A method of arranging blast holes in accordance with tunnel boring machine while drilling parameters

Abstract

This invention discloses a method for arranging blast holes based on drilling parameters of a tunnel rock drill, relating to the field of blasting engineering technology. The method includes: simultaneously drilling at the tunnel face using a rock drill, collecting and recording drilling parameters at regular intervals for the bottom 10cm section of all cut holes and auxiliary holes during that advance; then determining the rock hardness characteristics at the drill hole location based on the collected drilling parameters, and simultaneously identifying the softest rock region Wn at the bottom of the drill hole for that advance; when drilling the next advance, placing the center point of the cut area at the center point of the softest rock region Wn, and then arranging the cut holes, auxiliary holes, and peripheral holes. This invention, when arranging drill holes and blast holes at the tunnel face, takes into account the differences in rock hardness within the blasting range, effectively avoiding waste of explosives or poor blasting results.

Description

Technical Field

[0001] This invention relates to the field of blasting engineering technology, and in particular to a method for arranging blast holes according to the drilling parameters of a tunnel drilling machine. Background Technology

[0002] Tunnel construction is an important engineering project in the construction of railways, highways and other infrastructure. At present, the commonly used methods for tunnel excavation at home and abroad are drill-and-blast method, shield tunneling method and tunnel boring machine method, among which the drill-and-blast method is the most widely used method.

[0003] The drill-and-blast method involves drilling, charging explosives, and blasting to excavate rock. This method has evolved from early manual drilling using hand-held chisels and hammers to the current use of multi-arm drilling rigs with drill rods. However, there are still many problems that need improvement in the drilling and blasting layout at the tunnel face.

[0004] In traditional drill-and-blast construction, the arrangement of boreholes and blast holes at the tunnel face is generally carried out according to the construction plan from start to finish. As the tunnel is continuously excavated, the differences and changes in the hardness of the rock within the blasting range are not taken into account, which often leads to waste of explosives or even poor blasting effect, affecting the quality and progress of the tunnel excavation project.

[0005] Even when adjusting the drilling and blast hole layout based on the blasting effect of the existing advance, it usually relies on the engineering experience of blasting engineers for rough adjustments, and cannot reasonably and precisely improve the blasting effect.

[0006] Therefore, in tunnel excavation using the drill-and-blast method, in order to avoid the waste of explosives and improve the blasting effect, it is necessary to design a method for arranging boreholes based on the drilling parameters of the tunnel rock drill, which can carry out rational and precise drilling and blast hole layout work. Summary of the Invention

[0007] In view of the above problems, in order to overcome the shortcomings of existing technologies and related products, the purpose of this invention is to propose a method for arranging blast holes according to the drilling parameters of a tunnel rock drill. By adjusting the arrangement of boreholes and blast holes according to the drilling parameters of the tunnel rock drill, the differences in rock hardness within the blasting range can be taken into account, thereby effectively avoiding the waste of explosives or poor blasting effect.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a method for arranging blast holes based on the drilling parameters of a tunnel rock drill, comprising the following steps:

[0010] Step 1: Using a rock drill, drill blast holes in sequence at the nth excavation advance of the tunnel: cut holes, auxiliary holes, and peripheral holes. While drilling, collect the drilling parameters from the rock drill at time intervals t for the section from 10cm to the bottom of the hole for all cut holes and auxiliary holes at that advance. Save the drilling parameters as an array. The drilling parameter array should include the center coordinates of the bottom section of each hole, the average drill rod impact pressure, the average drill rod advance pressure, the average drill rod rotation pressure, and the average drilling speed.

[0011] Step 2: Determine the rock hardness at the bottom of each borehole based on the bottom drilling parameter array of the slotted hole and auxiliary hole of the nth drilling advance;

[0012] Step 3: By comparing the softness of the bottom of all the slotted holes and auxiliary holes during the nth advance, determine the coordinates Wn of the bottom of the blast hole where the rock is softest.

