Tungsten mine small-section roadway circular hole distribution slotting structure and construction method

Abstract

The invention relates to the field of metal mine construction, in particular to a slotting structure for circular hole distribution of a small-section roadway of a tungsten mine and a construction method, and the slotting structure and the steps S1, S2, S3, S4, S5, S6, S7, S8 and S9 for construction through the slotting structure are included. Through the arrangement of the slotting structure and the mode that the second slotting holes and the empty holes are formed in the circumference with the first slotting hole as the circle center, the blasting stress can be effectively dispersed, the utilization rate of explosives is effectively optimized, the slotting efficiency and stability are improved, in addition, small-diameter empty holes are replaced with large-diameter empty holes, the number of blast holes is reduced, and the blasting efficiency is improved. Meanwhile, the second slotting holes and the empty holes are arranged in a staggered mode, the purpose of reducing blast holes can be achieved, and the blasting effect is not affected. Through the setting of S1, S2, S3, S4, S5, S6, S7, S8 and S9, tunneling of the small-section roadway can be effectively guided, the standardization and repeatability of operation are effectively ensured, and the tunneling efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of metal mine construction, and in particular to a grooving structure and a construction method for circular holes in a small-section tunnel of a tungsten mine. Background Art

[0002] Metal mining in my country is mainly underground mining, and tunnels are an important part of underground mining in metal mines. In order to ensure continuous production and continuous operation, it is necessary to prepare for the next step of mining while mining. A large number of tunnels need to be excavated underground, and a corresponding number of working faces and mining areas need to be developed to ensure that the planned output is met; before a production level is mined, a new production level must be extended in advance in a planned manner to meet the production succession and ensure production capacity. Only by timely completing the construction of mines and the development and deepening work can the stable production, high yield and continuous development of mines be effectively guaranteed. "Equal emphasis on mining and excavation, excavation first", the rapid excavation of tunnels is a key technical measure to ensure high and stable production underground. Efficient tunnel excavation methods are conducive to shortening the construction time of the mine development system and the time to see the mine, and alleviating the problems of resource succession and capacity decline of some old mining enterprises.

[0003] In the related technologies, tunnel excavation techniques mainly include drilling and blasting and comprehensive excavation. For small mines, especially small tungsten mines, due to the vein shape of the ore body, their tunnels are almost all small-section tunnels, so only drilling and blasting can be used to excavate the tunnels, which limits the selectivity of drilling equipment. Therefore, the apertures are relatively small, resulting in the need to increase the number of blast holes with pre-buried explosives to ensure the blasting effect. Most of the related technologies improve the excavation efficiency by adjusting the slot structure while ensuring that the compensation space meets the conditions. For small-section tunnels, barrel-shaped slot structures are currently used, such as plum blossom hole slot structures, triangular column straight hole slot structures, spiral slot structures, multi-hole angular column joint slot structures, etc.

[0004] The various barrel-shaped slotting structures in the above-mentioned related technologies can theoretically achieve good results in the corresponding environment. However, in actual construction, due to the high requirements for various hole spacings, and the fact that construction personnel on site usually do not measure the position of each blast hole in advance, this will lead to poor actual application results. At the same time, when the slot holes and empty holes are densely packed, perforation is likely to occur during construction, affecting the blasting effect. Therefore, a new hole arrangement and slotting method is urgently needed to achieve efficient and rapid excavation of small-section tunnels. Summary of the invention

[0005] In order to achieve efficient and rapid excavation of small-section tunnels, the present application provides a grooving structure and a construction method for circular holes in small-section tunnels of tungsten mines.

[0006] In the first aspect, the present application provides a tungsten mine small-section tunnel circular hole cutting structure, using the following technical solutions:

[0007] A circular hole cutting structure for a small-section tunnel in a tungsten mine, comprising:

[0008] The first slotting hole is arranged on the rock face of the small-section tunnel;

[0009] A second slot hole is opened on the rock layer of the small-section roadway with the first slot hole as the center and d as the radius;

[0010] An empty hole is opened on the rock layer surface of the small-section tunnel with the first groove hole as the center and d as the radius. The aperture of the empty hole is larger than the apertures of the first groove hole and the second groove hole. There are multiple empty holes and the second groove holes. Multiple second groove holes correspond to multiple empty holes one by one and are arranged in a staggered manner.

