Method for calculating droplet size of spray in high-altitude tunnel and spray dust-settling system

Abstract

The application discloses a high-altitude tunnel spraying droplet particle size calculation method and a spraying dust-settling system, which comprises the following steps: step one, calculating a dust particle motion equation of a spherical dust particle in a vertical y direction; step two, according to the formula in the step one, obtaining a settling velocity v p ; step three, obtaining a spherical dust particle size d p ; step four, a relationship between a mist droplet particle size and a minimum particle size of spherical dust particles that can be captured by the mist droplet; and step five, calculating a maximum value of the spraying droplet particle size D w . The high-altitude tunnel spraying droplet particle size calculation method combines theoretical equations of a spraying droplet and dust particles in a high-altitude area, obtains a relationship formula between a mist droplet particle size and a minimum particle size of dust that can be captured by the mist droplet, and determines an inner diameter of a nozzle, so that the spraying droplet in the high-altitude area can effectively capture fine dust.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of tunnel construction dust control, and particularly relates to a high-altitude tunnel internal spraying droplet particle size calculation method and a spraying dust reduction system. BACKGROUND

[0002] The low pressure, high coldness, oxygen deficiency and other harsh environments faced by high-altitude tunnel construction have an impact on the migration law of dust generated in the construction process, increasing the difficulty of tunnel dust and harmful gas control. At present, the spraying dust reduction technology is considered 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 for coal mine tunnels, there are many breakthroughs in the field of dust reduction equipment research and development and parameter optimization.

[0003] In the actual excavation process of the drill-and-blast method tunnel in the high-altitude area, the position of the tunnel dust source changes with the excavation depth, and the high-concentration dust aggregation area moves in the construction process. In order to save costs and meet the actual engineering needs, the spraying equipment needs to be movable. At the same time, due to the low air pressure and air density in the high-altitude tunnel, the spraying water pressure and nozzle atomization characteristics need to be adjusted accordingly to ensure the dust reduction efficiency. Therefore, there is an urgent need for a movable intelligent spraying dust reduction system that can be applied to the high-altitude tunnel internal environment to protect the occupational health of workers in the harsh working conditions on the plateau. SUMMARY

[0004] The purpose of the present application is to provide a high-altitude tunnel internal spraying droplet particle size calculation method and a spraying dust reduction system. The theoretical equation of the spraying droplet and the dust particle in the high-altitude area is combined to determine the correction of the related parameters of the spraying dust reduction in the high-altitude area, and the relationship between the droplet particle size and the minimum particle size of the dust that can be captured is derived. On this basis, the inner diameter of the nozzle is determined to realize the effective capture of the fine dust by the spraying droplet in the high-altitude area.

[0005] The present application adopts the following technical scheme: a high-altitude tunnel internal spraying droplet particle size calculation method, comprising the following steps:

[0006] Step one, the dust particle motion equation of the spherical dust particle in the vertical y direction is calculated as:

[0007]

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

[0009]

[0010] When the spherical dust particle is in the constant speed settling, v=v p ,

[0011] Step two, the settling velocity v is obtained from the formula (11) in step one p :

[0012]

[0013] Step three, the spherical dust particle size d is obtained from the formula (12) in step two p :

[0014]

[0015] Step four, the relationship between the droplet size and the minimum size of the spherical dust particles that can be captured is as follows

[0016]

[0017] Step five, the maximum value of the spray droplet size D is calculated from the formula (13) and formula (14) in step three and step four w :

[0018]

[0019] From formula (15):

[0020]

[0021] Where, m p is the mass of the spherical dust particle; v y is the velocity of the spherical dust particle in the y direction; u y is the flow velocity of the air in the y direction; v = (u y -v y ); v p is the settling velocity; C D = 0.44 is the drag coefficient; ρ g is the air density at an altitude of H; ρ p is the density of the spherical dust particle; d min is the minimum size of the spherical dust particle captured; μ H is the air dynamic viscosity; D w is the spray droplet size; S tk is the Stokes number; is the average relative velocity of the spray droplet and the spherical dust particle; d p is the spherical dust particle size; g is the gravitational coefficient.