[0013] Step 4: Complete the nth blasting operation;

[0014] Step 5: Start the drilling operation for the (n+1)th advance, and place the centroid of the slotted area at coordinate Wn at the bottom of the blast hole for the nth advance, and determine the position of the slotted hole around coordinate Wn.

[0015] Step 6: Determine the positions of the auxiliary hole and surrounding holes for the (n+1)th advance around the slotted area;

[0016] Step 7: Repeat steps 1-6 to excavate the tunnel by blasting.

[0017] Furthermore, step 2 includes:

[0018] Step 21: Calculate the energy required for the rock drilling rig to drill a unit volume of rock, i.e., the drilling specific energy e, using the drilling parameters during drilling and the physical and mechanical parameters of the rock drill.

[0019]

[0020] In the formula, e is the energy required to drill through a unit volume of rock. i It is the energy consumed by the impact, e t It is the energy consumed by the thrust, e n η is the energy consumed by rotation, and p is the energy conversion efficiency of 40%-70%. i τ is the average drill pipe impact pressure, Δa is the difference between the regions before and after the impact piston, τ is the impact duration, f is the impact frequency, m is the piston mass, v is the average drilling speed, A is the cross-sectional area of ​​the borehole, and p is the average drilling speed. t is the average drill pipe pushing pressure, a is the cross-sectional area of ​​the thrust piston, n is the drill pipe rotation speed, and T is the torque, where T torque is the product of the average drill pipe rotation pressure, the drill pipe area, and the drill pipe radius.

[0021] Step 22: Calculate the uniaxial compressive strength of saturated rock using the rock crushing specific work:

[0022]

[0023]

[0024] Where: δ c ------Saturated uniaxial compressive strength of rock;

[0025] ----- Chisel and smash to make a difference;

[0026] Step 23: Calculate the rock's strength coefficient f.

[0027] Furthermore, the torque is calculated as: average drill pipe rotation pressure * maximum torque of the drilling rig / maximum drill pipe rotation pressure.

[0028] Furthermore, in step 6, when determining the positions of the auxiliary holes and peripheral holes for the (n+1)th advance around the slotted area, the auxiliary holes and peripheral holes are arranged according to the following principles:

[0029] (1) The distance between the auxiliary hole and the adjacent blast hole is 0.4 to 0.8 m, the distance between the non-bottom peripheral hole and the adjacent blast hole is 0.5 to 1.0 m, and the distance between the peripheral hole and the outline is 0.1 to 0.2 m;

[0030] (2) The spacing between adjacent bottom perimeter holes is 0.4 to 0.7 m. When blasting with slag, the spacing between the bottom perimeter holes is 0.4 m.

[0031] The opening of the bottom perimeter holes should be 0.1 to 0.2m higher than the roadway floor, but the bottom of the holes should be 0.1 to 0.2m lower than the floor. When blasting with dumped slag, the depth of the blast holes should be increased by about 0.2m.

[0032] The charge amount in the bottom peripheral holes is between that in the slotting holes and the auxiliary holes, and the charge height is 0.5 to 0.7 times the hole depth. When blasting with slag, 1 to 2 additional charge cartridges are added to each hole.

[0033] Compared with the prior art, the present invention adjusts the drilling and blasting hole layout according to the drilling parameters of the tunnel rock drill when drilling at the tunnel face. This can take into account the differences in rock hardness within the blasting range, thereby effectively avoiding waste of explosives or poor blasting effect. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a flowchart illustrating a method for arranging blast holes based on drilling parameters of a tunnel rock drill, provided by the present invention.

[0036] Figure 2 This is a layout diagram of all boreholes for the nth advance.

[0037] Figure 3 This is the layout diagram of the slotting area for the (n+1)th advance.

[0038] Figure 4 This is a layout diagram of all boreholes for the (n+1)th advance.

[0039] Figure 5 This is a layout diagram of cut holes in Class V surrounding rock. The unit in the diagram is meters.

[0040] Figure 6 This is a layout diagram of cut-out holes in Class IV surrounding rock. The unit in the diagram is meters (m). Detailed Implementation

[0041] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The accompanying drawings show preferred embodiments of the present invention. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to make the disclosure of the present invention more thorough and complete.

