Tunneling through gently inclined coal seams

Abstract

This invention discloses a method for tunneling through a gently dipping coal seam, comprising the following steps: determining the top and bottom surfaces of the gently dipping coal seam; determining a first working face parallel to the top surface above the top surface and a second working face parallel to the bottom surface below the bottom surface; horizontally excavating the geological body above the gently dipping coal seam using a bench method until the upper bench intersects with the first working face; excavating a pilot tunnel on the upper bench; blasting the pilot tunnel using a blasting method to expose the gently dipping coal seam and release gas; and excavating the gently dipping coal seam using a pre-reserved core soil method until it passes through the second working face. This invention uses the bench method to reduce the excavation cross-sectional area while simultaneously excavating the gently dipping coal seam in one go, meeting regulatory requirements and reducing construction difficulty; the pre-reserved core soil method for excavating through the gently dipping coal seam allows the pre-reserved geological body to assist in supporting the tunnel working face, reducing safety hazards and making tunnel excavation operations safer.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction technology, and in particular to a method for excavating a tunnel through a gently dipping coal seam. Background Technology

[0002] Gently dipping coal seams refer to coal seams with a dip angle of 8° to 25° during underground mining. According to regulations, when a tunnel passes through a gently dipping coal seam, the seam must be exposed in one operation. However, for tunnels with large excavation cross-sectional areas, excavating a gently dipping coal seam in one go is very difficult and can easily lead to tunnel collapse due to the large exposed cross-section, posing a significant safety hazard. Furthermore, due to the poor geological conditions of gently dipping coal seams, excavation work can easily disturb the geological mass, leading to tunnel collapse and posing a significant safety risk. Summary of the Invention

[0003] The main objective of this invention is to provide a method for tunnel excavation through gently inclined coal seams, which aims to solve the technical problems in the prior art where it is difficult to excavate gently inclined coal seams in one go when the excavation cross section is large, and the tunnel is prone to collapse when excavating gently inclined coal seams, posing a significant safety hazard.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a method for tunneling through a gently dipping coal seam, comprising the following steps: determining the top and bottom surfaces of the gently dipping coal seam; determining a first working face parallel to the top surface above the top surface and a second working face parallel to the bottom surface below the bottom surface; horizontally excavating the geological body above the gently dipping coal seam using a bench method until the upper bench intersects with the first working face; excavating a pilot tunnel on the upper bench; blasting the pilot tunnel using a blasting method to expose the gently dipping coal seam and release gas; and excavating the gently dipping coal seam using a pre-reserved core soil method until crossing the second working face.

[0006] Optionally, the step of horizontally excavating the geological body above the gently dipping coal seam using the step method until the upper step intersects with the first working face includes: determining a third working face above the first working face that is parallel to the first working face; excavating the geological body above the gently dipping coal seam in two layers using the step method until the upper step intersects with the third working face; and continuing to excavate the geological body within the range of the upper step in two layers using the step method until the upper step intersects with the first working face.

[0007] Optionally, the step of continuing to excavate the geological body within the range of the upper step in two layers using the step method until the upper step intersects with the first working face includes: dividing the upper step into a first step and a second step distributed vertically; determining the length of the first step according to the inclination angle of the gently inclined coal seam; and excavating the first step and the second step sequentially according to the length of the first step until the first step intersects with the first working face.

[0008] Optionally, the step of excavating through the gently dipping coal seam using the reserved core soil method until crossing the second working face includes: circumferentially excavating the geological body of the first bench except for the middle part of the tunnel until crossing the second working face; constructing the arch support structure of the tunnel; alternately excavating the geological body of the second bench from left to right until crossing the second working face; alternately excavating the geological body of the lower bench from left to right until crossing the second working face; constructing the side support structure of the tunnel; excavating the geological body in the middle part of the tunnel until crossing the second working face; and constructing the bottom support structure of the tunnel.

[0009] Optionally, the step of circumferentially excavating the geological body of the first step excluding the middle of the tunnel until it crosses the second working face includes: expanding the pilot tunnel to the outline of the first step; and circumferentially excavating the geological body of the first step excluding the middle of the tunnel until the first step crosses the second working face.