[0022] Further, the air density is:

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

[0024]

[0025] wherein: μ0 is the dynamic viscosity of air at 298.15 K; B is a gas species constant; T is the temperature at an altitude of 0 m;

[0026] Further,

[0027] wherein: G is the gravity of the spherical dust particle; F f is the buoyancy of the spherical dust particle; F D is the air gas resistance suffered by the spherical dust particle.

[0028] The application also discloses a high-altitude tunnel internal spraying dust-settling system, which is characterized by the spraying particle size obtained based on the high-altitude tunnel internal spraying liquid droplet particle size calculation method, and comprises an air-water spraying pipeline, an air-water spraying nozzle, a main control box, an air pressure and dust concentration sensor, a dry mist pipeline and a dry mist nozzle.

[0029] A plurality of air-water spraying nozzles are arranged on the air-water spraying pipeline and at intervals along the length direction of the air-water spraying pipeline; a plurality of dry mist nozzles are arranged on the dry mist pipeline and at intervals along the length direction of the dry mist pipeline; the spray outlet of the air-water spraying nozzle is larger than that of the dry mist nozzle, and the air-water spraying nozzle is used for spraying and settling large-particle dust; and the dry mist nozzle is used for spraying and settling fine dust.

[0030] When used in the tunnel flat guide tunneling process, the air-water spraying pipeline and the dry mist pipeline are consistent with the shape of the tunnel transverse section, are fixed on the tunnel inner wall, and are arranged at intervals along the front and back of the tunnel, wherein the front is defined as close to the tunnel opening surface, and the back is defined as far away from the tunnel opening surface; a plurality of air pressure and dust concentration sensors are arranged in the tunnel, and each air pressure and dust concentration sensor is connected with the main control box.

[0031] When used in the tunnel flat guide tunneling process, the air-water spraying pipeline and the dry mist pipeline are consistent with the shape of the tunnel transverse section, are fixed on the tunnel inner wall, and are arranged at intervals along the front and back of the tunnel, wherein the front is defined as close to the tunnel opening surface, and the back is defined as far away from the tunnel opening surface; a plurality of air pressure and dust concentration sensors are arranged in the tunnel, and each air pressure and dust concentration sensor is connected with the main control box.

[0032] The beneficial effects of the present application are: 1. For the environmental parameters of high altitude areas, combined with the theoretical equation of spray droplets and dust particles in high altitude areas, the correction of the related parameters of spray dust reduction in high altitude areas is clear, and the relationship between the droplet size and the minimum particle size of the dust that can be captured is obtained. The minimum particle size of the dust that can be captured is proportional to the droplet size, so the respiratory dust with small capture particle size needs to optimize the spray mode to obtain small particle size droplets. On this basis, the inner diameter of the nozzle is determined to realize the effective capture of fine dust by spray droplets in high altitude areas. 2. The gas-water spray and dry mist two-stage spray system is laid out, the gas-water spray pipeline settles large particle dust, and the dry mist pipeline settles fine dust. The mobile high-altitude tunnel spray dust reduction system of "dust source dust reduction-intelligent dust reduction-obstruction dust capture-prevention of secondary dust raising" realizes accurate and efficient dust reduction based on dust source following technology. 3. In high altitude areas, due to the low air dynamic viscosity, under the condition of the same droplet size, the minimum particle size of the dust captured will decrease, so the spray droplets in high altitude areas have better capture effect on fine dust. BRIEF DESCRIPTION OF DRAWINGS

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

[0034] Figure 2 It is a tunnel straight hole spray dust reduction system-arched bridge;

[0035] Figure 3 It is a tunnel straight hole spray dust reduction system-waterproof trolley.

[0036] Wherein: 1. water tank; 2. water supply pipeline; 3. dust suppressant adding device; 4. gas supply pipeline; 5. gas-water spray pipeline; 6. steel frame; 7. gas-water spray nozzle; 8. anchor bolt; 9. main control box; 10. gas pressure and dust concentration sensor; 11. dry mist pipeline; 12. dry mist nozzle. DETAILED DESCRIPTION

[0037] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0038] The present application provides a method for calculating the droplet size of spray in high altitude tunnels. High altitude refers to an altitude of 4000 meters or more, including the following:

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

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

[0041] The air density in high altitude area is smaller than that in plain area. In addition, the air density is also related to the geological environment, humidity and other factors in the excavation. However, other factors have small weight, and the geological environment, humidity and other factors are ignored, and the following formula is used to calculate the air density at the altitude H:

[0042]

[0043] Wherein: p g is the air density at the altitude H, and the unit is kg / m 3 .

