Cutting, pressure relief and outburst elimination method of double-trapezoid supporting rope saw for coal penetrating tunnel

Abstract

The invention discloses a double-trapezoid supporting rope saw cutting pressure relief and outburst elimination method for a coal penetrating tunnel, and belongs to the technical field of coal seam pressure relief and outburst elimination of the coal penetrating tunnel. Comprising the steps that a large-section coal uncovering tunnel face is planned into a first-stage trapezoidal area and a second-stage trapezoidal area on the cross section, and a trapezoidal table body between the planned second-stage trapezoidal area and a coal seam is used as a supporting structure for tunnel coal uncovering pressure relief; planning the tunnel face according to the occurrence condition of the coal seam in front of the tunnel face and the tunnel face of the large-section coal uncovering tunnel; and based on tunnel face planning and drilling operation conditions of the large-section coal uncovering tunnel, a reverse cutting method and a casing cutting method are adopted to continuously cut a coal seam and the middle part of a rock mass of a supporting structure. The double-trapezoid supporting structure is used for achieving directional pressure relief of the tunnel coal seam, permeability increasing and strengthening, efficient gas emission and cooperative crustal stress regulation and control, a free face is reserved in follow-up tunnel blasting construction, and the problems that in existing tunnel face coal uncovering outburst prevention conventional measures, cost is high, efficiency is low, and safety is insufficient are effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal seam pressure relief and outburst elimination in coal tunnels, and in particular relates to a method for pressure relief and outburst elimination by cutting with a double trapezoidal support rope saw in coal tunnels. Background Art

[0002] In coal-bearing strata, due to the softness of the coal structure and insufficient self-stabilization capacity, coupled with the dual influence of ground stress and gas pressure, the construction of large-section tunnels is very likely to cause face collapse and coal and gas outburst accidents.

[0003] At present, conventional measures for coal face coal burst prevention include pre-extraction of gas, drilling of discharge holes, reducing gas pressure, and supporting while digging to release ground stress. However, these measures are costly, inefficient, and unsafe.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0005] In order to solve the technical problems of high cost, low efficiency and insufficient safety of conventional measures for coal face coal burst prevention in the prior art, a method for cutting, unloading and eliminating coal burst by a double trapezoidal support rope saw for coal tunneling is provided.

[0006] The present invention provides a method for cutting, unloading, and eliminating outbursts by using a double trapezoidal support rope saw through a coal tunnel, comprising the following steps:

[0007] First, the large-section coal-uncovering tunnel face is planned into two first-level trapezoidal areas of different sizes in the cross section, and smaller second-level trapezoidal areas are subdivided from the two first-level trapezoidal areas. The trapezoidal platform between the planned second-level trapezoidal area and the coal seam is used as the supporting structure for coal-uncovering and pressure relief in the tunnel.

[0008] Then, according to the coal seam occurrence in front of the face and the face planning of the large-section coal-uncovering tunnel, precise construction positioning and drilling operations are carried out;

[0009] Finally, based on the planning of the face and drilling operation of the large-section coal-uncovering tunnel, a diamond wire saw was used to continuously cut the coal seam and the middle part of the rock mass of the supporting structure using the reverse cutting method and the sleeve cutting method to complete the permeability and pressure relief of the coal seam.

[0010] In some embodiments, the large-section coal-uncovering tunnel face is planned into two primary trapezoidal areas of different sizes in the cross section, and smaller secondary trapezoidal areas are subdivided from the two primary trapezoidal areas. The trapezoidal platform between the planned face and the coal seam is used as a supporting structure for coal-uncovering and pressure relief in the tunnel, including:

[0011] The face of a large-section coal-uncovering tunnel is planned in cross section into two first-level trapezoidal areas of different sizes superimposed on each other. The two first-level trapezoidal areas are divided into a plurality of blocks, each of which includes two second-level trapezoidal areas that are smaller than the first-level trapezoidal areas. The trapezoidal platform between the planned second-level trapezoidal area and the coal seam is used as a supporting structure for coal-uncovering and pressure relief in the tunnel.

[0012] In some embodiments, the large-section coal-uncovering tunnel face is planned into two primary trapezoidal areas of different sizes in the cross section, two smaller secondary trapezoidal areas are divided from the two primary trapezoidal areas, and the trapezoidal platform between the planned secondary trapezoidal area and the coal seam is used as a support structure for coal-uncovering and pressure relief in the tunnel, including:

[0013] The large-section coal-uncovering tunnel face is planned in cross section into two first-level trapezoidal areas of different sizes superimposed on each other, and the two first-level trapezoidal areas are divided into six blocks in total, and the six blocks include a first side portion, a second side portion, and a middle portion located between the first side portion and the second side portion, wherein the first side portion includes a first triangular block and a first quadrilateral block, and the bottom side of the first triangular block is co-edge with the top side of the first quadrilateral portion, the second side portion includes a second triangular block and a second quadrilateral block, and the bottom side of the second triangular block is co-edge with the top side of the second quadrilateral block, and the middle portion includes two second-level trapezoidal areas, and the bottom side of one second-level trapezoidal area is co-edge with the top side of the other second-level trapezoidal area.

