Method for calculating particle size of spray droplets in high-altitude tunnel and spray dust suppression system

Abstract

The invention discloses a method for calculating the particle size of spray droplets in a high-altitude tunnel and a spray dust suppression system. The method comprises the following steps: step 1, calculating a dust particle motion equation of spherical dust particles in a vertical y direction; 2, according to the formula in the step 1, the settling velocity vp is obtained; 3, the particle size dp of the spherical dust particles is obtained; step 4, determining the relationship between the particle size of the fog drops and the minimum particle size of the spherical dust particles capable of being captured by the fog drops; and 5, calculating the maximum value of the particle size Dw of the spray droplets: # imgabs0 #. The method for calculating the particle size of the spray droplets in the high-altitude tunnel is combined with a theoretical equation of the spray droplets and dust particles in a high-altitude area to obtain a relational expression between the particle size of the spray droplets and the minimum particle size of the dust which can be captured by the spray droplets, and the inner diameter of a nozzle is determined. Therefore, fine dust can be effectively captured by spraying liquid drops in a high-altitude area.

Description

Technical Field

[0001] The invention belongs to the technical field of dust control in tunnel construction, and specifically relates to a method for calculating the particle size of spray droplets in a high-altitude tunnel and a spray dust suppression system. Background Art

[0002] The harsh environment of low pressure, high cold, hypoxia, etc. faced by high-altitude tunnel construction affects the migration law of dust generated during the construction process, increasing the difficulty of controlling tunnel dust and harmful gases. At present, spray dust reduction technology is regarded as one of the most suitable and effective independent dust reduction technologies in the tunnel construction process. In recent years, as the main dust reduction method in coal mine tunnels, there have been many breakthroughs in the field of dust reduction equipment research and development and parameter optimization.

[0003] During the actual excavation of tunnels using the drill and blast method in high-altitude areas, the location of the dust source in the tunnel changes with the excavation depth, and the high-concentration dust gathering area moves during the construction process. In order to save costs and meet actual engineering needs, the spray equipment needs to be mobile. At the same time, due to the low air pressure and air density in high-altitude tunnels, the spray water pressure and nozzle atomization characteristics need to be adjusted in a targeted manner to ensure dust reduction efficiency. Therefore, there is an urgent need for a mobile intelligent spray dust reduction system that can be applied to the environment of high-altitude tunnels to protect the occupational health of workers in harsh working conditions on the plateau. Summary of the invention

[0004] The purpose of the present invention is to provide a method for calculating the particle size of spray droplets in high-altitude tunnels and a spray dust reduction system. Combined with the theoretical equations of spray droplets and dust particles in high-altitude areas, the correction of relevant parameters of spray dust reduction in high-altitude areas is clarified, and the relationship between the droplet particle size and the minimum particle size of dust that can be captured is obtained. On this basis, the inner diameter of the nozzle is determined to achieve effective capture of fine dust by spray droplets in high-altitude areas.

[0005] The present invention adopts the following technical solution: A method for calculating the particle size of spray droplets in a high-altitude tunnel comprises the following steps:

[0006] Step 1: Calculate the motion equation of spherical dust particles in the vertical y direction:

[0007]

[0008] When a spherical dust particle sinks at a settling velocity, the acceleration Then formula (1) is transformed into:

[0009]

[0010] When the spherical dust particles settle at a constant rate, v = v p ,

[0011] Step 2: According to the formula (11) in step 1, the sedimentation velocity v is obtained. p :

[0012]

[0013] Step 3: Calculate the particle size d of the spherical dust particles by using the formula (12) in step 2: p :

[0014]

[0015] Step 4: The relationship between the droplet size and the minimum size of the spherical dust particles it can capture is as follows:

[0016]

[0017] Step 5: Calculate the spray droplet diameter D by using the equations (13) and (14) in step 3 and step 4. w The maximum value of:

[0018]

[0019] From formula (15), we get:

[0020]

[0021] Among them, m p is the mass of spherical dust particles; v y u is the velocity of spherical dust particles in the y direction; y is the velocity of air flow in the y direction; v = (u y -v y );v p is the sedimentation velocity; C D =0.44, resistance coefficient; ρ g is the air density at an altitude of H; ρ p is the density of spherical dust particles; d min is the minimum particle size of the captured spherical dust particles; μ H is the aerodynamic viscosity; D w is the spray droplet size; S tk is the Stokes number; is the average relative velocity between the spray droplets and the spherical dust particles; d p is the particle size of spherical dust particles; g is the gravity coefficient.