[0010] Optionally, the step of excavating the guide pit on the upper step includes: horizontally excavating an arc-shaped opening at the lower part of the first step to form an upper guide pit; horizontally excavating a rectangular opening at the upper part of the second step to form a lower guide pit; and excavating the lower guide pit to the same horizontal depth as the upper guide pit, so that the upper guide pit and the lower guide pit are connected to form the guide pit.

[0011] Optionally, after the step of continuing to excavate the geological body within the range of the upper step in two layers using the step method until the upper step intersects with the first working face, the method further includes the following step: constructing an advanced support structure.

[0012] Optionally, the step of excavating the geological body above the gently dipping coal seam in two layers using the step method until the upper step intersects with the third working face includes: determining a fourth working face parallel to the third working face above the third working face; excavating the geological body above the gently dipping coal seam in two layers using the step method until the upper step intersects with the fourth working face; performing advanced geological prediction on the gently dipping coal seam from the fourth working face; adjusting the width of the upper step based on the information obtained from the advanced geological prediction; and continuing to excavate the geological body above the gently dipping coal seam in two layers using the step method from the fourth working face until the upper step intersects with the third working face, based on the width of the upper step.

[0013] Optionally, the step of continuing to excavate the geological body above the gently dipping coal seam in two layers using the step method from the fourth working face, based on the width of the upper step, until the upper step intersects with the third working face, includes: determining a fifth working face parallel to the fourth working face between the fourth and third working faces; excavating the geological body above the gently dipping coal seam in two layers using the step method from the fourth working face, based on the width of the upper step, until the upper step intersects with the fifth working face; performing outburst risk prediction on the gently dipping coal seam from the fifth working face; performing outburst control based on the information obtained from the outburst risk prediction; and continuing to excavate the geological body above the gently dipping coal seam in two layers using the step method from the fifth working face, based on the width of the upper step, until the upper step intersects with the third working face.

[0014] Optionally, the first working surface is located 2m above the top surface, the second working surface is located 2m below the bottom surface, the third working surface is located 5m above the top surface, the fourth working surface is located 20m above the top surface, and the fifth working surface is located 10m above the top surface.

[0015] The tunnel excavation method for gently dipping coal seams proposed in this invention utilizes a bench excavation method to excavate the geological body above the gently dipping coal seam. The large excavation cross-section is divided into an upper bench and a lower bench. A pilot tunnel is excavated in the upper bench, and the gently dipping coal seam is then exposed in one go using blasting. This method reduces the excavation cross-section area while simultaneously excavating the gently dipping coal seam in one go, meeting the specifications for excavating gently dipping coal seams, reducing construction difficulty, minimizing the risk of tunnel collapse, and improving construction safety. Furthermore, the method of reserving a core soil layer for excavating gently dipping coal seams with poor geological conditions reduces the disturbance to surrounding geological bodies caused by an excessively large excavation cross-section. The geological body located in the middle of the tunnel also provides auxiliary support to the tunnel working face, which helps maintain tunnel stability, reduces safety hazards, and makes tunnel excavation operations safer. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart illustrating the first embodiment of the tunnel excavation method for gently inclined coal seams according to the present invention.

[0018] Figure 2 for Figure 1 A detailed flowchart of step S30;

[0019] Figure 3 for Figure 1 A detailed flowchart of step S60;

[0020] Figure 4 for Figure 1 A detailed flowchart of step S40;

[0021] Figure 5 This is a side view schematic diagram of the tunnel passing through a gently dipping coal seam according to the present invention;

[0022] Figure 6 This is a schematic diagram of the cross-sectional structure of the tunnel of the present invention.

[0023] Explanation of icon numbers:

[0024] label name label name 10 Gently dipping coal seams 70 upper steps 11 Top surface 71 First step 12 Bottom 72 Second step 20 First working face 80 lower steps 30 Second working face 90 Pipeline 40 Third working face 91 Upper pilot tunnel 50 Fourth working face 92 Lower guide pit 60 Fifth working face

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] It should be noted that in the embodiments of the present invention, all directional indications (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0028] In this invention, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element. Furthermore, the meaning of "and / or" throughout the text includes three parallel options; for example, "A and / or B" includes option A, option B, or options where both A and B are satisfied.

[0029] In this invention, unless otherwise explicitly specified and limited, the terms "connection" and "fixed" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements.