[0014] In some embodiments, the block division sequence includes: firstly determining the length of the bottom side (AB) of the primary trapezoidal area (ABFE) according to the maximum span of the cross section, taking the width of the middle position of the truncated edge as the length of the bottom side (EF) of the primary trapezoidal area (EFDC), taking the length of the top side (CD) of the primary trapezoidal area (EFDC) at a width of 1 / 3 of the length of the bottom side (AB) of the primary trapezoidal area (ABFE), and then determining the heights of the two primary trapezoidal areas according to 1 / 2 of the height of the cross section, taking points (G) and (H) at equal distances on the bottom side (AB), and taking points (G) and (H) on the left and right of the center of the bottom side (EF). Point (M), point (N), connect point (M) with point (N) and point (G) with point (H) to obtain the secondary trapezoidal area (CDNM) and the secondary trapezoidal area (GHNM). Finally, the tunnel face is divided into 6 areas, among which point (A), point (B), point (E), and point (F) all have inclined projection points (a), point (b), point (e), and point (f) in the coal seam respectively. Point (C), point (D), point (G), point (H), point (M), and point (N) are projected as mirror projections in the coal seam, corresponding to point c, point d, point g, point h, point m, and point n respectively.

[0015] In some embodiments, accurate construction positioning and drilling operations are performed, including:

[0016] Inclined drilling is carried out at six corner points of the outer contour of two trapezoidal areas on the face of a large-section coal-uncovering tunnel.

[0017] In some embodiments, continuously cutting a coal seam using a wire saw by using a reverse cutting method and a sleeve cutting method comprises:

[0018] Step S31, based on the coal seam space of the borehole, using the reverse cutting method to first cut two sides and one bottom side of the first triangular block of the large-section coal-uncovering tunnel and two sides of the first quadrilateral block, and then cut two sides and one bottom side of the second triangular block of the large-section coal-uncovering tunnel and two sides of the second quadrilateral block;

[0019] Step S32, based on the coal seam space of the borehole, using a sleeve cutting method to first cut the rear edge of the first triangular block and the rear edge of the first quadrilateral block and then cut the rear edge of the second triangular block and the rear edge of the second quadrilateral block;

[0020] Step S33, based on the coal seam space of the borehole, adopt the reverse cutting method to cut the common edge of the primary trapezoidal area and the secondary trapezoidal area to complete the cutting of the coal seam.

[0021] In some embodiments, the wire saw is a diamond beaded wire saw.

[0022] In some embodiments, the slots cut by the diamond wire saw are not used for cutting and excavation, but can provide a free surface for subsequent blasting and excavation.

[0023] Compared with the prior art, the technical effects achieved by the present invention are as follows:

[0024] (1) The present invention utilizes the reverse cutting method and the sleeve cutting method to cut the coal seam rock mass without removing the coal seam rock mass, thereby ensuring construction safety.

[0025] (2) The present invention constructs a double trapezoidal support system, and realizes directional pressure relief, permeability enhancement, efficient gas discharge and coordinated regulation of ground stress in the coal seam through diamond wire saw cutting technology, which is stable and reliable and avoids face collapse.

[0026] (3) The present invention adopts block cutting to prevent abnormal gas outburst and maximize the use of the semicircular area of ​​the tunnel face, thereby improving the efficiency of permeability enhancement and pressure relief.

[0027] (4) The slots cut by the diamond wire saw of the present invention are not used for cutting and excavation, but can provide free surfaces for subsequent blasting and excavation, effectively reducing the cost of tunnel construction.

