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R3". Record the length of the borehole through the coal seam as B3 = R3" - R3. Then continue drilling. Stop drilling when the borehole depth is above R3" + 0.5m. The exploration of borehole No. 3 (3) is completed. After recording the borehole depth as R4, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R4". Record the length of the borehole through the coal seam as B4 = R4" - R4. Then continue drilling. Stop drilling when the borehole depth is above R4" + 0.5m. The exploration of borehole No. 4 (4) is completed. After recording the borehole depth as R5, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R5". Record the length of the borehole through the coal seam as B5 = R5" - R5. Then continue drilling. Stop drilling when the borehole depth is above R5" + 0.5m. The exploration of borehole No. 5 (5) is completed.

2. The method for arranging advance detection boreholes for tunnels along coal seams according to claim 1, characterized in that: Coal seam (7) is a coal seam located on the left side of tunnel (6).

3. The method for arranging advance detection boreholes for tunnels along coal seams according to claim 1, characterized in that: Coal seam (7) is a coal seam located on the right side of tunnel (6).

4. A method for advance detection borehole exploration of coal seam tunnels, characterized in that, The method for arranging advance detection boreholes for coal seam tunnels according to any one of claims 1-3 specifically includes the following steps: A spatial rectangular coordinate system is established with the center of the tunnel face as the origin O. The excavation direction of the tunnel centerline is taken as the positive X-axis, the vertical upward direction as the positive Z-axis, and the direction perpendicular to the X-axis to the left on the horizontal plane as the positive Y-axis. The position of the advance detection borehole in contact with the coal seam is designated as point A. The coordinates of point A in the rectangular spatial coordinate system are (x...). A y A , z A The angle between the drilling direction and the XOY plane is the vertical inclination angle α of the drilling, and the angle between the drilling direction and the XOZ plane is the horizontal inclination angle β of the drilling. The straight-line distance from the drilling origin O to the coal seam contact point A is the drilling length R when coal slag appears in the drilling cuttings. Let the distance from point A to the tunnel centerline be S. Among them, the vertical inclination angle α, the horizontal inclination angle β, and the borehole length R when coal slag appears in the borehole are all known data. The coordinates of point A (x, y, y) are deduced from α, β, and R using the following formula. A y A , z A The values ​​of ) and the distance S from point A to the centerline of the tunnel; The coordinates of the contact points between boreholes 1 (1), 2 (2), 3 (3), 4 (4), and 5 (5) and the coal seam (7) are (x1, y1, z1), (x2, y2, z2), (x3, y3, z3), (x4, y4, z4), and (x5, y5, z5), respectively. The S values ​​of the five advanced detection boreholes are respectively , , , as well as ; The minimum value S among S1~S5 min ={S1, S2, S3, S4, S5}, if S min When the distance between the coal seam (7) and the tunnel is less than the specified safety limit, the excavation of the tunnel (6) should be stopped and coal seam gas emission measures should be taken. If S min No coal seam gas emission is required when the distance between the coal seam and the tunnel exceeds the specified safety limit.

5. The method for advance detection borehole exploration of coal seam tunnels according to claim 4, characterized in that: The dip angle and strike of the coal seam (7) are detected based on the coordinates of the contact points between boreholes 1 (1), 2 (2), 4 (4), and 5 (5) and the coal seam (7). Let the angle between the coal seam (7) and the XOZ plane be θ, and the angle between the coal seam (7) and the XOY plane be ω. The specific steps include: A vector on the coal seam contact surface is determined by the coordinates (x1, y1, z1) of the contact point between borehole 1 (1) and the coal seam, and the coordinates (x2, y2, z2) of the contact point between borehole 2 (2) and the coal seam. =(x1-x2,y1-y2,z1-z2)=(u1,u2,u3); Another vector on the coal seam contact surface is determined by the coordinates (x4, y4, z4) of the contact point between borehole No. 4 (4) and the coal seam, and the coordinates (x5, y5, z5) of the contact point between borehole No. 5 (5) and the coal seam. =(x4-x5,y4-y5,z4-z5)=(v1,v2,v3); Two non-collinear vectors , The cross product determines a normal vector perpendicular to the coal seam contact surface. : According to the normal vector of the contact surface of coal seam (7) and a normal vector of the XOZ surface =(0,1,0) Calculate the angle θ between the coal seam (7) and the XOZ plane: According to the normal vector of the contact surface of coal seam (7) and a normal vector of the XOY plane =(0,0,1) Calculate the angle ω between the coal seam contact surface and the XOY plane: The angle θ between the coal seam (7) and the XOZ plane is the angle between the strike line of the coal seam (7) and the strike line of the tunnel (6), and the angle ω between the coal seam (7) and the XOY plane is the dip angle of the coal seam (7). min When the distance between the coal seam (7) and the tunnel (6) is less than the specified limit safety value, the excavation of the tunnel (6) should be stopped and coal seam gas emission measures should be taken. The dip angle and direction of the coal seam (7) mentioned above should be used as a basis for the subsequent drainage borehole layout plan.

6. The method for advance detection borehole exploration of coal seam tunnels according to claim 5, characterized in that: After recording the borehole depth as R1, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R1". Record the length of the borehole through the coal seam as B1 = R1" - R1. Then continue drilling. Stop drilling when the borehole depth is above R1" + 0.5m. The exploration of borehole No. 1 (1) is completed. After recording the borehole depth as R2, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R2". Record the length of the borehole through the coal seam as B2 = R2" - R2. Then continue drilling. Stop drilling when the borehole depth is above R2" + 0.5m. The exploration of borehole No. 2 (2) is completed. After recording the borehole depth as R3, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R3". Record the length of the borehole through the coal seam as B3 = R3" - R3. Then continue drilling. Stop drilling when the borehole depth is above R3" + 0.5m. The exploration of borehole No. 3 (3) is completed. After recording the borehole depth as R4, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R4". Record the length of the borehole through the coal seam as B4 = R4" - R4. Then continue drilling. Stop drilling when the borehole depth is above R4" + 0.5m. The exploration of borehole No. 4 (4) is completed. After recording the borehole depth as R5, continue drilling. When there is no coal slag in the drill cuttings, record the borehole depth as R5". Record the length of the borehole through the coal seam as B5 = R5" - R5. Then continue drilling. Stop drilling when the borehole depth is above R5" + 0.5m. The exploration of borehole No. 5 (5) is completed. The thickness h of the coal seam is calculated based on the arrangement angles α and β of any borehole, the length B of the borehole traversing the coal seam, and the angles θ and ω between the coal seam (7) and the XOZ plane: The thickness of the coal seam (7) was detected to provide a basis for the subsequent drilling layout scheme.

Images