[0022] Furthermore, the air density is:

[0023] Furthermore, the air viscosity at an altitude of H is:

[0024]

[0025] Where: μ0 is the dynamic viscosity of air at 298.15K; B is the gas type constant; T is the temperature at 0 meters above sea level;

[0026] Further,

[0027] Where: G is the gravity of spherical dust particles; F f is the buoyancy of spherical dust particles; F D It is the air resistance exerted on spherical dust particles.

[0028] The present invention also discloses a high-altitude tunnel spray dust reduction system, which is characterized in that the spray particle size obtained based on the above-mentioned method for calculating the spray droplet particle size in the high-altitude tunnel includes: an air-water spray pipeline, an air-water spray nozzle, a main control box, an air pressure and dust concentration sensor, a dry fog pipeline and a dry fog nozzle, wherein:

[0029] On the air-water spray pipeline, multiple air-water spray nozzles are arranged at intervals along its length; on the dry fog pipeline, multiple dry fog nozzles are arranged at intervals along its length; the spray outlet of the air-water spray nozzle is larger than the spray outlet of the dry fog nozzle, and the air-water spray nozzle is used to spray and settle large particles of dust; the dry fog nozzle is used to spray and settle fine dust;

[0030] When used in the tunnel flat-guide excavation process, the shape of the air-water spray pipeline and the dry fog pipeline is consistent with the shape of the tunnel cross-section, and is fixed to the inner wall of the tunnel in a circular shape; and the air-water spray pipeline and the dry fog pipeline are arranged at intervals along the front and back of the tunnel, where the front is defined as close to the tunnel opening and the back is defined as far away from the tunnel excavation surface; multiple air pressure and dust concentration sensors are arranged in the tunnel, and each air pressure and dust concentration sensor is connected to the main control box;

[0031] When used in the tunnel excavation process, the air-water spray pipeline is laid on both sides of the inverted trestle, and multiple air-water spray nozzles are arranged at intervals along its length; on the return air side tunnel wall in front of the inverted trestle; the dry fog pipeline is laid on the waterproof trolley side wall steel frame, and multiple dry fog nozzles are arranged at intervals along its length; air pressure and dust concentration sensors are laid on the return air side tunnel wall in front of the waterproof trolley steel frame; the main control box is laid on the tunnel side wall behind the inverted trestle, and each air pressure and dust concentration sensor is connected to the main control box.

[0032] The beneficial effects of the present invention are: 1. According to the environmental parameters of high altitude areas, combined with the theoretical equations of spray droplets and dust particles in high altitude areas, the correction of relevant parameters of spray dust reduction in high altitude areas is clarified, and the relationship between the droplet particle size and the minimum dust particle size that can be captured is obtained. The minimum dust particle size that can be captured is proportional to the droplet particle size. Therefore, in order to capture respirable dust with fine particle size, it is necessary to optimize the spray mode to obtain droplets of small particle size. On this basis, the inner diameter of the nozzle is determined to achieve effective capture of fine dust by spray droplets in high altitude areas. 2. A two-stage spray system of air-water spray and dry fog is deployed. The air-water spray pipeline settles large dust particles, and the dry fog pipeline settles fine dust. The mobile high-altitude tunnel spray dust reduction system of "dust source reduction-intelligent dust reduction-blocking dust capture-secondary dust prevention" is used to achieve accurate and efficient dust reduction based on dust source following technology. 3. Due to the low aerodynamic viscosity in high-altitude areas, the minimum particle size of the captured dust will be reduced under the condition of the same droplet particle size. Therefore, the spray droplets in high-altitude areas have a better effect on capturing fine dust. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a tunnel flat spray dust suppression system;

[0034] Figure 2 It is the tunnel main tunnel spray dust suppression system-inverted arch trestle;

[0035] Figure 3 It is the tunnel main tunnel spray dust suppression system - waterproof trolley.