[0011] By adopting the above technical scheme, with the first groove hole as the center of the circle, the second groove holes and the empty holes are arranged on the circumference, which can effectively disperse the blasting stress, effectively optimize the utilization rate of explosives, and enhance the efficiency and stability of groove cutting. When groove cutting, it is only necessary to mark a circle on the working surface in advance, and the remaining second groove holes and empty holes only need to be ensured to be on the contour of the circle. In addition, large-diameter empty holes are used instead of small-diameter empty holes to reduce the number of blast holes. At the same time, the second groove holes and the empty holes are staggered to achieve the purpose of reducing blast holes without affecting the blasting effect, avoiding the perforation phenomenon during construction due to dense blast holes. The present application has the effect of efficient and rapid excavation of small-section tunnels to a certain extent.

[0012] Optionally, the first slotting hole is located at the center of the rock face surface of the small-section tunnel.

[0013] By adopting the above technical solution, the selection of the center position of the rock layer will help to form a regular cross-section after blasting, improve the symmetry of excavation and the cutting effect, thereby ensuring the smooth progress of excavation work.

[0014] Optionally, d is the distance between the first cutout hole and the empty hole,

[0015] Wherein R is the radius of the empty hole, r is the radius of the first slot hole, and K is the rock expansion coefficient.

[0016] By adopting the above technical solution, the groove cutting accuracy can be controlled more accurately.

[0017] Optionally, the range of R is 70mm to 90mm, and the range of r is 40mm to 50mm.

[0018] By adopting the above technical solution, the regulation of this distance range is helpful to control the arrangement of empty holes for blasting and ensure the reasonable size of the hole diameter. Compared with related technologies, it can reduce 40% of blast holes and reduce the probability of perforation during construction due to dense blast holes.

[0019] In a second aspect, the present application further provides a construction method, which is applicable to a circular hole cutting structure of a small-section tunnel of a tungsten mine in the present application, comprising the following steps:

[0020] S1, first slot hole positioning mark, on-site construction personnel mark the center of the rock layer of the small-section tunnel;

[0021] S2, second slot hole positioning mark, with the position of the first slot hole positioning mark in S1 as the center, use an auxiliary tool to make a circle, and mark the second slot hole on the circumference;

[0022] S3, hole positioning mark, marking the hole on the circumference made in S2;

[0023] S4, the first slotting hole construction, the on-site construction personnel use rock drilling equipment to slot at the center mark of the rock surface of the small-section tunnel;

[0024] S5, second slotting hole construction, on-site construction personnel use rock drilling equipment to drill rocks at the second slotting hole mark on the rock surface of the small-section tunnel, and multiple second slotting holes are set;

[0025] S6, hollow hole construction, on-site construction personnel use rock drilling equipment to drill holes at the hollow hole marks on the rock surface of the small-section tunnel, and multiple hollow holes are set;

[0026] S7, pre-burying explosives, burying the explosives in the first cutout hole and the plurality of second cutout holes;

[0027] S8, detonating explosives, detonating explosives pre-buried in the first slot hole and the plurality of second slot holes, and completing the cross-section excavation;

[0028] S9. Repeat the above steps until the small-section tunnel is connected to the designated section and the construction is completed.

[0029] By adopting the above-mentioned technical scheme, when a small-section tunnel is to be excavated, the construction method of the present application is adopted, and the entire construction process is detailed, including the complete process from positioning marking to detonation of explosives. Each step is simple and efficient, effectively ensuring the standardization and repeatability of the operation, and ensuring that each step can be accurately executed, reducing potential errors in construction and improving work efficiency.

[0030] Optionally, S2 and S3 may be performed simultaneously, and S4, S5, and S6 may be performed simultaneously.

