Soft rock roadway tunneling forming presplitting blasting method

Abstract

The invention discloses a soft rock roadway tunneling forming presplitting blasting method, and belongs to the technical field of mine blasting. Comprising the following steps that S1, a roadway working face needing to be tunneled is punched; s2, the punched holes are charged with explosives; and S3, detonating the explosives according to the set detonating sequence. Through a punching mode of straight hole slotting, peripheral holes adopt a charging structure of segmented charging, a digital electronic detonator is used for detonating, slotting holes are firstly detonated, then pre-blasting treatment is carried out on the peripheral holes from a vault, small holes are formed, the air permeability is enhanced, the internal pressure is reduced, and the rock integrity is weakened; and then the auxiliary holes, the side wall periphery holes and the bottom plate holes are detonated in sequence, the excavation range is expanded, and reasonable interval time is set, so that disturbance to surrounding rock mass is reduced, and the forming quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of mine blasting, in particular to a soft rock tunnel excavation forming pre-splitting blasting method. Background Art

[0002] Soft rock is a complex rock mechanical medium with significant plastic deformation under a specific environment. Soft rock can be divided into two categories: geological soft rock and engineering soft rock. Geological soft rock refers to loose, loose, soft and weak rock layers with low strength, large porosity, poor cementation, significant influence of structural surface cutting and weathering, or containing a large amount of expansive clay minerals. This type of rock is mostly mudstone, shale, siltstone and mudstone, which is a naturally formed complex geological medium; engineering soft rock refers to engineering rock mass that can produce significant plastic deformation under the action of engineering force. Engineering soft rock emphasizes the size of the engineering force load borne by soft rock, and emphasizes the analysis and grasp of the relative essence of soft rock from the contradictory unity relationship between the strength of soft rock and the engineering force load. According to the differences in soft rock characteristics and the mechanism of significant plastic deformation, soft rock can be divided into four categories, namely expansive soft rock, high stress soft rock, jointed soft rock and composite soft rock. In soft rock tunnel excavation, blasting technology still occupies a key position, but the current blasting technology is affected by some objective conditions such as small tunnel width, few free surfaces, strong rock clamping effect, etc., resulting in problems such as unsatisfactory blasting effect, low blasthole utilization, far throwing of rock fragments, unconcentrated blast piles, and poor forming quality. Summary of the invention

[0003] The object of the present invention is to provide a pre-splitting blasting method for soft rock tunnel excavation, which uses a straight hole slot drilling method, a segmented charging structure for peripheral holes and uses digital electronic detonators for detonation, and first detonates the slot hole, then pre-blasts the peripheral holes from the arch to form small holes, enhances air permeability, reduces internal pressure, weakens rock integrity, and then detonates auxiliary holes, side wall peripheral holes and bottom plate holes in sequence to expand the excavation range and set a reasonable interval time, so as to reduce the disturbance to the surrounding rock mass and ensure the quality of the forming, so as to solve the problems raised by the above-mentioned background technology.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A soft rock tunnel excavation forming pre-splitting blasting method comprises the following steps:

[0006] S1: Drill holes on the working surface of the tunnel to be excavated;

[0007] S2: Charge the drilled holes;

[0008] S3: Detonate the explosives according to the set detonation sequence.

[0009] Furthermore, the specific punching method in S1 adopts a straight-eye slot punching method to form slot holes, auxiliary holes, peripheral holes and bottom holes.

[0010] Furthermore, the peripheral hole charge in S2 adopts a segmented charge structure, and the slot holes, auxiliary holes and peripheral holes are all detonated using digital electronic detonators.

[0011] Furthermore, the segmented charge structure reduces the peak pressure of the explosion shock wave through the air gap, thereby reducing the vibration impact of the explosion on the surrounding environment.

[0012] Furthermore, digital electronic detonators are used for accurate positioning of blasting points and rational arrangement of gunpowder quantity through precise control functions.

[0013] Furthermore, the detonation sequence set in S3 is as follows:

[0014] S301: Detonating the slot hole, by concentrating the explosives inside the rock, forming a concentrated energy release on the rock, thereby quickly creating an initial crushing area inside the rock;

[0015] S302: pre-blasting the surrounding holes from the top of the arch to form small holes;

[0016] S303: Then detonate the auxiliary holes, the side wall peripheral holes and the bottom holes in sequence.

