Tunnel face blasting hole arrangement structure

Abstract

The utility model relates to tunnel blasting engineering technical field, and disclose a kind of tunnel face of tunnel blasting hole arrangement structure, including face area, further including slotting hole and empty blast hole, face area is equipped with empty blast hole, internal edge dense hole screen and external edge dense hole screen are the cluster of aggregated hole groove formed by drilling;The utility model is by optimizing the relative position of slotting hole and empty blast hole, especially in the relatively larger face area outer edge region increased the arrangement of slotting hole, both can improve blasting efficiency and rock breaking degree, can also reduce construction cost and the disturbance influence to surrounding environment, is a kind of blast scheme with efficiency, cost and environment-friendly, the arrangement of internal edge and external edge dense hole screen is to improve the accuracy of blasting profile, guarantee the stability of surrounding rock, overall by inside to outside blasting mode is also more conducive to control blasting damage range, this design can also have adaptability to the type of face area rock, and hard rock effect is better.

Description

Technical Field

[0001] This utility model relates to the field of tunnel blasting engineering technology, and in particular to a tunnel face blasting hole arrangement structure. Background Technology

[0002] In tunnel excavation, blasting is a crucial method for achieving rock mass fracturing and tunneling. To ensure the safety and efficiency of blasting and minimize its impact on the surrounding environment, the rational arrangement of blasting holes at the tunnel face is of paramount importance. Currently, widely adopted blasting hole arrangements are based on linear rows, circular arrangements, or grid-like patterns. However, traditional arrangements suffer from problems such as uneven blasting effects, low fracturing efficiency, excessive blasting vibration, and difficulty in controlling damage to the surrounding rock along the tunnel route. With the development of tunnel engineering technology, higher requirements have been placed on blasting hole arrangements, including improving the control precision of the blasting range, reducing secondary damage caused by blasting, lowering vibration intensity, and achieving more uniform and efficient rock mass fracturing. However, existing blasting hole arrangements are largely based on experience and lack systematic design principles, resulting in limited blasting effects and failing to meet the multiple demands for efficiency, safety, and environmental protection in engineering projects. Therefore, there is an urgent need to propose an optimized blasting hole arrangement structure for the tunnel face to adapt to complex geological conditions, ensure construction safety and efficiency, and reduce disturbance to the surrounding environment and rock.

[0003] A search revealed a Chinese patent application, authorization announcement number CN211527217U, authorized on September 18, 2020, which proposed a tunnel blasting hole arrangement structure. This structure includes a densely packed edge hole curtain evenly circumferentially opened along the excavation outline of the tunnel face area, an inner layer of densely packed holes spaced longitudinally within the tunnel face area, inner slotted holes distributed in a wavy pattern between adjacent inner layer densely packed holes within the tunnel face area, and empty blasting holes. However, this invention does not densify the slotted hole arrangement in areas beyond half the radius of the tunnel face area, resulting in poor blasting effect and low blasting efficiency in the outer edge area of ​​the tunnel. In summary, the existing technology suffers from limitations such as unscientific blasting hole arrangement and unsatisfactory results. A novel and reasonable blasting hole arrangement structure is urgently needed to solve key technical problems such as low blasting efficiency, difficulty in vibration control, and uneven rock fragmentation, thereby improving the safety and economy of tunnel construction. Utility Model Content

[0004] In order to overcome the limitations of existing technologies, such as unscientific blasting hole layout and unsatisfactory results, which lead to low blasting efficiency, difficulty in vibration control, and uneven rock fragmentation.

[0005] The technical solution of this utility model is as follows: a tunnel face blasting hole arrangement structure, including a tunnel face area, and also including slotting holes and air blasting holes. Slotting holes are provided in the tunnel face area, and air blasting holes are provided in the tunnel face area. The edge of the tunnel face area is provided with a tunnel outer contour line. The bottom of the tunnel outer contour line is provided with an inner edge dense hole curtain. The surface of the tunnel outer contour line is uniformly distributed with an outer edge dense hole curtain. The slotting holes and air blasting holes are both located inside the inner edge dense hole curtain and the outer edge dense hole curtain. The inner edge dense hole curtain and the outer edge dense hole curtain are both clusters of holes and grooves formed by drilling.

[0006] Preferably, the air blast holes, slotting holes, internal edge dense hole curtain, and external edge dense hole curtain are all arranged perpendicular to the working face area.

