Rock-stable regional roadway sidewall smooth blasting construction method

Abstract

The present application belongs to the field of mine tunneling blasting, and relates to a rock stable area roadway sidewall smooth blasting construction method, comprising the following steps: obtaining a standard section, obtaining a number of charging eyes, obtaining a smooth blasting hole distance a, setting a hole network parameter, charging and filling of a smooth blasting hole, and setting an initiation network. The technology can improve sidewall eye mark preservation rate, reduce overbreak and underbreak, reduce disturbance of blasting on surrounding rock, and fully exert the self-bearing capacity of surrounding rock.

Description

Technical Field

[0001] This invention belongs to the field of mining tunneling and blasting, and relates to a method for smooth blasting of the sidewalls of roadways in rock-stable areas. Background Technology

[0002] This invention relates to the field of blasting construction technology in mine tunnel excavation, and in particular to a smooth blasting construction method for the sidewalls of roadways in rock-stable areas.

[0003] In underground mine tunnel excavation, detonating cord smooth blasting technology has been widely used in stable rock areas due to its ability to create clear and regular blast hole marks in the tunnel roof (arch). This technology can effectively control the roof profile and reduce excessive damage to the surrounding rock. However, existing construction methods, when applied to smooth blasting of the tunnel sidewalls, reveal significant technical defects: poor sidewall forming quality and unsatisfactory blast hole mark control, resulting in substantial over-excavation or under-excavation of the tunnel cross-section. This inaccurate blasting not only causes significant disturbance to the surrounding rock, damaging its integrity and preventing the effective utilization of its own bearing capacity, but also directly leads to the need for more support materials in the subsequent support stage, increasing the workload and difficulty of support construction, ultimately resulting in high overall construction costs.

[0004] Analysis of existing technologies reveals that the aforementioned problems mainly stem from the following shortcomings: Lack of dedicated charge structures: Currently, there are no dedicated interval charge structures designed to match the smooth blasting of tunnel walls. Charge control is often unreasonable, either resulting in excessive rock fragmentation due to over-dense charges or uneven contour surfaces due to insufficient charges.

[0005] Asynchronous detonation network: The existing detonation network fails to achieve precise synchronous detonation of the surrounding holes (including top and side holes) in the roadway. There is a time difference in detonation between the top and side holes, resulting in uncoordinated superposition and action of the explosive stress waves within the rock mass. This leads to uneven fracturing of the sidewall rock, making it difficult to form a coherent hole mark, and resulting in a low hole mark preservation rate.

[0006] Parameter mismatch: When reducing the explosive charge to minimize disturbance to the surrounding rock, parameters such as the thickness of the smooth blast layer (i.e., the rock layer between the peripheral holes and auxiliary holes), the number and spacing of auxiliary holes, etc., are not scientifically matched with the reduced blasting energy. This can easily lead to two adverse consequences: first, insufficient blasting energy, resulting in the tunnel excavation progress not meeting design requirements; second, uneven or concentrated energy release, causing excessive fragmentation of the smooth blast layer rock mass or residual "rock ledges," making it impossible to form a smooth sidewall surface.

[0007] Therefore, the existing smooth blasting technology for roadway walls can no longer meet the higher requirements for surrounding rock protection, forming quality and cost control. There is an urgent need to develop a special construction method that can accurately control blasting parameters, optimize the detonation sequence, significantly improve the hole effect of the wall and reduce disturbance to the surrounding rock. Summary of the Invention

[0008] This application provides a method for smooth blasting of roadway walls in rock-stable areas, which can improve the preservation rate of wall hole marks, reduce over-excavation and under-excavation, reduce the disturbance of blasting to the surrounding rock, and fully utilize the bearing capacity of the surrounding rock itself.