[0028] (5) The present invention can accurately cut coal seams over a large area multiple times, so that the cracks in the coal seams can expand and accelerate the adsorption, desorption and diffusion of gas therein, thereby achieving a highly efficient permeability enhancement and pressure relief effect, thereby solving the technical problems of high cost, low efficiency and insufficient safety of conventional measures for coal face coal mining and coal outburst prevention in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a block diagram of a large-section coal-uncovering tunnel face provided in one embodiment of the present invention;

[0030] Figure 2 It is a three-dimensional schematic diagram of the block structure of a large-section coal-uncovering tunnel face provided in one embodiment of the present invention;

[0031] Figure 3 It is a schematic diagram of the operation of a pressure relief and outburst elimination device for cutting coal seams with a double trapezoidal side rope saw through a coal tunnel provided in one embodiment of the present invention at a first viewing angle. DETAILED DESCRIPTION

[0032] The technical solution of the present invention is described below by specific embodiments in conjunction with the accompanying drawings. It should be understood that the one or more than four steps mentioned in the present invention do not exclude the existence of other methods and steps before and after the combination step, or other methods and steps can be inserted between these explicitly mentioned steps. It should also be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. Unless otherwise specified, the numbering of each method step is only for the purpose of identifying each method step, and is not intended to limit the order of arrangement of each method or to define the scope of implementation of the present invention. Changes or adjustments in their relative relationships can also be regarded as the scope of implementation of the present invention without substantial changes in the technical content.

[0033] The sources of the raw materials and instruments used in the examples are not particularly limited and can be purchased from the market or prepared according to conventional methods known to those skilled in the art.

[0034] Example:

[0035] The present invention provides a double trapezoidal support rope saw for cutting, relieving pressure and eliminating outbursts for a coal tunnel. The present invention can accurately cut a large area of ​​the coal seam multiple times, so that the cracks in the coal seam expand and accelerate the adsorption, desorption and diffusion of gas therein, thereby achieving a highly efficient permeability enhancement and pressure relief effect, and solving the technical problems of high cost, low efficiency and insufficient safety of conventional measures for coal face uncovering and outburst prevention in the prior art.

[0036] like Figure 1-3 As shown, in some embodiments, a method for cutting, relieving pressure and eliminating outbursts using a double trapezoidal support rope saw for passing through a coal tunnel is provided. During the implementation of the method for cutting, relieving pressure and eliminating outbursts using a double trapezoidal support rope saw for passing through a coal tunnel, a pressure relief and outburst eliminating device for cutting the coal seam using a double trapezoidal side rope saw for passing through a coal tunnel is adopted.

[0037] The pressure relief and bulge elimination device for cutting coal seams with a double trapezoidal edge rope saw through a coal tunnel includes a drilling machine and a rope saw machine; in some embodiments, the pressure relief and bulge elimination device also includes: a hydraulic support guide device for providing positioning and guidance for the rope saw, and the drilling hole provides a working space for the hydraulic support guide device and the rope saw machine. In some embodiments, the hydraulic support guide device includes: a positioning guide wheel and a hydraulic telescopic rod, and the positioning guide wheel is arranged on the hydraulic telescopic rod.

[0038] The double trapezoidal support rope saw cutting, pressure relief and outburst elimination method for coal tunnels is suitable for cutting the face of large-section coal-uncovering tunnels. Large-section coal-uncovering tunnels have the characteristics of large span, flatness, and large cross-sectional area. Coupled with the influence of gas pressure, coal and gas outbursts or face collapse accidents are very likely to occur.

[0039] The method for cutting, unloading and eliminating the outburst by using a double trapezoidal support rope saw through a coal tunnel comprises the following steps:

[0040] Step S1, planning the large-section coal-uncovering tunnel face into two first-level trapezoidal areas of different sizes (a large first-level trapezoidal area ABFE and a small first-level trapezoidal area EFDC) on the cross section, and separating two smaller second-level trapezoidal areas from the two first-level trapezoidal areas as the support structure of the large-section coal-uncovering tunnel face;

[0041] In some embodiments, the large-section coal-uncovering tunnel face is planned in a cross section into two first-level trapezoidal areas of different sizes and stacked up and down, the two first-level trapezoidal areas are divided into a plurality of blocks, the plurality of blocks include two second-level trapezoidal areas that are smaller than the first-level trapezoidal areas, and the two second-level trapezoidal areas serve as supporting structures for the large-section coal-uncovering tunnel face;

[0042] In the process of increasing the permeability and relieving the pressure on the coal seam, it is necessary to prevent the stress on the face of the large-section coal-uncovering tunnel from being too concentrated, so that the force applied to the surrounding rock is greater than the critical value and causes the face to collapse. The block excavation is a concept with multiple steps of tunnel excavation. While increasing the permeability and relieving the pressure, a double trapezoidal side support structure is formed. Under the premise of ensuring safety and no collapse, the area of ​​the coal seam cut by the rope saw can be as large as possible.

[0043] Among them, multi-step excavation is a method of tunnel excavation in stages and levels. It divides the large-section coal-unearthing tunnel face into multiple steps, and each step is excavated and supported in turn, so as to gradually advance the tunnel. This multi-step excavation helps to disperse and control the pressure from the surrounding rock mass and ensure construction safety.