[0007] Preferably, multiple sets of slotted holes for storing explosives are arranged at equal intervals on a straight line in the radial direction of the working face area.

[0008] Preferably, the included angle between adjacent slots distributed radially along the face region is 30°.

[0009] Preferably, multiple sets of air holes are evenly arranged at the center of two adjacent sets of slotting holes along the radial direction of the working face area.

[0010] Preferably, multiple rings of slotted holes are provided at the outer half of the radius of the working face area.

[0011] Preferably, the inner diameter of the air hole is larger than the inner diameter of the slotting hole, and the inner diameter of the slotting hole is larger than the inner diameter of the inner edge dense hole curtain and the outer edge dense hole curtain.

[0012] The beneficial effects of this utility model are:

[0013] 1. This utility model optimizes the relative positions of the slotting holes and air blast holes, especially by increasing the arrangement of slotting holes in the relatively large outer edge area of ​​the tunnel face. This not only improves blasting efficiency and rock fragmentation, but also reduces construction costs and disturbance to the surrounding environment. It is a blasting scheme that balances efficiency, cost, and environmental friendliness. The arrangement of dense holes at the inner and outer edges is to improve the accuracy of the blasting profile and ensure the stability of the surrounding rock. The overall blasting method from the inside out is also more conducive to controlling the blasting damage range. This design may also be adaptable to the types of rocks in the tunnel face area, with better results for hard rocks. Attached Figure Description

[0014] Figure 1 The diagram shown is a schematic representation of one embodiment of the tunnel face blasting hole arrangement structure of this utility model.

[0015] Figure 2 for Figure 1 A magnified view of part I in the middle.

[0016] Explanation of reference numerals in the attached drawings: 1. Cut hole; 2. Hole hole; 3. Dense hole curtain at the inner edge; 4. Dense hole curtain at the outer edge; 5. Outer contour line of the tunnel; 6. Working face area. Detailed Implementation

[0017] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] In tunnel blasting construction, to achieve efficient and safe blasting results, blasting holes are typically classified into three types: cut holes, peripheral holes, and auxiliary holes. Cut holes are primarily used to create a free face to facilitate subsequent blasting. Peripheral holes are drilled perpendicular to the tunnel face, and their blasted surface forms a plane perpendicular to the tunnel face; this design helps improve the cross-sectional shape after blasting. In actual construction, if a slope is encountered, additional drilling can be performed for a small amount of re-blasting to ensure the blasting effect meets expectations. Cut holes can be arranged in various ways, with single-row and double-row cut holes being the most common. Single-row cut holes are suitable for tunnels with smaller cross-sections, as their shallow cut depth allows for rapid formation of a free face. Double-row cut holes are suitable for tunnels with larger cross-sections; the staggered arrangement of two rows of cut holes creates a more stable free face, improving the blasting effect. The arrangement of peripheral holes is relatively fixed, usually perpendicular to the tunnel face, and the resulting plane provides good working conditions for subsequent processes. In practice, the angle and depth of the peripheral holes are adjusted according to different geological conditions and cross-sectional shapes. The main function of the auxiliary holes is to further break the rock and improve the blasting effect. They are usually arranged between the cut holes and the peripheral holes, and their even distribution ensures that the blasted rock blocks are of moderate size, facilitating subsequent debris removal and support work. During the blasting process, the density and depth of the auxiliary holes need to be adjusted according to geological conditions and blasting effects to ensure the smooth progress of the blasting. In tunnel blasting construction, the reasonable arrangement and scientific blasting of cut holes, peripheral holes, and auxiliary holes are key to ensuring construction safety and improving blasting efficiency. Through careful design and reasonable arrangement, efficient and safe blasting effects can be achieved, providing strong support for tunnel construction.

[0019] The tunnel face, being the deepest working face during tunnel excavation, needs to be continuously advanced. During this process, the strata act as the initial stress field for the tunnel. Under compressive stress, tunnel excavation disrupts the original triaxial stress balance of the surrounding rock, changing the stress state from triaxial to approximately biaxial, resulting in stress redistribution and a secondary stress state. This leads to deformation of the surrounding rock. To prevent excessive deformation, support structures are used in actual engineering to reduce it. In fact, the tunnel face exerts a constraint on the deformation of the surrounding rock during excavation, a phenomenon known as the tunnel face spatial effect. The existence of this spatial effect gives the surrounding rock a certain bearing capacity, enabling it to withstand some deformation.