[0036] Among them: 1. Water tank; 2. Water supply pipeline; 3. Dust suppressant adding device; 4. Air supply pipeline; 5. Air-water spray pipeline; 6. Steel frame; 7. Air-water spray nozzle; 8. Anchor bolts; 9. Main control box; 10. Air pressure and dust concentration sensor; 11. Dry mist pipeline; 12. Dry mist nozzle. DETAILED DESCRIPTION

[0037] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] The method for calculating the particle size of spray droplets in a high-altitude tunnel of the present invention, where high altitude refers to an altitude of more than 4,000 meters, includes the following:

[0039] As the altitude increases, the air becomes thinner, the atmospheric pressure is lower than that in plain areas, and changes in a nonlinear relationship. The formula between air pressure and air density is:

[0040] Where: P H is the air pressure at an altitude of H, in Pa; P0 is the standard atmospheric pressure, 101.325 kPa; H is the altitude, in m.

[0041] The air density in high altitude areas is lower than that in plain areas. In addition, the air density is also related to the geological environment and humidity of the excavation site. However, the weight of other factors is relatively small. Ignoring the geological environment, humidity and other factors, the air density at an altitude of H is calculated using the following formula:

[0042]

[0043] Where: g is the air density at an altitude of H, in kg / m 3 .

[0044] The greater the dynamic viscosity of the air, the greater the force exerted by the air on the spherical dust particles during diffusion. The viscosity of the gas increases with the increase of temperature, so the dynamic viscosity of the gas in high altitude areas is lower than that in plain areas. When the temperature T < 2000K, the air viscosity at an altitude of H can be calculated using the Satterland formula:

[0045]

[0046] Where: μ0 is the dynamic viscosity of air at 298.15K, which is 1.85×10 -5 Pa·s; B is the gas type constant. For air, B=110.4K.

[0047] The movement law of spherical dust particles in the tunnel is theoretically analyzed, and the particle size range of spherical dust particles that are difficult to settle are calculated, providing a basis for the parameter selection of spray dust suppression nozzle equipment.

[0048] The moving spherical dust particles cause disturbances in the surrounding medium, i.e., the gas, which manifests as resistance to the movement of the spherical dust particles. As long as there is a certain relative speed between the spherical dust particles and the gas, the gas will have resistance to the spherical dust particles. The air resistance F D for:

[0049]

[0050] Where: C D is the resistance coefficient. Since the airflow in the tunnel is turbulent, the value is 0.44; A p is the cross-sectional area of ​​spherical dust particles in the windward direction, in m 2 ; v = (u y -v y ), is the relative speed between spherical dust particles and air, in m / s; ρ g is the air density, in kg / m 3 ;d p It is the diameter of spherical dust particles, in m.

[0051] Dust is subject to gravity everywhere in the tunnel space, and the direction of gravity is vertically downward, which is the main force for the sedimentation of spherical dust particles. The gravity G of spherical dust particles is:

[0052]

[0053] Where: p is the density of spherical dust particles, in kg / m 3 ; V is the volume of spherical dust particles, in m 3 .

[0054] When the spherical dust particles move in the air, they are also subject to the buoyancy of the tunnel air. The buoyancy of the spherical dust particles is F f for:

[0055]

[0056] Where: g is the air density, in kg / m 3 .