[0017] Furthermore, the small holes formed by the pre-blasting process in S302 are used to become a temporary support structure for the rock mass where the unblasted auxiliary holes are located in a short period of time.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The soft rock tunnel excavation forming pre-splitting blasting method of the present invention adopts a straight hole slotting drilling method, a peripheral hole adopts a segmented charging structure and uses a digital electronic detonator for detonation, and first detonates the slotting hole, then pre-blasts the peripheral holes from the arch top to form small holes, enhances air permeability, reduces internal pressure, weakens rock mass integrity, and then detonates the auxiliary hole, the side wall peripheral hole and the bottom plate hole in sequence, expands the excavation range, and sets a reasonable interval time, so as to reduce the disturbance to the surrounding rock mass and ensure the forming quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic plan view of a straight-eye cut blasthole of the present invention;

[0021] Figure 2 It is a schematic diagram of the blasthole charging structure of the present invention. DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] See also Figure 1-2 In an embodiment of the present invention, a soft rock tunnel excavation forming pre-splitting blasting method is provided, comprising the following steps:

[0024] S1: Drill holes on the working face of the tunnel that needs to be excavated; because straight hole cutting can ensure a higher utilization rate of the blasthole when facing broken rocks and these rocks have sufficient expansion space, the drilling method adopts straight hole cutting. Under specific geological conditions and when the blasthole depth is not deep, this drilling method shows its unique advantages. When facing broken rocks and these rocks have sufficient expansion space, it ensures a higher utilization rate of the blasthole. This means that in a limited space, explosives can be placed in the blasthole more effectively, achieving more precise and efficient results.

[0025] S2: Charge the drilled holes; the peripheral hole charge adopts a segmented charge structure, because the segmented charge structure can reduce the peak pressure of the explosion shock wave through the air gap, reduce the over-crushing of the rocks around the blast hole, and thus reduce the vibration impact of the blasting on the surrounding environment. The slot holes, auxiliary holes and peripheral holes are all detonated with digital electronic detonators. Digital electronic detonators are an advanced blasting technology. Through precise control functions, they can achieve accurate positioning of the blasting point and reasonable arrangement of the amount of gunpowder. This technology uses digital transmission and intelligent control to make blasting operations more efficient, safe and reliable. Compared with traditional gunpowder detonators, digital electronic detonators have a higher test pass rate. This is because digital electronic detonators have strong anti-interference ability and can better resist the influence of external interference. Its digital transmission technology makes signal transmission more stable and reliable, reducing the occurrence of errors and failures.

[0026] S3: Detonate the explosives in the set detonation sequence, first detonate the cutout holes. This step concentrates the explosives inside the rock, forms a concentrated energy release to the rock, and quickly creates the initial crushing area inside the rock. This process lays the foundation for subsequent blasting operations, making subsequent blasting operations more efficient. Next, focus on the pre-blasting treatment of the arch area. This step is not only the beginning of the construction process, but also the cornerstone to ensure the overall blasting effect and the stability of the surrounding rock. Specifically, by pre-blasting the surrounding holes at the arch position, a series of finely laid small holes and crack networks are formed. This innovation greatly improves the permeability of the rock and effectively reduces the potential safety hazards caused by internal pressure accumulation. The formation of these small holes not only weakens the firmness of the original rock mass, but also paves a more favorable physical condition for subsequent blasting operations, reduces unnecessary disturbances to the surrounding unblasted rock mass, and reflects the dual consideration of environmental protection and economic benefits. In addition, the through cracks formed in the arch by pre-splitting blasting are far more important than simply reducing the stress of the surrounding rock. In the subsequent blasting process, especially when the auxiliary holes, side wall peripheral holes and bottom plate holes were detonated, the impact energy generated by the explosion was effectively absorbed, the propagation speed and range of the vibration wave were greatly slowed down, and the potential damage risk to the weak surrounding rock was significantly reduced. This strategic pre-work not only ensures the overall stability of the surrounding rock, but also reduces the secondary disasters caused by blasting, such as surrounding rock collapse and surface subsidence, ensuring the safety of construction.

[0027] Design principle: The straight-eye cutout in the embodiment of the present invention ensures that the utilization rate of the blasthole reaches a higher level when facing broken rocks and these rocks have sufficient expansion space. The segmented charging structure reduces the peak pressure of the explosion shock wave through air intervals, reduces the over-crushing of the rocks around the blasthole, and thus reduces the vibration impact of the blasting on the surrounding environment. The digital electronic detonator can achieve accurate positioning of the blasting point and reasonable arrangement of the amount of gunpowder through precise control functions. At the same time, because the digital electronic detonator has strong anti-interference ability, it can better resist the influence of external interference. Its digital transmission technology makes signal transmission more stable and reliable, reducing the occurrence of errors and faults. In terms of the detonation sequence, by first detonating the cutout eye, then pre-blasting the surrounding holes from the arch to form small holes, enhance air permeability, reduce internal pressure, weaken the integrity of the rock mass, and then detonate the auxiliary eye, the side wall surrounding eye and the bottom plate eye in sequence, expand the excavation range, reduce the disturbance to the surrounding rock mass, and ensure the quality of the forming.