[0044] In some embodiments, two primary trapezoidal areas are divided into six blocks, which include a first side portion, a second side portion, and a middle portion located between the first side portion and the second side portion, wherein the first side portion includes a first triangular block 3 and a first quadrilateral block 4, the base of the first triangular block 3 is co-edge-bound with the top of the first quadrilateral portion 4, the second side portion includes a second triangular block 5 and a second quadrilateral block 6, the base of the second triangular block 5 is co-edge-bound with the top of the second quadrilateral block 6, and the middle portion includes two secondary trapezoidal areas, the base of one secondary trapezoidal area 1 is co-edge-bound with the top of the other secondary trapezoidal area 2.

[0045] The block order is as follows:

[0046] The block division sequence includes: first, determine the length of the bottom side AB of the first-level trapezoidal area ABFE according to the maximum span of the section, take the width of the middle position of the truncated edge as the length of the bottom side EF of the first trapezoid EFDC, take the length of the top side CD of the first-level trapezoidal area EFDC at a width of 1 / 3 of the length of the bottom side AB of the first-level trapezoidal area ABFE, then determine the height of the two first-level trapezoidal areas according to 1 / 2 of the section height, take points G and H at equal distances on the bottom side AB, take points M and N on the left and right of the center of the bottom side EF, connect point M with point N and point G with point H, and obtain two second-level trapezoidal areas CDNM and second-level trapezoidal areas GHNM. Finally, divide the tunnel face into 6 areas, among which points A, B, E, and F all have inclined projection points a, b, e, and f in the coal seam, and points C, D, G, H, M, and N are projected as mirror projections in the coal seam, corresponding to points c, d, g, h, m, and n respectively. For details, refer to Figure 2 .

[0047] Dividing into 6 pieces is to provide a structural form for forming a double trapezoidal support. If it is divided into other numbers, the following problems will occur:

[0048] (1) If a rectangle is taken from the flat semicircle and divided into four pieces, the projection in the coal seam will be too small when cut with a rope saw, and the cutting area will be too small, which will not achieve the purpose of increasing permeability and relieving pressure;

[0049] (2) If it is simply divided into three rectangles, the supporting force may be insufficient, posing a risk of landslide.

[0050] Dividing the tunnel into 6 blocks can maximize the use of the semicircular tunnel face area and form a double trapezoidal support, which is the preferred block division method. In order to form a double trapezoidal support structure, the trapezoidal support is usually composed of horizontal braces, vertical braces and diagonal braces to form a stable geometric shape. Its design is to effectively share and transfer the pressure from the rock mass to prevent the collapse of the tunnel face and surrounding rock mass. The trapezoidal support has the following advantages:

[0051] (1) Superior mechanical properties: The trapezoidal structure can effectively disperse and transmit the complex stress from rock and soil, providing better stability.

[0052] (2) Strong adaptability: It is suitable for different types of tunnel sections, especially tunnels with semicircular or arched sections.

[0053] (3) Convenient construction: Compared with some complex support structures, the construction of trapezoidal support is relatively simple and easy to implement and maintain.

[0054] Step S2, based on the coal seam occurrence in front of the tunnel face and the tunnel face planning of the large-section coal-uncovering tunnel, use a drilling machine to drill holes at the positioning position;

[0055] In some embodiments, a long, inclined borehole is constructed to project the largest possible cutting area on the coal seam, thereby improving the efficiency of the permeability enhancement and pressure relief.

[0056] Before tunneling approaches the coal seam, advance detection measures must be taken to accurately grasp the coal seam's position, occurrence conditions and gas geological laws. In addition, during the construction process, comprehensive advance geological forecasting must be carried out by combining geological surveys, geophysical exploration, drilling and other means.

[0057] According to Article 49 of the Regulations on the Prevention and Control of Coal and Gas Outbursts, the regional coal seam gas outburst prevention measures in the coal-excavation area of ​​the through-layer drilling pre-extraction stone gate (including vertical and inclined shafts, etc.) should be implemented before the minimum normal distance of 7m from the coal seam to the coal-excavation working edge (the distance should be appropriately increased in the structural damage zone). The minimum control range of the drilling hole is: 12m outside the roadway contour line at the stone gate and vertical shaft and inclined shaft (6m at the bottom or lower wall of the steeply inclined coal seam), and at the same time, the minimum distance from the outer edge of the control range to the roadway contour line (including the contour line of the roadway of the expected coal-excavation section ahead) should be ensured to be not less than 5m, and when the drilling hole cannot penetrate the full thickness of the coal seam at one time, the minimum lead distance of the coal hole should be maintained at 15m. However, the increase in the cross-sectional area of ​​the large-section tunnel will significantly change the stress distribution of the surrounding rock. In order to avoid coal and gas outburst accidents caused by excavation disturbance and insufficient safety distance, the advance safety rock column distance of the regional outburst prevention measures needs to be increased accordingly. According to analogy engineering and experience analysis, the design value of the advance safety rock pillar for anti-burst measures in most tunnel coal-excavation areas is 10m, and the control range of the drilling should also be larger. Based on the occurrence of the coal seam in front of the face, the angle and length of the drilling hole are designed. According to the "Technical Specifications for Design and Construction of Highway Gas Tunnels" (JTG / T 3374-2020), there is no specific upper limit requirement for the depth of the gas tunnel discharge drilling hole. Under the premise of meeting the specifications, the angle is selected. A larger length will increase the effective area of ​​the rope saw cutting and improve the effect of pressure relief and burst elimination.