[0057] During tunnel drilling, grouting and slag removal, dust gushes out evenly and floats to various places in the tunnel with the wind flow. In the early stage of spherical dust particle gushing, the velocity component of spherical dust particles in a certain direction is often different from the air flow velocity. According to Newton's second law, the motion equations of dust particles in the x, y, and z directions are obtained as follows:

[0058]

[0059] Where: m p is the mass of spherical dust particles, kg; v x 、v y and v z is the speed of the spherical dust particle in the x, y and z directions, in m / s; u x 、u y and u z They are the flow velocities in the x, y and z directions respectively, in m / s.

[0060] The vertical force on spherical dust particles is analyzed. When the spherical dust particles just start to move, the vertical downward speed is very small and the resistance is also very small. During the sedimentation process, the dust particle speed increases continuously and the resistance also increases accordingly. When the resistance, buoyancy and gravity are balanced, the sedimentation speed of the spherical dust particles reaches the maximum and the spherical dust particles will settle at a constant speed. At this time, the speed of the spherical dust particles v = v p , which is the settling velocity of spherical dust particles. If the airflow is given an upward velocity, the direction is vertically upward, and the value is equal to v p , then the mass of the spherical dust particles will not fall but float in the air, which is called the suspension velocity, which is related to vp Equal in size and opposite in direction.

[0061] When the spherical dust particle sinks at a settling velocity, the acceleration dv / dt = 0, and formula (9) can be transformed into:

[0062]

[0063] The tunnel environment is a turbulent area. D =0.44 Substituting into formula (11), we get v p for:

[0064]

[0065] The relationship between the particle size of spherical dust particles, suspension wind speed, and air density is:

[0066]

[0067] From the analysis of formula (13), it can be seen that as the altitude increases, the air density in the environment decreases, and the particle size of the spherical dust particles corresponding to the same suspension speed decreases. At the same altitude, the greater the vertical upward suspension wind speed inside the tunnel, the larger the spherical dust particles suspended there.

[0068] The droplet size is an important factor affecting the dust reduction effect. By designing a coupling experiment between the droplet field and the dust field, the relationship between the droplet size and the minimum size of the spherical dust particles that can be captured is as follows:

[0069]

[0070] From the above formula (14), it can be seen that the minimum particle size of spherical dust particles that can be captured by droplets is proportional to the droplet size. Therefore, in order to capture spherical dust particles and fine respirable dust, it is necessary to optimize the spray method to obtain droplets with small particle sizes. At the same time, due to the low aerodynamic viscosity in high altitude areas, the minimum particle size of spherical dust particles captured will decrease under the condition of the same droplet size. Therefore, the spray droplets in high altitude areas have a better effect on capturing fine dust.

[0071] According to the air pressure sensor in the tunnel, the air pressure P H , temperature and sensor response to temperature T H The real-time test results of the vertical upward wind speed in the environment directly below the spray equipment by the temperature and wind speed sensors are compared with v p The size of the suspended spherical dust particles around the spray equipment is equal to d p According to the above calculation results, calculate the particle size range D of the spray droplets w , ensuring that the particle size of the suspended spherical dust particles is larger than the minimum dust particle size that can be captured by the spray droplets.

[0072] From formula (2), formula (3), formula (13) and formula (14), we can get:

[0073]

[0074] From formula (15), we get:

[0075]

[0076] That is, according to the air pressure P in the tunnel H , Temperature T H and the vertical wind speed test results, calculate the spray droplet D w The maximum value of D is set according to the particle size of suspended spherical dust particles near the tunnel spray, and the appropriate nozzle is adjusted to make the spray droplet size within D w Below, the suspended spherical dust particles can be accurately and efficiently settled. T is the temperature at 0 meters above sea level. Where: d min The minimum particle size of spherical dust particles captured, in m; μ H is the air dynamic viscosity, in Pa·s; D w is the droplet diameter, in m; S tk is the dimensionless inertia parameter, Stokes number; the unit is kg / m 3 ; It is the average relative speed between the mist droplets and the spherical dust particles, in m / s. p is the sedimentation velocity; C D =0.44, resistance coefficient; ρ g is the air density at an altitude of H; ρ p is the density of spherical dust particles; is the average relative velocity between the spray droplets and the spherical dust particles; d p is the particle size of spherical dust particles; g is the gravity coefficient.