[0042] Figure 1 A schematic flowchart of a method for arranging blast holes based on drilling parameters of a tunnel boring machine according to the present invention is shown:

[0043] like Figure 1 As shown, the method for arranging blast holes according to the drilling parameters of a tunnel rock drill provided by the present invention includes the following steps:

[0044] S1. Using a rock drill, drill blast holes in sequence during the nth excavation advance of the tunnel: cut holes, auxiliary holes, and peripheral holes. While drilling, collect the drilling parameters from the rock drill at time intervals t for the section from 10cm to the bottom of the hole for all cut holes and auxiliary holes during that advance. Save the drilling parameters as an array. The drilling parameter array should include the center coordinates of the bottom section of each hole, the average drill rod impact pressure, the average drill rod advance pressure, the average drill rod rotation pressure, and the average drilling speed.

[0045] The blast holes from the tunnel excavation in step 1, such as Figure 2 Depending on their location and function, they are divided into slotting holes, auxiliary holes (collapse holes), and peripheral holes.

[0046] During tunnel excavation and blasting, the arrangement of cut holes is extremely important because there is only one free face and the surrounding rock forces are very strong. Therefore, the arrangement of cut holes creates a cavity on the working face, serving as a second free face and providing favorable conditions for other blasting holes. Peripheral holes, also known as outline holes, control the shape and specifications of the tunnel cross-section. They blast away the surrounding rock, ultimately forming the designed cross-sectional outline of the tunnel and controlling its shape and specifications to ensure that the blasted tunnel cross-section, shape, and orientation meet design requirements. Auxiliary holes, also called collapse holes, expand and extend the cut area. These are numerous parallel or roughly parallel blasting holes between the cut holes and peripheral holes, sometimes including several auxiliary cut holes to further expand the cavity created by the cut hole blasting. Collapse holes are the main blasting holes for fracturing rock, utilizing the free face created by the cut to dislodge large amounts of rock.

[0047] In step 1, during the drill-and-blast tunnel excavation project, a large amount of engineering experience shows that the drilling parameters from 10cm from the bottom of the hole in the previous advance to the bottom of the hole have the highest correlation with the surrounding rock characteristics of the tunnel in the next advance.

[0048] S2. Determine the rock hardness at the bottom of each borehole based on the bottom drilling parameter array of the slotted hole and auxiliary hole of the nth drilling advance.

[0049] Drilling parameters include average drilling speed, average drill pipe impact pressure, average drill pipe advance pressure, average drill pipe rotation pressure, average water pressure, and average water flow rate. These parameters, along with other physical parameters of the drilling rig, allow us to calculate the energy consumed per unit volume of rock drilled. Generally, the harder, stronger, and more intact the rock, the more energy is consumed per unit volume of rock drilled.

[0050] According to research by domestic scholars, the rock-breaking process of a rock drilling rig involves three modes of action: impact, thrust, and rotation. Analysis shows that impact is the primary mode of rock breaking during the entire drilling process, generating stress concentration. Thrust utilizes axial static loads to create prestress within the rock, improving rock-breaking efficiency. Furthermore, applying thrust ensures close contact between the drill bit and the rock, facilitating the transmission of impact energy. Finally, rotation involves applying a rotational speed; the purpose of rotation is to move the drill bit teeth to aid in cutting the rock surrounding the impact borehole.

[0051] By using the drilling parameters during rock drilling and other physical and mechanical parameters of the rock drill, the energy required for the rock drilling rig to drill a unit volume of rock can be calculated, i.e., the drilling specific energy e (MJ / m³). 3 ).