[0030] In this invention, if there are descriptions involving "first," "second," etc., such descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0031] In this invention, the use of suffixes such as "module," "component," "part," "unit," or "unit" to denote elements is solely for the purpose of illustrative purposes and has no specific meaning in itself. Therefore, "module," "part," or "unit" can be used interchangeably.

[0032] For those skilled in the art, the specific meanings of the above terms in this invention can be understood according to the specific circumstances. Furthermore, the technical solutions of the various embodiments can be combined with each other; however, this is based on the premise that those skilled in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0033] The inventive concept of the present invention will be further explained below with reference to some specific embodiments.

[0034] This invention proposes a method for tunnel excavation through gently dipping coal seams, comprising the following steps:

[0035] Step S10: Determine the top and bottom surfaces of the gently dipping coal seam;

[0036] Step S20: Determine a first working surface parallel to the top surface above the top surface, and determine a second working surface parallel to the bottom surface below the bottom surface;

[0037] Step S30: Use the bench method to horizontally excavate the geological body above the gently dipping coal seam until the upper bench intersects with the first working face;

[0038] Step S40: Excavate a pilot tunnel on the upper step;

[0039] Step S50: The pilot tunnel is blasted using a blasting method to expose the gently dipping coal seam and release gas;

[0040] Step S60: Excavate the gently inclined coal seam using the reserved core soil method until it crosses the second working face.

[0041] like Figure 1 As shown, Figure 1 This is a schematic flowchart of the first embodiment of the tunnel excavation method for gently dipping coal seam 10 proposed in this invention. As the first embodiment of the tunnel excavation method for gently dipping coal seam 10 proposed in this invention, as... Figure 5 As shown, Figure 5 This is a side view of the tunnel passing through a gently inclined coal seam 10 according to the present invention. The top surface 11 and bottom surface 12 of the gently inclined coal seam 10 are both inclined. The first working face 20 is located above the top surface 11, and the distance between the first working face 20 and the top surface 11 in the vertical direction is a. The second working face 30 is located below the bottom surface 12, and the distance between the second working face 30 and the bottom surface 12 in the vertical direction is b. The tunnel is horizontally excavated and passes through the first working face 20, the top surface 11, the bottom surface 12 and the second working face 30 in sequence. Before the tunnel face intersects with the first working face 20, the tunnel excavation adopts the bench method, prioritizing the excavation of the upper bench 70 and maintaining a predetermined length between the upper bench 70 and the lower bench 80. The pilot tunnel 90 extends from the first working face 20 to the top surface 11, but does not intersect with the top surface 11. The geological body between the pilot tunnel 90 and the top surface 11 is exposed by blasting within the pilot tunnel 90, allowing the gently inclined coal seam 10 to be exposed and gas to be released. For the gently inclined coal seam 10 with poor geological conditions, the pre-reserved core soil method is used for excavation, that is, the geological body located in the middle of the tunnel cross section is preserved, and the geological body located around the tunnel cross section is excavated first. After the support structure around the tunnel is completed, the geological body located in the middle of the tunnel cross section is excavated last, until the second working face 30 is crossed.

[0042] The tunnel excavation method for crossing a gently dipping coal seam 10 proposed in this invention utilizes a bench excavation method to excavate the geological body above the gently dipping coal seam 10. The large excavation cross-section is divided into an upper bench 70 and a lower bench 80. A pilot tunnel 90 is excavated in the upper bench 70, and the gently dipping coal seam 10 is then removed in one go using blasting. This method reduces the excavation cross-section area while simultaneously removing the gently dipping coal seam 10, meeting the specifications for removing the gently dipping coal seam 10, reducing construction difficulty, minimizing the risk of tunnel collapse, and improving construction safety. Furthermore, the method of reserving a core soil layer for excavating through the gently dipping coal seam 10, which has poor geological conditions, reduces the disturbance to the surrounding geological body caused by an excessively large excavation cross-section area. The geological body located in the middle of the tunnel also provides auxiliary support to the tunnel working face, which helps maintain tunnel stability, reduces safety hazards, and makes tunnel excavation operations safer.

[0043] Based on the first embodiment, step S30 includes:

[0044] Step S31: Determine a third working surface above the first working surface, parallel to the first working surface;

[0045] Step S32: Excavate the geological body above the gently dipping coal seam in two layers using the bench method until the upper bench intersects with the third working face;

[0046] Step S33: Continue to excavate the geological body within the range of the upper step in two layers using the step method until the upper step intersects with the first working face.