[0077] The present invention discloses a mobile high-altitude tunnel excavation intelligent spray dust suppression system, which includes: an air-water spray pipeline 5, an air-water spray nozzle 7, a main control box 9, an air pressure and dust concentration sensor 10, a dry fog pipeline 11 and a dry fog nozzle 12, wherein:

[0078] A plurality of air-water spray nozzles 7 are arranged at intervals along the length of the air-water spray pipeline 5; a plurality of dry fog nozzles 12 are arranged at intervals along the length of the dry fog pipeline 11; the spray outlet of the air-water spray nozzle 7 is larger than the spray outlet of the dry fog nozzle 12, and the air-water spray nozzle 7 is used for spraying and settling large dust particles; the dry fog nozzle 12 is used for spraying and settling fine dust;

[0079] When used in tunnel boring process, such as Figure 1 As shown, the shapes of the air-water spray pipeline 5 and the dry fog pipeline 11 are consistent with the shape of the tunnel cross section, and are fixed to the inner wall of the tunnel in a circular shape; and the air-water spray pipeline 5 and the dry fog pipeline 11 are arranged at intervals along the front and back of the tunnel, wherein the front is defined as the front and the back is defined as the back away from the tunnel excavation surface; a plurality of air pressure and dust concentration sensors 10 are arranged in the tunnel, and each air pressure and dust concentration sensor 10 is connected to the main control box 9;

[0080] When used in the tunnel excavation process, the air-water spray pipeline 5 is arranged on both sides of the inverted trestle, and a plurality of air-water spray nozzles 7 are arranged at intervals along its length; on the return air side tunnel wall in front of the inverted trestle 10; the dry fog pipeline 11 is arranged on the waterproof trolley side wall steel frame, and a plurality of dry fog nozzles 12 are arranged at intervals along its length; an air pressure and dust concentration sensor 8 is arranged on the return air side tunnel wall in front of the waterproof trolley 9 steel frame; a main control box 8 is arranged on the tunnel side wall behind the inverted trestle 10, and each air pressure and dust concentration sensor 8 is connected to the main control box 8.

[0081] During the tunneling process, each air-water spray pipeline 5 is erected on a pipeline steel frame 6. The shape of the pipeline steel frame 6 is consistent with the shape of the tunnel cross section and is fixed to the inner wall of the tunnel in a circular shape, specifically by anchor bolts 6. The water tank 1 is arranged outside the tunnel; its specification is 0.35m*1.6m*1.5m.

[0082] The dust suppressant adding device 3 is arranged outside the tunnel and is connected to the water tank 1 through the water supply pipeline 2. The dust suppressant adding device 3 is a box body, and the dust suppressant concentrate is contained in the box body. The water supply pipeline 2 passes through the dust suppressant adding device 3 and is connected to the dust suppressant adding device 3 through the pipeline.

[0083] A main control box 9 is arranged about 70m behind the tunnel face, and an air pressure and dust concentration sensor 10 is arranged on the return air side near the tunnel face.

[0084] The working process is as follows: The air pressure and dust concentration sensor 10 measures the ambient air pressure and dust concentration data in the tunnel. When the dust concentration exceeds 4 mg / m 3 When the data is transmitted to the main control box 9 via wireless signals, the main control box 9 determines the opening of the spray equipment and the setting of the air and water pressure through the ambient air pressure data and the dust concentration data, and adjusts the pressure of the air and water spray pipeline 5.

[0085] The dust suppressant concentrate is fed into the water supply pipeline 2 for premixing, and then merged with the high-pressure gas in the air-water spray pipeline 5 and the dry fog pipeline 11, and atomized droplets are sprayed out through the air-water spray nozzle 7 and the dry fog nozzle 12. The air-water spray nozzle 7 settles large particles of dust, and the dry fog nozzle settles fine dust; when the dust concentration sensor 10 monitors that the dust concentration in the tunnel is reduced to 4mg / m3 When the following conditions occur, the main control box 9 control system stops working.