[0058] In the construction of large-section highway tunnels, the tunnel face can be regarded as an elliptical cross-section. Assuming its major axis length is a and its minor axis length is b, a point on the ellipse can be expressed by formula (1):

[0059]

[0060] a, b, φ represent a point on the ellipse. Through the advance geological survey and corresponding exploration drilling data during the tunnel excavation process, it is known that the coal seam inclination is α, the coal seam thickness is H, the angle between the tunnel and the coal seam is set to β, and the minimum normal distance between the drilling position and the coal seam is S. According to the drilling control range in the "Regulations on the Prevention and Control of Coal and Gas Outbursts", the variable distance Z outside the tunnel contour line at the coal uncovering site and the minimum distance W from the outer edge to the tunnel contour line are added.

[0061] The following formula applies to the point drilling of inclined long holes on the 6 ellipses A / B / C / D / E / F:

[0062] The horizontal component D of the borehole can be expressed by formula (2):

[0063]

[0064] The vertical component V of the borehole can be expressed by formula (3):

[0065] V = Hsin(α) + W + bsin(φ);

[0066] The minimum inclination angle of the borehole is:

[0067]

[0068] The minimum deflection angle of drilling is:

[0069]

[0070] The drilling length is given by formula (6):

[0071]

[0072] The formula for the inclination angle and length of the drilling hole at the M / N / E / F point is different from the above formula. It can be regarded as a trapezoidal cut side with a height of 1 / 4b, divided into two cases: the upper vertex and the lower vertex:

[0073] The minimum inclination angle of the upper vertex borehole M and borehole N is as follows:

[0074]

[0075] The minimum deflection angle of drilling hole M and drilling hole N is formula (8):

[0076]

[0077] The lengths of drilling holes M and N are given by formula (9):

[0078]

[0079] The minimum inclination angle of the lower vertex borehole E and borehole F is as follows:

[0080] θ = arctan(-cot(α));

[0081] The minimum deflection angle of drilling hole E and drilling hole F is formula (11):

[0082] ε=-α;

[0083] The drilling lengths of borehole E and borehole F are given by formula (12):

[0084]

[0085] In some embodiments, the height of the coal mining face in a large-section tunnel is 10m, the span is 15m, the coal seam thickness is 4.4m, the minimum normal distance from the borehole to the coal seam is 10m, the coal seam inclination is -5°, the angle between the tunnel and the coal seam is 45°, the specified distance outside the tunnel contour line at the coal mining location is 15m, and the minimum distance from the outer edge to the tunnel contour line is 7m.

[0086] The minimum inclination angle of borehole Aa is 14.57°, the minimum elevation angle of borehole Aa is 32.11°, and the length of borehole Aa is 26.34m.

[0087] The minimum inclination angle of borehole Cc is 25.57°, the minimum elevation angle of borehole Cc is 51.93°, and the length of borehole Cc is 26.99m.

[0088] The minimum inclination angle of borehole Mm is 87.49°, the minimum elevation angle of borehole Mm is 2.51°, and the length of borehole Mm is 14.41m.

[0089] The minimum inclination angle of borehole Ee is 85°, the minimum elevation angle of borehole Ee is 5°, and the length of borehole Ee is 9.42m.

[0090] The specific calculation process is as follows:

[0091]

[0092]

[0093] Therefore, the minimum inclination of borehole Aa is 14.57°, the minimum deviation of borehole Aa is 32.11°, and the length of borehole Aa is 26.34m.

[0094]

[0095] Therefore, the minimum inclination angle of borehole Cc is 25.57°, the minimum deviation angle of borehole Cc is 51.93°, and the length of borehole Cc is 26.99m.

[0096]

[0097] Therefore, the minimum inclination angle of borehole Mm is 87.49°, the minimum deviation angle of borehole Mm is 2.51°, and the length of borehole Mm is 14.41m.