[0009] To achieve the above technical objectives, the technical solution adopted in this application is as follows: a method for smooth blasting of roadway walls in rock-stable areas, comprising the following steps: Obtain the standard cross-section; the tunnel is 4.0m wide and 3.5m high, with a 1 / 3 three-center arch. Obtain the number of gun-loaded eyes, N=3.3 (fs 2 ) 1 / 3 In the formula, N is the total number of blast holes across the entire cross section, which is also the number of charge holes; f is the rock firmness coefficient, and s is the cross-sectional area of ​​the tunnel excavation. Obtain the hole spacing a for smooth blasting, a = (10-16)d, where d is the diameter of the blast hole; The perforation parameters are set according to the principle of uniform perforation distribution, and N charging holes are arranged. Light blasting hole loading and packing: In the light blasting holes in the top and side walls, φ32 emulsion explosive is used for decoupled and discontinuous loading; the decoupled and discontinuous loading means that the electronic detonator is installed at the end of the 32 emulsion and placed at the bottom of the blast hole, and an air gap is used between the 32 emulsions; the 32 emulsion, detonating cord, and detonator lead wire are tied to bamboo strips, and the end of the blast hole is packed. Detonation network setup: A digital electronic detonator is installed at the bottom of each blast hole, and all top and side holes form a detonating cord transmission network inside the holes; the digital electronic detonators in each blast hole are connected to the blasting main line outside the hole through detonator leads and then led to a unified detonation point, and the detonation delay time of the blast holes is set to the same millisecond value.

[0010] As an improved technical solution of this application, the blast hole filling operation first uses detonator packaging bags for initial sealing, and then uses water-soaked cardboard sheets to fill the remaining space of the blast hole in layers and tamp it down.

[0011] As an improved technical solution in this application, micro-delay detonation: full-section one-time micro-delay detonation is carried out in the detonation sequence of slotted hole - auxiliary hole - peripheral hole - bottom hole. The delay time interval of each digital electronic detonator is 500ms, and the delay time is set in 15 segments from 0ms to 7000ms.

[0012] As an improved technical solution of this application, it also includes adjustment of the light-explosion layer and auxiliary eye: the thickness of the light-explosion layer is controlled at 60cm±5cm, and the number of explosive eyes is N-1 or N-2.

[0013] As an improved technical solution of this application, the spacing between the slotted holes is (10d), and the spacing between the auxiliary holes, the surrounding holes, and the bottom holes is evenly arranged according to (14-20d).

[0014] Beneficial effects I. A decoupled and discontinuous interval charge structure for Φ32 emulsion explosive was designed for smooth blasting of the sidewall, which precisely controls the charge amount, greatly reduces the damage to the sidewall surrounding rock, significantly improves the preservation rate of blast hole traces in the sidewall, controls the over-excavation to within 10cm, and has no obvious under-excavation. Second, the detonation network combining detonating cord and digital electronic detonators is adopted to achieve synchronous detonation of the surrounding roof and sidewall openings, so that the sidewall rock is uniformly fractured, which solves the problem of uneven fracture of sidewall rock in the existing technology. Third, strictly control the thickness of the light blasting layer and appropriately reduce the number of auxiliary holes in the outer ring according to the reduction of the charge amount, match the blasting energy with the rock mass fragmentation requirements, ensure the blasting advance while avoiding excessive rock mass fragmentation, and ensure that the surrounding rock has no crushed rock and obvious cracks. IV. The hole mesh parameters and charge quantity of the construction method can be dynamically adjusted according to the actual site conditions. It is highly applicable, easy to operate, and can reduce the amount of support material used by more than 30% and the amount of support work by more than 25%, effectively reducing the construction cost of mine roadway excavation. 5. The packing process adopts a combination of sealing the holes in the detonator bag and packing with water-soaked cardboard boxes to ensure the packing is dense, prevent air leakage during explosion, and improve the utilization rate of explosion energy. Attached Figure Description

[0015] Figure 1 illustrates the charge structure of the 4.0m light blast hole of the present invention; in the figure: 1, electronic detonator; 2, 32 emulsion; 3, air gap; 4, detonator lead wire; 5, detonating cord; 6, bamboo strip; 7, blast hole filling.

[0016] Figure 2 illustrates the table for setting the delay time of the smooth blasting of the present invention.

[0017] Figure 3 illustrates the arrangement of the smooth blasting boreholes of the present invention. Detailed Implementation

[0018] This invention provides a method for smooth blasting of roadway walls in rock-stable areas. The method uses a standard cross-section of 4×3.5m to set the hole network parameters. The smooth blasting holes in the walls are constructed using Φ32 emulsion explosives with decoupled and discontinuous interval loading. The detonation network is combined with detonating cord and digital electronic detonators. The entire cross-section is detonated in a single, micro-delay blast in the order of cut holes-auxiliary holes-peripheral holes, thereby improving the smooth blasting effect of the walls.

[0019] A method for smooth blasting of roadway walls in rock-stabilized areas includes the following steps: Standard cross-sections were obtained, selected from the underground veins and access areas of the iron ore mine. These cross-sections were of the same type and were numerous and representative. Specifically, the roadway was 4.0m wide, 3.5m high, and had a 1 / 3 three-center arch.