[0047] like Figure 2 and Figure 5 As shown, Figure 2 for Figure 1 A detailed flowchart of step S30 is shown below; the third working face 40 is at a vertical distance c from the top surface 11. The tunnel is excavated horizontally and passes through the third and first horizontal surfaces in sequence. Before the tunnel intersects with the third horizontal surface, the tunnel is divided into an upper bench 70 and a lower bench 80, with the upper bench 70 being excavated first, and the upper bench 70 and lower bench 80 being distributed at preset length intervals. When the tunnel intersects with the third horizontal surface, the upper bench 70 is further divided into a first bench 71 and a second bench 72, and the entire tunnel cross-section is excavated in three layers to excavate the geological body above the gently dipping coal seam 10 until it intersects with the first working face 20.

[0048] The bench excavation method, used in layered tunnel excavation, can divide a large tunnel into smaller excavation faces while ensuring sufficient working space. This effectively reduces the disturbance to the surrounding geological body caused by a single excavation, thus improving the stability of the excavation face. After completing the excavation of the upper bench 70, appropriate support measures can be implemented according to the geological conditions before excavating the lower bench 80. This makes the excavation of the lower bench 80 safer, effectively reducing safety hazards and improving the overall safety of tunnel construction.

[0049] As a second embodiment of the present invention, step S33 includes:

[0050] Step S331: Divide the upper step into a first step and a second step, which are distributed vertically.

[0051] Step S332: Determine the length of the first step based on the inclination angle of the gently sloping coal seam;

[0052] Step S333: Excavate the first step and the second step sequentially according to the length of the first step until the first step intersects with the first working face.

[0053] Furthermore, after the upper bench 70 intersects with the third working face 40, the entire tunnel cross-section is divided from top to bottom into a first bench 71, a second bench 72, and a lower bench 80. The length of the first bench 71 is determined by the inclination angle of the gently sloping coal seam 10. During the layered excavation of the tunnel, the first bench 71 is excavated first, then the second bench 72 is excavated while maintaining the length of the first bench 71, and finally the lower bench 80 is excavated while maintaining the preset length of the upper bench 70, so that the three benches are distributed at intervals in the horizontal direction until the first bench 71 intersects with the first working face 20.

[0054] As the tunnel excavation face gradually approaches the top surface 11 of the gently dipping coal seam 10 until it intersects with the third working face, the geological conditions inside the tunnel gradually deteriorate. The entire tunnel cross-section is divided into three steps, and excavation is carried out layer by layer from top to bottom. The three steps are spaced at predetermined lengths in the horizontal direction, which can further reduce the cross-sectional area of ​​a single excavation face, thereby further reducing the disturbance of the surrounding geological body to the tunnel and improving the safety of tunnel construction.

[0055] Based on the second embodiment, step S60 includes:

[0056] Step S61: Circumferentially excavate the geological body of the first step, excluding the middle part of the tunnel, until the second working face is crossed;

[0057] Step S62: Construct the arch support structure of the tunnel;

[0058] Step S63: Excavate the geological body of the second step alternately from left to right until the second working face is crossed;

[0059] Step S64: Excavate the geological body of the lower step alternately from left to right until the second working face is crossed;

[0060] Step S65: Construct the side support structure of the tunnel;

[0061] Step S66: Excavate the geological body in the middle of the tunnel until the second working face is reached;

[0062] Step S67: Construct the bottom support structure of the tunnel.

[0063] like Figure 3 As shown, Figure 3 for Figure 1 A detailed flowchart of step S60 is shown below. When excavating through the gently dipping coal seam 10, the tunnel cross-section is further divided into a first bench 71, a second bench 72, and a lower bench 80. The geological body in the middle of the tunnel is also divided into three parts. When excavating the first bench 71, the portion of the geological body in the middle of the tunnel located on the first bench 71 is retained. Only the geological body surrounding the first bench 71 is excavated circumferentially. A gap exists between the upper part of the first bench 71 and the tunnel roof to facilitate the construction of the tunnel's arch support structure. When excavating the geological body within the second bench 72, the geological body of the second bench 72 is divided into left and right parts on the cross-section. The geological body within the second bench 72 is excavated alternately from left to right, that is, one part of the geological body is retained within the same cross-section while the other part is excavated, until the second working face 30 is crossed. Similarly, when excavating the geological body within the lower bench 80, the geological body of the lower bench 80 is divided into left and right parts on the cross-section. The geological body within the lower bench 80 is excavated alternately from left to right, until the second working face 30 is crossed. After excavating the geological bodies within the second step 72 and the lower step 80, the side support structure of the tunnel can be constructed. After completing the arch support structure and side support structure of the tunnel, the reserved geological bodies in the middle of the tunnel are excavated to complete the excavation of the geological bodies inside the tunnel. Finally, the bottom support structure of the tunnel is constructed.