[0052] The formula is:

[0053]

[0054] In the formula, e is the energy required to drill through a unit volume of rock (MJ / m³). 3 ), e i The energy consumed by the impact (e) i MJ / m 3 ), e t It is the energy consumed by the thrust (e) t MJ / m 3 ), e n It is the energy consumed by rotation (e) n MJ / m 3 ), η is the energy conversion efficiency, which is approximately 40%-70%, p i It is the impact force (MPa), and Δa is the difference between the front and rear regions of the impact piston (mm). 2 τ is the impact duration (s), f is the impact frequency (Hz), m is the piston mass (kg), v is the drilling speed (m / s), and A is the cross-sectional area of ​​the borehole (m²). 2 ), p t It is the thrust (MPa), and 'a' is the cross-sectional area of ​​the thrust piston (mm²). 2 ), where n is the drill pipe rotation speed (r / min) and T is the torque (N*m). T torque is the product of the average drill pipe rotation pressure, the drill pipe area, and the drill pipe radius. The actual data processing method is based on the manufacturer's maximum torque of 671 N*M and maximum rotation pressure of 210 bar for the rock drilling rig. Therefore, the torque under different rotation pressures is calculated by using the ratio 671 / 210.

[0055] In addition, the mathematical relationship between the uniaxial compressive strength of saturated rock and the specific work of rock crushing was obtained through experimental research, as shown in equation (2): The uniaxial compressive strength of saturated rock, or simply compressive strength, is the ultimate compressive stress value of a rock specimen at failure under uniaxial compression conditions, and the specific work of rock crushing is... It is the work consumed in breaking a unit volume of rock.

[0056]

[0057] Where: δ c ------Saturated uniaxial compressive strength of rock, MPa;

[0058] ------Work done by chiseling, J / cm 3 ;

[0059] Experimental studies have revealed that, for the same type of rock, the drilling specific energy e (MJ / m) 3 ) and crushing specific work a (J / cm 3 They are almost equal, that is Simultaneously, the unit symbol conversion is 1 MJ / m 3 =1J / cm 3 .

[0060] After calculating the uniaxial compressive strength of the rock, it can be divided into 10 grades according to its strength coefficient (f). The higher the grade, the easier the rock is to break (i.e., the lower the strength coefficient, the softer the rock). The strength coefficient is also known as the Protodyakonov coefficient.

[0061]

[0062] In the formula: f-----rock firmness coefficient, unit 1;

[0063] The robustness coefficient grading table is shown in Table 1:

[0064] Table 1

[0065]

[0066] S3. By comparing the softness and hardness of the bottom of all the slotted holes and auxiliary holes during the nth advance, determine the coordinates Wn of the bottom of the blast hole where the rock at the bottom is the softest.

[0067] S4. Complete the remaining blasting operations for the nth advance: charging, detonation, and slag removal.

[0068] Blasting operations include drilling, charging, detonation, slag removal, and transportation. Therefore, after completing the drilling and collecting drilling parameters within a certain drilling depth, the remaining blasting operations need to be completed.

[0069] S5, such as Figure 3 Start the drilling operation for the (n+1)th advance, and place the centroid of the cut area at the coordinate Wn of the bottom of the blast hole for the nth advance, and determine the position of the cut hole around the coordinate Wn.

[0070] The area enclosed by the perimeter of the cut hole during this advance is the cut zone, and the center of this area is the centroid of the cut zone.

[0071] S6, such as Figure 4 Determine the positions of the auxiliary holes and peripheral holes for the (n+1)th advance in the grooved area.

[0072] The auxiliary holes and peripheral holes are arranged according to the following principles:

[0073] (1) The holes should be evenly distributed to make full use of energy and ensure that the rock collapses along the designed outline. The spacing depends on the rock properties. Generally, the distance between auxiliary holes and adjacent blast holes is 0.4 to 0.8 m, the distance between non-bottom peripheral holes and adjacent blast holes is 0.5 to 1.0 m, and the distance between peripheral holes and the outline is 0.1 to 0.2 m.

[0074] (2) The arrangement of holes around the bottom is relatively difficult, and blind blasting is likely to occur when there is water accumulation. Therefore:

[0075] 1) The spacing between adjacent bottom perimeter holes is 0.4 to 0.7 m. When blasting with slag, the spacing between bottom perimeter holes is 0.4 m.