[0086] When one drilling and blasting construction process is completed and the next section is to be constructed, the anchor bolts 8 are removed, the spray pipe 6 steel frame is taken down, and the spray pipe steel frame 6 is re-deployed at a suitable position in front of the excavation face through the anchor bolts 8. The above steps are repeated to achieve intelligent, precise and efficient dust reduction for flat-guide excavation during the high-altitude tunnel drilling and blasting construction process.

[0087] When applied to the tunnel main tunnel inverted arch trestle, such as Figure 2 and 3 As shown, it is suitable for the main tunnel section of the tunnel constructed by the drill and blast method. The water tank 1 is installed below the guardrail of the inverted arch trestle. The size of the water tank 1 is 0.35m*1.6m*1.5m. The spray nozzle angle is adjusted so that the air-water spray can cover the entire tunnel section. The main control box 8 is arranged on the tunnel side wall behind the inverted arch trestle 10. The air pressure and dust concentration sensor 9 is arranged on the tunnel side wall on the return air side in front of the inverted arch trestle 10 to complete the arrangement of the fixed steel frame air-water spray system of the inverted arch trestle on the tunnel main tunnel excavation face.

[0088] The working process is as follows: When the air pressure and dust concentration sensor 9 measures the concentration to be more than 4 mg / m 3 When the dust suppressant adding device 3 inputs the dust suppressant concentrate into the water supply pipeline 2 for premixing, the dust suppressant concentrate is mixed with the high-pressure gas in the air-water spray pipeline 5, and the air-water spray nozzle 7 is controlled by the main control box 8. When the air pressure and dust concentration sensor 10 monitors that the dust concentration in the tunnel is reduced to 4 mg / m 3 When the drilling and blasting construction process is completed and the next section is under construction, the spray equipment does not need to be disassembled, and moves to the position near the next section face along with the invert trestle 10, and repeats the above steps to achieve the sedimentation of large dust particles in the tunnel excavation process during the drilling and blasting construction of high-altitude tunnels.

[0089] A water tank 1 with a size of 0.35m*1.6m*1.5m is installed on the platform above the steel frame of the waterproof trolley 9, and is connected to the dust suppressant adding device 3 through a water supply pipe 2. Three sets of dry fog equipment are symmetrically arranged at the first to third horizontal frame positions of the waterproof trolley. The dry fog pipeline 5 is fixed on the side wall steel frame of the waterproof trolley. The dry fog nozzle 6 is arranged at the horizontal frame position of the waterproof trolley. The main control box 7 is installed on the waterproof board stand position on the rear side wall of the waterproof trolley. The air pressure and dust concentration sensor 8 is arranged on the side wall of the tunnel on the return air side in front of the steel frame of the waterproof trolley 9, completing the layout of the integrated dry fog system of the waterproof trolley on the tunnel main tunnel excavation face.

[0090] When one drilling and blasting construction process is completed and the next section is under construction, the spray equipment does not need to be disassembled. It moves with the 9 waterproof trolley steel frame to a position near the next section's face and repeats the above steps to achieve the sedimentation of fine dust during the main tunnel excavation process during the high-altitude tunnel drilling and blasting construction process.

[0091] A mobile high-altitude tunnel excavation intelligent spray dust reduction method comprises the following steps:

[0092] A movable high-altitude tunnel excavation intelligent spray dust reduction system is installed in the tunnel's horizontal guide and main tunnel. There are two groups of movable high-altitude tunnel excavation intelligent spray dust reduction systems. One group is an air-water spray system, which is installed 50m away from the heading and is used to settle large particles of dust; the other group is a dry fog system, which is installed 70m away from the heading and is used to settle fine dust.

[0093] In the tunnel guideway, the spray dust suppression system is arranged in a suspended double-section layout; in the tunnel main tunnel, the air-water spray system is fixed to the air-water spray system, and the dry fog system is arranged on a waterproof trolley.