[0064] Layered excavation of the gently dipping coal seam 10 minimizes the cross-sectional area of ​​the excavation, reducing disturbance to the coal seam and safety hazards during tunnel excavation. Reserving a geological mass in the middle of the tunnel allows it to support the tunnel face, effectively improving its stability and enabling timely installation of support structures. This ensures safe excavation of the geological mass in the middle of the tunnel, thereby enhancing overall construction safety.

[0065] In one embodiment, step S61 includes:

[0066] Step S611: Expand the guide pit to the outline of the first step;

[0067] Step S612: Circumferentially excavate the geological body of the first step except for the middle part of the tunnel until the first step crosses the second working face.

[0068] Furthermore, after the gently dipping coal seam 10 is exposed by blasting in the pilot tunnel 90, excavation proceeds from the inside of the pilot tunnel 90 outwards until the boundary line of the pilot tunnel 90 is expanded to the outline of the first bench 71. Excavation then continues circumferentially around the geological body surrounding the first bench 71 until the second working face 30 is reached. After the gently dipping coal seam 10 is exposed by blasting in the pilot tunnel 90, the pilot tunnel 90 expands and deepens under the action of the blasting. Tunnel excavation is then carried out on this basis. The construction steps are rationally arranged, effectively improving construction efficiency.

[0069] Based on the first embodiment, step S40 includes:

[0070] Step S41: Horizontally excavate an arc-shaped opening at the lower part of the first step to form an upper guide pit;

[0071] Step S42: A rectangular opening is horizontally excavated at the upper part of the second step to form a lower guide pit;

[0072] Step S43: Excavate the lower guide pit to the same horizontal depth as the upper guide pit, so that the upper guide pit and the lower guide pit are connected to form the guide pit.

[0073] like Figure 4 and Figure 6 As shown, Figure 4 for Figure 1 A detailed flowchart of step S40; Figure 6 This is a schematic diagram of the cross-sectional structure of the tunnel of the present invention. The upper pilot tunnel 91 is located on the first step 71, and the lower pilot tunnel 92 is located on the second step 72. The second step 72 and the first step 71 are spaced apart in the horizontal direction. Therefore, the excavation length of the lower pilot tunnel 92 is greater than the excavation length of the upper pilot tunnel 91, so that the working face of the upper pilot tunnel 91 is flush with the working face of the lower pilot tunnel 92, and the upper pilot tunnel 91 and the lower pilot tunnel 92 are interconnected to form a pilot tunnel 90. The upper pilot tunnel 91 is arc-shaped, which allows the top of the pilot tunnel to better bear the weight of the geological body at the top of the tunnel, thereby improving the structural stability of the pilot tunnel.

[0074] In one embodiment, after step S33, the method further includes:

[0075] Step S34: Construct the advanced support structure.

[0076] When the tunnel is excavated to the point where the upper bench 70 intersects with the first working face 20, the excavation working face is close to the gently inclined coal seam 10. The critical surface between the gently inclined coal seam 10 and the surrounding bottom layer is a structurally weak layer. When excavating through the critical layer, the tunnel entrance is prone to collapse. Therefore, before excavating through the critical layer, an advanced support structure is constructed according to the specific geological conditions. This can stabilize the geological body near the critical layer in advance, prevent collapse during tunnel excavation, and thus improve the safety of tunnel excavation.

[0077] In one embodiment, step S32 includes:

[0078] Step S321: Determine a fourth working surface above the third working surface, parallel to the third working surface;

[0079] Step S322: Excavate the geological body above the gently dipping coal seam in two layers using the bench method until the upper bench intersects with the fourth working face;

[0080] Step S323: The fourth working face performs advanced geological prediction on the gently dipping coal seam;

[0081] Step S324: Adjust the width of the upper step according to the information obtained from the advanced geological forecast;

[0082] Step S325: Based on the width of the upper step, the fourth working face continues to excavate the geological body above the gently dipping coal seam in two layers using the step method until the upper step intersects with the third working face.