[0098]

[0099] Therefore, the minimum inclination angle of borehole Ee is 85°, the minimum deviation angle of borehole Ee is 85°, and the length of borehole Ee is 9.42m.

[0100] According to the implementation technology of this invention, the target area for drilling control covers the range of drilling control in the Provisions on Prevention and Control of Coal and Gas Outbursts, so that the target range for coal seam pressure relief and permeability enhancement by rope saw cutting can meet the requirements of coal seam gas pressure relief and permeability enhancement; at the same time, the coal seam rock mass can be cut without removing the coal seam rock mass to ensure construction safety.

[0101] In some embodiments, inclined drilling is performed at six corner points of the outer contours of two primary trapezoidal areas on the face of a large-section coal-uncovering tunnel.

[0102] Step S3, finally, based on the face planning and drilling conditions of the large-section coal-uncovering tunnel, a wire saw is used to continuously cut the coal seam and the middle part of the rock mass of the supporting structure by using the reverse cutting method and the sleeve cutting method to complete the permeability enhancement and pressure relief of the coal seam. In some embodiments, the wire saw is a diamond beaded wire rope.

[0103] In some embodiments, continuously cutting a coal seam using a wire saw with a reverse cutting method and a sleeve cutting method includes:

[0104] Step S31, based on the coal seam space of the borehole, the reverse cutting method is used to first cut the two sides (side CceE and side CcmM) and one bottom EemM of the first triangular block 3 of the large-section coal-uncovering tunnel and the two sides (side AaeE and side GgmM) of the first quadrilateral block 4, and then cut the two sides (side DdnN and side DdfF) and one bottom FfnN of the second triangular block 5 of the large-section coal-uncovering tunnel and the two sides (side HhnN and side BbfF) of the second quadrilateral block 6; one side must be cut first and then the other side, because it is necessary to monitor and prevent abnormal gas outflow at all times to ensure the safety of construction workers. When the gas pressure is less than 0.74MPa specified in the gas tunnel construction and the gas concentration is less than 1%, the next section can be cut. Block cutting should be combined with real-time monitoring of gas, and it is best to have an interval of more than 2 hours in between. The stress of the surrounding rock should also be monitored to prevent direct collapse of the face.

[0105] like Figure 3 As shown, specifically, taking cutting EemM as an example, the positioning guide wheel 1 is pushed to the deepest part of the borehole and fixed by using the hydraulic telescopic rod 2, and the diamond bead rope 3 is wound around the positioning guide wheel 1 of the support guide device in the two boreholes where the cutting edge is required. The rope saw is required to be closely attached to the tunnel face between the two boreholes by adjusting the position of the tensioning device 6 and the rope saw machine 5, and the cutting position on the tunnel face is adjusted and fixed by using the rotary wheel 4. The rope saw machine 5 is started to cut the coal and rock mass at a uniform speed, and the rope saw 3 is continuously tightened and cut forward by the movement of the rope saw machine 5 and the tensioning device 6 until the rope saw 3 cuts to the connecting line position of the two positioning guide wheels 1. At the same time, the water spraying device is turned on at the rope feeding end to wash out the cut coal and rock debris.

[0106] Step S32, based on the coal seam space of the borehole, the back edge ecm of the first triangular block 3 and the back edge aemg of the first quadrilateral block 4 are first cut by the sleeve cutting method, and then the back edge dfn of the second triangular block 5 and the back edge bfnh of the second quadrilateral block 6 are cut;

[0107] The cutting order is to cut the rear ecm and rear dfn first, and then cut the rear aemg and rear bfnh after monitoring the stress change and no abnormal gas outburst. The set cutting method is that when the three sides of the quadrilateral have been cut, the rear of the rock mass can be cut directly;

[0108] Specifically, taking the cutting rear edge aemg as an example, on the premise that the AEea edge, GMmg edge, and EMme edge are all cut, the positioning guide wheel is pushed to the deepest point a of the borehole Aa and the deepest point g of the borehole Gg by using a hydraulic telescopic rod and fixed, and at the same time, the cutting flat edge of the two-point positioning guide wheel is adjusted to be on the same flat edge as the pre-cut edge of the coal seam, and then the rope is put on the cut flat edge to determine the loop of the rope cutting, which is: rope saw machine → tensioning wheel → rotary wheel → positioning guide wheel at point a → coal seam rock body at point e → coal seam rock body at point m → positioning guide wheel at point g → rotary wheel → tensioning wheel → rope saw machine. By adjusting the tensioning device and the position of the rope saw machine, the rope saw at the coal body is close to the coal seam, and the cutting position is adjusted and fixed by using the rotary wheel. Turn on the rope saw machine to cut the coal seam, and at the same time, open the water spray device at the rope inlet end to wash out the cut coal rock debris.