[0044] The greater the dynamic viscosity of air, the greater the force of air acting on the spherical dust particles in the diffusion process. The viscosity of gas increases with the increase of temperature, so the dynamic viscosity of gas in high altitude area is smaller than that in plain area. When the temperature T is less than 2000K, the air viscosity at the altitude H can be calculated by the Sutherland formula:

[0045]

[0046] In the formula: μ0is the dynamic viscosity of air at 298.15K, which is 1.85×10 -5 Pa·s; B is a constant for gas type, and for air, B=110.4K.

[0047] Theoretical analysis of the movement law of spherical dust particles in the tunnel, calculation of the particle size range of spherical dust particles which are difficult to settle, and provision of basis for parameter selection of the spray dust removal nozzle equipment.

[0048] The movement of spherical dust particles causes disturbance of the surrounding medium, i.e. gas, which is manifested as the resistance of gas to the movement of spherical dust particles. As long as there is a certain relative speed between the spherical dust particles and the gas, the gas has resistance to the spherical dust particles, and the air resistance F D is:

[0049]

[0050] In the formula: C D is the resistance coefficient, which is 0.44 because the airflow in the tunnel is turbulent; A p is the cross-sectional area of the spherical dust particles in the wind direction, and the unit is m 2 ; v=(u y -v y ) is the relative speed between the spherical dust particles and the air, and the unit is m / s; p g is the air density, and the unit is kg / m 3 ; d p is the diameter of the spherical dust particles, and the unit is m.

[0051] The dust is subjected to gravity everywhere in the tunnel space, and the gravity direction is vertically downward, which is the main force for the spherical dust particle to settle. The gravity G of the spherical dust particle is:

[0052]

[0053] In the formula, p p is the density of the spherical dust particle, with the unit of kg / m 3 ; and V is the volume of the spherical dust particle, with the unit of m 3 .

[0054] In the process of the spherical dust particle moving in the air, the spherical dust particle is also subjected to the buoyancy of the tunnel air. The buoyancy F f of the spherical dust particle is:

[0055]

[0056] In the formula, p g is the density of the air, with the unit of kg / m 3 .

[0057] During the drilling, shotcreting and slagging processes of the tunnel, the dust uniformly gushes out and floats to various places in the tunnel with the air flow. At the initial stage of the spherical dust particle gushing, the velocity component of the spherical dust particle in a certain direction is often different from the air flow velocity. According to Newton's second law, the dust particle motion equations in the x, y and z directions are obtained as:

[0058]

[0059] In the formula, m p is the mass of the spherical dust particle, kg; v x , v y and v z are the x, y and z direction movement velocities of the spherical dust particle, with the unit of m / s; u x , u y and u z are the x, y and z direction flow velocities of the air flow, with the unit of m / s.

[0060] For the vertical force analysis of the spherical dust particle, the vertical downward velocity of the spherical dust particle is very small at the initial stage of the movement, and the resistance is also very small. During the settling process, the dust particle velocity continuously increases, and the resistance also increases. When the resistance, the buoyancy and the gravity are balanced, the settling velocity of the spherical dust particle reaches the maximum, and the spherical dust particle will settle at a constant speed. At this time, the velocity v of the spherical dust particle is v p , which is the settling velocity of the spherical dust particle. If an upward velocity of the air flow is given, the direction is vertically upward, and the numerical value is equal to v p , then the mass of the spherical dust particle will not fall but float in the air, which is called the suspension velocity, and it is related to vp equal size and opposite direction.

[0061] When the spherical dust particles sink at the settling velocity, the acceleration dv / dt = 0, then formula (9) can be transformed into:

[0062]

[0063] The tunnel environment is a turbulent zone, and C D = 0.44 is substituted into formula (11), v p is:

[0064]

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

[0066]

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

[0068] The droplet size is an important factor affecting the dust suppression effect. Through the design of the coupling experiment of the droplet field and the dust field, the relationship between the droplet size and the minimum particle size of the spherical dust particles it can capture is as follows:

[0069]

[0070] From formula (14) above, the minimum particle size of the spherical dust particles that can be captured by the droplet is proportional to the droplet size, so the respiratory dust that captures the fine spherical dust particles needs to optimize the spraying method to get small droplets. At the same time, due to the low air dynamic viscosity in high altitude areas, under the condition of the same droplet size, the minimum particle size of the spherical dust particles captured will decrease, so the spraying droplets in high altitude areas have better effect on capturing fine dust.

