Method for preventing and controlling rock burst of main roadway group through axial kerf fracturing in horizontal hole of top plate

Abstract

The invention relates to a method for preventing and controlling rock burst of a main roadway group by axial kerf fracturing in a horizontal hole of a roof, which comprises the following steps of: determining a thick hard sandstone layer covered on a coal seam as a pressure relief target layer according to a drill hole histogram of the main roadway group, and tunneling a pressure relief measure roadway in the pressure relief target layer; a drill site is arranged on the pressure relief measure roadway, a pressure relief hole is drilled, a plurality of pressure relief seams are cut in the axial direction of the pressure relief hole, and hydraulic fracturing is carried out on the pressure relief seams to form fractures; and repeating and forming a fracture area, and covering the main roadway group by the projection surface of the pressure relief area on the coal seam in the vertical direction. According to the method for preventing and controlling the rock burst of the main roadway group through axial kerf fracturing in the horizontal hole of the top plate, dense kerf fracturing is carried out on the rock stratum above the main roadway group, so that the overlying rock stratum of the main roadway group is integrally weakened, the self-weight stress and the tectonic stress level above the main roadway group are reduced, the main roadway group is located in a low-stress area, and the rock burst of the main roadway group is prevented. Therefore, safe use of the main roadway in a low-stress area is achieved, and the stress concentration degree and the impact danger during the use of the main roadway are greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of safe mining of coal mines, and in particular to a method for preventing and controlling rock burst in a large tunnel group by axial slit fracturing in a horizontal hole of a roof. Background Art

[0002] The main coal seam tunnels serve the entire mine and are usually arranged in groups. Their service life can reach several decades. The coal pillars between the tunnels of the coal seam tunnel group are the main load-bearing bodies, and the stress is highly concentrated. Under the long-term load-bearing action, the coal pillars between the tunnels will produce creep damage, which will lead to a significant decrease in their stability and become the cause of the imbalance of the rock mass above the coal seam, resulting in an increased risk of rock burst. In related technologies, some support measures can prevent the occurrence of rock burst, but the effective period is short and it is difficult to achieve the service life of several decades for the large tunnel group. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] To this end, an embodiment of the present invention proposes a method for preventing and controlling rock bursts in a large tunnel group by axial slit fracturing in a horizontal hole in the roof. The rock strata above the large tunnel group are subjected to intensive slit fracturing, so that the overlying rock strata of the large tunnel group are weakened as a whole, the self-weight stress and structural stress levels in the large tunnel group area are reduced, and the large tunnel group 1 is placed in a low stress area, thereby achieving safe use of the large tunnels in the low stress area and greatly reducing the stress concentration and impact risk during the use of the large tunnels.

[0005] The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in a roof according to an embodiment of the present invention comprises the following steps:

[0006] Step 1: According to the drilling column chart of the large tunnel group, the thick hard sandstone layer overlying the coal seam is determined as the pressure relief target layer, and a pressure relief measure tunnel is excavated in the pressure relief target layer;

[0007] Step 2, setting up a drilling site on the pressure relief measure tunnel, drilling a pressure relief hole on at least one side of the drilling site, cutting a plurality of pressure relief seams along the axial direction of the pressure relief hole, and conducting hydraulic fracturing in the pressure relief seams to form fissures;

[0008] Step 3, multiple drilling sites are arranged at intervals in the extension direction of the pressure relief measure tunnel, and step 2 is repeated to form a fracture area. The edge of the pressure relief measure tunnel to the outside of the fracture area forms a pressure relief area, and the projection surface of the pressure relief area on the coal seam in the up and down directions covers the large tunnel group.