[0109] Step S33, based on the coal seam space of the borehole, the reverse cutting method is used to cut the common edge MmnN of the secondary trapezoidal area 1 and the secondary trapezoidal area 2 to complete the cutting of the coal seam. Cutting the common edge MmnN is a stress release method. Under normal circumstances, the supported secondary trapezoidal area 1 and the secondary trapezoidal area 2 will not have too much stress concentration because the rock mass is not taken out, and the risk of collapse is relatively small. However, if the coal body cutting causes too serious damage to the coal seam, the contact edge of the coal-rock mass on the back side of the trapezoid is destroyed, affecting the stability of the coal rock, resulting in a large amount of stress concentrated on the supported secondary trapezoidal area 1 and the secondary trapezoidal area 2, which may be directly pushed out. However, cutting the common edge MmnN can greatly reduce the concentration of stress, release pressure, ensure that the two trapezoidal supports are independent, further maintain stability, and prevent the collapse of the face.

[0110] Repeatedly use the sleeve cutting method to continuously cut the coal seam to complete pressure relief, permeability enhancement and stress release; multiple sleeve cutting methods are used to cut the coal body. Considering the damage of rope saw cutting to the borehole, the length of the support guide device is adjusted from far to near during the sleeve cutting work. In this process, the cutting flat edges of the two positioning guide wheels in the bottom drill hole are still guaranteed to be on the same flat edge as the pre-cut edge of the coal seam. Repeat the sleeve cutting steps to perform multiple slits to relieve pressure on the coal seam. In order to facilitate the movement of the rope saw machine in the tunnel, a track-type rope saw machine is used and equipped with a traction device to ensure that it provides sufficient tension during cutting.

[0111] In order to facilitate the movement of the wire saw machine in the tunnel, a track-type wire saw machine is used and equipped with a traction device to ensure that it provides sufficient tension during cutting.

[0112] During the implementation process, diamond wire saws are used to cut coal seams and rock strata, achieving high efficiency and quietness, increasing construction stability and further reducing costs.

[0113] It can be used in conjunction with gas extraction drilling to achieve better gas discharge effects and reduce the risk of coal and gas outbursts.

[0114] The present invention utilizes the reverse cutting method and the sleeve cutting method to cut the coal seam rock mass without removing the coal seam rock mass, thereby ensuring construction safety; the present invention constructs a double trapezoidal support system, which is stable and reliable and avoids collapse of the face; the present invention adopts block cutting to prevent abnormal gas outbursts and maximize the use of the semicircular area of ​​the tunnel face, thereby improving the efficiency of increased permeability and pressure relief. The present invention can fully provide space for coal seam stress release and accelerate the speed of gas pressure release to achieve the purpose of pressure relief, increased permeability and sudden relief before coal uncovering, fully release ground stress, and leave supporting rock mass at the face, thereby eliminating the risk of collapse that may be caused by cutting the coal seam. The present invention has the characteristics of improving coal seam extraction efficiency, low cost, high safety, and stability and reliability.

[0115] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A method for cutting, unloading and eliminating pressure by using a double trapezoidal support rope saw through a coal tunnel, characterized in that: The following steps are involved: First, the large-section coal-uncovering tunnel face is planned into two first-level trapezoidal areas of different sizes in the cross section, and smaller second-level trapezoidal areas are subdivided from the two first-level trapezoidal areas. The trapezoidal platform between the planned second-level trapezoidal area and the coal seam is used as the supporting structure for coal-uncovering and pressure relief in the tunnel. Then, according to the coal seam occurrence in front of the face and the face planning of the large-section coal-uncovering tunnel, precise construction positioning and drilling operations are carried out; Finally, based on the planning of the face and drilling operation of the large-section coal-uncovering tunnel, a diamond wire saw was used to continuously cut the coal seam and the middle part of the rock mass of the supporting structure using the reverse cutting method and the sleeve cutting method to complete the permeability and pressure relief of the coal seam.

2. The method for cutting, relieving pressure and eliminating outbursts by using a double trapezoidal support wire saw for coal tunneling according to claim 1 is characterized in that: The large-section coal-uncovering tunnel face is planned into two first-level trapezoidal areas of different sizes on the cross section, and smaller second-level trapezoidal areas are subdivided from the two first-level trapezoidal areas. The trapezoidal platform between the planned face and the coal seam is used as the supporting structure for coal-uncovering and pressure relief in the tunnel, including: The face of a large-section coal-uncovering tunnel is planned in cross section into two first-level trapezoidal areas of different sizes superimposed on each other. The two first-level trapezoidal areas are divided into a plurality of blocks, each of which includes two second-level trapezoidal areas that are smaller than the first-level trapezoidal areas. The trapezoidal platform between the planned second-level trapezoidal area and the coal seam is used as a supporting structure for coal-uncovering and pressure relief in the tunnel.