[0031] By adopting the above technical solution, steps S2 and S3 are carried out simultaneously, that is, the positioning marks of the second slot hole and the empty hole can be completed at the same time, and the slot hole openings from S4 to S6 can also be carried out at the same time. This parallel construction method speeds up the overall construction speed, reduces the construction time, and improves the construction efficiency.

[0032] Optionally, the positioning tool in S1 is a laser level, and the auxiliary tool in S2 is a marking pin and a marking rope, and the marking rope can rotate around the marking pin.

[0033] By adopting the above technical solutions, laser levels, marking nails, marking ropes and other tools are used for positioning to ensure accurate positioning. High-precision positioning tools help reduce construction errors, ensure the accurate arrangement of slot holes and empty holes, and improve excavation results.

[0034] Optionally, the number of the second slotted holes in S5 is equal to the number of the hollow holes in S6.

[0035] The adoption of the above technical solution helps to evenly distribute stress during blasting, ensuring the stability of the tunnel cut and the regularity of the excavation section.

[0036] Optionally, the order of detonating the explosives in S8 is to first detonate the first slotted hole, then detonate the second slotted hole which is closer to the adjacent empty hole, and finally detonate the second slotted hole which is farther from the adjacent empty hole, and the time interval between detonations is 50-100ms.

[0037] By adopting the above technical solution, the detonation sequence is controlled to gradually release the blasting energy. The time interval is controlled within 50-100ms, which can effectively control the propagation of the blasting shock wave, reduce the damage to the surrounding rock of the tunnel, and ensure the safety and efficiency of the blasting.

[0038] In summary, the present application includes at least one of the following beneficial technical effects:

[0039] 1. By setting the slot structure, taking the first slot hole as the center of the circle, setting the second slot hole and the empty hole on the circumference, the blasting stress can be effectively dispersed, the utilization rate of explosives can be effectively optimized, and the efficiency and stability of the slot can be enhanced. In addition, large-diameter empty holes are used instead of small-diameter empty holes to reduce the number of blast holes. At the same time, the second slot holes and the empty holes are staggered, which can achieve the purpose of reducing blast holes without affecting the blasting effect, and avoid the perforation phenomenon during construction due to dense blast holes. The present application has the effect of efficient and rapid excavation of small-section tunnels to a certain extent;

[0040] 2. The distance formula of the empty hole The setting can control the cutting accuracy more accurately;

[0041] 3. The settings of S1, S2, S3, S4, S5, S6, S7, S8, and S9 can effectively guide the excavation of small-section tunnels in this application. The entire construction process is detailed, including the complete process from positioning marking to detonation of explosives. Each step is simple and efficient, effectively ensuring the standardization and repeatability of the operation, and ensuring that each step can be accurately executed, reducing potential errors in construction and improving work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the arrangement of a circular hole cutting structure of a small-section tunnel in a tungsten mine according to an embodiment of the present application.

[0043] Figure 2 This is a distance relationship diagram between the first slot hole and the empty hole in a circular hole arrangement of a small-section tunnel in a tungsten mine in an embodiment of the present application.

[0044] Figure 3 This is a diagram of the arrangement of the trenching structure after construction using a circular hole arrangement construction method for a small-section tunnel in a tungsten mine according to an embodiment of the present application.

[0045] Description of reference numerals:

[0046] 1. The first slotted hole; 2. The second slotted hole; 3. The empty hole. DETAILED DESCRIPTION

[0047] The following is combined with Figure 1-Figure 3 This application is described in further detail.

[0048] The embodiment of the present application discloses a groove structure and a construction method for circular hole arrangement in a small-section tunnel of a tungsten mine.

[0049] It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0050] In order to facilitate understanding, this application needs to further explain the background technology. In the current actual construction environment, various barrel-shaped slotting structures can theoretically achieve good results in the corresponding environment, but to some extent, the requirements for the distance between each hole are high, and workers will not measure the position of each blast hole in advance during on-site construction, which will lead to poor results in actual application. In addition, when the slot holes and empty holes are dense, perforation is likely to occur during construction, affecting the blasting effect. Therefore, the invention of a simple circular hole arrangement slotting method is of great significance to truly realize the efficient excavation of small-section tunnels. In other words, from the perspective of technical personnel in this field, this application has overcome technical prejudice to a certain extent, and it is not simply an improvement on the shape. It is difficult to come up with the solution of this application without a lot of creative work.

