Energy-gathered cutting and micro-vibration blasting method for weathered rock stratum

Abstract

The application discloses a weathered rock stratum energy-gathering cutting micro-vibration blasting method, which comprises the following steps: (1) determining the number and depth of frozen holes; (2) drilling holes; (3) controlling boundary cutting; (4) arranging not less than two temperature measuring holes on the middle perpendicular line of the frozen hole connecting line, the depth of the temperature measuring hole being the same as that of the frozen hole, and arranging a temperature sensor in the hole; (5) installing a frozen pipe; (6) starting a liquid nitrogen supply device, after the liquid nitrogen in the frozen pipe reaches a specified liquid level, the controller automatically stops the liquid nitrogen supply, and the liquid level of the liquid nitrogen in the frozen pipe is maintained to fluctuate within a reasonable range; (7) performing trial blasting by using a smaller explosive charge than a normal construction explosive charge; (8) filling a gas fracturing device into a main blast hole and plugging, connecting a gas supply Dewar flask to the gas inlet pipeline of the fracturing device, cutting the gas inlet pipeline after gas charging is completed and preparing for ignition, and pre-splitting cutting eliminates the clamping effect of boundary rocks, thereby reducing the explosive charge required for rock mass excavation and further reducing the blasting hazard effect.

Description

Technical Field

[0001] This invention relates to a method for shaped charge cutting and micro-vibration blasting of weathered rock strata, belonging to the field of blasting. Background Technology

[0002] As Chinese residents' environmental awareness and legal consciousness increase, the requirements for controlling blasting hazards are also rising. Furthermore, the construction of numerous tunnels and infrastructure projects further escalates the demands for controlled blasting interface operations. This drives the intelligent and refined development of my country's engineering blasting industry, leading to a growing demand for blasting technology research and development. Compared to conventional blasting techniques, environmental and engineering design requirements are higher, resulting in greater demands for blasting energy utilization. For the complex environment of high-altitude, cold, and ecologically fragile areas, a low-energy, low-vibration blasting technique is needed. This technique should precisely control the blasting excavation boundary to minimize impact on vegetation in non-excavation areas, and control the harmful effects of blasting vibration, flyrock, noise, and shock waves during blasting operations. Summary of the Invention

[0003] Purpose of the invention: To overcome the shortcomings of existing technologies, this invention provides a method for shaped charge cutting of weathered rock strata using micro-vibration blasting. The boundary cutter, in conjunction with pre-inducing cracks in the blast holes, can precisely induce the explosive energy to act on the formation and propagation of cracks, significantly improving the utilization rate of explosive energy. It can form high-quality penetrating planar cracks with a smaller amount of explosive, effectively reducing the blasting hazards. At the same time, the pre-splitting cutting eliminates the clamping effect of boundary rocks, reducing the amount of explosive required for rock mass excavation and further reducing the blasting hazards.

[0004] Technical solution: To solve the above technical problems, the present invention provides a method for shaped charge cutting of weathered rock strata using micro-vibration blasting, comprising the following steps: (1) Using existing data: the relative positional relationship between the blasting area and the protected target, the rock properties between the blasting area and the protected target, the magnitude of vibration generated by the blasting operation and the maximum allowable vibration of the protected target, determine the number of freezing holes and the depth of the freezing holes; (2) Drill blast holes along the cutting line in the area to be cut, and drill freezing holes in the freezing zone according to the requirements of step (1). The blast holes are divided into boundary control blast holes and main blast holes. The boundary control blast holes have a diameter of 40 or 50 mm and the charge is a boundary control cutter. The main blast holes have a diameter of 90 mm and the charge is a gas fracturing device. (3) Install the boundary cutter into the boundary blasting holes of the three blasting boundaries, connect them with digital electronic detonators, and detonate in three sections with delayed detonation. Each boundary is a section. (4) Arrange no less than two temperature measuring holes on the vertical line of the line connecting the freezing holes. The depth of the temperature measuring holes is the same as that of the freezing holes. Arrange temperature sensors in the holes. (5) Place the cryotube into the cryohole and seal the cryotube with a sealing device. Install a liquid nitrogen injection pipe, a vent pipe and a level gauge on the sealing device. Connect the liquid nitrogen injection pipe to the liquid nitrogen supply device. (6) Start the liquid nitrogen supply device. After the liquid nitrogen in the freezing tube reaches the specified level, the controller will automatically stop the liquid nitrogen supply and maintain the liquid nitrogen level in the freezing tube within a reasonable range. (7) Monitor the temperature sensor readings. When the temperature of the frozen wall reaches the specified value, it indicates that the frozen wall has been formed. Use a smaller amount of explosives than the normal construction amount for test blasting, and set up blasting vibration meters on both sides of the frozen wall. If the attenuation ratio of the blasting vibration after passing through the frozen wall meets the requirements, proceed to step (8). (8) Install and plug the gas fracturing device into the main blast hole. Connect the gas inlet pipe of the fracturing device to the gas supply dewar. After the gas is filled, cut off the gas inlet pipe and prepare for ignition. After the main blast hole is ignited, clear the blast pile and carry out the next round of blasting and drilling.