[0009] The method for preventing and controlling rock bursts in a large tunnel group by axial slit fracturing in a horizontal hole in a roof according to an embodiment of the present invention comprises excavating a pressure relief measure tunnel in a pressure relief target layer, drilling holes at intervals in the extension direction of the pressure relief measure tunnel, setting a plurality of pressure relief slits in the axial direction of the pressure relief holes, and performing hydraulic fracturing on the pressure relief slits to form a fracture area. The pressure relief area formed by the fracture area and the pressure relief measure tunnel covers the large tunnel group, that is, the rock strata above the large tunnel group are subjected to intensive slit fracturing, so that the overlying rock strata of the large tunnel group are weakened as a whole, and the self-weight stress and tectonic stress levels of the large tunnel group area are reduced, so that the large tunnel group is in a low stress area, and the safe use of the large tunnels is achieved in the low stress area, which greatly reduces the stress concentration degree and the risk of rock bursts during the use of the large tunnels.

[0010] In some embodiments, the pressure relief measure tunnel is located 8-15 m above the coal seam;

[0011] And / or, the pressure relief measure tunnel is adjacent to or located in the middle of the pressure relief target layer in the up-down direction;

[0012] And / or, the pressure relief measure tunnel is adjacent to or located in the middle of the large tunnel group in the width direction, and the extension direction of the pressure relief measure tunnel is the same as the extension direction of the large tunnel group.

[0013] In some embodiments, the pressure relief holes are drilled on both sides of the drilling site, and the bottoms of the two pressure relief holes in the same drilling site are located at least 15m outside the large tunnel group.

[0014] In some embodiments, in step 2, when cutting multiple pressure relief seams, the multiple pressure relief seams are cut sequentially in the direction from the bottom of the pressure relief hole to the hole mouth; and / or the distance between the pressure relief seam adjacent to the bottom of the pressure relief hole and the bottom of the pressure relief hole is 3-6m.

[0015] In some embodiments, the plurality of pressure relief slits on the pressure relief hole are arranged at equal intervals;

[0016] And / or, in the axial direction of the pressure relief hole, the distance between two adjacent pressure relief seams is 5-8m.

[0017] In some embodiments, there are multiple cracks on the pressure relief seam, and the multiple cracks on the pressure relief seam extend in different directions.

[0018] In some embodiments, in step 2, if the thickness of the pressure relief target layer is less than 8m, the pressure relief seams are cut on both sides of the pressure relief hole in the horizontal direction at the same depth of the pressure relief hole; if the thickness of the pressure relief target layer is greater than 8m, the pressure relief seams are cut on both sides of the pressure relief hole in the horizontal direction and on both sides in the up and down directions at the same depth of the pressure relief hole.

[0019] In some embodiments, the distance between the pressure relief joint adjacent to the pressure relief measure tunnel and the pressure relief measure tunnel is 3-6 m.

[0020] In some embodiments, the plurality of pressure relief holes are arranged at equal intervals;

[0021] and / or, in the extension direction of the pressure relief measure tunnel, the distance between two adjacent pressure relief holes is 8-11m;

[0022] And / or, in step 2 and step 3, a plurality of the pressure relief holes are drilled in sequence in a backward manner according to the extension direction of the pressure relief measure tunnel.

[0023] In some embodiments, at least one of the fractures of the drill site is in communication with a fracture of an adjacent drill site. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a plan view of the cutting and fracturing of the thick hard rock layer overlying the large tunnel group;

[0025] Figure 2 This is a cross-sectional view of the cutting and fracturing of the thick hard rock layer overlying the large tunnel group;

[0026] Reference numerals:

[0027] Large tunnel group 1, large tunnel 11, pressure relief target layer 2, pressure relief measure tunnel 21, pressure relief holes 3, pressure relief joints 4, and fissures 5. DETAILED DESCRIPTION

[0028] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0029] Please refer to the attached Figure 1 and Figure 2 , a method for preventing and controlling rock burst in a large tunnel group by axial slit fracturing in a horizontal hole in a roof according to an embodiment of the present invention is described in detail.

[0030] The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole of a roof according to an embodiment of the present invention comprises the following steps:

[0031] Step 1, according to the drilling column chart of the large tunnel group 1, determine that the thick hard sandstone layer overlying the coal seam is the pressure relief target layer 2, and excavate the pressure relief measure tunnel 21 in the pressure relief target layer 2.