[0051] It should also be noted that the importance of the slot structure lies in that during the rock blasting process, if accurate blasting cannot be achieved, the rock is prone to "squeezing to death", that is, insufficient compensation space. Compensation space refers to the additional space reserved to cope with the crushing and expansion effect (i.e., rock volume expansion) produced after rock blasting. This is a key concept because when a rock or ore body is blasted, the volume of the broken rock usually increases. Specifically, the rock is tightly arranged in its intact state, but once it is blasted by explosives, gaps will be generated between the broken pieces, resulting in an increase in the total volume. During the excavation process, the setting of compensation space usually has the following functions. 1. Accommodate the expansion volume of broken rock: The crushing and expansion coefficient (K value) of the rock after blasting is usually between 1.2 and 1.6, which means that the rock volume may increase by 20% to 60%. If there is not enough space reserved for these broken and swollen rocks, the crushed stones after blasting may squeeze the surrounding rock formations, causing instability in the surrounding rock or hindering excavation work; 2. Reduce the concentration of blasting stress: The existence of compensation space can reduce the excessive energy accumulated in one place during blasting, thereby avoiding excessive impact on the tunnel caused by excessive concentration of blasting stress and reducing damage to the surrounding rock; 3. Improve subsequent cleaning and excavation work: With compensation space, the crushed stones produced after blasting will have a place to accumulate, which is convenient for mechanical or manual cleaning, which can speed up the excavation progress and improve construction efficiency. The above-mentioned related concepts are relatively well known to those skilled in the art, and are only specifically explained here for a better understanding of this application.

[0052] Below, the specific scheme of this application is explained in detail.

[0053] In a first aspect, the present application provides a grooving structure with circular holes in a small-section tunnel of a tungsten mine, comprising:

[0054] The first slot hole 1 is arranged on the rock face of the small-section tunnel.

[0055] Specifically, the first slot hole 1 is located at the center of the rock face surface of the small-section tunnel.

[0056] The first slot hole 1 is set at the center of the rock layer of the small-section tunnel. First, as the center position of the entire layout, it can facilitate the release of the initial stress blasting energy in the subsequent blasting process. The rock mass near this hole is released first, forming a larger space. Secondly, because it is located in the center of the rock layer, the damage to the surrounding rock can be effectively reduced during the subsequent blasting process, thereby improving the safety of the subsequent blasting process. At the same time, selecting the center point as the position of the first slot hole 1 can optimize the blasting efficiency of the entire slot layout, and can also reduce the use of explosives, which is of great significance both in terms of efficiency and cost.

[0057] A second slot hole 2 is opened on the rock layer of the small-section tunnel with the first slot hole 1 as the center and d as the radius;

[0058] An empty hole 3 is opened on the rock layer surface of the small-section tunnel with the first groove hole 1 as the center and d as the radius. The aperture of the empty hole 3 is larger than the apertures of the first groove hole 1 and the second groove hole 2. There are multiple empty holes 3 and multiple second groove holes 2, and multiple second groove holes 2 correspond to multiple empty holes 3 one by one and are arranged in a staggered manner.

[0059] Specifically, d is the distance between the first slotted hole 1 and the empty hole 3, Wherein R is the aperture of the empty hole 3, r is the aperture of the first slot hole 1, and K is the rock expansion coefficient.

[0060] For ease of understanding, refer to Figure 2 , to derive the above d:

[0061] The compensation space should meet the volume required after the ore and rock are crushed and expanded, otherwise it will be "squeezed to death", thus affecting the blasting effect. It should satisfy the following relationship:

[0062] Sk ≤ S+S1+S2 (1-1)

[0063] Where S is the pre-blasting rock mass, k is the rock expansion coefficient, S1 is the first slot hole 1, and S2 is the empty hole 3.