[0076] 2) The opening of the bottom perimeter hole should be 0.1 to 0.2m higher than the roadway floor, but the bottom of the hole should be 0.1 to 0.2m lower than the floor. When blasting with slag, the depth of the blast hole should be increased by about 0.2m.

[0077] 3) The charge amount in the bottom peripheral holes is between that in the slotting holes and the auxiliary holes, and the charge height is 0.5 to 0.7 times the hole depth. When blasting with slag, add 1 to 2 charge cartridges to each hole.

[0078] S7. Repeat steps S1-S6 to excavate the tunnel by blasting.

[0079] The present invention provides a method for arranging boreholes based on the drilling parameters of a tunnel rock drill. This method can adjust the arrangement of boreholes and blast holes, taking into account the differences in rock hardness within the blasting range, thereby effectively avoiding waste of explosives or poor blasting results.

[0080] Examples of tunnel blasting projects:

[0081] I. Project Overview

[0082] The Sanqingshan Tunnel is located in Shangrao City, Jiangxi Province, with a total length of 11,861 meters. The highest point of the tunnel has a maximum dimension of 12.94 meters, and the widest point is 14.86 meters. The tunnel cross-section was constructed according to the design requirements of the railway department. The strata at the tunnel site are mainly Yanshanian granite, Sinian siltstone, siliceous rocks, and quartz sandstone. The surrounding rock is relatively good, mainly consisting of Class IV and V rock. The tunnel entrance section has a burial depth of approximately 50–100 meters, while the remaining sections have burial depths of 200–500 meters.

[0083] II. Principles of Blasting Design

[0084] 1. Ensure that the cross-sectional dimensions and the flatness of the outline surface after blasting excavation meet the design requirements, with over-excavation not exceeding 15cm and under-excavation not exceeding 5cm.

[0085] 2. The blasted excavated rock fragments are of uniform size and the debris piles are concentrated, making it easy to load and transport the debris.

[0086] 3. Based on design requirements and geological conditions, determine reasonable blasting parameters and detonation methods to minimize disturbance to the surrounding rock mass of the tunnel.

[0087] 4. While ensuring the blasting effect, minimize the length of the blast holes and the amount of blasting materials required to blast a unit of rock mass, thereby reducing blasting costs.

[0088] 5. While ensuring construction quality, accelerate the construction progress.

[0089] 6. Taking full account of environmental protection and civilized construction requirements, adopt advanced, reasonable, safe, reliable, and economical blasting construction schemes to ensure the smooth progress of the project.

[0090] III. Overall Construction Plan

[0091] The surrounding rock conditions of the tunnel are relatively good. The tunnel is accessed from the entrance and exit and a full-section one-time drill and blast excavation scheme is adopted, that is, the central trench is cut, the auxiliary holes are opened around the perimeter, and the surrounding area is blasted according to the design outline.

[0092] IV. Explosive Design

[0093] 1. Excavation cycle advance. The surrounding rock of this tunnel is mainly Class IV and V. The excavation cycle advance is 3.0m for Class IV surrounding rock and 3.5m for Class V surrounding rock.

[0094] 2. Explosive consumption per unit. The explosive consumption per unit for Class IV surrounding rock is approximately 0.8 kg / m³. 3 The explosive consumption for Class V surrounding rock is approximately 1.0 kg / m³. 3 .

[0095] 3. Drilling layout. Based on the overall plan for full-section excavation, the drilling layout is as follows: central slotting holes, auxiliary holes around the perimeter, and smooth blasting holes around the edges.

[0096] 1) Drilling diameter: Holes were drilled using a hand-held pneumatic drill. Except for the central hollow hole of the slotted hole, whose diameter d1 = 89 mm, all other holes had a diameter of d = 42 mm. The drilling platform was self-made, consisting of three layers with four drilling machines on each layer, enabling three-dimensional operation.

[0097] 2) Cut-out Holes: The cut-out holes are located in the lower middle part of the tunnel and are arranged in a double wedge shape, with two empty holes in the middle and nine cut-out holes on each of the left and right sides. The row spacing of the cut-out holes is 0.9m, and the hole spacing is 0.4m. The cut-out hole arrangement is as follows. Figures 1-2 .