[0032] The borehole column chart of the large tunnel group 1 can show the overlying strata information of the large tunnel group 1, such as the thickness and lithology of the overlying strata. By analyzing the overlying strata information of the coal seam where the large tunnel group 1 is located, the position and height of the unloading target layer 2 are determined.

[0033] See also Figure 1 and Figure 2 In this embodiment, the large tunnel group 1 includes four large tunnels 11, the tunnel width is 5m, and the coal pillars between the tunnels are 40m, that is, the distance between two large tunnels 11 is 40m. The area of ​​the large tunnel group 1 includes four large tunnels 11 and the coal pillars between the tunnels, that is, the area enclosed by the large tunnel 11 located on the far left and the large tunnel 11 located on the far right. It should be noted that in this embodiment, the number, width and length of the large tunnels 11 of the large tunnel group 1 are not limited.

[0034] Step 2, a drilling site is set up on the pressure relief measure tunnel 21, a pressure relief hole 3 is drilled on at least one side of the drilling site, a plurality of pressure relief seams 4 are cut along the axial direction of the pressure relief hole 3, and hydraulic fracturing is performed on the pressure relief seams 4 to form fissures 5. Hydraulic fracturing breaks the rock by injecting high-pressure liquid into the pressure relief target layer 2, and the fissures 5 formed by hydraulic fracturing change the stress state of the rock formation, which can effectively weaken the strength of the rock formation where the fissures 5 are located.

[0035] Step 3: In the extension direction of the pressure relief measure tunnel 21 (for example Figure 1 A plurality of drilling sites are arranged at intervals in the front-to-back direction (in the front-to-back direction), and step 2 is repeated to form a fracture area, and the edge of the pressure relief measure tunnel 21 to the outside of the fracture area forms a pressure relief area, and the projection surface of the pressure relief area on the coal seam along the up-down direction covers the projection surface of the large tunnel group 1 on the coal seam along the up-down direction. In other words, the projection surface of the pressure relief area on the coal seam along the up-down direction covers the projection surface of the large tunnel group 1 on the coal seam along the up-down direction.

[0036] Specifically, since the pressure relief hole 3 is arranged on the side of the pressure relief measure tunnel 21, the extension (length) direction of the pressure relief hole 3 is perpendicular to the extension (length) direction of the pressure relief measure tunnel 21, and the pressure relief hole 3 is cut and fractured at intervals in the axial direction, thereby forming cracks 5 distributed vertically and horizontally, that is, the cracks 5 are distributed in the extension direction and width direction of the pressure relief measure tunnel 21. The outside of the crack area refers to the side of the crack area away from the pressure relief measure tunnel 21, and the inside of the crack area refers to the side of the crack area adjacent to the pressure relief measure tunnel 21. It should be noted that the edge of the pressure relief measure tunnel 21 to the outside of the crack area defines the pressure relief area in the width direction. It can be understood that in the length direction, the edge of the pressure relief area is the edge of the crack area on both sides of the length (extension) direction of the pressure relief measure tunnel 21.

[0037] The method for preventing and controlling rock burst in a large tunnel group by axial slit fracturing in a horizontal hole in the roof of an embodiment of the present invention comprises: excavating a pressure relief measure tunnel 21 in the pressure relief target layer 2, drilling holes at intervals in the extension direction of the pressure relief measure tunnel 21, arranging a plurality of pressure relief slits 4 in the axial direction of the pressure relief hole, and performing hydraulic fracturing on the pressure relief slits 4, thereby forming a fracture area. The fracture area and the pressure relief area formed by the pressure relief measure tunnel 21 cover the large tunnel group 1, that is, the rock strata above the large tunnel group 1 are intensively slit fracturing, which is beneficial to the effect of continuous fracturing of the thick and hard roof and avoiding mutual interference between the use of the large tunnel and the pressure relief process, so that the overlying rock strata of the large tunnel group 1 are weakened as a whole, and the self-weight stress and structural stress levels above the large tunnel group 1 are reduced in advance, so that the large tunnel group 1 is in a low stress area, and the safe use of the large tunnels in the low stress area is achieved, which greatly reduces the stress concentration degree and the impact risk during the use of the large tunnel 11.