[0064] according to Figure 2 , the geometric relationship diagram of the distance between the charging hole (also the first slot hole) and the empty hole 3. From formula (1-1), the distance relationship between the first slot hole 1 and the empty hole 3 can be deduced as follows:

[0065]

[0066] The present invention proposes to arrange a first slot hole 1 at the center of the tunnel and three large-diameter holes 3 around it, as follows Figure 1 As shown, according to formula (1-2), the distance between the charge hole and the empty hole 3, that is, the radius of the circular contour, is calculated as follows:

[0067]

[0068] Through the above formula, the blasting parameters can be reasonably designed to optimize the rock crushing effect, thereby improving construction efficiency and reducing unnecessary energy waste.

[0069] Furthermore, in the embodiment of the present application, since it is specifically applied to a small-section tunnel, the range of R is set to 70 mm to 90 mm. The conventional design is to set R to 40 mm to 45 mm.

[0070] It should be noted here that a small-section tunnel generally refers to a tunnel in which the area of ​​the rock formation is less than or equal to 6.25 m2. This is relatively well known to those skilled in the art, so it will not be elaborated in detail in the embodiments of this application.

[0071] The regulation of this distance range helps to control the arrangement of the empty holes 3 for blasting and ensure a reasonable size of the hole diameter. Compared with 40mm to 45mm in the related art, it can reduce 40% of the blast holes and reduce the probability of perforation during construction due to dense blast holes.

[0072] The implementation principle of a circular hole arrangement groove structure of a small-section tunnel in a tungsten mine according to an embodiment of the present application is as follows: taking the first groove hole 1 as the center of the circle, the second groove holes 2 and the empty holes 3 are arranged on the circumference, which can effectively disperse the blasting stress, effectively optimize the utilization rate of explosives, and enhance the efficiency and stability of groove cutting. When groove cutting, it is only necessary to mark a circle on the working surface in advance, and the remaining second groove holes 2 and empty holes 3 only need to be ensured to be on the contour of the circle. In addition, large-diameter empty holes 3 are used instead of small-diameter empty holes 3 to reduce the number of blast holes. At the same time, the second groove holes 2 and the empty holes 3 are staggered, which can achieve the purpose of reducing blast holes without affecting the blasting effect, and avoid the perforation phenomenon during construction due to dense blast holes. The present application has the effect of efficient and rapid excavation of small-section tunnels to a certain extent.

[0073] Second, refer to Figure 1 and Figure 3 The present application also provides a construction method, which is applicable to the circular hole cutting structure of the small-section tunnel of the tungsten mine of the present application, and comprises the following steps:

[0074] S1, the first slot hole 1 positioning mark, the on-site construction personnel position the center of the rock surface layer of the small-section tunnel.

[0075] Specifically, the positioning tool in S1 is a laser level.

[0076] Laser level can effectively find the midpoint of the rock layer of small-section roadway. Its advantages such as high precision, horizontal reference, convenient layout and visual positioning make it an ideal tool for rock layer positioning and construction. Through the use of laser level, the accurate positioning of the first slot hole 1 can be ensured, thus laying a solid foundation for subsequent slotting and roadway excavation.

[0077] S2, the second slot hole 2 positioning mark, with the position of the first slot hole 1 positioning mark in S1 as the center, use an auxiliary tool to make a circle, and mark the second slot hole 2 on the circumference.

[0078] Specifically, the auxiliary tools in S2 are a marking pin and a marking rope, and the marking rope can rotate around the marking pin. It should be noted here that the marking pin and the marking rope are not specifically shown in the drawings of the present application specification.

[0079] That is to say, in step S2, the on-site construction personnel only need to position the marking nail at the position of the first groove, and then rotate the marking rope around the marking nail according to the designed radius. During the rotation, a mark can be left on the rock surface. Then the position of the second groove hole 2 only needs to be selected on the marked circumference.