[0094] Since the cross section of the horizontal guide is small and there are fewer construction machines, the spray system is easy to install and disassemble, so a suspended double-section layout is designed. It is fixed to the side wall and top of the tunnel in a circular direction through 6 anchor bolts to achieve full-section spray dust reduction; since the cross section of the main tunnel is large and there are more construction machines, the spray system is difficult to install and disassemble, so the spray system is installed on the engineering machinery and equipment, and moves with the machinery and equipment to complete the dust source tracking.

[0095] The dynamic charge principle is used to detect particle pollutants in the tunnel online. During the production process, dust particles will generate dust particle charges due to impact, friction and electrostatic induction. Detecting the charge carried by dust particles can detect dust concentration. The maximum measurement range is 0~500mg / m 3 , sensitivity reaches 0.05mg / m 3 . It can effectively monitor dust removal equipment, emissions of particulate pollutants, etc.

[0096] When a large amount of dust is generated during drilling and blasting construction near the tunnel face, the dust concentration sensor 10 installed on the return air side in front of the spray system detects that the dust concentration exceeds the standard, and the data is transmitted to the main control box. The main control box 9 converts the concentration signal into an electrical signal to control the dust suppressant adding device 3 and the air-water spray nozzle 7 to work.

[0097] Set the spraying cycle and sensor signal to control the addition of dust suppressant and the operation of the spray nozzle. Form the logic of spray start and stop according to the needs of the site. Through low-load technology and single-chip integrated circuit technology, a full wireless connection mode with the sensor is realized to reduce installation and maintenance costs. The built-in explosion-proof battery can be circulated for more than one year. The main part of the electric control box is connected to the ball valve, and a high-intensity transmission signal and high-frequency transmission protocol are used, making the system run more stable.

[0098] Control the air-water spray and dry fog operation, monitor the environmental air pressure, temperature and humidity and other parameters in the high-altitude tunnel on-site, combine the theoretical equation of spray droplets and spherical dust particles in high-altitude areas, and clarify the correction of spray dust reduction related parameters in high-altitude areas. Through on-site testing of parameters such as dust dispersion in key dust-producing processes of the drilling and blasting method, match the corresponding optimal droplet dust capture particle size, and adjust the spray air-water pressure according to the optimal droplet dust capture particle size.

[0099] When the current drilling and blasting construction process of the tunnel main tunnel and flat guide is completed and the next construction cycle begins, the flat guide suspension double-section air-water spray-dry fog system is dismantled and deployed in the new construction section. The air-water spray system of the inverted trestle steel frame and the integrated dry fog system of the waterproof trolley move forward with the equipment to achieve dust source following intelligent, precise and efficient spray dust reduction, controlling costs while ensuring the occupational health of operators

[0100] During the construction of the tunnel flat guide, when one process of the drilling and blasting method is completed and the construction work of the next section is carried out, the anchor bolts are removed, the spray pipe steel frame is taken down, and the spray pipe steel frame is re-installed through the anchor bolts to deploy the spray system at the appropriate position in front of the excavation face. Repeat the above steps to achieve intelligent, precise and efficient dust reduction for flat guide excavation during the construction of high-altitude tunnels using the drilling and blasting method.

[0101] During the construction of the main tunnel of the tunnel, when one drilling and blasting process is completed and the construction of the next section is carried out, the spray equipment does not need to be disassembled. It moves with the invert trestle and the waterproof trolley steel frame to a position near the heading of the next section, and repeats the above steps to achieve the sedimentation of large particles of dust during the main tunnel excavation process during the drilling and blasting construction of high-altitude tunnels.