[0005] Preferably, in step (5), the opening of the cryogenic tube is provided with a sealing device, and the sealing device is provided with a liquid nitrogen injection pipe, a vent pipe and a level gauge. One end of the level gauge is located inside the pipe. The liquid nitrogen injection pipe is connected to the liquid nitrogen supply device. The liquid nitrogen supply device is connected to the controller signal, and the controller is connected to the level gauge. When the liquid nitrogen in the cryogenic tube decreases due to evaporation, the controller controls the liquid nitrogen supply device to inject liquid nitrogen into the cryogenic tube. When the liquid nitrogen in the cryogenic tube reaches the specified requirements, the controller controls the liquid nitrogen supply device to stop injecting liquid nitrogen.

[0006] Preferably, in step (4), one temperature sensor is installed every 1 to 2 m inside the temperature measuring hole.

[0007] Preferably, the refrigeration tube is a steel tube.

[0008] Beneficial effects: The weathered rock strata shaped charge cutting micro-vibration blasting method of the present invention, with boundary control cutter and pre-inducing cracks in the blast hole, can accurately induce the explosive energy to act on the formation and propagation of cracks, significantly improving the utilization rate of explosive energy. It can form high-quality penetrating plane cracks with less explosive charge, effectively reducing the blasting hazard effect. At the same time, the pre-splitting cutting eliminates the clamping effect of boundary rocks, reducing the amount of explosive required for rock mass excavation, further reducing the blasting hazard effect. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of a blasting operation.

[0010] Figure 2 The vibration reduction principle of the freezing wall and the determination of the freezing wall width are explained.

[0011] Figure 3 It has a freezing pore structure.

[0012] Figure 4 This is the structure of the temperature measuring hole.

[0013] In the diagram: 1. Freezing wall; 2. Freezing hole; 3. Temperature measuring hole; 4. Vent pipe; 5. Liquid level gauge; 6. Liquid nitrogen injection pipe; 7. Freezing pipe; 8. Temperature sensor; 9. Signal line; 10. Main blast hole; 11. Boundary control blast hole. Detailed Implementation

[0014] The invention will now be further described with reference to the accompanying drawings.

[0015] like Figure 1 As shown, when blasting occurs in the area to be blasted, the resulting vibrations propagate in all directions. If the vibration at the protected target exceeds a certain value, the protected target will be damaged. A freezing wall is installed between the protected target and the blasting area. When the seismic waves generated by the blast encounter the freezing wall during propagation, due to the difference in wave impedance between the freezing wall and the surrounding rock medium, the seismic waves undergo irregular diffuse reflection. The intensity of the seismic waves behind the freezing wall is greatly reduced, thus ensuring that the vibration at the protected target does not exceed its maximum allowable vibration. To achieve vibration reduction, the width and depth of the freezing wall should ensure that when blasting occurs at any point within the blasting area, the protected target should be within the shadow area behind the freezing wall. Figure 2 As shown in the diagram, the freezing wall is installed near the blasting area, typically at 2 / 5 of the distance between the blasting area and the protected target.