[0028] Among them, the through-crack technology implemented in advance in the arch plays multiple roles in the rock mechanics effect. First, by introducing a controlled crack in the initial stage, it effectively releases and reduces the high pressure stress accumulated inside the surrounding rock, avoiding the fatigue damage of the rock mass caused by long-term high stress state, and the risk of sudden geological disasters such as rock burst and spalling. At the same time, this pre-formed arch crack becomes a temporary supporting structure for the rock mass where the unblasted auxiliary hole is located in a short period of time. This is because the presence of the crack increases the stability of the rock mass, allowing the rock mass around the unblasted auxiliary hole to remain intact, reducing the stress concentration and instability risk caused by subsequent blasting operations on the surrounding rock, and ensuring the safety and controllability of the entire excavation process.

[0029] During the blasting operation, the pre-existing arch cracks played a significant role in absorbing energy and reducing vibration. When the subsequent auxiliary holes were blasted, the crack space acted as an energy buffer, effectively absorbing and dispersing the powerful shock wave energy generated by the explosion, thereby slowing down the propagation speed and intensity of the vibration effect in the rock mass. This dispersion and consumption effect significantly reduced the cumulative damage effect of the explosion stress wave on the surrounding weak surrounding rock, and effectively protected those fragile rock formations that may be easily broken, displaced or even collapsed due to high-intensity blasting.

[0030] To sum up: the soft rock tunnel excavation forming pre-splitting blasting method provided by the present invention lays a solid foundation for the entire excavation process through fine pre-blasting treatment, realizes optimization control from local to overall, and greatly improves the technical level and economic benefits of soft rock tunnel excavation. This method not only improves construction efficiency, but also reduces safety hazards.

[0031] The core of the method of the present invention lies in its innovative pre-splitting blasting design: by pre-detonating the peripheral holes at the dome position, a finely laid-out network of small holes and cracks is formed. The layout and size of these small holes are carefully designed and calculated to ensure that while weakening the solidity of the original rock mass, the disturbance to the surrounding unblasted area can be minimized. This design not only improves the permeability of the rock and reduces the risk of internal pressure accumulation, but also creates more favorable physical conditions for subsequent blasting operations.

[0032] In addition, the through cracks formed by the pre-splitting blasting played a crucial role in the subsequent blasting process, effectively absorbing the impact energy generated by the explosion and greatly slowing down the propagation speed and range of the vibration wave. This design not only significantly reduces the potential risk of damage to the weak surrounding rock, but also reduces the secondary disasters caused by blasting. This strategic pre-work not only ensures the overall stability of the surrounding rock, but also reflects the high attention paid to environmental protection and sustainable development.

[0033] In practical applications, the pre-splitting blasting method also needs to be flexibly adjusted according to specific circumstances. For example, different blasting parameters and strategies are required for rocks of different types and properties. At the same time, it is also necessary to make real-time adjustments and optimizations based on the specific conditions and environmental factors of the construction site. However, no matter how the adjustment and optimization plan is made, its core goal is to further improve construction efficiency, reduce safety risks and achieve a friendly impact on the environment.

[0034] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A soft rock tunnel excavation forming pre-splitting blasting method, characterized in that: The following steps are involved: S1: Drill holes on the working surface of the tunnel to be excavated; S2: Charge the drilled holes; S3: Detonate the explosives according to the set detonation sequence.

2. A soft rock tunnel excavation forming pre-splitting blasting method as claimed in claim 1, characterized in that: The specific punching method in S1 adopts a straight-eye slot punching method to form slot holes, auxiliary holes, peripheral holes and bottom holes.

3. A soft rock tunnel excavation forming pre-splitting blasting method as claimed in claim 2, characterized in that: The peripheral hole charging in S2 adopts a segmented charging structure, and the slot holes, auxiliary holes and peripheral holes are all detonated using digital electronic detonators.

4. A soft rock tunnel excavation forming pre-splitting blasting method as claimed in claim 3, characterized in that: The segmented charge structure reduces the peak pressure of the explosion shock wave through air gaps, thereby reducing the vibration impact of the explosion on the surrounding environment.

5. A soft rock tunnel excavation forming pre-splitting blasting method as claimed in claim 3, characterized in that: Digital electronic detonators are used for accurate positioning of blasting points and rational arrangement of gunpowder quantity through precise control functions.

6. A soft rock tunnel excavation forming pre-splitting blasting method as claimed in claim 1, characterized in that: The detonation sequence set in S3 is as follows: S301: Detonating the slot hole, by concentrating the explosives inside the rock, forming a concentrated energy release on the rock, thereby quickly creating an initial crushing area inside the rock; S302: pre-blasting the surrounding holes from the top of the arch to form small holes; S303: Then detonate the auxiliary holes, the side wall peripheral holes and the bottom holes in sequence.

7. A soft rock tunnel excavation forming pre-splitting blasting method as claimed in claim 6, characterized in that: The small holes formed by the pre-blasting process in S302 are used to become a temporary support structure for the rock mass where the unblasted auxiliary holes are located in a short period of time.

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