[0083] like Figure 5 As shown, the distance d between the fourth working face 50 and the top surface 11 in the vertical direction is d. Since the gently dipping coal seam 10 is a geological layer prone to outbursts, with a relatively deep burial depth and high risk, its distribution pattern may differ from the initially determined distribution positions of the top surface 11 and bottom surface 12. Therefore, when the tunnel excavation reaches the fourth working face 50, which is closer to the gently dipping coal seam 10, advanced geological prediction of the gently dipping coal seam 10 can be conducted from the fourth working face 50. This can effectively improve the exploration accuracy of the gently dipping coal seam 10, provide a more detailed understanding of its distribution, thereby reducing the risk of outbursts and effectively improving tunnel construction safety.

[0084] In one embodiment, step S325 includes:

[0085] Step S325a: Determine a fifth working surface parallel to the fourth working surface between the fourth working surface and the third working surface;

[0086] Step S325b: Based on the width of the upper bench, the geological body above the gently dipping coal seam is excavated in two layers from the fourth working face using the bench method until the upper bench intersects with the fifth working face;

[0087] Step S325c: The fifth working face performs outburst risk prediction on the gently dipping coal seam;

[0088] Step S325d: Perform hazard mitigation based on the information obtained from the hazard prediction;

[0089] Step S325e: Based on the width of the upper bench, the fifth working face continues to excavate the geological body above the gently dipping coal seam in two layers using the bench method until the upper bench intersects with the third working face.

[0090] Furthermore, such as Figure 5 As shown, the fifth working face 60 is 'e' away from the top surface 11 in the vertical direction. When the tunnel excavation reaches the intersection of the upper bench 70 and the fifth working face 60, the tunnel excavation face is relatively close to the gently dipping coal seam 10. Predicting the outburst risk of the gently dipping coal seam 10 from the fifth working face 60 can make the prediction more accurate, facilitating targeted outburst control by construction personnel based on the prediction results. This further reduces the risk of an outburst in the gently dipping coal seam 10, thereby improving construction safety.

[0091] In one embodiment, the first working surface is located 2m above the top surface, the second working surface is located 2m below the bottom surface, the third working surface is located 5m above the top surface, the fourth working surface is located 20m above the top surface, and the fifth working surface is located 10m above the top surface.

[0092] It can be explained that the fourth working face 50, the fifth working face 60, the third working face 40, and the first working face 20 are distributed from top to bottom above the top surface 11 of the gently inclined coal seam 10 and are all parallel to the top surface 11. The second working face 30 is located below the bottom surface 12 of the gently inclined coal seam 10 and is parallel to the bottom surface 12. Figure 5 As shown, a = 2m, b = 2m, c = 5m, d = 10m, e = 20m. The distance between each working face and the gently inclined coal seam 10 is determined based on experience. This ensures that when conducting advanced geological forecasting, outburst risk prediction, excavation, and method changes for the gently inclined coal seam 10, the working face maintains a sufficient distance from the gently inclined coal seam 10. This allows for the early prediction of potential hazards during excavation, thereby improving construction safety.

[0093] It should be noted that the sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments. The above embodiments are only optional embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made under the inventive concept of the present invention using the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are all included within the patent protection scope of the present invention.

Claims

1. A method for tunneling through gently dipping coal seams, characterized in that, The method includes: Determine the top and bottom surfaces of the gently dipping coal seam; A first working surface parallel to the top surface is defined above the top surface, and a second working surface parallel to the bottom surface is defined below the bottom surface; The geological body above the gently dipping coal seam is excavated horizontally using the step method until the upper step intersects with the first working face; the excavation sections formed by the step method excavation of the geological body above the gently dipping coal seam are the upper step and the lower step, respectively. Excavate a pilot pit on the upper step; The pilot tunnel was blasted to expose the gently dipping coal seam and release gas. The gently sloping coal seam was excavated using the reserved core soil method until it crossed the second working face; The step of horizontally excavating the geological body above the gently dipping coal seam using the bench method until the upper bench intersects with the first working face includes: A third working surface is defined above the first working surface and parallel to the first working surface; The geological body above the gently dipping coal seam is excavated in two layers using the step method until the upper step intersects with the third working face; Continue using the step method to excavate the geological body within the range of the upper step in two layers until the upper step intersects with the first working face.