[0020] Obtain the number of gun-loaded eyes, N=3.3 (fs 2 ) 1 / 3 In the formula, N is the total number of blast holes across the entire cross section, which is also the number of charge holes; f is the rock firmness coefficient, and s is the cross-sectional area of ​​the tunnel excavation. Calculate the number of blast holes to obtain the hole spacing a for smooth blasting, a = (10-16)d, where d is the diameter of the blast hole, and calculate the blasting parameters; set the hole mesh parameters, the relationship between s and a, and arrange N charging holes according to the principle of uniform hole distribution, and arrange the blast holes reasonably; calculate that the hole spacing for smooth blasting is between 450mm and 720mm.

[0021] In the top hole and side wall blast holes, φ32 emulsion explosives were used for decoupled and discontinuous loading, combined with... Figure 1 The specific structure is described as follows: the electronic detonator 1 is installed at the end of the 32 emulsion 2 and placed at the bottom of the blast hole; an air gap 3 is used between the 32 emulsion 2 and the 32 emulsion 2; the 32 emulsion 2, the detonating cord 5, and the detonator lead wire 4 are tied to the bamboo strip 6; the blast hole end is filled 7; in the top hole and the side wall of the blast hole, φ32 emulsion explosive is used for decoupled and discontinuous charging to maintain a decoupled and discontinuous charging structure with a 30cm interval; when the explosive is charged to a position 1.0m away from the opening of the blast hole, the blast hole filling operation begins.

[0022] Detonation network setup: A digital electronic detonator is installed at the bottom of each blast hole. All top and side holes are interconnected by detonating cords laid inside the holes to form a detonating cord transmission network. The digital electronic detonators in each blast hole are led to a unified detonation point outside the hole via lead wires, and their detonation delay time is set to the same millisecond value.

[0023] In some embodiments, the borehole filling operation first involves using detonator packaging bags for initial sealing, followed by filling the remaining space in the borehole with layers of water-soaked cardboard sheets and tamping them down.

[0024] In some implementations, micro-delay detonation is used: a full-section, one-time micro-delay detonation is carried out in the detonation sequence of cut-in hole - auxiliary hole - peripheral hole - bottom hole. The delay time interval of the digital electronic detonators in each section is 500ms, and the delay time is set in 15 sections ranging from 0ms to 7000ms. Cut-in holes and peripheral holes are arranged based on the requirements of borehole depth and tunnel size, while auxiliary holes and bottom holes are arranged based on the blasting environment, blasting throwing effect, and over- or under-excavation requirements of the floor.

[0025] In some implementations, the light-explosion layer and auxiliary eye adjustment are also included: the thickness of the light-explosion layer is controlled at 60cm±5cm, and the number of explosive eyes is N-1 or N-2.

[0026] In some implementations, the spacing between the slotted holes is smaller, taking 350mm (10d), and the spacing between the auxiliary holes, peripheral holes, and bottom holes is evenly arranged at 60-80cm (14-20d).

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments.

[0028] As shown in Figure 1-3, a method for smooth blasting of the sidewalls in a roadway in a rock-stable area includes the following steps: 1. Hole network parameter settings: Using a standard cross-section of 4×3.5m, 41 charge holes and 6 cut holes are arranged, for a total of 47 blast holes; 13 peripheral holes are set, including 7 top holes and 6 side holes. The blast hole diameter is 45mm (the minimum spacing between cut holes is 350mm, and the spacing between auxiliary holes and peripheral holes is evenly distributed at 60-80cm, adjusted according to the blasting effect). Due to the slight offset of the roadway on site, the spacing of 3 blast holes is slightly adjusted by 3cm.

[0029] 2. Loading and Packing of Smooth Detonation Holes: The smooth blasting holes in the sidewalls are 4.0m deep. Φ32 emulsion explosives (32 emulsion) are used for decoupled and discontinuous loading. One 300g whole emulsion explosive is loaded at the bottom of the hole, and six 150g half emulsion explosives are tied upwards at 30cm intervals. The total charge per hole is 4 units, with a total charge of 1200g. When the charge reaches 1.0m from the hole opening, the connection between the explosive roll and the detonating cord is sealed with a detonator bag. Then, water-soaked cardboard boxes are torn into pieces and filled into the blast hole. The filling is tamped down with a tamping rod to form a packing body, ensuring that the packing is dense and airtight. The charging structure strictly follows the charging structure diagram of the 4.0m smooth blasting hole in Appendix 1.