[0038] Furthermore, the sandstone layer above the coal seam is the pressure relief target layer 2. The sandstone layer is hard and usually thick, and the rock burst formed is more dangerous to the large tunnel group 1. By taking the thick hard sandstone layer as the pressure relief target layer 2 and weakening the thick hard sandstone layer, the original rock stress and structural stress level above the large tunnel group 1 can be further reduced, ensuring that the large tunnel group 1 is in a low stress area, ensuring the safe use of the large tunnel in the low stress area, and greatly reducing the stress concentration and impact hazard during the use of the large tunnel 11.

[0039] like Figure 2 As shown, above the coal seam is a mudstone layer with a thickness of 5.6 m, and above the mudstone layer is a fine sandstone layer with a thickness of 9.7 m.

[0040] In some embodiments, the pressure relief measure tunnel 21 is located 8-15 m above the coal seam. For example, the pressure relief measure tunnel 21 is located 8 m, 9 m, 10 m, 11 m, 13 m or 15 m above the coal seam.

[0041] Furthermore, the pressure relief measure tunnel 21 is adjacent to or located in the middle of the pressure relief target layer 2 in the vertical direction. As a result, the fissures 5 in the pressure relief target layer 2 are distributed more evenly, which can enhance the weakening and decompression effect of the pressure relief target layer 2, and then ensure that the self-weight stress and structural stress level above the large tunnel group 1 are reduced, further ensure that the large tunnel group 1 is in a low stress area, ensure the safe use of the large tunnel in the low stress area, and greatly reduce the stress concentration and impact risk during the use of the large tunnel 11.

[0042] like Figure 2 As shown, the pressure relief measure tunnel 21 is located 11m above the coal seam.

[0043] Furthermore, the pressure relief measure tunnel 21 is adjacent to or located in the middle of the large tunnel group 1 in the width direction, and the extension direction of the pressure relief measure tunnel 21 is the same as the extension direction of the large tunnel group 1. Thus, the length of each pressure relief hole 3 is shortened, the construction difficulty of the pressure relief hole 3 is reduced, and the construction efficiency of the method for preventing and controlling rock burst in the large tunnel group by axial slit fracturing in the horizontal hole of the roof according to the embodiment of the present invention is improved.

[0044] The pressure relief measure tunnel 21 is located in the middle of the large tunnel group 1 in the width direction, and then in step 2, pressure relief holes 3 are drilled on both sides of the drilling site. That is, there are pressure relief holes 3 on both sides of the pressure relief measure tunnel 21 in the width direction.

[0045] Furthermore, the bottoms of the two pressure relief holes 3 in the same drilling site are located at least 15m outside the large tunnel group 1. This ensures that the fissures 5 on the pressure relief seams 4 at the bottom of the pressure relief holes 3 can be located outside the large tunnel group 1, not only completely covering the large tunnel group 1, but also covering part of the area outside the large tunnel group 1, and then ensuring that the fissure area on the thick hard roof above the large tunnel group 1 covers part of the area outside the large tunnel group 1, further ensuring that the overall weakened area of ​​the thick hard roof covers the outside of the large tunnel group 1, thereby ensuring that the coal seam large tunnel group 1 and part of the area outside it are in a protected state, further effectively reducing the impact risk, and improving the safety and stability of the large tunnel group 1 during long-term use.

[0046] For details, see Figure 2 The width of the pressure relief tunnel 21 is 5m, the depth of the pressure relief hole 3 is 90m, and the bottom of the pressure relief hole 3 is located 22.5m outside the large tunnel group 1.

[0047] In some embodiments, in step 2, when cutting multiple pressure relief slits 4, multiple pressure relief slits 4 are cut in sequence from the bottom of the pressure relief hole 3 to the hole mouth. The distance between the pressure relief slit 4 adjacent to the bottom of the pressure relief hole 3 and the bottom of the pressure relief hole 3 is 3-6m.

[0048] For example, the first pressure relief seam 4 is cut at a position 3-6 m away from the bottom of the pressure relief hole 3, and then hydraulic fracturing is carried out at the first pressure relief seam 4, and then the seam cutting device is moved backward to cut the second pressure relief seam 4, and so on. The backward moving seam cutting device is highly safe and easy to operate.