Claims

1. A method for calculating the particle size of spray droplets in a high-altitude tunnel, characterized in that: The steps include: Step 1: Calculate the motion equation of spherical dust particles in the vertical y direction: When a spherical dust particle sinks at a settling velocity, the acceleration Then formula (8) is transformed into: When the spherical dust particles settle at a constant rate, v = v p ; Step 2: According to the formula (11) in step 1, the sedimentation velocity v is obtained. p : Step 3: Calculate the particle size d of the spherical dust particles by using the formula (12) in step 2: p : Step 4: The relationship between the droplet size and the minimum size of the spherical dust particles that can be captured is as follows: Step 5: Calculate the spray droplet diameter D by using the equations (13) and (14) in step 3 and step 4. w The maximum value of: From formula (15), we get: Among them, m p is the mass of spherical dust particles; v y is the velocity of spherical dust particles in the y direction; u y is the velocity of air flow in the y direction; v = (u y -v y );v p is the sedimentation velocity; C D =0.44, resistance coefficient; ρ g is the air density at an altitude of H; η p is the density of spherical dust particles; d min is the minimum particle size of the captured spherical dust particles; μ H is the aerodynamic viscosity; D w is the spray droplet size; S tk is the Stokes number; is the average relative velocity between the spray droplets and the spherical dust particles; d p is the particle size of spherical dust particles; g is the gravity coefficient.

2. The method for calculating the particle size of spray droplets in a high altitude tunnel according to claim 1, characterized in that: The density of air is:

3. The method for calculating the particle size of spray droplets in a high altitude tunnel according to claim 2, characterized in that: The viscosity of air at an altitude of H is: Where: μ0 is the dynamic viscosity of air at 298.15K; B is the gas type constant; T is the temperature at an altitude of 0 meters.

4. The method for calculating the particle size of spray droplets in a high altitude tunnel according to claim 3, characterized in that: Where: G is the gravity of spherical dust particles; F f is the buoyancy of spherical dust particles; F D It is the air resistance exerted on spherical dust particles.

5. The spray dust suppression system in high altitude tunnels is characterized by: The spray particle size obtained in the method for calculating the spray droplet particle size in a high-altitude tunnel according to any one of claims 1 to 4 comprises: an air-water spray pipeline (5), an air-water spray nozzle (7), a main control box (9), an air pressure and dust concentration sensor (10), a dry fog pipeline (11) and a dry fog nozzle (12), wherein: A plurality of the gas-water spray nozzles (7) are arranged at intervals along the length of the gas-water spray pipeline (5); a plurality of the dry fog nozzles (12) are arranged at intervals along the length of the dry fog pipeline (11); the spray outlet of the gas-water spray nozzle (7) is larger than the spray outlet of the dry fog nozzle (12); the gas-water spray nozzle (7) is used for spraying and settling large dust particles; and the dry fog nozzle (12) is used for spraying and settling fine dust. When used in the tunnel excavation process, the air-water spray pipeline (5) and the dry fog pipeline (11) have a shape consistent with the shape of the tunnel cross section and are fixed to the inner wall of the tunnel in a circular shape; and the air-water spray pipeline (5) and the dry fog pipeline (11) are arranged at intervals along the front and back of the tunnel, wherein the front is defined as the one close to the tunnel opening and the rear is defined as the one far from the tunnel excavation surface; a plurality of the air pressure and dust concentration sensors (10) are arranged in the tunnel, and each of the air pressure and dust concentration sensors (10) is connected to the main control box (9); When used in the tunnel excavation process, the air-water spray pipeline (5) is arranged on both sides of the inverted trestle, and a plurality of the air-water spray nozzles (7) are arranged at intervals along the length direction thereof; on the return air side tunnel wall in front of the inverted trestle (10); the dry fog pipeline (11) is arranged on the waterproof trolley side wall steel frame, and a plurality of the dry fog nozzles (12) are arranged at intervals along the length direction thereof; an air pressure and dust concentration sensor (8) is arranged on the return air side tunnel wall in front of the waterproof trolley (9) steel frame; and a main control box (8) is arranged on the tunnel side wall position behind the inverted trestle (10), and each of the air pressure and dust concentration sensors (8) is connected to the main control box (8).

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