3. The method for cutting, unloading, and eliminating outbursts with a double trapezoidal support wire saw for coal tunneling according to claim 1, characterized in that: The large-section coal-uncovering tunnel face is planned into two first-level trapezoidal areas of different sizes in the cross section, and two smaller second-level trapezoidal areas are divided from the two first-level trapezoidal areas. The trapezoidal platform between the planned second-level trapezoidal area and the coal seam is used as the supporting structure for coal-uncovering and pressure relief in the tunnel, including: The large-section coal-uncovering tunnel face is planned in cross section into two first-level trapezoidal areas of different sizes superimposed on each other, and the two first-level trapezoidal areas are divided into six blocks in total, and the six blocks include a first side portion, a second side portion, and a middle portion located between the first side portion and the second side portion, wherein the first side portion includes a first triangular block and a first quadrilateral block, and the bottom side of the first triangular block is co-edge with the top side of the first quadrilateral portion, the second side portion includes a second triangular block and a second quadrilateral block, and the bottom side of the second triangular block is co-edge with the top side of the second quadrilateral block, and the middle portion includes two second-level trapezoidal areas, and the bottom side of one second-level trapezoidal area is co-edge with the top side of the other second-level trapezoidal area.

4. The method for cutting, unloading, and eliminating outbursts with a double trapezoidal support wire saw for a coal tunnel according to claim 3, characterized in that: The block division sequence includes: first, determine the length of the bottom side (AB) of the first-level trapezoidal area (ABFE) according to the maximum span of the section, take the width of the middle position of the truncated edge as the length of the bottom side (EF) of the first-level trapezoidal area (EFDC), take the length of the top side (CD) of the first-level trapezoidal area (EFDC) at a width of 1 / 3 of the length of the bottom side (AB) of the first-level trapezoidal area (ABFE), then determine the height of the two first-level trapezoidal areas according to 1 / 2 of the section height, take points (G) and (H) at equal distances on the bottom side (AB), and take point (M) on the left and right of the center of the bottom side (EF) , point (N), connect point (M) with point (N) and point (G) with point (H) to obtain the secondary trapezoidal area (CDNM) and the secondary trapezoidal area (GHNM). Finally, the tunnel face is divided into 6 areas, among which point (A), point (B), point (E), and point (F) all have inclined projection points (a), (b), (e), and (f) in the coal seam respectively. Point (C), point (D), point (G), point (H), point (M), and point (N) are projected as mirror projections in the coal seam, corresponding to point c, point d, point g, point h, point m, and point n respectively.

5. The method for cutting, relieving pressure and eliminating outbursts by using a double trapezoidal support wire saw for coal tunneling according to claim 3 is characterized in that: Carry out precise construction positioning and drilling operations, including: Inclined drilling is carried out at six corner points of the outer contour of two trapezoidal areas on the face of a large-section coal-uncovering tunnel.

6. The method for cutting, unloading, and eliminating outbursts by using a double trapezoidal support wire saw for coal tunneling according to claim 3, characterized in that: Continuous cutting of coal seams using wire saws using reverse cutting and sleeve cutting methods includes: Step S31, based on the coal seam space of the borehole, using the reverse cutting method to first cut two sides and one bottom side of the first triangular block of the large-section coal-uncovering tunnel and two sides of the first quadrilateral block, and then cut two sides and one bottom side of the second triangular block of the large-section coal-uncovering tunnel and two sides of the second quadrilateral block; Step S32, based on the coal seam space of the borehole, using a sleeve cutting method to first cut the rear edge of the first triangular block and the rear edge of the first quadrilateral block and then cut the rear edge of the second triangular block and the rear edge of the second quadrilateral block; Step S33, based on the coal seam space of the borehole, adopt the reverse cutting method to cut the common edge of the primary trapezoidal area and the secondary trapezoidal area to complete the cutting of the coal seam.

7. The method for cutting, relieving pressure and eliminating outbursts by using a double trapezoidal support wire saw for a coal tunnel according to claim 1, characterized in that: The wire saw is a diamond beaded wire rope.

8. The method for cutting, relieving pressure and eliminating outbursts by using a double trapezoidal support wire saw for a coal tunnel according to claim 1, characterized in that: The slots cut by the diamond wire saw are not used for cutting and excavation, but can provide free surfaces for subsequent blasting and excavation.

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