[0049] For example, the distance between the pressure relief slit 4 adjacent to the bottom of the pressure relief hole 3 and the bottom of the pressure relief hole 3 is 3 m, 4 m, 5 m, 5.5 m or 6 m.

[0050] In this embodiment, the distance between the pressure relief slit 4 adjacent to the bottom of the pressure relief hole 3 and the bottom of the pressure relief hole 3 is 5 m.

[0051] Furthermore, the multiple pressure relief seams 4 on the pressure relief hole 3 are arranged at equal intervals, so that the pressure relief seams 4 and the cracks 5 are distributed more evenly along the axial direction of the pressure relief hole 3, and the cracks 5 in the crack area are distributed more evenly, so that the weakening and decompression effect of the pressure relief target layer 2 is evenly distributed, which is further beneficial to the continuous fracturing of the thick and hard roof effect, ensuring the reduction of the self-weight stress and structural stress level above the large tunnel group 1, further ensuring that the large tunnel group 1 is in a low stress area, ensuring the safe use of the large tunnels in the low stress area, and greatly reducing the stress concentration and impact risk of the large tunnel 11 during use.

[0052] In the axial direction of the pressure relief hole 3, the distance between two adjacent pressure relief seams 4 is 5-8m. Figure 1 and Figure 2 In the left and right directions, the distance between two adjacent pressure relief seams 4 is 5-8m. Thus, it is possible to provide space for hydraulic fracturing on two adjacent pressure relief seams 44, avoid the connection between the fissures 5 on two adjacent pressure relief seams 44, maintain pressure for the next hydraulic fracturing process, and avoid water leakage from the formed fissures 5 during the next hydraulic fracturing process to affect the formation of the fissures 5, thereby ensuring the formation effect of the fissures 5 and the density of the fissures 55 in the dense slit fracturing area.

[0053] Specifically, in the axial direction of the pressure relief hole 3, the distance between two adjacent pressure relief seams 4 is 7m.

[0054] In some embodiments, the length of the pressure relief seam 4 is 0.5-1 m. For example, the length of the pressure relief seam 4 is 0.5 m, 0.6 m, 0.8 m, 0.9 m or 1 m.

[0055] In this embodiment, the length of the pressure relief seam 4 is 0.5 m.

[0056] In some embodiments, in step 2, if the thickness of the pressure relief target layer 2 is less than 8 m, at the same depth position of the pressure relief hole 3, pressure relief seams 4 are cut on both sides of the pressure relief hole 3 in the horizontal direction, that is, Figure 1 In the process, horizontal pressure relief seams 4 are cut on both sides of the same depth position of the pressure relief hole 3 in the front-back direction, and then hydraulic fracturing is carried out on the pressure relief seams 4. If the thickness of the pressure relief target layer 2 is greater than 8m, pressure relief seams 4 are cut on both sides of the pressure relief hole 3 in the horizontal direction and in the up-down direction at the same depth position of the pressure relief hole 3, that is, horizontal pressure relief seams 4 are cut on both sides of the same depth position of the pressure relief hole 3 in the front-back direction, and vertical pressure relief seams 4 are cut on both sides of the up-down direction of the pressure relief hole 3, and then hydraulic fracturing is carried out on the pressure relief seams 4.

[0057] Different thicknesses of the target layers 2 for pressure relief create different impact hazards. The method for preventing and controlling rock bursts in the large tunnel group 1 by axial fracturing in the horizontal hole of the roof in the embodiment of the present invention selects whether to perform fracturing in the upper and lower directions of the pressure relief hole 3 according to the thickness of the rock formation. That is, for thick and hard rock formations with a large thickness, fracturing in the upper and lower directions of the pressure relief hole 3 is performed, then the density of the cracks 5 is large and the fracturing is more intensive, thereby achieving a better weakening effect on the entire rock formation, ensuring that the large tunnel group 1 can still be protected when the rock formation is thicker, thereby effectively reducing the risk of impact.