[0016] A method for shaped charge cutting of weathered rock strata using micro-vibration blasting includes the following steps: (1) Using existing data: the relative positional relationship between the blasting area and the protected target, the rock properties between the blasting area and the protected target, the magnitude of vibration generated by the blasting operation and the maximum allowable vibration of the protected target, determine the number of freezing holes and the depth of the freezing holes; (2) Drill blast holes along the cutting line in the area to be cut, and drill freezing holes in the freezing zone according to the requirements of step (1). The blast holes are divided into boundary control blast holes and main blast holes. The boundary control blast holes have a diameter of 40 or 50 mm and the charge is a boundary control cutter. The main blast holes have a diameter of 90 mm and the charge is a gas fracturing device. (3) Install the boundary cutter into the boundary blasting holes of the three blasting boundaries, connect them with digital electronic detonators, and detonate in three sections with delayed detonation. Each boundary is a section. (4) Arrange no less than two temperature measuring holes on the vertical line of the line connecting the freezing holes. The depth of the temperature measuring holes is the same as that of the freezing holes. Arrange temperature sensors in the holes. (5) Place the cryotube into the cryohole and seal the cryotube with a sealing device. Install a liquid nitrogen injection pipe, a vent pipe and a level gauge on the sealing device. Connect the liquid nitrogen injection pipe to the liquid nitrogen supply device. (6) Start the liquid nitrogen supply device. After the liquid nitrogen in the freezing tube reaches the specified level, the controller will automatically stop the liquid nitrogen supply and maintain the liquid nitrogen level in the freezing tube within a reasonable range. (7) Monitor the temperature sensor readings. When the temperature of the frozen wall reaches the specified value, it indicates that the frozen wall has been formed. Use a smaller amount of explosives than the normal construction amount for test blasting, and set up blasting vibration meters on both sides of the frozen wall. If the attenuation ratio of the blasting vibration after passing through the frozen wall meets the requirements, proceed to step (8). (8) Install and plug the gas fracturing device into the main blast hole. Connect the gas inlet pipe of the fracturing device to the gas supply dewar. After the gas is filled, cut off the gas inlet pipe and prepare for ignition. After the main blast hole is ignited, clear the blast pile and carry out the next round of blasting and drilling.

[0017] To install a cryogenic wall between the blasting zone and the protected target: First, drill one (or more) row of freezing holes between the blasting area and the protected target. The width and depth of the freezing holes should ensure that the protected target is within the shadow area behind the freezing wall when blasting occurs at any point within the blasting area. The spacing of the freezing holes can be selected based on vibration reduction requirements, construction period, and weather conditions: the smaller the spacing, the better the vibration reduction effect and the shorter the freezing wall formation time. If the construction period allows, a larger spacing can be chosen to reduce workload; additional freezing holes can be added later if the vibration reduction effect is found to be unsatisfactory through test blasting. The diameter of the freezing holes has no effect on the formation of the freezing wall and can be selected from the equipment required for blasting operations.

[0018] After the freezing hole is constructed, a freezing pipe is installed inside. The freezing pipe is a metal tube sealed at the bottom, with a sealing device at the top. The sealing device is equipped with a liquid nitrogen injection pipe, a vent pipe, and a level gauge. The liquid nitrogen injection pipe is connected to the liquid nitrogen supply device and controlled by the level gauge: when the liquid nitrogen level in the freezing pipe is below a specified value, the liquid nitrogen supply device injects liquid nitrogen into the freezing pipe; when the liquid nitrogen level in the freezing pipe reaches the specified value, the liquid nitrogen supply device stops injecting liquid nitrogen into the freezing pipe. The vent pipe is used to discharge evaporated liquid nitrogen out of the freezing pipe, maintaining the pressure inside the freezing pipe consistent with the outside pressure, and preventing foreign objects from entering the freezing pipe. Drill at least two temperature measuring holes on one side of the freezing hole. The purpose of the temperature measuring holes is to monitor the condition of the freezing wall. The depth of the temperature measuring holes is the same as the depth of the freezing hole. The temperature measuring holes should be a certain distance away from the freezing hole, that is, the line connecting the temperature measuring holes and the line connecting the freezing hole should not coincide, leaving room for later densification of the freezing hole or the addition of a row of freezing holes. After installing one temperature sensor every 1-2m along the depth direction inside the temperature measuring holes, backfill with cement mortar. Turn on the liquid nitrogen supply device to inject liquid nitrogen into the refrigeration tubes. When the liquid level reaches the specified value, the supply device will automatically stop and maintain the specified liquid level. Turn on the temperature measuring device. When the temperature reaches the specified value, it indicates that the refrigeration wall has been formed.