[0071] According to the real-time test results of the air pressure sensor in the tunnel, the air pressure P H , temperature, and the sensor on the temperature T H , the real-time test results of the vertical upward wind speed in the environment directly below the spraying equipment, and the size of v p , the size of the suspended spherical dust particles d p around the spraying equipment is calculated, according to the above calculation results, the particle size range D w of the spraying droplets is calculated, to ensure that the particle size of the suspended spherical dust particles is greater than the minimum particle size of the dust that can be captured by the spraying droplets.

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

[0073]

[0074] From formula (15):

[0075]

[0076] Namely, according to the test results of the air pressure P H , the temperature T H and the vertical upward wind speed in the tunnel, the maximum value of the spray droplet D w is calculated, according to the particle size of the suspended spherical dust particles near the spray of the tunnel, a matching spray head is adjusted, so that the particle size of the spray droplet is below D w , and the accurate and efficient settlement of the suspended spherical dust particles is realized. T is the temperature at an altitude of 0 meters. In the formula: d min is the minimum particle size of the captured spherical dust particles, in meters; μ H is the air dynamic viscosity, in Pa·s; D w is the droplet particle size, in meters; S tk is the dimensionless inertia parameter, the Stokes number; in kg / m 3 ; is the average relative speed of the droplet and the spherical dust particles, in m / s. s p is the settling velocity; C D = 0.44 is the drag coefficient; ρ g is the air density at an altitude of H; ρ p is the density of the spherical dust particles; is the average relative speed of the spray droplet and the spherical dust particles; d p is the particle size of the spherical dust particles; and g is the gravity coefficient.

[0077] The application discloses a movable high-altitude tunneling intelligent spray dust-settling system, which is based on the spray particle size obtained by the spray droplet particle size calculation method in the high-altitude tunnel, and comprises a gas-water spray pipeline 5, a gas-water spray nozzle 7, a main control box 9, a gas pressure and dust concentration sensor 10, a dry mist pipeline 11 and a dry mist nozzle 12.

[0078] A plurality of gas-water spray nozzles 7 are arranged on the gas-water spray pipeline 5 and are spaced apart along the length direction of the gas-water spray pipeline 5; a plurality of dry mist nozzles 12 are arranged on the dry mist pipeline 11 and are spaced apart along the length direction of the dry mist pipeline 11; the spray outlet of the gas-water spray nozzle 7 is larger than that of the dry mist nozzle 12, the gas-water spray nozzle 7 is used for spraying and settling large-particle dust, and the dry mist nozzle 12 is used for spraying and settling fine dust.

[0079] When used in the process of tunneling, as shown in Figure 1 The gas-water spray pipeline 5 and the dry fog pipeline 11 are consistent with the shape of the tunnel cross section, and are fixed on the tunnel inner wall in a surrounding shape. The gas-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 close to the tunnel opening surface, and the back is defined as far from the tunnel opening 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 process of tunneling, the gas-water spray pipeline 5 is arranged on both sides of the inverted arch bridge, and a plurality of gas-water spray nozzles 7 are arranged at intervals along the length of the inverted arch bridge. The air return side of the tunnel side wall is in front of the inverted arch bridge 10. The dry fog pipeline 11 is arranged on the steel frame of the waterproof trolley side wall, and a plurality of dry fog nozzles 12 are arranged at intervals along the length of the dry fog pipeline 11. The air pressure and dust concentration sensor 8 is arranged on the air return side of the tunnel side wall in front of the steel frame of the waterproof trolley 9. The main control box 8 is arranged on the tunnel side wall behind the inverted arch bridge 10, and each air pressure and dust concentration sensor 8 is connected to the main control box 8.