[0058] Specifically, the pressure relief seam 4 is cut out by using abrasive jet technology.

[0059] The distance between the pressure relief joint 4 adjacent to the pressure relief measures tunnel 21 and the pressure relief measures tunnel 21 is 3-6m.

[0060] In this embodiment, the distance between the pressure relief joint 4 adjacent to the pressure relief measure tunnel 21 and the pressure relief measure tunnel 21 is 5 m.

[0061] Furthermore, there are multiple fissures 5 on the pressure relief joint 4, and the extension directions of the multiple fissures 5 on the pressure relief joint 4 are different, thereby further weakening the strength of the rock formation, further reducing the self-weight stress and structural stress levels above the large tunnel group 1, further ensuring that the large tunnel group 1 is in a low stress area, ensuring the safe use of the large tunnels in the low stress area, and greatly reducing the stress concentration and impact risk during the use of the large tunnel 11.

[0062] In some embodiments, multiple pressure relief holes 3 are arranged at equal intervals, so that the pressure relief seams 4 and cracks 5 are distributed more evenly along the axial direction of the pressure relief measure tunnel 21, further improving the uniformity of the distribution of cracks 5 in the crack area, so that the weakening and decompression effect of the pressure relief target layer 2 is evenly distributed, further ensuring the reduction of the self-weight stress and structural stress level above the large tunnel group 1, ensuring that the large tunnel group 1 is in a low stress area, ensuring the safe use of the large tunnels in the low stress area, and greatly reducing the stress concentration and impact risk during the use of the large tunnel 11.

[0063] Furthermore, in the extension direction of the pressure relief measure tunnel 21 , the distance between two adjacent pressure relief holes 3 is 8-11 m. A plurality of pressure relief holes 3 are drilled in sequence in a backward manner in the extension direction of the pressure relief measure tunnel 21 .

[0064] For example, the first drilling site is set in the pressure relief measure lane 21, and a pressure relief hole 3 is drilled on both sides of the first drilling site, and then the drilling device is retreated 8-11m, and a second drilling site is set there, and a pressure relief hole 3 is drilled on both sides of the second drilling site, and so on. The retreating mobile drilling device is highly safe and easy to operate for drilling.

[0065] Specifically, in the extension direction of the pressure relief measure tunnel 21, the distance between two adjacent pressure relief holes 3 is 8m, 9m, 10m or 11m. In this embodiment, in the extension direction of the pressure relief measure tunnel 21, the distance between two adjacent pressure relief holes 3 is 10m.

[0066] Furthermore, at least one fissure 5 of a drilling site is connected to a fissure 5 of an adjacent drilling site.

[0067] At least one fissure 5 on one borehole on the same side of two adjacent drilling sites is connected to at least one fissure 5 on another borehole. Figure 1 In the figure, for the two right pressure relief holes 3 at the two rearmost drilling sites, at least one crack 5 on one pressure relief hole 3 is connected to at least one crack 5 on another drilling hole. Figure 1 It can be seen that the crack 5 located on the rightmost pressure relief seam 4 is connected.

[0068] The fissures 5 of two adjacent drilling sites are connected to avoid blind fracturing areas, thereby avoiding blind pressure relief areas, further ensuring that the thick hard roof is weakened as a whole, ensuring that the large tunnel group 1 is in a protected state, and effectively reducing the risk of impact.

[0069] Therefore, through the method for preventing and controlling rock burst in the large tunnel group 1 by axial cutting and fracturing in the horizontal holes of the roof according to the embodiment of the present invention, intensive cutting and fracturing are carried out on the thick hard roof overlying the coal seam in the pressure relief measure tunnel 21, so that the thick hard roof is weakened and transformed as a whole, so that the large tunnel is in a protected state, thereby effectively reducing the risk of rock burst, effectively reducing the possibility of rock burst during the use of the large tunnel group 1, and ensuring the safety and stability of the large tunnel group 1 during use.