[0030] 3. Detonation network setup: Install one digital electronic detonator at the bottom of each sidewall blasting hole. Insert detonating cord 5 into all the holes in the surrounding top and sidewall holes and connect them to each other. All detonating cords 5 outside the holes are led to a unified detonation point through one digital electronic detonator 1. Set the delay time of all digital electronic detonators outside the holes in the surrounding holes to 6500ms (14 segments).

[0031] 4. Micro-delay initiation: Implement full-section one-time micro-delay initiation in the following order: cut hole (sections 1-5, 0-2000ms) → auxiliary hole (sections 6-13, 2500-6000ms) → peripheral hole (section 14, 6500ms) → bottom hole (section 15, 7000ms). The initiation sequence follows the initiation sequence diagram in Appendix 2. The delay time of each detonator is strictly implemented according to the delay time setting table in Appendix 3, with an interval of 500ms. A special detonator is used to trigger the detonator lead wire during initiation.

[0032] 5. Adjustment of the blasting layer and auxiliary holes: The thickness of the blasting layer is controlled at 60cm. Since the total charge is reduced after the blasting holes in the sidewall are charged with intervals, the number of auxiliary holes in the outer ring of the original design is reduced by 2 to ensure that the blasting energy matches the rock mass breaking requirements.

[0033] After construction in this embodiment, the preservation rate of blast hole traces in the roadway sidewalls is ≥60%, the over-excavation is controlled within 8cm, there is no under-excavation, the sidewall surrounding rock has no crushed rock and obvious cracks, the bearing capacity of the surrounding rock itself is fully utilized, the amount of subsequent support materials used is reduced by 35%, and the support workload is reduced by 28%.

Claims

1. A method for smooth blasting of roadway walls in rock-stable areas, characterized in that, Includes the following steps: Obtain the standard cross-section; the tunnel is 4.0m wide and 3.5m high, with a 1 / 3 three-center arch. Obtain the number of gun-loaded eyes, N=3.3 (fs 2 ) 1 / 3 In the formula, N is the total number of blast holes across the entire cross section, which is also the number of charge holes; f is the rock firmness coefficient, and s is the cross-sectional area of ​​the tunnel excavation. Obtain the hole spacing a for smooth blasting, a = (10-16)d, where d is the diameter of the blast hole; The perforation parameters are set according to the principle of uniform perforation distribution, and N charging holes are arranged. Light blasting hole loading and packing: In the light blasting holes in the top and side walls, φ32 emulsion explosive is used for decoupled and discontinuous loading; the decoupled and discontinuous loading means that the electronic detonator is installed at the end of the 32 emulsion and placed at the bottom of the blast hole, and an air gap is used between the 32 emulsions; the 32 emulsion, detonating cord, and detonator lead wire are tied to bamboo strips, and the end of the blast hole is packed. Detonation network setup: A digital electronic detonator is installed at the bottom of each blast hole, and all top and side holes form a detonating cord transmission network inside the holes; the digital electronic detonators in each blast hole are connected to the blasting main line outside the hole through detonator leads and then led to a unified detonation point, and the detonation delay time of the blast holes is set to the same millisecond value.

2. The method for smooth blasting of roadway walls in rock-stable areas according to claim 1, characterized in that, The blast hole filling operation first uses detonator packaging bags for initial sealing, and then uses water-soaked cardboard sheets to fill the remaining space of the blast hole in layers and tamp it down.

3. The method for smooth blasting of roadway walls in rock-stable areas according to claim 1, characterized in that, Micro-delay detonation: Full-section one-time micro-delay detonation is carried out in the detonation sequence of slotted hole - auxiliary hole - peripheral hole - bottom hole. The delay time interval of digital electronic detonators in each section is 500ms, and the delay time is set in 15 sections from 0ms to 7000ms.

4. The method for smooth blasting of roadway walls in rock-stable areas according to claim 1, characterized in that, It also includes adjustments to the light-explosion layer and auxiliary eyes: the thickness of the light-explosion layer is controlled at 60cm±5cm, and the number of explosive eyes is N-1 or N-2.

5. The method for smooth blasting of roadway walls in rock-stable areas according to claim 1, characterized in that, The spacing between the slotted holes is (10d), and the spacing between the auxiliary holes, the surrounding holes, and the bottom holes is evenly arranged according to (14-20d).

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