[0019] Once the temperature of the freezing wall reaches the specified value, test blasting can be carried out. During the test blast, a smaller amount of explosive than that used in normal blasting operations should be used. Vibration meters should be placed on both sides of the freezing wall. If the attenuation ratio of the blast vibration after passing through the freezing wall meets the requirements, normal construction can begin. If the vibration reduction effect is insufficient, the density or number of freezing holes should be increased to ensure the specified vibration reduction effect.

[0020] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for shaped charge cutting of weathered rock strata using micro-vibration blasting, characterized in that, Includes the following steps: (1) Using existing data: the relative positional relationship between the blasting area and the protected target, the rock properties between the blasting area and the protected target, the magnitude of vibration generated by the blasting operation and the maximum allowable vibration of the protected target, determine the number of freezing holes and the depth of the freezing holes; (2) Drill blast holes along the cutting line in the area to be cut, and drill freezing holes in the freezing zone according to the requirements of step (1). The blast holes are divided into boundary control blast holes and main blast holes. The boundary control blast holes have a diameter of 40 or 50 mm and the charge is a boundary control cutter. The main blast holes have a diameter of 90 mm and the charge is a gas fracturing device. (3) Install the boundary cutter into the boundary blasting holes of the three blasting boundaries, connect them with digital electronic detonators, and detonate in three sections with delayed detonation. Each boundary is a section. (4) Arrange no less than two temperature measuring holes on the vertical line of the line connecting the freezing holes. The depth of the temperature measuring holes is the same as that of the freezing holes. Arrange temperature sensors in the holes. (5) Place the cryogenic tube into the cryogenic hole and seal the cryogenic tube with a sealing device. The sealing device is equipped with a liquid nitrogen injection pipe, a vent pipe and a level gauge. The liquid nitrogen injection pipe is connected to the liquid nitrogen supply device. The cryogenic tube is equipped with a sealing device at its opening. One end of the level gauge is located inside the pipe. The liquid nitrogen supply device is connected to the controller signal. The controller is connected to the level gauge. When the liquid nitrogen level in the cryogenic tube decreases due to evaporation, the controller controls the liquid nitrogen supply device to inject liquid nitrogen into the cryogenic tube. When the liquid nitrogen level in the cryogenic tube reaches the specified requirement, the controller controls the liquid nitrogen supply device to stop injecting liquid nitrogen. (6) Start the liquid nitrogen supply device. After the liquid nitrogen in the freezing tube reaches the specified level, the controller will automatically stop the liquid nitrogen supply and maintain the liquid nitrogen level in the freezing tube within a reasonable range. (7) Monitor the temperature sensor readings. When the temperature of the freezing wall reaches the specified value, it indicates that the freezing wall has been formed. Test blasting was conducted using a smaller amount of explosives than normal, and blasting vibration meters were placed on both sides of the frozen wall. If the attenuation ratio of the blasting vibration after passing through the frozen wall met the requirements, step (8) was performed. (8) Install and plug the gas fracturing device into the main blast hole. Connect the gas inlet pipe of the fracturing device to the gas supply dewar. After the gas is filled, cut off the gas inlet pipe and prepare for ignition. After the main blast hole is ignited, clear the blast pile and carry out the next round of blasting and drilling.

2. The method for shaped charge cutting and micro-vibration blasting of weathered rock strata according to claim 1, characterized in that: In step (4), a temperature sensor is installed every 1-2m inside the temperature measuring hole.

3. The method for shaped charge cutting and micro-vibration blasting of weathered rock strata according to claim 1, characterized in that: The refrigeration pipe is a steel pipe.

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