[0070] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0071] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0072] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0073] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0074] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in the roof, characterized in that: The following steps are involved: Step 1, according to the drilling column diagram of the large tunnel group (1), determine that the thick hard sandstone layer overlying the coal seam is the pressure relief target layer (2), and excavate a pressure relief measure tunnel (21) in the pressure relief target layer (2); Step 2, setting up a drilling site on the pressure relief measure tunnel (21), drilling a pressure relief hole (3) on at least one side of the drilling site, cutting a plurality of pressure relief seams (4) along the axial direction of the pressure relief hole (3), and carrying out hydraulic fracturing in the pressure relief seams (4) to form fissures (5); Step 3, arranging a plurality of drilling sites at intervals in the extension direction of the pressure relief measure tunnel (21), repeating step 2 to form a fracture area, and forming a pressure relief area from the edge of the pressure relief measure tunnel (21) to the outer side of the fracture area, and the projection surface of the pressure relief area on the coal seam in the up and down directions covers the large tunnel group (1).

2. The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in the roof according to claim 1, characterized in that: The pressure relief measure tunnel (21) is located 8-15 m above the coal seam; And / or, the pressure relief measure tunnel (21) is adjacent to or located in the middle of the pressure relief target layer (2) in the up-down direction; And / or, the pressure relief measure tunnel (21) is adjacent to or located in the middle of the large tunnel group (1) in the width direction, and the extension direction of the pressure relief measure tunnel (21) is the same as the extension direction of the large tunnel group (1).

3. The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in the roof according to claim 1, characterized in that: The pressure relief holes (3) are drilled on both sides of the drilling site, and the bottoms of the two pressure relief holes (3) in the same drilling site are located at least 15m outside the large tunnel group (1).

4. The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in the roof according to claim 1, characterized in that: In step 2, when cutting a plurality of the pressure relief slits (4), the plurality of the pressure relief slits (4) are cut out in sequence in the direction from the bottom of the pressure relief hole (3) to the hole mouth; and / or, the distance between the pressure relief slit (4) adjacent to the bottom of the pressure relief hole (3) and the bottom of the pressure relief hole (3) is 3-6 m.

5. The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in a roof according to claim 1, characterized in that: The plurality of pressure relief slits (4) on the pressure relief hole (3) are arranged at equal intervals; And / or, in the axial direction of the pressure relief hole (3), the distance between two adjacent pressure relief seams (4) is 5-8 m.

6. The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in a roof according to claim 1, characterized in that: There are a plurality of cracks (5) on the pressure relief seam (4), and the extension directions of the plurality of cracks (5) on the pressure relief seam (4) are different.

7. The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in a roof according to claim 1, characterized in that: In step 2, if the thickness of the pressure relief target layer (2) is less than 8 m, the pressure relief seams (4) are cut out at the same depth position of the pressure relief hole (3) on both sides in the horizontal direction of the pressure relief hole (3); if the thickness of the pressure relief target layer (2) is greater than 8 m, the pressure relief seams (4) are cut out at the same depth position of the pressure relief hole (3) on both sides in the horizontal direction and on both sides in the up-down direction of the pressure relief hole (3).

8. The method for preventing and controlling rock burst in a large tunnel group (1) by axial fracturing in a horizontal hole in the roof according to claim 1, characterized in that: The distance between the pressure relief joint (4) adjacent to the pressure relief measure tunnel (21) and the pressure relief measure tunnel (21) is 3-6m.

9. The method for preventing and controlling rock burst in a large tunnel group by axial fracturing in a horizontal hole in a roof according to claim 1, characterized in that: The plurality of pressure relief holes (3) are arranged at equal intervals; and / or, in the extension direction of the pressure relief measure tunnel (21), the distance between two adjacent pressure relief holes (3) is 8-11 m; And / or, in step 2 and step 3, a plurality of the pressure relief holes (3) are drilled in sequence in a backward manner according to the extension direction of the pressure relief measure tunnel (21).

10. The method for preventing and controlling rock burst in a large tunnel group (1) by axial fracturing in a horizontal hole in the roof according to claim 9, characterized in that: At least one of the fissures (5) of the drilling site is in communication with the fissure (5) of the adjacent drilling site.

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