[0080] S3, hole 3 positioning mark, mark the hole 3 on the circumference made in S2.

[0081] Specifically, the marking of the empty hole 3 is the same as the marking of the second slotted hole 2, and S2 and S3 can be performed simultaneously.

[0082] Steps S2 and S3 are performed synchronously, that is, the positioning marks of the second groove hole 2 and the empty hole 3 can be completed at the same time, which effectively improves the construction efficiency.

[0083] S4, the first slot hole 1 is constructed. On-site construction personnel use rock drilling equipment to drill a hole at the center mark of the rock surface layer of the small-section tunnel.

[0084] S5, construction of the second slot hole 2, on-site construction personnel use rock drilling equipment to drill rocks at the second slot hole 2 mark on the rock surface layer of the small-section tunnel, and multiple second slot holes 2 are set.

[0085] S6, construction of empty hole 3, on-site construction personnel use rock drilling equipment to drill holes at the empty hole 3 marks on the rock surface of the small-section tunnel, and multiple empty holes 3 are set.

[0086] Specifically, S4, S5, and S6 can be performed simultaneously.

[0087] The opening of the slot holes from S4 to S6 can also be carried out simultaneously. This parallel construction method speeds up the overall construction speed, reduces the construction time, and improves the construction efficiency.

[0088] It should be noted here that the number of the second slotted holes 2 and the empty holes 3 is set to three in the embodiments of the present application. In other embodiments, the second slotted holes 2 and the empty holes 3 can also be set to other numbers, such as one, two, four, five, etc., which are all embodiments that can be implemented in the present application. However, it should be noted that the setting of three second slotted holes 2 and empty holes 3 provided in the present application is the best embodiment for small-section laneways. Three second slotted holes 2 and empty holes 3, and staggered arrangement of the second slotted holes 2 and the empty holes 3 can achieve the purpose of reducing blastholes without affecting the blasting effect, and avoid perforation during construction due to dense blastholes.

[0089] Furthermore, the number of the second cutout holes 2 in S5 is equal to the number of the hollow holes 3 in S6.

[0090] It helps to evenly distribute stress during blasting, ensuring the stability of tunnel cutting and the regularity of excavation section.

[0091] S7, pre-burying explosives, burying the explosives in the first slot hole 1 and the plurality of second slot holes 2.

[0092] S8, detonating explosives, detonating explosives pre-buried in the first slot hole 1 and the plurality of second slot holes 2, and completing cross-section excavation.

[0093] S9. Repeat the above steps until the small-section tunnel is connected to the designated section and the construction is completed.

[0094] Specifically, about S7, S8, S9, in the present application embodiment, the explosive used is emulsion explosive. In other embodiments, the commonly used explosives such as ammonium nitrate explosive, gelatinous explosive, ammonium nitrate explosive can also be used, which are all preferred embodiments of the present application.

[0095] Furthermore, the order of detonating the explosives in S8 is to first detonate the first slotted hole 1, then detonate the second slotted hole 2 which is closer to the adjacent empty hole 3, and finally detonate the second slotted hole 2 which is farther from the adjacent empty hole 3, and the time interval between detonations is 50-100ms.

[0096] It should be noted here that, under normal circumstances, an interval of 25 ms is relatively normal, because the explosives are detonated instantly, and as long as the cracks are blasted open, additional space can be provided for subsequent detonations. This is relatively easy to understand for those skilled in the art, so it will not be elaborated in detail in the embodiments of this application.

[0097] Control the detonation sequence to gradually release the blasting energy. The time interval is controlled within 50-100ms, which can effectively control the propagation of the blasting shock wave, reduce the damage to the surrounding rock of the tunnel, and ensure the safety and efficiency of the blasting.

[0098] In general, through the settings of S1, S2, S3, S4, S5, S6, S7, S8, and S9, when a small-section tunnel is to be excavated, the construction method of the present application is adopted, and the entire construction process is detailed, including the complete process from positioning marking to detonation of explosives. Each step is simple and efficient, effectively ensuring the standardization and repeatability of the operation, and ensuring that each step can be accurately executed, reducing potential errors in construction and improving work efficiency.