[0098] 3) Auxiliary holes: Auxiliary holes are vertical holes. Auxiliary hole spacing: a = (8~12)d = 0.70m; borehole utilization rate η = 90%; hole depth: L = l / 90%. The hole depths for Class IV and V surrounding rock are 3.3m and 3.8m, respectively.

[0099] 4) Smooth blasting holes: To facilitate construction and ensure the excavation cross-section matches the design cross-section, smooth blasting holes are drilled 0.2m from the excavation outline and inclined outwards at a 4° angle. The hole spacing b = (10~18)d = 0.60m; the smooth blasting hole density coefficient m is taken as 0.8, and the minimum resistance line: w = b / m = 0.75m. See the hole layout for details. Figure 5 and Figure 6 .

[0100] V. Charge Structure Design

[0101] The explosive used is No. 2 rock emulsion explosive. The medicine roll is 20cm long, and each section weighs 0.15kg.

[0102] 1. Filling length: L1=(10~20)d=0.50m.

[0103] 2. Charge structure:

[0104] 1) Cutting hole. The length of the blast hole is 1.6 to 4.1 m. The length of the charge from the bottom of the hole is 1.2 to 3.6 m. 6 to 18 sections of charge are loaded continuously, and the remaining part is filled in.

[0105] 2) Auxiliary holes. For Class IV surrounding rock, the borehole length is 3.3m, and the charge length from the bottom of the hole is 3.3m - 0.5m = 2.8m, with 14 sections of charge loaded continuously, and the remaining part filled in. For Class V surrounding rock, the borehole length is 3.8m, and the charge length is 3.8m - 0.6m = 3.2m, with 16 sections of charge loaded continuously, and the remaining part filled in.

[0106] 3) Smooth blasting holes. For Class IV surrounding rock, the hole length is 3.3m, and for Class V surrounding rock, the hole length is 3.8m. The linear charge density is 0.20kg / m, and the charge is applied at intervals.

[0107] VI. Construction shall be carried out according to the method of the present invention.

[0108] Step 1: Using a rock drill, drill blast holes in sequence at the nth excavation advance of the tunnel: cut holes, auxiliary holes, and peripheral holes. While drilling, collect the drilling parameters of the bottom 10cm section of all cut holes and auxiliary holes at time t from the rock drill at that advance, and save the drilling parameters as an array. The drilling parameter array should include the center coordinates of the bottom section of each borehole, the average drill rod impact pressure, the average drill rod advance pressure, the average drill rod rotation pressure, and the average drilling speed.

[0109] Step 2: Determine the rock hardness at the bottom of each borehole based on the bottom drilling parameter array of the slotted hole and auxiliary hole of the nth drilling advance.

[0110] By taking into account the drilling parameters and the mechanical performance parameters of the rock drilling rig, the energy required to drill a unit volume of rock in each hole is calculated, i.e., the specific energy required for breaking up rocks. This parameter is used to classify the hardness of the rock.

[0111] Step 3: By comparing the softness of the bottom of all the slotted holes and auxiliary holes during the nth advance, determine the coordinates Wn of the bottom of the blast hole where the rock is softest.

[0112] Step 4: Complete the remaining blasting operations for the nth advance: charging, detonation, and slag removal, etc.

[0113] Step 5: Start the drilling operation for the (n+1)th advance, and place the centroid of the slotted area at coordinate Wn at the bottom of the blast hole for the nth advance, and determine the position of the slotted hole around coordinate Wn.

[0114] Step 6: Determine the positions of the auxiliary hole and surrounding holes for the (n+1)th advance around the slotted area.

[0115] Step 7: Repeat steps 1-6 to excavate the tunnel by blasting.

[0116] Contents not described in detail in this specification are prior art known to those skilled in the art. The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments or make equivalent substitutions for some of the technical features. Any equivalent modifications made using the content of this specification and drawings, directly or indirectly applied to other related technical fields, are similarly within the patent protection scope of this invention.