2. The method for tunneling through gently dipping coal seams as described in claim 1, characterized in that, The step of continuing to excavate the geological body within the upper bench area in two layers using the bench method until the upper bench intersects with the first working face includes: The upper step is divided into a first step and a second step, which are distributed vertically. The length of the first step is determined based on the inclination angle of the gently sloping coal seam. Excavate the first step and the second step sequentially according to the length of the first step, until the first step intersects with the first working face.

3. The method for tunneling through gently dipping coal seams as described in claim 2, characterized in that, The steps of excavating through the gently dipping coal seam using the pre-reserved core soil method until crossing the second working face include: The geological body of the first step, excluding the middle part of the tunnel, is excavated circumferentially until the second working face is reached; Construct the arch support structure for the tunnel; The geological body of the second step is excavated alternately from left to right until the second working face is crossed; The geological body of the lower step is excavated alternately from left to right until the second working face is reached; Construct the side support structure for the tunnel; Excavate the geological body in the middle of the tunnel until it passes through the second working face; Construct the bottom support structure of the tunnel.

4. The method for tunneling through gently dipping coal seams as described in claim 3, characterized in that, The step of circumferentially excavating the geological body of the first step, excluding the middle of the tunnel, until crossing the second working face includes: Expand the guide pit to the outline of the first step; The geological body of the first step, excluding the middle part of the tunnel, is excavated circumferentially until the first step crosses the second working face.

5. The method for tunneling through gently dipping coal seams as described in claim 2, characterized in that, The step of excavating the pilot tunnel on the upper step includes: An arc-shaped opening is horizontally excavated at the lower part of the first step to form an upper guide pit; A rectangular opening is horizontally excavated at the upper part of the second step to form a lower pilot tunnel; The lower guide pit is excavated to the same horizontal depth as the upper guide pit, so that the upper guide pit and the lower guide pit are connected to form the guide pit.

6. The method for tunneling through gently dipping coal seams as described in any one of claims 2 to 5, characterized in that, After the step of continuing to excavate the geological body within the range of the upper bench in two layers using the bench method until the upper bench intersects with the first working face, the method further includes: Construct advanced support structures.

7. The method for tunnel excavation through gently dipping coal seams as described in any one of claims 2 to 5, characterized in that, The steps of excavating the geological body above the gently dipping coal seam in two layers using the bench method until the upper bench intersects with the third working face include: A fourth working surface, parallel to the third working surface, is determined above the third working surface; The geological body above the gently dipping coal seam is excavated in two layers using the step method until the upper step intersects with the fourth working face; The fourth working face is used to conduct advanced geological prediction of the gently dipping coal seam; The width of the upper step is adjusted based on the information obtained from the advanced geological forecast; Based on the width of the upper bench, the fourth working face continues to excavate the geological body above the gently dipping coal seam in two layers using the bench method until the upper bench intersects with the third working face.

8. The method for tunneling through gently dipping coal seams as described in claim 7, characterized in that, The step of continuing to excavate the geological body above the gently dipping coal seam in two layers using the step method, based on the width of the upper bench, until the upper bench intersects with the third working face, includes: A fifth working surface, parallel to the fourth working surface, is determined between the fourth working surface and the third working surface; Based on the width of the upper step, the geological body above the gently dipping coal seam is excavated in two layers from the fourth working face using the step method until the upper step intersects with the fifth working face; The fifth working face is used to predict the outburst risk of the gently dipping coal seam. Prominent hazard management is carried out based on the information obtained from the aforementioned prominent hazard prediction; Based on the width of the upper bench, the fifth working face continues to excavate the geological body above the gently dipping coal seam in two layers using the bench method until the upper bench intersects with the third working face.

9. The method for tunneling through gently dipping coal seams as described in claim 8, characterized in that, The first working surface is located 2m above the top surface, the second working surface is located 2m below the bottom surface, the third working surface is located 5m above the top surface, the fourth working surface is located 20m above the top surface, and the fifth working surface is located 10m above the top surface.

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