[0099] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A circular hole cutting structure for a small-section tunnel in a tungsten mine, characterized in that: include: A first slot hole (1) is arranged on the rock face of a small-section tunnel; A second slot hole (2) is opened on the rock layer surface of the small-section tunnel with the first slot hole (1) as the center and d as the radius; An empty hole (3) is opened on the rock layer surface of the small-section tunnel with the first slot hole (1) as the center and d as the radius. The diameter of the empty hole (3) is larger than the diameters of the first slot hole (1) and the second slot hole (2). A plurality of the empty holes (3) and the second slot holes (2) are provided. The plurality of the second slot holes (2) correspond to the plurality of the empty holes (3) one by one and are arranged in a staggered manner.

2. The circular hole cutting structure of a small-section tunnel in a tungsten mine according to claim 1 is characterized in that: The first slot hole (1) is located at the center of the rock face surface of the small-section tunnel.

3. The circular hole cutting structure of a small-section tunnel in a tungsten mine according to claim 1 is characterized in that: The d is the distance between the first cutout hole (1) and the empty hole (3), Wherein R is the radius of the empty hole (3), r is the radius of the first slot hole (1), and K is the rock expansion coefficient.

4. The circular hole cutting structure of a small-section tunnel in a tungsten mine according to claim 3 is characterized in that: The range of R is 70 mm to 90 mm, and the range of r is 40 mm to 50 mm.

5. A construction method, applied to a circular hole cutting structure of a small-section tunnel in a tungsten mine as described in any one of claims 1 to 4 of the present application, characterized in that: The following steps are involved: S1, first slot hole (1) positioning mark, on-site construction personnel position the center of the rock layer of the small-section tunnel; S2, second slot hole (2) positioning mark, taking the position of the first slot hole (1) positioning mark in S1 as the center, use an auxiliary tool to make a circle, and mark the second slot hole (2) on the circumference of the circle; S3, empty hole (3) positioning mark, marking the empty hole (3) on the circumference made in S2; S4, construction of the first slot hole (1), on-site construction personnel use rock drilling equipment to slot at the center mark of the rock surface of the small-section tunnel; S5, construction of the second slot hole (2), the on-site construction personnel use rock drilling equipment to drill a second slot hole (2) mark on the rock surface of the small-section tunnel, and a plurality of second slot holes (2) are provided; S6, construction of the empty hole (3), on-site construction personnel use rock drilling equipment to drill holes at the empty hole (3) marks on the rock surface of the small-section tunnel, and multiple empty holes (3) are provided; S7, pre-burying explosives, burying the explosives in the first cutout hole (1) and in the plurality of second cutout holes (2); S8, detonating explosives, detonating the explosives pre-buried in the first slot hole (1) and the plurality of second slot holes (2), and completing the cross-section excavation; S9. Repeat the above steps until the small-section tunnel is connected to the designated section and the construction is completed.

6. The construction method according to claim 5, characterized in that: The S2 and S3 are performed synchronously, the S2 and S3 can be performed synchronously, and the S4, S5, and S6 can be performed synchronously.

7. The construction method according to claim 5, characterized in that: The positioning tool in S1 is a laser level, and the auxiliary tool in S2 is a marking pin and a marking rope, and the marking rope can rotate around the marking pin.

8. The construction method according to claim 5, characterized in that: The number of the second cutout holes (2) in S5 is equal to the number of the hollow holes (3) in S6.

9. The construction method according to claim 5, characterized in that: When the rock surface area S of the small-section tunnel is less than or equal to 6.25 m2, the number of the second slot holes (2) and the empty holes (3) is no more than 3.

10. The construction method according to claim 5, characterized in that: The order of detonating the explosives in S8 is to first detonate the first slotted hole (1), then detonate the second slotted hole (2) which is closer to the adjacent empty hole (3), and finally detonate the second slotted hole (2) which is farther from the adjacent empty hole (3). The time interval between detonations is 50-100ms.

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