Claims

1. A method for arranging blast holes based on the drilling parameters of a tunnel boring machine, characterized in that, Includes the following steps: Step 1: Using a rock drill, drill blast holes in sequence at the nth excavation advance of the tunnel: cut holes, auxiliary holes, and peripheral holes. While drilling, collect the drilling parameters from the rock drill at time intervals t for the section from 10cm to the bottom of the hole for all cut holes and auxiliary holes at that advance. Save the drilling parameters as an array. The drilling parameter array should include the center coordinates of the bottom section of each hole, the average drill rod impact pressure, the average drill rod advance pressure, the average drill rod rotation pressure, and the average drilling speed. Step 2: Determine the rock hardness at the bottom of each borehole based on the bottom drilling parameter array of the slotted hole and auxiliary hole of the nth drilling advance; Step 3: By comparing the softness of the bottom of all the slotted holes and auxiliary holes during the nth advance, determine the coordinates Wn of the bottom of the blast hole where the rock is softest. Step 4: Complete the nth blasting operation; Step 5: Start the drilling operation for the (n+1)th advance, and place the centroid of the slotted area at coordinate Wn at the bottom of the blast hole for the nth advance, and determine the position of the slotted hole around coordinate Wn. Step 6: Determine the positions of the auxiliary hole and surrounding holes for the (n+1)th advance around the slotted area; Step 7: Repeat steps 1-6 to excavate the tunnel by blasting.

2. The method according to claim 1, characterized in that, Step 2 includes: Step 21: Calculate the energy required for the rock drill to penetrate a unit volume of rock, i.e., the drilling specific energy e, using the drilling parameters during drilling and the physical and mechanical parameters of the rock drill. Equation (1); In the formula, e is the energy required to drill through a unit volume of rock. i It is the energy consumed by the impact, e t It is the energy consumed by the thrust, e n η is the energy consumed by rotation, and p is the energy conversion efficiency of 40%-70%. i τ is the average drill pipe impact pressure, ∆a is the difference between the regions before and after the impact piston, τ is the impact duration, f is the impact frequency, m is the piston mass, v is the average drilling speed, A is the cross-sectional area of ​​the borehole, and p t is the average drill pipe pushing pressure, a is the cross-sectional area of ​​the thrust piston, n is the drill pipe rotation speed, and T is the torque, where T torque is the product of the average drill pipe rotation pressure, the drill pipe area, and the drill pipe radius. Step 22: Calculate the saturated uniaxial compressive strength of the rock using the rock crushing specific work: Equation (2) In the formula: ------Saturated uniaxial compressive strength of rock; ------ Chisel and smash to death; Step 23: Calculate the rock's strength coefficient f. .

3. The method according to claim 2, characterized in that, The torque is calculated as: average drill rod rotation pressure * maximum drill drill torque / maximum drill rod rotation pressure.

4. The method according to claim 1, characterized in that, Step 6: When determining the positions of the auxiliary holes and peripheral holes for the (n+1)th advance around the slotted area, the auxiliary holes and peripheral holes shall be arranged according to the following principles: (1) The distance between the auxiliary hole and the adjacent blast hole is 0.4 to 0.8 m, the distance between the non-bottom peripheral hole and the adjacent blast hole is 0.5 to 1.0 m, and the distance between the peripheral hole and the outline is 0.1 to 0.2 m; (2) The spacing between adjacent bottom perimeter holes is 0.4 to 0.7 m. When blasting with slag, the spacing between bottom perimeter holes is 0.4 m. The opening of the bottom perimeter holes should be 0.1 to 0.2m higher than the roadway floor, but the bottom of the holes should be 0.1 to 0.2m lower than the floor. When blasting with dumped slag, the depth of the blast holes should be increased by about 0.2m. The charge amount in the bottom peripheral holes is between that in the slotting holes and the auxiliary holes, and the charge height is 0.5 to 0.7 times the hole depth. When blasting with slag, 1 to 2 additional charge cartridges are added to each hole.

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