[0081] In the process of tunneling, each gas-water spray pipeline 5 is arranged on the pipeline steel frame 6, and the shape of the pipeline steel frame 6 is consistent with the shape of the tunnel cross section. The pipeline steel frame 6 is fixed on the tunnel inner wall in a surrounding shape, specifically by anchor bolts 6. The water tank 1 is arranged outside the tunnel, and the 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 box body contains dust suppressant concentrate. 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] The main control box 9 is arranged at a position about 70m behind the tunnel face, and the air pressure and dust concentration sensor 10 is arranged on the air return side near the tunnel face.

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

[0085] The dust suppressant concentrate is input into the water supply pipeline 2 for premixing, and is mixed with high-pressure gas in the gas-water spray pipeline 5 and the dry fog pipeline 11. The gas-water spray nozzles 7 and the dry fog nozzles 12 spray out atomized droplets. The gas-water spray nozzles 7 settle large particles of dust, and the dry fog nozzles settle fine dust. When the dust concentration sensor 10 monitors that the dust concentration in the tunnel decreases 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 under construction, the anchor bolts 8 are removed, the spray pipe 6 steel frame is taken down, and the spray pipe steel frame 6 is re-installed in 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 during the drilling and blasting construction of high-altitude tunnels.

[0087] When applied to the tunnel main hole inverted arch trestle, such as Figure 2 and 3 As shown, this system is suitable for the main tunnel section of a drill-and-blast tunnel. A water tank 1, measuring 0.35m x 1.6m x 1.5m, is installed below the guardrail of the inverted arch trestle. The spray nozzle angle is adjusted to ensure that the air-water spray covers the entire tunnel cross-section. A main control box 8 is located on the tunnel sidewall behind the inverted arch trestle 10. An air pressure and dust concentration sensor 9 is located on the return air sidewall in front of the inverted arch trestle 10. This completes the layout of the fixed steel frame air-water spray system for the inverted arch trestle on the tunnel's 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 4mg / 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 the dust concentration in the tunnel and drops to 4mg / m 3 When the following conditions occur, the main control box 8 controls the air-water spray system to stop working. When a drilling and blasting construction process is completed and the next section is constructed, the spray equipment does not need to be disassembled. It moves with the inverted arch trestle 10 to a position near the next section's tunnel face 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.

[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 the 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 return air side tunnel side wall 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 excavation face.

[0090] When the drilling and blasting method construction of a process is completed, the next section of the construction operation is carried out, the spraying equipment does not need to be disassembled, and is moved to the vicinity of the next section of the tunnel face following the 9 waterproof trolley steel frame, and the above steps are repeated to realize the settlement of fine dust in the process of drilling and blasting method construction of high altitude tunnel.

[0091] A movable high-altitude tunnel excavation intelligent spraying dust-settling method, comprising the following steps:

[0092] In the tunnel guide, the movable high-altitude tunnel excavation intelligent spraying dust-settling system is arranged, and the movable high-altitude tunnel excavation intelligent spraying dust-settling system is two groups, wherein one group is a gas-water spraying system arranged at a distance of 50m from the tunnel face for settling large particle dust; the other group is a dry mist system arranged at a distance of 70m from the tunnel face for settling fine dust.

[0093] In the tunnel guide, the spraying dust-settling system is suspended and arranged in two sections; in the tunnel, the gas-water spraying system is fixed to the gas-water spraying system, and the dry mist system is arranged on the waterproof trolley.

[0094] Due to the small section of the guide and the less construction machinery, the spraying system is easy to install and disassemble, and the suspended double-section arrangement is designed. The spraying dust-settling is realized by being fixed in the tunnel side wall and the top end through the anchor bolt 6. Due to the large section of the tunnel and the more construction machinery, the spraying system is difficult to install and disassemble, so the spraying system is arranged on the engineering machinery equipment and moves with the machinery equipment to complete the dust source following.

[0095] The dynamic charge principle is adopted to detect the particle pollutants in the tunnel online. The dust particles will generate dust particle charges due to impact, friction and electrostatic induction in the production process. The dust concentration can be detected by detecting the charge amount of the dust particles. The maximum measurement range is 0-500mg / m 3 , and the sensitivity reaches 0.05mg / m 3 . The dust-settling equipment and the discharge of particle pollutants can be effectively monitored.

[0096] When the drilling and blasting method construction near the tunnel face produces a large amount of dust, the dust concentration sensor 10 arranged in front of the spraying system on the air return side 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-settling agent adding device 3 and the gas-water spraying nozzle 7 to work.