[0020] Therefore, the influence of the tunnel face spatial effect on the deformation of the surrounding rock should be fully considered in tunnel support design. The convergence constraint method, which considers both the tunnel face spatial effect and the support action on the deformation of the surrounding rock, is well-suited for analyzing the dynamic interaction between the surrounding rock and the support, and is a commonly used tunnel support design method. Determining reasonable support timing and methods through the convergence constraint method can fully utilize the self-stabilizing capacity of the surrounding rock and reduce the waste of support materials. This is of great significance for minimizing the deformation of the surrounding rock caused by tunnel excavation. In summary, during tunnel construction, the tunnel face mainly plays a role in maintaining stability and reducing surrounding rock deformation, providing crucial support and protection for the smooth progress of the entire construction process.

[0021] Smooth blasting refers to a high-precision blasting control technique used in tunnel excavation. This involves adjusting blasting parameters and methods to implement "micro-delay blasting" in sections. The resulting profile conforms to design requirements, and the excavated surface is smooth and regular. According to Chen Qinghuai, project manager of the Meng-Hua Railway project at China Railway Beijing Engineering Bureau, smooth blasting ensures that the tunnel excavation cross-section shape and dimensions meet design requirements. The resulting rock walls are smooth and regularly shaped, and the surrounding rock outside the excavation profile remains undamaged. This enhances construction safety while reducing over-excavation and under-excavation, effectively improving project quality and construction progress, and lowering construction costs.

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0023] Please see Figure 1 - Figure 2This utility model provides an embodiment: a tunnel face blasting hole arrangement structure, including a face area 6, and also including slotting holes 1 and air blasting holes 2. The face area 6 is provided with slotting holes 1 and air blasting holes 2. The edge of the face area 6 is provided with a tunnel outer contour line 5. The bottom of the tunnel outer contour line 5 is provided with an inner edge dense hole curtain 3. The surface of the tunnel outer contour line 5 is uniformly distributed with an outer edge dense hole curtain 4. The slotting holes 1 and air blasting holes 2 are both located inside the inner edge dense hole curtain 3 and the outer edge dense hole curtain 4. The inner edge dense hole curtain 3 and the outer edge dense hole curtain 4 are both clusters of holes and grooves formed by drilling.

[0024] Please see Figure 1 and Figure 2 In this embodiment, the air blast holes 2, the slotting holes 1, the inner edge dense hole curtain 3, and the outer edge dense hole curtain 4 are all arranged perpendicular to the working face region 6. Multiple sets of slotting holes 1 for storing explosives are arranged at equal intervals on a straight line in the radial direction of the working face region 6. The included angle between adjacent slotting holes 1 distributed in the radial direction of the working face region 6 is 30°. Multiple sets of air blast holes 2 are evenly arranged in the radial direction of the working face region 6 at the center position of two adjacent sets of slotting holes 1. Multiple rings of slotting holes 1 are arranged in a ring direction around the outer half of the radius of the working face region 6. The inner diameter of the air blast holes 2 is larger than the inner diameter of the slotting holes 1, and the inner diameter of the slotting holes 1 is larger than the inner diameter of the inner edge dense hole curtain 3 and the outer edge dense hole curtain 4.

[0025] Based on a specific engineering tunnel, the tunnel face area 6 has a radius of 3.7m, a tunnel cross-sectional area of ​​42.99m², an outer edge dense perforated curtain 4 with a spacing of 50cm, an inner edge dense perforated curtain 3 with a diameter of 40mm, a borehole 2 with a diameter of 80mm, and a cut hole 1 with a diameter of 40mm. The radial spacing between two adjacent layers of borehole 2 is 80cm, and the radial spacing between two adjacent layers of cut holes 1 is 46cm. The diameter of the explosive in each cut hole 1 is 32mm, and the explosive charge in each cut hole is 3.6kg. Note: Figure 1-2 This is for illustrative purposes only and does not represent the specific scenario presented in this case.

[0026] The blasting employed a segmented controlled blasting method, generally proceeding gradually from the inside out. Specifically, it can be divided into the following three steps:

[0027] 1. Radial cut hole 1 is detonated first: a slot cavity is detonated first to add a new free surface for the blasting of other blasting points, so as to reduce the clamping effect of the rock. A continuous charge structure is adopted. Since the cut holes 1 are concentrated and high-power explosives are used, the purpose is to form a hollow area in the central area of ​​the working face area 6, so as to create conditions and space for subsequent blasting. The hollow structure of the air hole 2 weakens and buffers the shock wave inside the working face area 6, making the blasting process more stable.

[0028] 2. The circumferentially distributed cut holes 1 are then detonated. After the radial cut holes 1 are formed, blasting begins from the inner part of the cut hole 1 area outside the radius 1 / 2 and proceeds outwards sequentially. This means that the holes closer to the cut hole 1 area are detonated first, and then the outer holes are gradually detonated. This sequence allows rock fragments to fall or move, thereby improving blasting efficiency. The inner edge dense hole curtain 3 and the outer edge dense hole curtain 4 are used to control the forming profile of the tunnel cross-section. Therefore, the inner edge dense hole curtain 3 and the outer edge dense hole curtain 4 have the smallest charge and mostly use intermittent charging.

[0029] 3. Segmented Delayed Blasting: To achieve better control over the blasting effect, segmented delayed detonation is typically used. This means that each ring or group of blast holes is not detonated simultaneously, but sequentially according to a preset delay time. This allows for better control over the release of blasting energy and the direction of rock fragmentation, improving blasting efficiency and reducing blasting vibration.

[0030] This blasting method combines multiple technologies such as cut-and-cover blasting, segmented controlled blasting, and delayed blasting, aiming to achieve efficient, safe, and environmentally friendly tunnel excavation. Cut-and-cover blasting creates space for subsequent blasting, while blasting from the inside out in concentric rings improves blasting efficiency. Controlled blasting and delayed blasting are used to precisely control the blasting range and reduce vibration, ultimately achieving the best blasting effect.

[0031] Through the above steps, this utility model optimizes the relative positions of the slotting holes 1 and the air blast holes 2, especially by increasing the arrangement of the slotting holes 1 in the relatively large outer edge area of ​​the tunnel face 6. This not only improves blasting efficiency and rock fragmentation, but also reduces construction costs and disturbance to the surrounding environment. It is a blasting scheme that balances efficiency, cost, and environmental friendliness. The arrangement of the dense hole curtain at the inner and outer edges is to improve the accuracy of the blasting profile and ensure the stability of the surrounding rock. The overall blasting method from the inside out is also more conducive to controlling the blasting damage range. This design may also be adaptable to the types of rocks in the tunnel face area, with better results for hard rocks.

Claims

1. A tunnel face blasthole arrangement comprising a face area (6); characterized in that: The tunnel also comprises undercut holes (1) and empty blast holes (2), the undercut holes (1) are arranged in the tunnel face area (6), the empty blast holes (2) are arranged in the tunnel face area (6), the edge of the tunnel face area (6) is provided with a tunnel outer contour line (5), the bottom of the tunnel outer contour line (5) is provided with an inner edge dense hole curtain (3), the surface of the tunnel outer contour line (5) is uniformly distributed with an outer edge dense hole curtain (4), the undercut holes (1) and the empty blast holes (2) are located inside the inner edge dense hole curtain (3) and the outer edge dense hole curtain (4), and the inner edge dense hole curtain (3) and the outer edge dense hole curtain (4) are both groups of aggregated hole grooves formed by drilling.

2. A tunnel face blasthole arrangement according to claim 1, characterised in that: The empty blast holes (2), the undercut holes (1), the inner edge dense hole curtain (3) and the outer edge dense hole curtain (4) are all arranged perpendicularly to the tunnel face area (6).

3. A tunnel face blasthole arrangement according to claim 2, characterised in that: Multiple groups of undercut holes (1) for storing explosives are arranged at equal intervals on a straight line in the radial direction of the tunnel face area (6).

4. A tunnel face blasthole arrangement according to claim 3, characterised in that: The included angle between adjacent undercut holes (1) distributed in the radial direction of the tunnel face area (6) is 30°.

5. A tunnel face blasthole arrangement according to claim 4, characterised in that: Multiple groups of empty blast holes (2) are uniformly arranged at the center positions of adjacent two groups of undercut holes (1) in the radial direction of the tunnel face area (6).

6. A tunnel face blasthole arrangement according to claim 5, characterised in that: Multiple rings of undercut holes (1) are arranged in a ring direction at the periphery of one half of the radius of the tunnel face area (6).

7. A tunnel face blasthole arrangement according to claim 6, characterised in that: The inner diameter of the empty blast hole (2) is greater than that of the undercut hole (1), and the inner diameter of the undercut hole (1) is greater than that of the inner edge dense hole curtain (3) and the outer edge dense hole curtain (4).

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