[0097] The spray cycle and sensor signal are set to control the dust suppressant addition and spray nozzle operation. The spray start-stop logic is formed according to the site needs. Through low-load technology and single-chip integrated circuit technology, a full wireless connection mode with the sensor is realized, the installation and maintenance costs are reduced, the self-provided explosion-proof battery can work for more than one year, the main part of the electric control box is connected with the ball valve, the high-strength transmission signal high-frequency transmission protocol is used, and the system operation is more stable.

[0098] The gas-water spray and dry mist work are controlled, the environmental air pressure, temperature and humidity parameters are monitored on the high-altitude tunnel site, the high-altitude region spray droplet and spherical dust particle theoretical equation is combined, and the high-altitude region spray dust related parameter correction is clear. Through on-site testing of dust dispersion degree and other parameters of key dust production process of drill and blast method, the corresponding optimal mist droplet dust capture particle size is matched, and the spray gas-water pressure is adjusted according to the optimal mist droplet dust capture particle size.

[0099] When the current drill and blast method construction process of the tunnel main tunnel and flat guide is finished, the flat guide suspension type double-section gas-water spray-dry mist system is disassembled, laid in the new construction section, and the inverted arch trestle steel gas-water spray system and waterproof trolley integrated dry mist system are moved forward with the equipment, realizing dust source following type intelligent precise and efficient spray dust reduction, controlling the cost and protecting the occupational health of the operating personnel

[0100] During the construction process of the tunnel flat guide, when the drill and blast method one process is finished, the spray pipeline steel frame is disassembled, and the spray pipeline steel frame is laid in the front of the heading face by anchoring the spray pipeline steel frame with the spray pipeline steel frame, and the above steps are repeated, realizing intelligent precise and efficient dust reduction of the flat guide heading in the drill and blast method construction process of the high-altitude tunnel.

[0101] During the construction process of the tunnel main tunnel, when the drill and blast method one process is finished, the spray equipment does not need to be disassembled, and is moved to the vicinity of the next section of the heading face with the inverted arch trestle and waterproof trolley steel frame, and the above steps are repeated, realizing the settlement of large particle dust in the main tunnel heading process in the drill and blast method construction process of the high-altitude tunnel.

Claims

1. A method for calculating the droplet size of a spray in a high altitude tunnel, characterized in that, The method comprises the following steps: Step one, the dust particle motion equation of spherical dust particles in the vertical y direction is calculated as: （9）； Acceleration of a spherical dust particle when sinking with a settling velocity = 0, then equation (9) transforms into: （11）； At the isokinetic settling of the spherical dust particles, ; Step two, obtain the sedimentation velocity according to the formula (11) in the step one : （12）； Step three, the particle size of spherical dust particles is obtained from the formula (12) in step two : （13）； Step 4: Spray droplet size The minimum particle size d of the spherical dust particles it can capture min The relationship between them is as follows: （14）； Step five, calculate the spray droplet size from the formula (13) and formula (14) in step three and step four The maximum value of: （15）； From equation (15), we have: （16）； in, is the mass of spherical dust particles; v y is the y-direction moving speed of spherical dust particles; u y is the air flow velocity in the y direction; = ; is the sedimentation velocity; , is the drag coefficient; is the air density at an altitude of H; is the density of spherical dust particles; is the minimum particle size of the captured spherical dust particles; The altitude is H Dynamic viscosity of air at ; is the spray droplet size; is the Stokes number; is the average relative velocity between the spray droplets and the spherical dust particles; Spherical dust particle size; is the acceleration due to gravity.

2. The method of claim 1, wherein the method is used for calculating the droplet size of a spray in a high altitude tunnel. The air density is: (2); the air pressure at an altitude of H , and the temperature at an altitude of H .

3. The method of claim 2, wherein the method is used for calculating the droplet size of a spray in a high-altitude tunnel. The altitude is The air dynamic viscosity at the location is: （3）； wherein: is the dynamic viscosity of air at 298.15 K; B is a gas species constant; is the temperature at sea level 0 m.

4. The method of claim 3, wherein the method is used for calculating the droplet size of a spray in a high-altitude tunnel. ； where: Fg is the gravitational force of the spherical dust particle; f Fb is the buoyant force of the spherical dust particle; Fa is the air gas resistance experienced by the spherical dust particle.

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